Cherenkov and scintillation light separation in organic liquid scintillators

NASA Astrophysics Data System (ADS)

Caravaca, J.; Descamps, F. B.; Land, B. J.; Yeh, M.; Orebi Gann, G. D.

2017-12-01

The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3 % and 63± 8% for time- and charge-based separation, respectively, with scintillation contamination of 36± 5% and 38± 4%. LAB/PPO data is consistent with a rise time of τ _r=0.72± 0.33 ns.

Looking inside volcanoes with the Imaging Atmospheric Cherenkov Telescopes

NASA Astrophysics Data System (ADS)

Del Santo, M.; Catalano, O.; Cusumano, G.; La Parola, V.; La Rosa, G.; Maccarone, M. C.; Mineo, T.; Sottile, G.; Carbone, D.; Zuccarello, L.; Pareschi, G.; Vercellone, S.

2017-12-01

Cherenkov light is emitted when charged particles travel through a dielectric medium with velocity higher than the speed of light in the medium. The ground-based Imaging Atmospheric Cherenkov Telescopes (IACT), dedicated to the very-high energy γ-ray Astrophysics, are based on the detection of the Cherenkov light produced by relativistic charged particles in a shower induced by TeV photons interacting with the Earth atmosphere. Usually, an IACT consists of a large segmented mirror which reflects the Cherenkov light onto an array of sensors, placed at the focal plane, equipped by fast electronics. Cherenkov light from muons is imaged by an IACT as a ring, when muon hits the mirror, or as an arc when the impact point is outside the mirror. The Cherenkov ring pattern contains information necessary to assess both direction and energy of the incident muon. Taking advantage of the muon detection capability of IACTs, we present a new application of the Cherenkov technique that can be used to perform the muon radiography of volcanoes. The quantitative understanding of the inner structure of a volcano is a key-point to monitor the stages of the volcano activity, to forecast the next eruptive style and, eventually, to mitigate volcanic hazards. Muon radiography shares the same principle as X-ray radiography: muons are attenuated by higher density regions inside the target so that, by measuring the differential attenuation of the muon flux along different directions, it is possible to determine the density distribution of the interior of a volcano. To date, muon imaging of volcanic structures has been mainly achieved with detectors made up of scintillator planes. The advantage of using Cherenkov telescopes is that they are negligibly affected by background noise and allow a consistently improved spatial resolution when compared to the majority of the current detectors.

Separation of scintillation and Cherenkov lights in linear alkyl benzene

DOE PAGES

Li, Mohan; Guo, Ziyi; Yeh, Minfang; ...

2016-09-11

To separate scintillation and Cherenkov lights in water-based liquid scintillator detectors is a desired feature for future neutrino and proton decay experiments. Linear alkyl benzene (LAB) is one important ingredient of a water-based liquid scintillator currently under development. In this paper we report on the separation of scintillation and Cherenkov lights observed in an LAB sample. The rise and decay times of the scintillation light are measured to be (7.7±3.0)ns and (36.6±2.4)ns, respectively, while the full width [–3σ, 3σ] of the Cherenkov light is 12 ns and is dominated by the time resolution of the photomultiplier tubes. Here, the scintillationmore » light yield was measured to be (1.01±0.12)×103photons/MeV.« less

Cherenkov and scintillation light separation in organic liquid scintillators

DOE PAGES

Caravaca, J.; Descamps, F. B.; Land, B. J.; ...

2017-11-29

The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338 ± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3 % and 63 ± 8 % for time- and charge-based separation, respectively, with scintillation contamination of 36 ± 5 % andmore » 38 ± 4 %. LAB/PPO data is consistent with a rise time of τ r = 0.72 ± 0.33 ns.« less

Cherenkov and scintillation light separation in organic liquid scintillators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caravaca, J.; Descamps, F. B.; Land, B. J.

The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338 ± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3 % and 63 ± 8 % for time- and charge-based separation, respectively, with scintillation contamination of 36 ± 5 % andmore » 38 ± 4 %. LAB/PPO data is consistent with a rise time of τ r = 0.72 ± 0.33 ns.« less

Optical dosimetry of radiotherapy beams using Cherenkov radiation: the relationship between light emission and dose.

PubMed

Glaser, Adam K; Zhang, Rongxiao; Gladstone, David J; Pogue, Brian W

2014-07-21

Recent studies have proposed that light emitted by the Cherenkov effect may be used for a number of radiation therapy dosimetry applications. There is a correlation between the captured light and expected dose under certain conditions, yet discrepancies have also been observed and a complete examination of the theoretical differences has not been done. In this study, a fundamental comparison between the Cherenkov emission and absorbed dose was explored for x-ray photons, electrons, and protons using both a theoretical and Monte Carlo-based analysis. Based on the findings of where dose correlates with Cherenkov emission, it was concluded that for x-ray photons the light emission would be optimally suited for narrow beam stereotactic radiation therapy and surgery validation studies, for verification of dynamic intensity-modulated and volumetric modulated arc therapy treatment plans in water tanks, near monoenergetic sources (e.g., Co-60 and brachy therapy sources) and also for entrance and exit surface imaging dosimetry of both narrow and broad beams. For electron use, Cherenkov emission was found to be only suitable for surface dosimetry applications. Finally, for proton dosimetry, there exists a fundamental lack of Cherenkov emission at the Bragg peak, making the technique of little use, although post-irradiation detection of light emission from radioisotopes could prove to be useful.

Cherenkov imaging and biochemical sensing in vivo during radiation therapy

NASA Astrophysics Data System (ADS)

Zhang, Rongxiao

While Cherenkov emission was discovered more than eighty years ago, the potential applications of imaging this during radiation therapy have just recently been explored. With approximately half of all cancer patients being treated by radiation at some point during their cancer management, there is a constant challenge to ensure optimal treatment efficiency is achieved with maximal tumor to normal tissue therapeutic ratio. To achieve this, the treatment process as well as biological information affecting the treatment should ideally be effective and directly derived from the delivery of radiation to the patient. The value of Cherenkov emission imaging was examined here, primarily for visualization of treatment monitoring and then secondarily for Cherenkov-excited luminescence for tissue biochemical sensing within tissue. Through synchronized gating to the short radiation pulses of a linear accelerator (200Hz & 3 micros pulses), and applying a gated intensified camera for imaging, the Cherenkov radiation can be captured near video frame rates (30 frame per sec) with dim ambient room lighting. This procedure, sometimes termed Cherenkoscopy, is readily visualized without affecting the normal process of external beam radiation therapy. With simulation, phantoms and clinical trial data, each application of Cherenkoscopy was examined: i) for treatment monitoring, ii) for patient position monitoring and motion tracking, and iii) for superficial dose imaging. The temporal dynamics of delivered radiation fields can easily be directly imaged on the patient's surface. Image registration and edge detection of Cherenkov images were used to verify patient positioning during treatment. Inter-fraction setup accuracy and intra-fraction patient motion was detectable to better than 1 mm accuracy. Cherenkov emission in tissue opens up a new field of biochemical sensing within the tissue environment, using luminescent agents which can be activated by this light. In the first study of its kind with external beam irradiation, a dendritic platinum-based phosphor (PtG4) was used at micro-molar concentrations (~5 microM) to generate Cherenkov-induced luminescent signals, which are sensitive to the partial pressure of oxygen. Both tomographic reconstruction methods and linear scanned imaging were investigated here to examine the limits of detection. Recovery of optical molecular distributions was shown in tissue phantoms and small animals, with high accuracy (~1 microM), high spatial resolution (~0.2 mm) and deep-tissue detectability (~2 cm for Cherenkov luminescence scanned imaging (CELSI)), indicating potentials for in vivo and clinical use. In summary, many of the physical and technological details of Cherenkov imaging and Cherenkov-excited emission imaging were specified in this study.

Light concentrator of the wide field of view Cherenkov telescope

NASA Astrophysics Data System (ADS)

Yang, Rui; Sheng, Xi Yi; Liao, Bo Lin

2016-10-01

The Wide Field of View Cherenkov Telescope (WFCT) is mainly constituted by optical reflector and focal-plane photomultiplier (PMT) array camera. In order to avoid loss of Cherenkov signal resulting from the dead area between circular PMT tubes and invalid fringe of each PMT, the light concentrator used as front window of PMT is considered to improve detective efficiency. Basing on the edge-ray principle and features of WFCT, several light concentrators are designed and simulated with ZEMAX. The result shows that the hollow hexahedral compound parabolic concentrator (hex-CPC) has good performance in collecting light. Moreover, the samples of the hollow hexahedral CPC have been manufactured and tested.

Cherenkov radiation of superluminal particles

NASA Astrophysics Data System (ADS)

Rohrlich, Daniel; Aharonov, Yakir

2002-10-01

Any charged particle moving faster than light through a medium emits Cherenkov radiation. We show that charged particles moving faster than light through the vacuum emit Cherenkov radiation. How can a particle move faster than light? The weak speed of a charged particle can exceed the speed of light. By definition, the weak velocity w is <Ψfin|v|Ψin>/<Ψfin|Ψin>, where v is the velocity operator and |Ψin> and |Ψfin> are, respectively, the states of a particle before and after a velocity measurement. We discuss the consistency of weak values and show that superluminal weak speed is consistent with relativistic causality.

Cherenkov and scintillation light separation on the CheSS experiment

NASA Astrophysics Data System (ADS)

Caravaca, Javier; Land, Benjamin; Descamps, Freija; Orebi Gann, Gabriel D.

2016-09-01

Separation of the scintillation and Cherenkov light produced in liquid scintillators enables outstanding capabilities for future particle detectors, the most relevant being: particle directionality information in a low energy threshold detector and improved particle identification. The CheSS experiment uses an array of small, fast photomultipliers (PMTs) and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in liquid scintillator using two techniques: based on the photon density and using the photon hit time information. A charged particle ionizing a scintillation medium produces a prompt Cherenkov cone and late isotropic scintillation light, typically delayed by several ns. The fast response of our PMTs and DAQ provides a precision well below the ns level, making possible the time separation. Furthermore, the usage of the new developed water-based liquid scintillators (WbLS) enhances the separation since it allows tuning of the Cherenkov/Scintillation ratio. Latest results on the separation for pure liquid scintillators and WbLS will be presented.

Wavelet imaging cleaning method for atmospheric Cherenkov telescopes

NASA Astrophysics Data System (ADS)

Lessard, R. W.; Cayón, L.; Sembroski, G. H.; Gaidos, J. A.

2002-07-01

We present a new method of image cleaning for imaging atmospheric Cherenkov telescopes. The method is based on the utilization of wavelets to identify noise pixels in images of gamma-ray and hadronic induced air showers. This method selects more signal pixels with Cherenkov photons than traditional image processing techniques. In addition, the method is equally efficient at rejecting pixels with noise alone. The inclusion of more signal pixels in an image of an air shower allows for a more accurate reconstruction, especially at lower gamma-ray energies that produce low levels of light. We present the results of Monte Carlo simulations of gamma-ray and hadronic air showers which show improved angular resolution using this cleaning procedure. Data from the Whipple Observatory's 10-m telescope are utilized to show the efficacy of the method for extracting a gamma-ray signal from the background of hadronic generated images.

Photodetectors for the Advanced Gamma-ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Wagner, Robert G.; Advanced Gamma-ray Imaging System AGIS Collaboration

2010-03-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation very high energy gamma-ray observatory. Design goals include an order of magnitude better sensitivity, better angular resolution, and a lower energy threshold than existing Cherenkov telescopes. Each telescope is equipped with a camera that detects and records the Cherenkov-light flashes from air showers. The camera is comprised of a pixelated focal plane of blue sensitive and fast (nanosecond) photon detectors that detect the photon signal and convert it into an electrical one. Given the scale of AGIS, the camera must be reliable and cost effective. The Schwarzschild-Couder optical design yields a smaller plate scale than present-day Cherenkov telescopes, enabling the use of more compact, multi-pixel devices, including multianode photomultipliers or Geiger avalanche photodiodes. We present the conceptual design of the focal plane for the camera and results from testing candidate! focal plane sensors.

Prototyping hexagonal light concentrators using high-reflectance specular films for the Large-Sized Telescopes of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Okumura, A.; Dang, T. V.; Ono, S.; Tanaka, S.; Hayashida, M.; Hinton, J.; Katagiri, H.; Noda, K.; Teshima, M.; Yamamoto, T.; Yoshida, T.

2017-12-01

We have developed a prototype hexagonal light concentrator for the Large-Sized Telescopes of the Cherenkov Telescope Array. To maximize the photodetection efficiency of the focal-plane camera pixels for atmospheric Cherenkov photons and to lower the energy threshold, a specular film with a very high reflectance of 92-99% has been developed to cover the inner surfaces of the light concentrators. The prototype has a relative anode sensitivity (which can be roughly regarded as collection efficiency) of about 95 to 105% at the most important angles of incidence. The design, simulation, production procedure, and performance measurements of the light-concentrator prototype are reported.

Characterizing Scintillation and Cherenkov Light in Water-Based Liquid Scintillators

NASA Astrophysics Data System (ADS)

Land, Benjamin; Caravaca, Javier; Descamps, Freija; Orebi Gann, Gabriel

2016-09-01

The recent development of Water-based Liquid Scintillator (WbLS) has made it possible to produce scintillating materials with highly tunable light yields and excellent optical clarity. This allows for a straightforward combination of the directional properties of Cherenkov light with the greater energy resolution afforded by the typically brighter scintillation light which lends itself well to a broad program of neutrino physics. Here we explore the light yields and time profiles of WbLS materials in development for Theia (formerly ASDC) as measured in CheSS: our bench-top Cherenkov and scintillation separation R&D project at Berkeley Lab. This work was supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02-05CH11231.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Mohan; Guo, Ziyi; Yeh, Minfang

To separate scintillation and Cherenkov lights in water-based liquid scintillator detectors is a desired feature for future neutrino and proton decay experiments. Linear alkyl benzene (LAB) is one important ingredient of a water-based liquid scintillator currently under development. In this paper we report on the separation of scintillation and Cherenkov lights observed in an LAB sample. The rise and decay times of the scintillation light are measured to be (7.7±3.0)ns and (36.6±2.4)ns, respectively, while the full width [–3σ, 3σ] of the Cherenkov light is 12 ns and is dominated by the time resolution of the photomultiplier tubes. Here, the scintillationmore » light yield was measured to be (1.01±0.12)×103photons/MeV.« less

Gamma bang time/reaction history diagnostics for the National Ignition Facility using 90 degrees off-axis parabolic mirrors.

PubMed

Malone, R M; Herrmann, H W; Stoeffl, W; Mack, J M; Young, C S

2008-10-01

Gas Cherenkov detectors (GCDs) have been used to convert fusion gamma into photons to achieve gamma bang time and reaction history measurements. The GCDs designed for OMEGA used Cassegrain reflector optics in order to fit inside a 10 in. manipulator. A novel design for the National Ignition Facility using 90 degrees off-axis parabolic mirrors will increase light collection efficiency from fusion gammas and achieve minimum time dispersion. The broadband Cherenkov light (from 200 to 800 nm) is relayed into a high-speed detector using three parabolic mirrors. Because light is collected from many source planes throughout the CO(2) gas volume, the detector is positioned at the stop position rather than at an image position. The stop diameter and its position are independent of the light-generation location along the gas cell. The current design collects light from a 100 mm diameter by 500 mm long gas volume. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they fly through the CO(2) gas volume. A cluster of four channels will allow for increased dynamic range as well as for different gamma energy threshold sensitivities.

NICHE: Non-Imaging Cherenkov Light Observation at the TA Site

NASA Astrophysics Data System (ADS)

Tsunesada, Yoshiki; Omura, Yugo; Shin, BokKyun; Bergman, Douglas R.; Krizmanic, John F.; Nonaka, Toshiyuki

The Non-Imaging CHErenkov Array (NICHE) is a low energy extension to the Telescope Array and TALE using an array of closely spaced (70-100 m) light collectors covering an area of up to a square km. The target is cosmic rays with energies above the knee, including the "transition region" above which Galactic cosmic rays are no more confined by the galactic magnetic field. It will be deployed in the field of view of TALE and will overlap it in energy range. TALE can observe events in the energy range 3-30 PeV by non-imaging air-Cherenkov, so NICHE and TALE will observe imaging/non-imaging Cherenkov hybrid events. NICHE itself will use both the Cherenkov lateral distribution and the Cherenkov time-width lateral distribution in measuring air showers. These two methods will allow shower energy and Xmax to be determined to infer primary types of cosmic nuclei. A prototype of the array with 15 counters, called j-NICHE, is currently being built. We describe the design of the experiment and the status of the detector development.

Video-rate optical dosimetry and dynamic visualization of IMRT and VMAT treatment plans in water using Cherenkov radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glaser, Adam K., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu; Andreozzi, Jacqueline M.; Davis, Scott C.

Purpose: A novel technique for optical dosimetry of dynamic intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans was investigated for the first time by capturing images of the induced Cherenkov radiation in water. Methods: A high-sensitivity, intensified CCD camera (ICCD) was configured to acquire a two-dimensional (2D) projection image of the Cherenkov radiation induced by IMRT and VMAT plans, based on the Task Group 119 (TG-119) C-Shape geometry. Plans were generated using the Varian Eclipse treatment planning system (TPS) and delivered using 6 MV x-rays from a Varian TrueBeam Linear Accelerator (Linac) incident on a water tank dopedmore » with the fluorophore quinine sulfate. The ICCD acquisition was gated to the Linac target trigger pulse to reduce background light artifacts, read out for a single radiation pulse, and binned to a resolution of 512 × 512 pixels. The resulting videos were analyzed temporally for various regions of interest (ROI) covering the planning target volume (PTV) and organ at risk (OAR), and summed to obtain an overall light intensity distribution, which was compared to the expected dose distribution from the TPS using a gamma-index analysis. Results: The chosen camera settings resulted in 23.5 frames per second dosimetry videos. Temporal intensity plots of the PTV and OAR ROIs confirmed the preferential delivery of dose to the PTV versus the OAR, and the gamma analysis yielded 95.9% and 96.2% agreement between the experimentally captured Cherenkov light distribution and expected TPS dose distribution based upon a 3%/3 mm dose difference and distance-to-agreement criterion for the IMRT and VMAT plans, respectively. Conclusions: The results from this initial study demonstrate the first documented use of Cherenkov radiation for video-rate optical dosimetry of dynamic IMRT and VMAT treatment plans. The proposed modality has several potential advantages over alternative methods including the real-time nature of the acquisition, and upon future refinement may prove to be a robust and novel dosimetry method with both research and clinical applications.« less

Monte Carlo study of the coincidence resolving time of a liquid xenon PET scanner, using Cherenkov radiation

NASA Astrophysics Data System (ADS)

Gomez-Cadenas, J. J.; Benlloch-Rodríguez, J. M.; Ferrario, P.

2017-08-01

In this paper we use detailed Monte Carlo simulations to demonstrate that liquid xenon (LXe) can be used to build a Cherenkov-based TOF-PET, with an intrinsic coincidence resolving time (CRT) in the vicinity of 10 ps. This extraordinary performance is due to three facts: a) the abundant emission of Cherenkov photons by liquid xenon; b) the fact that LXe is transparent to Cherenkov light; and c) the fact that the fastest photons in LXe have wavelengths higher than 300 nm, therefore making it possible to separate the detection of scintillation and Cherenkov light. The CRT in a Cherenkov LXe TOF-PET detector is, therefore, dominated by the resolution (time jitter) introduced by the photosensors and the electronics. However, we show that for sufficiently fast photosensors (e.g, an overall 40 ps jitter, which can be achieved by current micro-channel plate photomultipliers) the overall CRT varies between 30 and 55 ps, depending on the detection efficiency. This is still one order of magnitude better than commercial CRT devices and improves by a factor 3 the best CRT obtained with small laboratory prototypes.

Fast, Large-Area, Wide-Bandgap UV Photodetector for Cherenkov Light Detection

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Wrbanek, Susan Y.

2013-01-01

Due to limited resources available for power and space for payloads, miniaturizing and integrating instrumentation is a high priority for addressing the challenges of manned and unmanned deep space missions to high Earth orbit (HEO), near Earth objects (NEOs), Lunar and Martian orbits and surfaces, and outer planetary systems, as well as improvements to high-altitude aircraft safety. New, robust, and compact detectors allow future instrumentation packages more options in satisfying specific mission goals. A solid-state ultraviolet (UV) detector was developed with a theoretical fast response time and large detection area intended for application to Cherenkov detectors. The detector is based on the wide-bandgap semiconductor zinc oxide (ZnO), which in a bridge circuit can detect small, fast pulses of UV light like those required for Cherenkov detectors. The goal is to replace the role of photomultiplier tubes in Cherenkov detectors with these solid-state devices, saving on size, weight, and required power. For improving detection geometry, a spherical detector to measure high atomic number and energy (HZE) ions from any direction has been patented as part of a larger space radiation detector system. The detector will require the development of solid-state UV photodetectors fast enough (2 ns response time or better) to detect the shockwave of Cherenkov light emitted as the ions pass through a quartz, sapphire, or acrylic ball. The detector must be small enough to fit in the detector system structure, but have an active area large enough to capture enough Cherenkov light from the sphere. The detector is fabricated on bulk single-crystal undoped ZnO. Inter - digitated finger electrodes and contact pads are patterned via photolithography, and formed by sputtered metal of silver, platinum, or other high-conductivity metal.

The Development of Atmospheric Cherenkov Detectors at Milagro to Measure Cosmic-Ray Composition

NASA Astrophysics Data System (ADS)

Atkins, Robert; Dingus, Brenda; Benbow, Wystan; Coyne, Don; Kelley, Linda; Williams, David; Goodman, Jordan; Haines, Todd; Hoffman, Cyrus; Samuelson, Frank; Sinnis, Gus; McEnery, Julie; Mohanty, Gora; Stephens, Tom; Stochaj, Steve; Tumer, Tumay; Yodh, Gaurang

2002-04-01

Cosmic-ray composition in the region of the knee is being measured with the array of wide angle Cherenkov telescopes (WACT). WACT consists of six atmospheric Cherenkov telescopes (ACTs) located around the Milagro experiment. WACT is at an atmospheric depth of 750 g/cm^2 and is located 40 miles west of Los Alamos National Lab. WACT measures composition by examining the lateral distribution of Cherenkov light produced by cosmic-ray induced extensive air showers. Simulation and preliminary data analysis from the winter 2001/2002 observing campaign will be presented.

Light-weight spherical mirrors for Cherenkov detectors

NASA Astrophysics Data System (ADS)

Cisbani, E.; Colilli, S.; Crateri, R.; Cusanno, F.; Fratoni, R.; Frullani, S.; Garibaldi, F.; Giuliani, F.; Gricia, M.; Iodice, M.; Iommi, R.; Lucentini, M.; Mostarda, A.; Pierangeli, L.; Santavenere, F.; Urciuoli, G. M.; De Leo, R.; Lagamba, L.; Nappi, E.; Braem, A.; Vernin, P.

2003-01-01

Light-weight spherical mirrors have been appositely designed and built for the gas threshold Cherenkov detectors of the two Hall A spectrometers. The mirrors are made of a 1 mm thick aluminized plexiglass sheet, reinforced by a rigid backing consisting of a phenolic honeycomb sandwiched between two carbon fiber mats epoxy glued. The produced mirrors have a thickness equivalent to 0.55% of radiation length, and an optical slope error of about 5.5 mrad. These characteristics make these mirrors suitable for the implementation in Cherenkov threshold detectors. Ways to improve the mirror features are also discussed in view of their possible employment in RICH detectors.

Characterizing Scitillation and Cherenkov Light Yield in Water-Based Liquid Scintillators

NASA Astrophysics Data System (ADS)

Land, B. J.; Caravaca, J.; Descamps, F. B.; Orebi Gann, G. D.

2016-03-01

The recent development of Water-based Liquid Scintillator (WbLS) has made it possible to produce scintillating materials with highly tunable light yields and excellent optical clarity. This allows for a straightforward combination of the directional properties of Cherenkov light with the greater energy resolution afforded by the typically brighter scintillation light, which lends itself well to a broad program of neutrino physics. Here we explore the light yields and optical properties of WbLS materials in development for Theia (formerly ASDC) as measured in our benchtop Theia R&D at Berkeley Lab and extrapolate to larger detectors.

Design of light concentrators for Cherenkov telescope observatories

NASA Astrophysics Data System (ADS)

Hénault, François; Petrucci, Pierre-Olivier; Jocou, Laurent; Khélifi, Bruno; Manigot, Pascal; Hormigos, Stéphane; Knödlseder, Jürgen; Olive, Jean-François; Jean, Pierre; Punch, Michael

2013-09-01

The Cherenkov Telescope Array (CTA) will be the largest cosmic gamma ray detector ever built in the world. It will be installed at two different sites in the North and South hemispheres and should be operational for about 30 years. In order to cover the desired energy range, the CTA is composed of typically 50-100 collecting telescopes of various sizes (from 6 to 24-m diameters). Most of them are equipped with a focal plane camera consisting of 1500 to 2000 Photomultipliers (PM) equipped with light concentrating optics, whose double function is to maximize the amount of Cherenkov light detected by the photo-sensors, and to block any stray light originating from the terrestrial environment. Two different optical solutions have been designed, respectively based on a Compound Parabolic Concentrator (CPC), and on a purely dioptric concentrating lens. In this communication are described the technical specifications, optical designs and performance of the different solutions envisioned for all these light concentrators. The current status of their prototyping activities is also given.

SU-F-T-166: On the Nature of the Background Visible Light Observed in Fiber Optic Dosimetry of Proton Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darafsheh, A; Kassaee, A; Finlay, J

Purpose: The nature of the background visible light observed during fiber optic dosimetry of proton beams, whether it is due to Cherenkov radiation or not, has been debated in the literature recently. In this work, experimentally and by means of Monte Carlo simulations, we shed light on this problem and investigated the nature of the background visible light observed in fiber optics irradiated with proton beams. Methods: A bare silica fiber optics was embedded in tissue-mimicking phantoms and irradiated with clinical proton beams with energies of 100–225 MeV at Roberts Proton Therapy Center. Luminescence spectroscopy was performed by a CCD-coupledmore » spectrograph to analyze in detail the emission spectrum of the fiber tip across the visible range of 400–700 nm. Monte Carlo simulation was performed by using FLUKA Monte Carlo code to simulate Cherenkov light and ionizing radiation dose deposition in the fiber. Results: The experimental spectra of the irradiated silica fiber shows two distinct peaks at 450 and 650 nm, whose spectral shape is different from that of Cherenkov radiation. We believe that the nature of these peaks are connected to the point defects of silica including oxygen-deficiency center (ODC) and non-bridging oxygen hole center (NBOHC). Monte Carlo simulations confirmed the experimental observations that Cherenkov radiation cannot be solely responsible for such a signal. Conclusion: We showed that Cherenkov radiation is not the dominant visible signal observed in bare fiber optics irradiated with proton beams. We observed two distinct peaks at 450 and 650 nm whose nature is connected with the point defects of silica fiber including oxygen-deficiency center and non-bridging oxygen hole center.« less

The CLAS12-RICH hybrid geometry

NASA Astrophysics Data System (ADS)

Angelini, Giovanni; CLAS12-RICH Collaboration

2017-01-01

A Ring-imaging Cherenkov detector (RICH) has been designed for the CLAS12 spectrometer (JLAB, Hall B) in order to increase the particle identification. Among the approved physics program focused upon 3D imaging of the nucleon, some Semi Inclusive Deep Inelastic Scattering experiments (E12-09-007, E12-09-008, E12-09-009) demand an efficient kaon identification across the momentum range from 3 to 8 GeV/c. The detector exploits a novel elaborated hybrid geometry based on a complex focusing mirror system that will reduce the area instrumented with photon detectors. For forward scattered particles (θ <12°) with momenta p = 3-8 GeV/c, a proximity imaging method with direct Cherenkov light detection will be used. For larger angles of 12° < θ <35° and momenta of p = 3-6 GeV/c, the Cherenkov light will be focused by a spherical mirror, undergo two further passes through the aerogel radiator and will be reflected from planar mirrors before detection. A carefully study on reflections has been performed considering microscopic and macroscopic effects. In addition, a new feature has been introduced in the CLAS12 simulation software in order to generate the geometry of the detector by using a computer-aided design (CAD) file for an accurate geometrical description. U.S. Department of Energy, GWU Columbian College Art and Science Facilitating Fund Award (CCAS CCFF).

Cherenkov light imaging tests with state-of-the-art solid state photon counter for the CLAS12 RICH detector

NASA Astrophysics Data System (ADS)

Balossino, Ilaria; Barion, L.; Contalbrigo, M.; Lenisa, P.; Lucherini, V.; Malaguti, R.; Mirazita, M.; Movsisyan, A.; Squerzanti, S.; Turisini, M.

2017-12-01

A large area ring-imaging Cherenkov detector will be operated for hadron identification in the 3 GeV / c to 8 GeV / c momentum range at the CLAS12 experiment at the upgraded continuous electron beam accelerator facility of Jefferson Lab. The detector, consisting of aerogel radiator, composite mirrors and photon counters, will be built with a hybrid optics design to allow the detection of Cherenkov light for both forward and large angle hadron tracks. The active area has to be densely packed and highly segmented, covering about 1m2 with pixels of 6mm2 , and to allow a time resolution of 1 ns. A technology that can offer a cost-effective solution and low material budget could be Silicon Photomultipliers (SiPM) thanks to their high gain at low bias voltage, fast timing, good single-photoelectron resolution and insensitivity to magnetic fields. An investigation is ongoing on samples of 3 × 3mm2 SiPM of different micro-cell size to assess the single photon detection capability in the presence of high dark count rate due to thermal generation effects, after-pulses or optical cross-talk and to study the response to the moderate radiation damage expected at CLAS12. In this work, a brief review of the latest and most interesting results from these studies will be shown.

The Topo-trigger: a new concept of stereo trigger system for imaging atmospheric Cherenkov telescopes

NASA Astrophysics Data System (ADS)

López-Coto, R.; Mazin, D.; Paoletti, R.; Blanch Bigas, O.; Cortina, J.

2016-04-01

Imaging atmospheric Cherenkov telescopes (IACTs) such as the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes endeavor to reach the lowest possible energy threshold. In doing so the trigger system is a key element. Reducing the trigger threshold is hampered by the rapid increase of accidental triggers generated by ambient light (the so-called Night Sky Background NSB). In this paper we present a topological trigger, dubbed Topo-trigger, which rejects events on the basis of their relative orientation in the telescope cameras. We have simulated and tested the trigger selection algorithm in the MAGIC telescopes. The algorithm was tested using MonteCarlo simulations and shows a rejection of 85% of the accidental stereo triggers while preserving 99% of the gamma rays. A full implementation of this trigger system would achieve an increase in collection area between 10 and 20% at the energy threshold. The analysis energy threshold of the instrument is expected to decrease by ~ 8%. The selection algorithm was tested on real MAGIC data taken with the current trigger configuration and no γ-like events were found to be lost.

Analysis on the emission and potential application of Cherenkov radiation in boron neutron capture therapy: A Monte Carlo simulation study.

PubMed

Shu, Di-Yun; Geng, Chang-Ran; Tang, Xiao-Bin; Gong, Chun-Hui; Shao, Wen-Cheng; Ai, Yao

2018-07-01

This paper was aimed to explore the physics of Cherenkov radiation and its potential application in boron neutron capture therapy (BNCT). The Monte Carlo toolkit Geant4 was used to simulate the interaction between the epithermal neutron beam and the phantom containing boron-10. Results showed that Cherenkov photons can only be generated from secondary charged particles of gamma rays in BNCT, in which the 2.223 MeV prompt gamma rays are the main contributor. The number of Cherenkov photons per unit mass generated in the measurement region decreases linearly with the increase of boron concentration in both water and tissue phantom. The work presented the fundamental basis for applications of Cherenkov radiation in BNCT. Copyright © 2018 Elsevier Ltd. All rights reserved.

Single-Cycle Terahertz Pulse Generation from OH1 Crystal via Cherenkov Phase Matching

NASA Astrophysics Data System (ADS)

Uchida, Hirohisa; Oota, Kengo; Okimura, Koutarou; Kawase, Kodo; Takeya, Kei

2018-06-01

OH1 crystal is an organic nonlinear optical crystal with a large nonlinear optical constant. However, it has dispersion of refractive indices in the terahertz (THz) frequency. This limits the frequencies that satisfy the phase matching conditions for THz wave generation. In this study, we addressed the phase matching conditions for THz wave generation by combining an OH1 crystal with prism-coupled Cherenkov phase matching. We observed the generation of single-cycle THz pulses with a spectrum covering a frequency range of 3 THz. These results prove that combining prism-coupled Cherenkov phase matching with nonlinear optical crystals yields a THz wave generation method that is insusceptible to crystal dispersion.

Single-Cycle Terahertz Pulse Generation from OH1 Crystal via Cherenkov Phase Matching

NASA Astrophysics Data System (ADS)

Uchida, Hirohisa; Oota, Kengo; Okimura, Koutarou; Kawase, Kodo; Takeya, Kei

2018-03-01

OH1 crystal is an organic nonlinear optical crystal with a large nonlinear optical constant. However, it has dispersion of refractive indices in the terahertz (THz) frequency. This limits the frequencies that satisfy the phase matching conditions for THz wave generation. In this study, we addressed the phase matching conditions for THz wave generation by combining an OH1 crystal with prism-coupled Cherenkov phase matching. We observed the generation of single-cycle THz pulses with a spectrum covering a frequency range of 3 THz. These results prove that combining prism-coupled Cherenkov phase matching with nonlinear optical crystals yields a THz wave generation method that is insusceptible to crystal dispersion.

The GCT camera for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Lapington, J. S.; Abchiche, A.; Allan, D.; Amans, J.-P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J.-J.; Bose, R.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Buckley, J.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Daniel, M. K.; De Franco, A.; De Frondat, F.; Dournaux, J.-L.; Dumas, D.; Ernenwein, J.-P.; Fasola, G.; Funk, S.; Gironnet, J.; Graham, J. A.; Greenshaw, T.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J.-M.; Jankowsky, D.; Jegouzo, I.; Jogler, T.; Kawashima, T.; Kraus, M.; Laporte, P.; Leach, S.; Lefaucheur, J.; Markoff, S.; Melse, T.; Minaya, I. A.; Mohrmann, L.; Molyneux, P.; Moore, P.; Nolan, S. J.; Okumura, A.; Osborne, J. P.; Parsons, R. D.; Rosen, S.; Ross, D.; Rowell, G.; Rulten, C. B.; Sato, Y.; Sayede, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Sol, H.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Tibaldo, L.; Trichard, C.; Varner, G.; Vink, J.; Watson, J. J.; White, R.; Yamane, N.; Zech, A.; Zink, A.; Zorn, J.; CTA Consortium

2017-12-01

The Gamma Cherenkov Telescope (GCT) is one of the designs proposed for the Small Sized Telescope (SST) section of the Cherenkov Telescope Array (CTA). The GCT uses dual-mirror optics, resulting in a compact telescope with good image quality and a large field of view with a smaller, more economical, camera than is achievable with conventional single mirror solutions. The photon counting GCT camera is designed to record the flashes of atmospheric Cherenkov light from gamma and cosmic ray initiated cascades, which last only a few tens of nanoseconds. The GCT optics require that the camera detectors follow a convex surface with a radius of curvature of 1 m and a diameter of 35 cm, which is approximated by tiling the focal plane with 32 modules. The first camera prototype is equipped with multi-anode photomultipliers, each comprising an 8×8 array of 6×6 mm2 pixels to provide the required angular scale, adding up to 2048 pixels in total. Detector signals are shaped, amplified and digitised by electronics based on custom ASICs that provide digitisation at 1 GSample/s. The camera is self-triggering, retaining images where the focal plane light distribution matches predefined spatial and temporal criteria. The electronics are housed in the liquid-cooled, sealed camera enclosure. LED flashers at the corners of the focal plane provide a calibration source via reflection from the secondary mirror. The first GCT camera prototype underwent preliminary laboratory tests last year. In November 2015, the camera was installed on a prototype GCT telescope (SST-GATE) in Paris and was used to successfully record the first Cherenkov light of any CTA prototype, and the first Cherenkov light seen with such a dual-mirror optical system. A second full-camera prototype based on Silicon Photomultipliers is under construction. Up to 35 GCTs are envisaged for CTA.

Luminescence of water or ice as a new detection method for magnetic monopoles

NASA Astrophysics Data System (ADS)

Pollmann, Anna Obertacke

2017-12-01

Cosmic ray detectors use air as a radiator for luminescence. In water and ice, Cherenkov light is the dominant light producing mechanism when the particle's velocity exceeds the Cherenkov threshold, approximately three quarters of the speed of light in vacuum. Luminescence is produced by highly ionizing particles passing through matter due to the electronic excitation of the surrounding molecules. The observables of luminescence, such as the wavelength spectrum and decay times, are highly dependent on the properties of the medium, in particular, temperature and purity. The results for the light yield of luminescence of previous measurements vary by two orders of magnitude. It will be shown that even for the lowest measured light yield, luminescence is an important signature of highly ionizing particles below the Cherenkov threshold. These could be magnetic monopoles or other massive and highly ionizing exotic particles. With the highest observed efficiencies, luminescence may even contribute significantly to the light output of standard model particles such as the PeV IceCube neutrinos. We present analysis techniques to use luminescence in neutrino telescopes and discuss experimental setups to measure the light yield of luminescence for the particular conditions in neutrino detectors.

Inauguration and first light of the GCT-M prototype for the Cherenkov telescope array

NASA Astrophysics Data System (ADS)

Watson, J. J.; De Franco, A.; Abchiche, A.; Allan, D.; Amans, J.-P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J.-J.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Daniel, M. K.; De Frondat, F.; Dournaux, J.-L.; Dumas, D.; Ernenwein, J.-P.; Fasola, G.; Funk, S.; Gironnet, J.; Graham, J. A.; Greenshaw, T.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J.-M.; Jegouzo, I.; Jogler, T.; Kraus, M.; Lapington, J. S.; Laporte, P.; Lefaucheur, J.; Markoff, S.; Melse, T.; Mohrmann, L.; Molyneux, P.; Nolan, S. J.; Okumura, A.; Osborne, J. P.; Parsons, R. D.; Rosen, S.; Ross, D.; Rowell, G.; Rulten, C. B.; Sato, Y.; Sayède, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Sol, H.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Tibaldo, L.; Trichard, C.; Vink, J.; White, R.; Yamane, N.; Zech, A.; Zink, A.; Zorn, J.; CTA Consortium

2017-01-01

The Gamma-ray Cherenkov Telescope (GCT) is a candidate for the Small Size Telescopes (SSTs) of the Cherenkov Telescope Array (CTA). Its purpose is to extend the sensitivity of CTA to gamma-ray energies reaching 300 TeV. Its dual-mirror optical design and curved focal plane enables the use of a compact camera of 0.4 m diameter, while achieving a field of view of above 8 degrees. Through the use of the digitising TARGET ASICs, the Cherenkov flash is sampled once per nanosecond contin-uously and then digitised when triggering conditions are met within the analogue outputs of the photosensors. Entire waveforms (typically covering 96 ns) for all 2048 pixels are then stored for analysis, allowing for a broad spectrum of investigations to be performed on the data. Two prototypes of the GCT camera are under development, with differing photosensors: Multi-Anode Photomultipliers (MAPMs) and Silicon Photomultipliers (SiPMs). During November 2015, the GCT MAPM (GCT-M) prototype camera was integrated onto the GCT structure at the Observatoire de Paris-Meudon, where it observed the first Cherenkov light detected by a prototype instrument for CTA.

Evaluation of the basic propertied of the novel 1.5 in. size PMTs from Hamamatsu Photonics and Electron Tubes Enterprises

NASA Astrophysics Data System (ADS)

Toyama, T.; Hanabata, Y.; Hose, J.; Menzel, U.; Mirzoyan, R.; Nakajima, D.; Takahashi, M.; Teshima, M.; Yamamoto, T.

2015-07-01

Currently the standard light sensors for Imaging Atmospheric Cherenkov Telescopes are the classical photo multiplier tubes that are using bialkali photocathodes. About 8 years ago we initiated an improvement program with the Photo Multiplier Tube manufacturers Hamamatsu in Japan, Electron Tubes Enterprises in England and Photonis in France for the needs of Imaging Atmospheric Cherenkov Telescopes. As a result, after about 40 years of "stagnation" of the peak Quantum Efficiency on the level of 25-27%, new PMTs appeared with a peak QE of 35%. These have got the name "super-bialkali". The second significant upgrade has happened very recently, as a result of a dedicated improvement program for the candidate PMT for Cherenkov Telescope Array. The latter is going to be the next generation major instrument in the field of very high energy gamma astrophysics and will consist of over 100 telescopes of three different sizes of 23 m, 12 m and 4-7 m. Now PMTs with average peak Quantum Efficiency of approximately 40% became available. Also, the photo electron collection efficiency of the previous generation PMTs of 80-90% has been enhanced towards 95-98% for the new ones. The after-pulsing of novel PMTs has been reduced towards the level of 0.02% for the set threshold of 4 photo electrons. Hamamatsu produced the PMT R-12992-100 as the final version for Cherenkov Telescope Array project. Electron Tubes produced the latest PMT D569/3SA as intermediate version and will produce the final version in 2015. We will report on the PMT development work by the companies Electron Tubes Enterprises and Hamamatsu Photonics K.K., show the achieved results and the current status.

Development of the fast and efficient gamma detector using Cherenkov light for TOF-PET

NASA Astrophysics Data System (ADS)

Canot, C.; Alokhina, M.; Abbon, P.; Bard, J. P.; Tauzin, G.; Yvon, D.; Sharyy, V.

2017-12-01

In this paper we present two configurations of innovative gamma detectors using Cherenkov light for time-of-flight—Positron Emission Tomography (PET). The first uses heavy crystals as a Cherenkov radiator to develop a demonstrator for a whole body PET scanner with high detection efficiency. We demonstrated a 30% detection efficiency and a 180 ps (FWHM) time resolution, mainly limited by the time transit spread of the photomultiplier. The second configuration uses an innovative liquid, the TriMethyl Bismuth, to develop a high precision brain-scanning PET device with time-of-flight capability. According to Geant4 simulation, we expect to reach a precision of 150 ps (FWHM) and an efficiency of about 25%.

Investigation into Cherenkov light scattering and refraction on aerogel surface

NASA Astrophysics Data System (ADS)

Barnyakov, A. Yu.; Barnyakov, M. Yu.; Bobrovnikov, V. S.; Buzykaev, A. R.; Danilyuk, A. F.; Katcin, A. A.; Kirilenko, P. S.; Kononov, S. A.; Korda, D. V.; Kravchenko, E. A.; Kudryavtsev, V. N.; Kuyanov, I. A.; Onuchin, A. P.; Ovtin, I. V.; Podgornov, N. A.; Predein, A. Yu.; Prisekin, V. G.; Protsenko, R. S.; Shekhtman, L. I.

2017-12-01

The work concerns the development of aerogel radiators for RICH detectors. Aerogel tiles with a refractive index of 1.05 were tested with a RICH prototype on the electron beam on the VEPP-4M collider. It has been shown that polishing with silk tissue yields good surface quality, the amount of light loss at this surface being about 5-7%. The Cherenkov angle resolution was measured for a tile in two conditions: with a clean exit face and with a polished exit face. The number of photons detected was 13.3 and 12.7 for the clean and polished surfaces, respectively. The Cherenkov angle resolution for the polished surface is 55% worse, which can be explained with the forward scattering on the polished surface. A tile with a crack inside was also tested. The experimental data show that the Cherenkov angle resolution is the same for tracks crossing the crack area and in a crack-free area.

Progress in Cherenkov femtosecond fiber lasers

PubMed Central

Liu, Xiaomin; Svane, Ask S.; Lægsgaard, Jesper; Tu, Haohua; Boppart, Stephen A.; Turchinovich, Dmitry

2016-01-01

We review the recent developments in the field of ultrafast Cherenkov fiber lasers. Two essential properties of such laser systems – broad wavelength tunability and high efficiency of Cherenkov radiation wavelength conversion are discussed. The exceptional performance of the Cherenkov fiber laser systems are highlighted - dependent on the realization scheme, the Cherenkov lasers can generate the femtosecond output tunable across the entire visible and even the UV range, and for certain designs more than 40 % conversion efficiency from the pump to Cherenkov signal can be achieved. The femtosecond Cherenkov laser with all-fiber architecture is presented and discussed. Operating in the visible range, it delivers 100–200 fs wavelength-tunable pulses with multimilliwatt output power and exceptionally low noise figure an order of magnitude lower than the traditional wavelength tunable supercontinuum-based femtosecond sources. The applications for Cherenkov laser systems in practical biophotonics and biomedical applications, such as bio-imaging and microscopy, are discussed. PMID:27110037

Progress in Cherenkov femtosecond fiber lasers.

PubMed

Liu, Xiaomin; Svane, Ask S; Lægsgaard, Jesper; Tu, Haohua; Boppart, Stephen A; Turchinovich, Dmitry

2016-01-20

We review the recent developments in the field of ultrafast Cherenkov fiber lasers. Two essential properties of such laser systems - broad wavelength tunability and high efficiency of Cherenkov radiation wavelength conversion are discussed. The exceptional performance of the Cherenkov fiber laser systems are highlighted - dependent on the realization scheme, the Cherenkov lasers can generate the femtosecond output tunable across the entire visible and even the UV range, and for certain designs more than 40 % conversion efficiency from the pump to Cherenkov signal can be achieved. The femtosecond Cherenkov laser with all-fiber architecture is presented and discussed. Operating in the visible range, it delivers 100-200 fs wavelength-tunable pulses with multimilliwatt output power and exceptionally low noise figure an order of magnitude lower than the traditional wavelength tunable supercontinuum-based femtosecond sources. The applications for Cherenkov laser systems in practical biophotonics and biomedical applications, such as bio-imaging and microscopy, are discussed.

GCT, the Gamma-ray Cherenkov Telescope for multi-TeV science with the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Sol, H.; Dournaux, J.-L.; Laporte, P.

2016-12-01

GCT is a gamma-ray telescope proposed for the high-energy section of the Cherenkov Telescope Array (CTA). A GCT prototype telescope has been designed, built and installed at the Observatoire de Paris in Meudon. Equipped with the first GCT prototype camera developed by an international collaboration, the complete GCT prototype was inaugurated in December 2015, after getting its first Cherenkov light on the night sky in November. The phase of tests, assessment, and optimisation is now coming to an end. Pre-production of the first GCT telescopes and cameras should start in 2017, for an installation on the Chilean site of CTA in 2018.

A future wide field-of-view TeV gamma-ray observatory in the Southern Hemisphere

NASA Astrophysics Data System (ADS)

Mostafa, Miguel; HAWC Collaboration

2017-01-01

High-energy gamma-ray observations are an essential probe of cosmic-ray acceleration. Detection of the highest energies and the shortest timescales of variability are key motivations when designing the next generation of gamma-ray experiments. The Milagro experiment was the first-generation of gamma-ray detectors based on the water-Cherenkov technique, and demonstrated that it is possible to continuously monitor a large fraction of the TeV sky. The second-generation water-Cherenkov experiment, the High Altitude Water Cherenkov observatory, consists of an array of 300 water-Cherenkov detectors covering an area of 22,000 m2 at 4,100 m a.s.l. The larger effective area, the higher altitude, and the optical isolation of the detectors led to a 15-fold increase in sensitivity relative to Milagro. Instruments with a wide field of view and large duty cycle are capable of surveying the TeV sky, mapping the diffuse emission, detecting emission from extended regions, and observing transient events such as gamma ray bursts. They also have the potential for discovering electromagnetic counterparts to gravitational waves and astrophysical neutrinos. I will present the preliminary design of a third-generation water-Cherenkov observatory located at very high altitude in South America.

Indirect detection of Particle Dark Matter with gamma rays - status and perspectives

NASA Astrophysics Data System (ADS)

Conrad, Jan

2014-03-01

In this contribution I review the present status and discuss some prospects for indirect detection of dark matter with gamma rays. Thanks mainly to the Fermi Large Area Telescope (Fermi-LAT), searches in gamma-rays have reached sensitivities that allow to probe the most interesting parameter space of the weakly interacting massive particles (WIMP) paradigm. This gain in sensitivity is naturally accompanied by a number of detection claims or indications. At WIMP masses above roughly a TeV current Imaging Air Cherenkov Telescopes (HESS, VERITAS, MAGIC) become more sensitive than the Fermi-LAT, the most promising recent development being the first light for the second phase HESS II telescope with significantly lower energy threshold. Predictions for the next generation air Cherenkov telescope, Cherenkov Telescope Array (CTA), together with forecasts on future Fermi-LAT constraints arrive at the exciting possibility that the cosmological benchmark cross-section could be probed from masses of a few GeV to a few TeV. Consequently, non-detection would pose a challenge to the WIMP paradigm, but the reached sensitivities also imply that-optimistically-a detection within the next decade is in the cards. Time allowing, I will comment on complementarity between the different approaches to WIMP detection.

R&D of a High-Performance DIRC Detector for a Future Electron-Ion Collider

NASA Astrophysics Data System (ADS)

Allison, Stacey Lee

An Electron-Ion Collider (EIC) is proposed as the next big scientific facility to be built in the United States, costing over $1 billion in design and construction. Each detector concept for the electron/ion beam interaction point is integrated into a large solenoidal magnet. The necessity for excellent hadronic particle identification (pion/kaon/proton) in the barrel region of the solenoid has pushed research and development (R&D) towards a new, high-performance Detection of Internally Reflected Cherenkov light (DIRC) detector design. The passage of a high energy charged particle through a fused silica bar of the DIRC generates optical Cherenkov radiation. A large fraction of this light propagates by total internal reflection to the end of the bar, where the photon trajectories expand in a large volume before reaching a highly segmented photo-detector array. The spatial and temporal distribution of the Cherenkov light at the photo-detector array allows one to reconstruct the angle of emission of the light relative to the incident charged particle track. In order to reach the desired performance of 3sigma pi/K separation at 6 GeV/c particle momentum a new 3-layer spherical lens focusing optic with a lanthanum crown glass central layer was designed to have a nearly flat focal plane. In order to validate the EIC DIRC simulation package, a synergistic test beam campaign was carried out in 2015 at the CERN PS with the PANDA Barrel DIRC group using a prototype DIRC detector. Along with the analysis of the CERN test beam data, measurements of the focal plane of the 3-layer lens were performed using a custom-built laser setup at Old Dominion University. Radiation hardness of the lanthanum crown glass was tested using a 160 keV X-ray source and a monochromator at the Catholic University of America. Results of these test-bench experiments and the analysis of the 2015 CERN test beam data are presented here.

R&D of a high-performance DIRC detector for a future electron-ion collider

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allison, Staceu L.

An Electron-Ion Collider (EIC) is proposed as the next big scientific facility to be built in the United States, costing over $1 billion in design and construction. Each detector concept for the electron/ion beam interaction point is integrated into a large solenoidal magnet. The necessity for excellent hadronic particle identification (pion/kaon/proton) in the barrel region of the solenoid has pushed research and development (R&D) towards a new, high-performance Detection of Internally Reflected Cherenkov light (DIRC) detector design. The passage of a high energy charged particle through a fused silica bar of the DIRC generates optical Cherenkov radiation. A large fractionmore » of this light propagates by total internal reflection to the end of the bar, where the photon trajectories expand in a large volume before reaching a highly segmented photo-detector array. The spatial and temporal distribution of the Cherenkov light at the photo-detector array allows one to reconstruct the angle of emission of the light relative to the incident charged particle track. In order to reach the desired performance of 3sigma pi/K separation at 6 GeV/c particle momentum a new 3-layer spherical lens focusing optic with a lanthanum crown glass central layer was designed to have a nearly at focal plane. In order to validate the EIC DIRC simulation package, a synergistic test beam campaign was carried out in 2015 at the CERN PS with the PANDA Barrel DIRC group using a prototype DIRC detector. Along with the analysis of the CERN test beam data, measurements of the focal plane of the 3-layer lens were performed using a custom-built laser setup at Old Dominion University. Radiation hardness of the lanthanum crown glass was tested using a 160 keV X-ray source and a monochromator at the Catholic University of America. Results of these test-bench experiments and the analysis of the 2015 CERN test beam data are presented here.« less

TH-AB-209-04: 3D Light Sheet Luminescence Imaging with Cherenkov Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruza, P; Lin, H; Jarvis, L

Purpose: To recover a three-dimensional density distribution of luminescent molecular probes located several centimeters deep within a highly scattering tissue. Methods: We developed a novel sheet beam Cherenkov-excited luminescence scanned imaging (CELSI) methodology. The sample was irradiated by a horizontally oriented, vertically scanned 6 MV X-ray sheet beam (200mm × 5mm, 0.2mm vertical step) from a radiotherapy linear accelerator. The resulting Cherenkov light emission – and thus luminescent probe excitation – occurred exclusively along the irradiation plane due to a short diffusion path of secondary particles and Cherenkov photons. Cherenkov-excited luminescence was detected orthogonally to the sheet beam by gated,more » intensified charge coupled device camera. Analogously to light sheet microscopy, a series of luminescence images was taken for varied axial positions (depths) of the Cherenkov light sheet in sample. Knowledge of the excitation plane position allowed a 3D image stack deconvolution and depth-variant attenuation correction. The 3D image post-processing yielded a true spatial density distribution of luminescent molecules in highly scattering tissue. Results: We recovered a three-dimensional shape and position of 400 µL lesion-mimicking phantom tubes containing 25 µM solution of PtG4 molecular probe from 3 centimeter deep tissue-like media. The high sensitivity of CELSI also allowed resolving 100 micron capillaries of test solution. Functional information of partial oxygen pressure at the site of PtG4 molecular probe was recovered from luminescence lifetime CELSI. Finally, in-vivo sheet beam CELSI localized milimeter-sized PtG4-labelled tumor phantoms in multiple biological objects (hairless mice) from single scan. Conclusion: Presented sheet beam CELSI technique greatly extended the useful depth range of luminescence molecular imaging. More importantly, the light sheet microscopy approach was successfully adapted to CELSI, providing means to recover a completely attenuation-corrected 3D image of luminescent probe distribution. Gated CELSI acquisition yielded functional information of a spatially resolved oxygen concentration map of deep lying targets. This work was supported by NIH research grant R01CA109558 and R21EB017559, as well as by Pilot Grant Funds from the Norris Cotton Cancer Center.« less

Space Radiation Detector with Spherical Geometry

NASA Technical Reports Server (NTRS)

Wrbanek, John D. (Inventor); Fralick, Gustave C. (Inventor); Wrbanek, Susan Y. (Inventor)

2011-01-01

A particle detector is provided, the particle detector including a spherical Cherenkov detector, and at least one pair of detector stacks. In an embodiment of the invention, the Cherenkov detector includes a sphere of ultraviolet transparent material, coated by an ultraviolet reflecting material that has at least one open port. The Cherenkov detector further includes at least one photodetector configured to detect ultraviolet light emitted from a particle within the sphere. In an embodiment of the invention, each detector stack includes one or more detectors configured to detect a particle traversing the sphere.

Space Radiation Detector with Spherical Geometry

NASA Technical Reports Server (NTRS)

Wrbanek, John D. (Inventor); Fralick, Gustave C. (Inventor); Wrbanek, Susan Y. (Inventor)

2012-01-01

A particle detector is provided, the particle detector including a spherical Cherenkov detector, and at least one pair of detector stacks. In an embodiment of the invention, the Cherenkov detector includes a sphere of ultraviolet transparent material, coated by an ultraviolet reflecting material that has at least one open port. The Cherenkov detector further includes at least one photodetector configured to detect ultraviolet light emitted from a particle within the sphere. In an embodiment of the invention, each detector stack includes one or more detectors configured to detect a particle traversing the sphere.

Bokeh mirror alignment for Cherenkov telescopes

NASA Astrophysics Data System (ADS)

Ahnen, M. L.; Baack, D.; Balbo, M.; Bergmann, M.; Biland, A.; Blank, M.; Bretz, T.; Bruegge, K. A.; Buss, J.; Domke, M.; Dorner, D.; Einecke, S.; Hempfling, C.; Hildebrand, D.; Hughes, G.; Lustermann, W.; Mannheim, K.; Mueller, S. A.; Neise, D.; Neronov, A.; Noethe, M.; Overkemping, A.-K.; Paravac, A.; Pauss, F.; Rhode, W.; Shukla, A.; Temme, F.; Thaele, J.; Toscano, S.; Vogler, P.; Walter, R.; Wilbert, A.

2016-09-01

Imaging Atmospheric Cherenkov Telescopes (IACTs) need imaging optics with large apertures and high image intensities to map the faint Cherenkov light emitted from cosmic ray air showers onto their image sensors. Segmented reflectors fulfill these needs, and composed from mass production mirror facets they are inexpensive and lightweight. However, as the overall image is a superposition of the individual facet images, alignment remains a challenge. Here we present a simple, yet extendable method, to align a segmented reflector using its Bokeh. Bokeh alig nment does not need a star or good weather nights but can be done even during daytime. Bokeh alignment optimizes the facet orientations by comparing the segmented reflectors Bokeh to a predefined template. The optimal Bokeh template is highly constricted by the reflector's aperture and is easy accessible. The Bokeh is observed using the out of focus image of a near by point like light source in a distance of about 10 focal lengths. We introduce Bokeh alignment on segmented reflectors and demonstrate it on the First Geiger-mode Avalanche Cherenkov Telescope (FACT) on La Palma, Spain.

Designing a new type of neutron detector for neutron and gamma-ray discrimination via GEANT4.

PubMed

Shan, Qing; Chu, Shengnan; Ling, Yongsheng; Cai, Pingkun; Jia, Wenbao

2016-04-01

Design of a new type of neutron detector, consisting of a fast neutron converter, plastic scintillator, and Cherenkov detector, to discriminate 14-MeV fast neutrons and gamma rays in a pulsed n-γ mixed field and monitor their neutron fluxes is reported in this study. Both neutrons and gamma rays can produce fluorescence in the scintillator when they are incident on the detector. However, only the secondary charged particles of the gamma rays can produce Cherenkov light in the Cherenkov detector. The neutron and gamma-ray fluxes can be calculated by measuring the fluorescence and Cherenkov light. The GEANT4 Monte Carlo simulation toolkit is used to simulate the whole process occurring in the detector, whose optimum parameters are known. Analysis of the simulation results leads to a calculation method of neutron flux. This method is verified by calculating the neutron fluxes using pulsed n-γ mixed fields with different n/γ ratios, and the results show that the relative errors of all calculations are <5%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Aerogel Cherenkov detector for characterizing the intense flash x-ray source, Cygnus, spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Y., E-mail: yhkim@lanl.gov; Herrmann, H. W.; McEvoy, A. M.

2016-11-15

An aerogel Cherenkov detector is proposed to measure the X-ray energy spectrum from the Cygnus—intense flash X-ray source operated at the Nevada National Security Site. An array of aerogels set at a variety of thresholds between 1 and 3 MeV will be adequate to map out the bremsstrahlung X-ray production of the Cygnus, where the maximum energy of the spectrum is normally around 2.5 MeV. In addition to the Cherenkov radiation from aerogels, one possible competing light-production mechanism is optical transition radiation (OTR), which may be significant in aerogels due to the large number of transitions from SiO{sub 2} clustersmore » to vacuum voids. To examine whether OTR is a problem, four aerogel samples were tested using a mono-energetic electron beam (varied in the range of 1–3 MeV) at NSTec Los Alamos Operations. It was demonstrated that aerogels can be used as a Cherenkov medium, where the rate of the light production is about two orders magnitude higher when the electron beam energy is above threshold.« less

Cherenkov Video Imaging Allows for the First Visualization of Radiation Therapy in Real Time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarvis, Lesley A., E-mail: Lesley.a.jarvis@hitchcock.org; Norris Cotton Cancer Center at the Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire; Zhang, Rongxiao

Purpose: To determine whether Cherenkov light imaging can visualize radiation therapy in real time during breast radiation therapy. Methods and Materials: An intensified charge-coupled device (CCD) camera was synchronized to the 3.25-μs radiation pulses of the clinical linear accelerator with the intensifier set × 100. Cherenkov images were acquired continuously (2.8 frames/s) during fractionated whole breast irradiation with each frame an accumulation of 100 radiation pulses (approximately 5 monitor units). Results: The first patient images ever created are used to illustrate that Cherenkov emission can be visualized as a video during conditions typical for breast radiation therapy, even with complex treatment plans,more » mixed energies, and modulated treatment fields. Images were generated correlating to the superficial dose received by the patient and potentially the location of the resulting skin reactions. Major blood vessels are visible in the image, providing the potential to use these as biological landmarks for improved geometric accuracy. The potential for this system to detect radiation therapy misadministrations, which can result from hardware malfunction or patient positioning setup errors during individual fractions, is shown. Conclusions: Cherenkoscopy is a unique method for visualizing surface dose resulting in real-time quality control. We propose that this system could detect radiation therapy errors in everyday clinical practice at a time when these errors can be corrected to result in improved safety and quality of radiation therapy.« less

Coherent ultra-violet to near-infrared generation in silica ridge waveguides

PubMed Central

Yoon Oh, Dong; Yang, Ki Youl; Fredrick, Connor; Ycas, Gabriel; Diddams, Scott A.; Vahala, Kerry J.

2017-01-01

Short duration, intense pulses of light can experience dramatic spectral broadening when propagating through lengths of optical fibre. This continuum generation process is caused by a combination of nonlinear optical effects including the formation of dispersive waves. Optical analogues of Cherenkov radiation, these waves allow a pulse to radiate power into a distant spectral region. In this work, efficient and coherent dispersive wave generation of visible to ultraviolet light is demonstrated in silica waveguides on a silicon chip. Unlike fibre broadeners, the arrays provide a wide range of emission wavelength choices on a single, compact chip. This new capability is used to simplify offset frequency measurements of a mode-locked frequency comb. The arrays can also enable mode-locked lasers to attain unprecedented tunable spectral reach for spectroscopy, bioimaging, tomography and metrology. PMID:28067233

Camera Concepts for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Nepomuk Otte, Adam

2009-05-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. Design goals are ten times better sensitivity, higher angular resolution, and a lower energy threshold than existing Cherenkov telescopes. Each telescope is equipped with a camera that detects and records the Cherenkov-light flashes from air showers. The camera is comprised of a pixelated focal plane of blue sensitive and fast (nanosecond) photon detectors that detect the photon signal and convert it into an electrical one. The incorporation of trigger electronics and signal digitization into the camera are under study. Given the size of AGIS, the camera must be reliable, robust, and cost effective. We are investigating several directions that include innovative technologies such as Geiger-mode avalanche-photodiodes as a possible detector and switched capacitor arrays for the digitization.

Experiment to demonstrate separation of Cherenkov and scintillation signals

DOE PAGES

Caravaca, J.; Descamps, F. B.; Land, B. J.; ...

2017-05-05

The ability to separately identify the Cherenkov and scintillation light components produced in scintillating mediums holds the potential for a major breakthrough in neutrino detection technology, allowing development of a large, low-threshold, directional detector with a broad physics program. Furthermore, the CHESS (CHErenkov/Scintillation Separation) experiment employs an innovative detector design with an array of small, fast photomultiplier tubes and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in a scintillating medium based on photon hit time and detected photoelectron density. Our paper describes the physical properties and calibration of CHESS along with first results. The ability to reconstructmore » Cherenkov rings are demonstrated in a water target, and a time precision of 338 ± 12 ps FWHM is achieved. Finally, Monte Carlo–based predictions for the ring imaging sensitivity with a liquid scintillator target predict an efficiency for identifying Cherenkov hits of 94 ± 1 % and 81 ± 1 % in pure linear alkyl benzene (LAB) and LAB loaded with 2 g/L of a fluor, PPO, respectively, with a scintillation contamination of 12 ± 1 % and 26 ± 1 % .« less

Experiment to demonstrate separation of Cherenkov and scintillation signals

NASA Astrophysics Data System (ADS)

Caravaca, J.; Descamps, F. B.; Land, B. J.; Wallig, J.; Yeh, M.; Orebi Gann, G. D.

2017-05-01

The ability to separately identify the Cherenkov and scintillation light components produced in scintillating mediums holds the potential for a major breakthrough in neutrino detection technology, allowing development of a large, low-threshold, directional detector with a broad physics program. The CHESS (CHErenkov/Scintillation Separation) experiment employs an innovative detector design with an array of small, fast photomultiplier tubes and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in a scintillating medium based on photon hit time and detected photoelectron density. This paper describes the physical properties and calibration of CHESS along with first results. The ability to reconstruct Cherenkov rings is demonstrated in a water target, and a time precision of 338 ±12 ps FWHM is achieved. Monte Carlo-based predictions for the ring imaging sensitivity with a liquid scintillator target predict an efficiency for identifying Cherenkov hits of 94 ±1 % and 81 ±1 % in pure linear alkyl benzene (LAB) and LAB loaded with 2 g/L of a fluor, PPO, respectively, with a scintillation contamination of 12 ±1 % and 26 ±1 % .

A Prototype Combination TPC Cherenkov Detector with GEM Readout for Tracking and Particle Identification and its Potential Use at an Electron Ion Collider

NASA Astrophysics Data System (ADS)

Woody, Craig; Azmoun, Babak; Majka, Richard; Phipps, Michael; Purschke, Martin; Smirnov, Nikolai

2018-02-01

A prototype detector is being developed which combines the functions of a Time Projection Chamber for charged particle tracking and a Cherenkov detector for particle identification. The TPC consists of a 10×10×10 cm3 drift volume where the charge is drifted to a 10×10 cm2 triple GEM detector. The charge is measured on a readout plane consisting of 2×10 mm2 chevron pads which provide a spatial resolution ˜ 100 μm per point in the chevron direction along with dE/dx information. The Cherenkov portion of the detector consists of a second 10×10 cm2 triple GEM with a photosensitive CsI photocathode on the top layer. This detector measures Cherenkov light produced in the drift gas of the TPC by high velocity particles which are above threshold. CF4 or CF4 mixtures will be used as the drift gas which are highly transparent to UV light and can provide excellent efficiency for detecting Cherenkov photons. The drift gas is also used as the operating gas for both GEM detectors. The prototype detector has been constructed and is currently being tested in the lab with sources and cosmic rays, and additional tests are planned in the future to study the detector in a test beam.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Archambault, L; Papaconstadopoulos, P; Seuntjens, J

Purpose: To study Cherenkov light emission in plastic scintillation detectors (PSDs) from a theoretical point of view to identify situations that may arise where the calibration coefficient obtained in one condition is not applicable to another condition. By identifying problematic situations, we hope to provide guidance on how to confidently use PSDs. Methods: Cherenkov light emission in PSD was modelled using basic physical principles. In particular, changes in refractive index as a function of wavelength were accounted for using the Sellmeier empirical equation. Both electron and photon beams were considered. For photons, realistic distributions of secondary charged particles were calculatedmore » using Klein-Nishina’s formula. Cherenkov production and collection in PSDs were studied for a range of parameters including beam energy, charged particle momentum distribution, detector orientation and material composition. Finally, experimental validation was made using a commercial plastic scintillation detector. Results: In specific situations, results show that the Cherenkov spectrum coupled in the PSD can deviate from its expected behaviour (i.e. one over the square of the wavelength). In these cases were the model is realistic it is possible to see a peak wavelength instead of a monotonically decreasing function. Consequences of this phenomenon are negligible when the momentum of charged particle is distributed randomly, but in some clinically relevant cases, such as an electron beam at depth close to R50 or for photon beams with minimal scatter component, the value of the calibration coefficient can be altered. Experimental tests with electron beams showed changes in the Cherenkov light ratio, the parameter used in the calibration of PSDs, up to 2–3% depending on the PSD orientation. Conclusion: This work is the first providing a physical explanation for apparent change in PSD calibration coefficient. With this new information at hand, it will be possible to better guide the clinical use of PSDs.« less

Testing light concentrators prototypes for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Hénault, François; Petrucci, Pierre-Olivier; Jocou, Laurent; Arezki, Brahim; Magnard, Yves; Khélifi, Bruno; Manigot, Pascal; Olive, Jean-François; Jean, Pierre; Punch, Michael

2017-09-01

With more than 30 Medium-Size Telescopes (MST) located in both North and South hemispheres, the Cherenkov Telescope Array (CTA) shall be the largest cosmic gamma ray detector ever built. Each MST focal plane consists in an array of some 1800 photomultipliers equipped with their own light concentrating optics in order to maximizing the amount of Cherenkov radiation collected by the telescope and to block stray light originating from ground environment. Within the CTA Consortium, the Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) is in charge of designing, subcontracting the realization to industry, and testing the MST light concentrators. Two different optical solutions were pre-selected, respectively based on CPCs (Winston cones) and non-imaging concentrating lenses. Prototypes were manufactured by different industrial companies and tested in our laboratory on a test bench specifically built for the project. After shortly describing both optical designs, this communication is essentially focused at experimental results. Each type of concentrator has been submitted to extensive performance measurements, including radiometric efficiency at different wavelengths, rejection curves, and qualitative shape error test. The final selected concentrator is the CPC, although non-imaging lenses exhibit interesting properties in terms of radiometric performance.

Characterization and Modeling of a Water-based Liquid Scintillator

DOE PAGES

L. J. Bignell; Beznosko, D.; Diwan, M. V.; ...

2015-12-15

We characterised Water-based Liquid Scintillator (WbLS) using low energy protons, UV-VIS absorbance, and fluorescence spectroscopy. We have also developed and validated a simulation model that describes the behaviour of WbLS in our detector configurations for proton beam energies of 210 MeV, 475 MeV, and 2 GeV and for two WbLS compositions. These results have enabled us to estimate the light yield and ionisation quenching of WbLS, as well as to understand the influence of the wavelength shifting of Cherenkov light on our measurements. These results are relevant to the suitability of WbLS materials for next generation intensity frontier experiments.

The ASTRI SST-2M prototype for the next generation of Cherenkov telescopes: a single framework approach from requirement analysis to integration and verification strategy definition

NASA Astrophysics Data System (ADS)

Fiorini, Mauro; La Palombara, Nicola; Stringhetti, Luca; Canestrari, Rodolfo; Catalano, Osvaldo; Giro, Enrico; Leto, Giuseppe; Maccarone, Maria Concetta; Pareschi, Giovanni; Tosti, Gino; Vercellone, Stefano

2014-08-01

ASTRI is a flagship project of the Italian Ministry of Education, University and Research, which aims to develop an endto- end prototype of one of the three types of telescopes to be part of the Cherenkov Telescope Array (CTA), an observatory which will be the main representative of the next generation of Imaging Atmospheric Cherenkov Telescopes. The ASTRI project, led by the Italian National Institute of Astrophysics (INAF), has proposed an original design for the Small Size Telescope, which is aimed to explore the uppermost end of the Very High Energy domain up to about few hundreds of TeV with unprecedented sensitivity, angular resolution and imaging quality. It is characterized by challenging and innovative technological solutions which will be adopted for the first time in a Cherenkov telescope: a dual-mirror Schwarzschild-Couder configuration, a modular, light and compact camera based on silicon photomultipliers, and a front-end electronic based on a specifically designed ASIC. The end-to-end project is also including all the data-analysis software and the data archive. In this paper we describe the process followed to derive the ASTRI specifications from the CTA general requirements, a process which had to take into proper account the impact on the telescope design of the different types of the CTA requirements (performance, environment, reliability-availability-maintenance, etc.). We also describe the strategy adopted to perform the specification verification, which will be based on different methods (inspection, analysis, certification, and test) in order to demonstrate the telescope compliance with the CTA requirements. Finally we describe the integration planning of the prototype assemblies (structure, mirrors, camera, control software, auxiliary items) and the test planning of the end-to-end telescope. The approach followed by the ASTRI project is to have all the information needed to report the verification process along all project stages in a single layer. From this unique layer it is possible to, in a semi-automatic way, generate updated project documentation and progress report.

Extremely frequency-widened terahertz wave generation using Cherenkov-type radiation.

PubMed

Suizu, Koji; Koketsu, Kaoru; Shibuya, Takayuki; Tsutsui, Toshihiro; Akiba, Takuya; Kawase, Kodo

2009-04-13

Terahertz (THz) wave generation based on nonlinear frequency conversion is promising way for realizing a tunable monochromatic bright THz-wave source. Such a development of efficient and wide tunable THz-wave source depends on discovery of novel brilliant nonlinear crystal. Important factors of a nonlinear crystal for THz-wave generation are, 1. High nonlinearity and 2. Good transparency at THz frequency region. Unfortunately, many nonlinear crystals have strong absorption at THz frequency region. The fact limits efficient and wide tunable THz-wave generation. Here, we show that Cherenkov radiation with waveguide structure is an effective strategy for achieving efficient and extremely wide tunable THz-wave source. We fabricated MgO-doped lithium niobate slab waveguide with 3.8 microm of thickness and demonstrated difference frequency generation of THz-wave generation with Cherenkov phase matching. Extremely frequency-widened THz-wave generation, from 0.1 to 7.2 THz, without no structural dips successfully obtained. The tuning frequency range of waveguided Cherenkov radiation source was extremely widened compare to that of injection seeded-Terahertz Parametric Generator. The tuning range obtained in this work for THz-wave generation using lithium niobate crystal was the widest value in our knowledge. The highest THz-wave energy obtained was about 3.2 pJ, and the energy conversion efficiency was about 10(-5) %. The method can be easily applied for many conventional nonlinear crystals, results in realizing simple, reasonable, compact, high efficient and ultra broad band THz-wave sources.

Temporal signatures of the Cherenkov light induced by extensive air showers of cosmic rays detected with the Yakutsk array

NASA Astrophysics Data System (ADS)

Ivanov, A. A.; Timofeev, L. V.

2016-05-01

We analyze temporal characteristics of signals from the wide field-of-view (WFOV) Cherenkov telescope (CT) detecting extensive air showers (EAS) of cosmic rays (CRs) in coincidence with surface detectors of the Yakutsk array. Our aim is to reveal causal relationships between measured characteristics and physical properties of EAS.

Signal intensity analysis and optimization for in vivo imaging of Cherenkov and excited luminescence

NASA Astrophysics Data System (ADS)

LaRochelle, Ethan P. M.; Shell, Jennifer R.; Gunn, Jason R.; Davis, Scott C.; Pogue, Brian W.

2018-04-01

During external beam radiotherapy (EBRT), in vivo Cherenkov optical emissions can be used as a dosimetry tool or to excite luminescence, termed Cherenkov-excited luminescence (CEL) with microsecond-level time-gated cameras. The goal of this work was to develop a complete theoretical foundation for the detectable signal strength, in order to provide guidance on optimization of the limits of detection and how to optimize near real time imaging. The key parameters affecting photon production, propagation and detection were considered and experimental validation with both tissue phantoms and a murine model are shown. Both the theoretical analysis and experimental data indicate that the detection level is near a single photon-per-pixel for the detection geometry and frame rates commonly used, with the strongest factor being the signal decrease with the square of distance from tissue to camera. Experimental data demonstrates how the SNR improves with increasing integration time, but only up to the point where the dominance of camera read noise is overcome by stray photon noise that cannot be suppressed. For the current camera in a fixed geometry, the signal to background ratio limits the detection of light signals, and the observed in vivo Cherenkov emission is on the order of 100×  stronger than CEL signals. As a result, imaging signals from depths  <15 mm is reasonable for Cherenkov light, and depths  <3 mm is reasonable for CEL imaging. The current investigation modeled Cherenkov and CEL imaging of two oxygen sensing phosphorescent compounds, but the modularity of the code allows for easy comparison of different agents or alternative cameras, geometries or tissues.

Signal intensity analysis and optimization for in vivo imaging of Cherenkov and excited luminescence.

PubMed

LaRochelle, Ethan P M; Shell, Jennifer R; Gunn, Jason R; Davis, Scott C; Pogue, Brian W

2018-04-20

During external beam radiotherapy (EBRT), in vivo Cherenkov optical emissions can be used as a dosimetry tool or to excite luminescence, termed Cherenkov-excited luminescence (CEL) with microsecond-level time-gated cameras. The goal of this work was to develop a complete theoretical foundation for the detectable signal strength, in order to provide guidance on optimization of the limits of detection and how to optimize near real time imaging. The key parameters affecting photon production, propagation and detection were considered and experimental validation with both tissue phantoms and a murine model are shown. Both the theoretical analysis and experimental data indicate that the detection level is near a single photon-per-pixel for the detection geometry and frame rates commonly used, with the strongest factor being the signal decrease with the square of distance from tissue to camera. Experimental data demonstrates how the SNR improves with increasing integration time, but only up to the point where the dominance of camera read noise is overcome by stray photon noise that cannot be suppressed. For the current camera in a fixed geometry, the signal to background ratio limits the detection of light signals, and the observed in vivo Cherenkov emission is on the order of 100×  stronger than CEL signals. As a result, imaging signals from depths  <15 mm is reasonable for Cherenkov light, and depths  <3 mm is reasonable for CEL imaging. The current investigation modeled Cherenkov and CEL imaging of two oxygen sensing phosphorescent compounds, but the modularity of the code allows for easy comparison of different agents or alternative cameras, geometries or tissues.

Terahertz Difference-Frequency Quantum Cascade Laser Sources on Silicon

DTIC Science & Technology

2016-12-22

temperature. The introduction of the Cherenkov waveguide scheme in these devices grown on semi- insulating InP substrates enabled generation of tens...room temperature, a factor of 5 improvement over the best reference devices on a native semi- insulating InP substrate. © 2016 Optical Society of America...implementation of the Cherenkov emission scheme [10]. Cherenkov THz DFG-QCLs reported so far use a semi- insulating (SI) InP substrate. SI InP

Neutrino Telescopes

NASA Astrophysics Data System (ADS)

de Marzo, C. N.

2002-06-01

Neutrino astronomy is one of the frontier of the high energy astrophysics. I discuss how to build a neutrino telescope and which requirements such a detector must fulfil. A measurable flux of astrophysical neutrinos is predicted by several models for a detector at the cubic kilometer scale. The way pursued until now in building such huge apparatuses is Cherenkov light detection in water or in ice. There have been attempts to build neutrino telescopes and also some projects are yet under construction or under way to start. This situation is reviewed and also techniques alternatives to the Cherenkov light detection are mentioned.

Parametric analysis of cherenkov light LDF from EAS for high energy gamma rays and nuclei: Ways of practical application

NASA Astrophysics Data System (ADS)

Elshoukrofy, A. Sh. M.; Postnikov, E. B.; Korosteleva, E. E.; Sveshnikova, L. G.; Motaweh, H. A.

2017-06-01

In this paper we propose a `knee-like' approximation of the lateral distribution of the Cherenkov light from extensive air showers in the energy range 30-3000 TeV and study a possibility of its practical application in high energy ground-based gamma-ray astronomy experiments (in particular, in TAIGA-HiSCORE). The approximation has a very good accuracy for individual showers and can be easily simplified for practical application in the HiSCORE wide angle timing array in the condition of a limited number of triggered stations.

Cherenkov Radiation Control via Self-accelerating Wave-packets.

PubMed

Hu, Yi; Li, Zhili; Wetzel, Benjamin; Morandotti, Roberto; Chen, Zhigang; Xu, Jingjun

2017-08-18

Cherenkov radiation is a ubiquitous phenomenon in nature. It describes electromagnetic radiation from a charged particle moving in a medium with a uniform velocity larger than the phase velocity of light in the same medium. Such a picture is typically adopted in the investigation of traditional Cherenkov radiation as well as its counterparts in different branches of physics, including nonlinear optics, spintronics and plasmonics. In these cases, the radiation emitted spreads along a "cone", making it impractical for most applications. Here, we employ a self-accelerating optical pump wave-packet to demonstrate controlled shaping of one type of generalized Cherenkov radiation - dispersive waves in optical fibers. We show that, by tuning the parameters of the wave-packet, the emitted waves can be judiciously compressed and focused at desired locations, paving the way to such control in any physical system.

Sonoluminescence Explained by the Standpoint of Coherent Quantum Vacuum Dynamics and its Prospects for Energy Production

NASA Astrophysics Data System (ADS)

Maxmilian Caligiuri, Luigi; Musha, Takaaki

Sonoluminescence, or its more frequently studied version known as Single Bubble Sonoluminescence, consisting in the emission of light by a collapsing bubble in water under ultrasounds, represents one of the most challenging and interesting phenomenon in theoretical physics. In fact, despite its relatively easy reproducibility in a simple laboratory, its understanding within the commonly accepted picture of condensed matter remained so far unsatisfactory. On the other hand, the possibility to control the physical process involved in sonoluminescence, representing a sort of nuclear fusion on small scale, could open unthinkable prospects of free energy production from water. Different explanations has been proposed during the past years considering, in various way, the photoemission to be related to electromagnetic Zero Point Field energy dynamics, by considering the bubble surface as a Casimir force boundary. More recently a model invoking Cherenkov radiation emission from superluminal photons generated in quantum vacuum has been successfully proposed. In this paper it will be shown that the same results can be more generally explained and quantitative obtained within a QED coherent dynamics of quantum vacuum, according to which the electromagnetic energy of the emitted photons would be related to the latent heat involved in the phase transition from water's vapor to liquid phase during the bubble collapse. The proposed approach could also suggest an explanation of a possible mechanism of generation of faster than light (FTL) photons required to start Cherenkov radiation as well as possible applications to energy production from quantum vacuum.

Light-Trap: a SiPM upgrade for VHE astronomy and beyond

NASA Astrophysics Data System (ADS)

Ward, J. E.; Cortina, J.; Guberman, D.

2016-11-01

Ground-based gamma-ray astronomy in the Very High Energy (VHE, E > 100 GeV) regime has fast become one of the most interesting and productive sub-fields of astrophysics today. Utilizing the Imaging Atmospheric Cherenkov Technique (IACT) to reconstruct the energy and direction of incoming gamma-ray photons from the universe, several source-classes have been revealed by previous and current generations of IACT telescopes (e.g. Whipple, MAGIC, HESS and VERITAS). The next generation pointing IACT experiment, the Cherenkov Telescope Array (CTA), will provide increased sensitivity across a wider energy range and with better angular resolution. With the development of CTA, the future of IACT pointing arrays is being directed towards having more and more telescopes (and hence cameras), and therefore the need to develop low-cost pixels with acceptable light-collection efficiency is clear. One of the primary paths to the above goal is to replace Photomultiplier Tubes (PMTs) with Silicon-PMs (SiPMs) as the pixels in IACT telescope cameras. However SiPMs are not yet mature enough to replace PMTs for several reasons: sensitivity to unwanted longer wavelengths while lacking sensitivity at short wavelengths, small physical area, high cost, optical cross-talk and dark rates. Here we propose a novel method to build relatively low-cost SiPM-based pixels utilising a disk of wavelength-shifting material, which overcomes some of these drawbacks by collecting light over a larger area than standard SiPMs and improving sensitivity to shorter wavelengths while reducing background. We aim to optimise the design of such pixels, integrating them into an actual 7-pixel cluster which will be inserted into a MAGIC camera and tested during real observations. Results of simulations, laboratory measurements and the current status of the cluster design and development will be presented.

Operating performance of the gamma-ray Cherenkov telescope: An end-to-end Schwarzschild-Couder telescope prototype for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Dournaux, J. L.; De Franco, A.; Laporte, P.; White, R.; Greenshaw, T.; Sol, H.; Abchiche, A.; Allan, D.; Amans, J. P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J. J.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Daniel, M.; De Frondat, F.; Dumas, D.; Ernenwein, J. P.; Fasola, G.; Funk, S.; Gaudemard, J.; Graham, J. A.; Gironnet, J.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J. M.; Jégouzo, I.; Jogler, T.; Kawashima, T.; Kraus, M.; Lapington, J. S.; Lefaucheur, J.; Markoff, S.; Melse, T.; Morhrmann, L.; Molnyeux, P.; Nolan, S. J.; Okumura, A.; Parsons, R. D.; Ross, D.; Rowell, G.; Sato, Y.; Sayède, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Tibaldo, L.; Trichard, C.; Vink, J.; Watson, J.; Yamane, N.; Zech, A.; Zink, A.; CTA Consortium

2017-02-01

The Cherenkov Telescope Array (CTA) consortium aims to build the next-generation ground-based very-high-energy gamma-ray observatory. The array will feature different sizes of telescopes allowing it to cover a wide gamma-ray energy band from about 20 GeV to above 100 TeV. The highest energies, above 5 TeV, will be covered by a large number of Small-Sized Telescopes (SSTs) with a field-of-view of around 9°. The Gamma-ray Cherenkov Telescope (GCT), based on Schwarzschild-Couder dual-mirror optics, is one of the three proposed SST designs. The GCT is described in this contribution and the first images of Cherenkov showers obtained using the telescope and its camera are presented. These were obtained in November 2015 in Meudon,

High power long pulse microwave generation from a metamaterial structure with reverse symmetry

NASA Astrophysics Data System (ADS)

Lu, Xueying; Stephens, Jacob C.; Mastovsky, Ivan; Shapiro, Michael A.; Temkin, Richard J.

2018-02-01

Experimental operation of a high power microwave source with a metamaterial (MTM) structure is reported at power levels to 2.9 MW at 2.4 GHz in full 1 μs pulses. The MTM structure is formed by a waveguide that is below cutoff for TM modes. The waveguide is loaded by two axial copper plates machined with complementary split ring resonators, allowing two backward wave modes to propagate in the S-Band. A pulsed electron beam of up to 490 kV, 84 A travels down the center of the waveguide, midway between the plates. The electron beam is generated by a Pierce gun and is focused by a lens into a solenoidal magnetic field. The MTM plates are mechanically identical but are placed in the waveguide with reverse symmetry. Theory indicates that both Cherenkov and Cherenkov-cyclotron beam-wave interactions can occur. High power microwave generation was studied by varying the operating parameters over a wide range, including the electron beam voltage, the lens magnetic field, and the solenoidal field. Frequency tuning with a magnetic field and beam voltage was studied to discriminate between operation in the Cherenkov mode and the Cherenkov-cyclotron mode. Both modes were observed, but pulses above 1 MW of output power were only seen in the Cherenkov-cyclotron mode. A pair of steering coils was installed prior to the interaction space to initiate the cyclotron motion of the electron beam and thus encourage the Cherenkov-cyclotron high power mode. This successfully increased the output power from 2.5 MW to 2.9 MW (450 kV, 74 A, 9% efficiency).

Sum-frequency nonlinear Cherenkov radiation generated on the boundary of bulk medium crystal.

PubMed

Wang, Xiaojing; Cao, Jianjun; Zhao, Xiaohui; Zheng, Yuanlin; Ren, Huaijin; Deng, Xuewei; Chen, Xianfeng

2015-12-14

We demonstrated experimentally a method to generate the sum-frequency Nonlinear Cherenkov radiation (NCR) on the boundary of bulk medium by using two synchronized laser beam with wavelength of 1300 nm and 800 nm. It is also an evidence that the polarization wave is always confined to the boundary. Critical conditions of surface sum-frequency NCR under normal and anomalous dispersion condition is discussed.

Redshifted Cherenkov Radiation for in vivo Imaging: Coupling Cherenkov Radiation Energy Transfer to multiple Förster Resonance Energy Transfers

NASA Astrophysics Data System (ADS)

Bernhard, Yann; Collin, Bertrand; Decréau, Richard A.

2017-03-01

Cherenkov Radiation (CR), this blue glow seen in nuclear reactors, is an optical light originating from energetic β-emitter radionuclides. CR emitter 90Y triggers a cascade of energy transfers in the presence of a mixed population of fluorophores (which each other match their respective absorption and emission maxima): Cherenkov Radiation Energy Transfer (CRET) first, followed by multiple Förster Resonance Energy transfers (FRET): CRET ratios were calculated to give a rough estimate of the transfer efficiency. While CR is blue-weighted (300-500 nm), such cascades of Energy Transfers allowed to get a) fluorescence emission up to 710 nm, which is beyond the main CR window and within the near-infrared (NIR) window where biological tissues are most transparent, b) to amplify this emission and boost the radiance on that window: EMT6-tumor bearing mice injected with both a radionuclide and a mixture of fluorophores having a good spectral overlap, were shown to have nearly a two-fold radiance boost (measured on a NIR window centered on the emission wavelength of the last fluorophore in the Energy Transfer cascade) compared to a tumor injected with the radionuclide only. Some CR embarked light source could be converted into a near-infrared radiation, where biological tissues are most transparent.

Redshifted Cherenkov Radiation for in vivo Imaging: Coupling Cherenkov Radiation Energy Transfer to multiple Förster Resonance Energy Transfers.

PubMed

Bernhard, Yann; Collin, Bertrand; Decréau, Richard A

2017-03-24

Cherenkov Radiation (CR), this blue glow seen in nuclear reactors, is an optical light originating from energetic β-emitter radionuclides. CR emitter 90 Y triggers a cascade of energy transfers in the presence of a mixed population of fluorophores (which each other match their respective absorption and emission maxima): Cherenkov Radiation Energy Transfer (CRET) first, followed by multiple Förster Resonance Energy transfers (FRET): CRET ratios were calculated to give a rough estimate of the transfer efficiency. While CR is blue-weighted (300-500 nm), such cascades of Energy Transfers allowed to get a) fluorescence emission up to 710 nm, which is beyond the main CR window and within the near-infrared (NIR) window where biological tissues are most transparent, b) to amplify this emission and boost the radiance on that window: EMT6-tumor bearing mice injected with both a radionuclide and a mixture of fluorophores having a good spectral overlap, were shown to have nearly a two-fold radiance boost (measured on a NIR window centered on the emission wavelength of the last fluorophore in the Energy Transfer cascade) compared to a tumor injected with the radionuclide only. Some CR embarked light source could be converted into a near-infrared radiation, where biological tissues are most transparent.

TH-C-17A-03: Dynamic Visualization and Dosimetry of IMRT and VMAT Treatment Plans by Video-Rate Imaging of Cherenkov Radiation in Pure Water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glaser, A; Andreozzi, J; Davis, S

Purpose: A novel optical dosimetry technique for the QA and verification of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) radiotherapy plans was investigated for the first time by capturing images of the induced Cherenkov radiation in water. Methods: An intensified CCD camera (ICCD) was used to acquire a two-dimensional (2D) projection image of the Cherenkov radiation induced by IMRT and VMAT plans, based on the Task Group 119 C-Shape geometry. Plans were generated using the Varian Eclipse treatment planning system (TPS) and delivered using 6 MV x-rays from a Varian TrueBeam Linear Accelerator (Linac) incident on a watermore » tank. The ICCD acquisition was gated to the Linac, operated for single pulse imaging, and binned to a resolution of 512×512 pixels. The resulting videos were analyzed temporally for regions of interest (ROI) covering the planning target volume (PTV) and organ at risk (OAR) and summed to obtain an overall light distribution, which was compared to the expected dose distribution from the TPS using a gammaindex analysis. Results: The chosen camera settings resulted in data at 23.5 frames per second. Temporal intensity plots of the PTV and OAR ROIs confirmed the preferential delivery of dose to the PTV versus the OAR, and the gamma analysis yielded 95.2% and 95.6% agreement between the light distribution and expected TPS dose distribution based upon a 3% / 3 mm dose difference and distance-to-agreement criterion for the IMRT and VMAT plans respectively. Conclusion: The results from this initial study demonstrate the first documented use of Cherenkov radiation for optical dosimetry of dynamic IMRT and VMAT treatment plans. The proposed modality has several potential advantages over alternative methods including the real-time nature of the acquisition, and upon future refinement may prove to be a robust and novel dosimetry method with both research and clinical applications. NIH R01CA109558 and R21EB017559.« less

Fitting PMT Responses with an Artificial Neural Network

NASA Astrophysics Data System (ADS)

Kemmerer, William; Niculescu, Gabriel

2017-09-01

Correctly modeling the low light responce of photodetectors such as photomultiplier tubes (PMT) is crucial for the operation of particle detection relying on the Cherenkov effect. The Gas Ring Imaging Cherenkov (GRINCH) in the SuperBigBite Spectrometer (SBS) at Jefferson Lab will rely on an array of 510 29 mm 9125B PMTs. To select the tubes for this array, more than 900 were tested and their low-light response function was fitted. An Artificial Neural Network was defined and trained to extract the relevant PMT parameters without carrying out a detailed fir of the ADC spectrum. These results will be discussed here. NSF.

p-polarized Cherenkov THz wave radiation generated by optical rectification for a Brewster-cut LiNbO3 crystal

NASA Astrophysics Data System (ADS)

Liu, Pengxiang; Xu, Degang; Liu, Changming; Lv, Da; Lv, Yingjin; Wang, Peng; Yao, Jianquan

2011-08-01

In this paper, we investigated p-polarized Cherenkov radiation excited by an ultra-short laser pulse focused into a line in an LiNbO3 crystal. The geometries of p- and s-polarized THz generation were both analyzed. We did further calculations on p-polarized THz radiation and designed a Brewster-cut geometry. The radiated energy and conversion efficiency were roughly estimated. Compared with s-polarized waves radiated from a Cherenkov-cut crystal, p-polarized THz radiation has lower energy and conversion efficiency, but higher intensity and better beam quality. The effect of angular dispersion between the spectral components of the THz pulse after refraction at the Brewster surface was also discussed.

Reverse surface-polariton cherenkov radiation

PubMed Central

Tao, Jin; Wang, Qi Jie; Zhang, Jingjing; Luo, Yu

2016-01-01

The existence of reverse Cherenkov radiation for surface plasmons is demonstrated analytically. It is shown that in a metal-insulator-metal (MIM) waveguide, surface plasmon polaritons (SPPs) excited by an electron moving at a speed higher than the phase velocity of SPPs can generate Cherenkov radiation, which can be switched from forward to reverse direction by tuning the core thickness of the waveguide. Calculations are performed in both frequency and time domains, demonstrating that a radiation pattern with a backward-pointing radiation cone can be achieved at small waveguide core widths, with energy flow opposite to the wave vector of SPPs. Our study suggests the feasibility of generating and steering electron radiation in simple plasmonic systems, opening the gate for various applications such as velocity-selective particle detections. PMID:27477061

Muon imaging of volcanoes with Cherenkov telescopes

NASA Astrophysics Data System (ADS)

Carbone, Daniele; Catalano, Osvaldo; Cusumano, Giancarlo; Del Santo, Melania; La Parola, Valentina; La Rosa, Giovanni; Maccarone, Maria Concetta; Mineo, Teresa; Pareschi, Giovanni; Sottile, Giuseppe; Zuccarello, Luciano

2017-04-01

The quantitative understanding of the inner structure of a volcano is a key feature to model the processes leading to paroxysmal activity and, hence, to mitigate volcanic hazards. To pursue this aim, different geophysical techniques are utilized, that are sensitive to different properties of the rocks (elastic, electrical, density). In most cases, these techniques do not allow to achieve the spatial resolution needed to characterize the shallowest part of the plumbing system and may require dense measurements in active zones, implying a high level of risk. Volcano imaging through cosmic-ray muons is a promising technique that allows to overcome the above shortcomings. Muons constantly bombard the Earth's surface and can travel through large thicknesses of rock, with an energy loss depending on the amount of crossed matter. By measuring the absorption of muons through a solid body, one can deduce the density distribution inside the target. To date, muon imaging of volcanic structures has been mainly achieved with scintillation detectors. They are sensitive to noise sourced from (i) the accidental coincidence of vertical EM shower particles, (ii) the fake tracks initiated from horizontal high-energy electrons and low-energy muons (not crossing the target) and (iii) the flux of upward going muons. A possible alternative to scintillation detectors is given by Cherenkov telescopes. They exploit the Cherenkov light emitted when charged particles (like muons) travel through a dielectric medium, with velocity higher than the speed of light. Cherenkov detectors are not significantly affected by the above noise sources. Furthermore, contrarily to scintillator-based detectors, Cherenkov telescopes permit a measurement of the energy spectrum of the incident muon flux at the installation site, an issue that is indeed relevant for deducing the density distribution inside the target. In 2014, a prototype Cherenkov telescope was installed at the Astrophysical Observatory of Serra La Nave (southern flank of Mt. Etna, Italy; 1740m a.s.l.), in the framework of ASTRI, a flagship project of the Italian Ministry of Education, University and Research, led by the Italian National Institute of Astrophysics (INAF). This offers the opportunity to test the use of a Cherenkov telescope for imaging volcanic structures. Starting from this know-how, we plan to develop a new prototype of Cherenkov detector with suitable characteristics for installation in the summit zone of Etna volcano (around 3000m a.s.l.).

Technical Note: On maximizing Cherenkov emissions from medical linear accelerators.

PubMed

Shrock, Zachary; Yoon, Suk W; Gunasingha, Rathnayaka; Oldham, Mark; Adamson, Justus

2018-04-19

Cherenkov light during MV radiotherapy has recently found imaging and therapeutic applications but is challenged by relatively low fluence. Our purpose is to investigate the feasibility of increasing Cherenkov light production during MV radiotherapy by increasing photon energy and applying specialized beam-hardening filtration. GAMOS 5.0.0, a GEANT4-based framework for Monte Carlo simulations, was used to model standard clinical linear accelerator primary photon beams. The photon source was incident upon a 17.8 cm 3 cubic water phantom with a 94 cm source to surface distance. Dose and Cherenkov production was determined at depths of 3-9 cm. Filtration was simulated 15 cm below the photon beam source. Filter materials included aluminum, iron, and copper with thicknesses of 2-20 cm. Histories used depended on the level of attenuation from the filter, ranging from 100 million to 2 billion. Comparing average dose per history also allowed for evaluation of dose-rate reduction for different filters. Overall, increasing photon beam energy is more effective at improving Cherenkov production per unit dose than is filtration, with a standard 18 MV beam yielding 3.3-4.0× more photons than 6 MV. Introducing an aluminum filter into an unfiltered 2400 cGy/min 10 MV beam increases the Cherenkov production by 1.6-1.7×, while maintaining a clinical dose rate of 300 cGy/min, compared to increases of ~1.5× for iron and copper. Aluminum was also more effective than the standard flattening filter, with the increase over the unfiltered beam being 1.4-1.5× (maintaining 600 cGy/min dose rate) vs 1.3-1.4× for the standard flattening filter. Applying a 10 cm aluminum filter to a standard 18 MV, photon beam increased the Cherenkov production per unit dose to 3.9-4.3× beyond that of 6 MV (vs 3.3-4.0× for 18 MV with no aluminum filter). Through a combination of increasing photon energy and applying specialized beam-hardening filtration, the amount of Cherenkov photons per unit radiotherapy dose can be increased substantially. © 2018 American Association of Physicists in Medicine.

Cherenkov flashes and fluorescence flares on telescopes: New lights on UHECR spectroscopy while unveiling neutrinos astronomy

NASA Astrophysics Data System (ADS)

Fargion, D.; Oliva, P.; Massa, F.; Moreno, G.

2008-04-01

Multi-GeV and TeVs gamma sources are currently observed by their Cherenkov flashes on telescopes (as Magic, Hess and Veritas), looking vertically up into the sky. These detectors while pointing horizontally should also reveal the fluorescence flare tails of nearby down-going air-showers. Such air-showers, born at higher (tens of km) altitudes, are growing and extending up to lowest atmospheres (EeVs) or up to higher (few km) quotas (PeVs). These fluorescence signals extend the Cherenkov telescopes to a much higher cosmic ray spectroscopy. Vice versa, as it has been foreseen and only recently observed, the opposite takes place. Fluorescence telescopes made for UHECR detection (as AUGER ones) may be blazed by inclined Cherenkov lights: less energetic but frequent (PeVs) CR are expected to be often detected. Nearly dozens of blazing Cherenkov at EeV should be already found each year in AUGER, possibly in hybrid mode (FD SD, fluorescence and/or surface detector). Many more CR events (tens of thousands or hundreds of thousands) at PeVs energies should blaze Cherenkov lights each year on the AUGER fluorescence telescopes. Their UV filter may partially hide their signals and they cannot, unfortunately, be seen in any hybrid mode. At these comparable energies, the rarest UHE resonant anti-neutrino ν+e interactions in air at MW2/2me=6.3PeV energy offer enhanced W neutrino astronomy showering at air horizon, at ˜90, while crossing deep atmosphere column depth or Earth (Ande) boundaries. However, AUGER fluorescence detector (FD) are facing opposite way. An additional decay channel also rises (after resonant neutrino skimming Earth) via their secondary τ exit in air, by decay in flight via amplified showering: ν+e→W→ν+τ. Moreover, expected horizontal UHE GZK neutrinos ντν at EeVs energy, powered by guaranteed cosmogenic GZK [K.Greisen, Phys. Rev. Lett. 16 (1966) 748; G.T. Zatsepin, V.A. Kuz’min, Zh. Eks. Teor. Fiz., Pis’ma Red. 4 (1966) 144], νμν flavor conversions (in cosmic distances), are also producing penetrating UHE EeV lepton taus that could sample, better and deeper than PeVs ones, the Earth skin. Such almost horizontal and up-going tau showers, originated by UHE astronomical neutrino, may shower and flash by fluorescence and/or Cherenkov diffused lights at AUGER sky in a few years (nearly three). Vice versa, at Hess, MAGIC and VERITAS horizons, at tens or a hundred km distances, the same up-going ττ¯ air-showers might rise via fluorescence. On axis they might blaze (rarely) as a Cherenkov flashes below the horizons, possibly correlated to BL Lac or GRB activity. Also UHE (1 0.1 EeV) GZK τ showering can be observed upward once reflected onto clouds. The geomagnetic splitting may tag the energy as well as the inclined shower footprint as seen in a recent peculiar event in AUGER. Additional stereoscopic detection may define the event origination distance and its consequent primary composition, extending our understanding on UHECR composition.

Comparison of Cherenkov excited fluorescence and phosphorescence molecular sensing from tissue with external beam irradiation.

PubMed

Lin, Huiyun; Zhang, Rongxiao; Gunn, Jason R; Esipova, Tatiana V; Vinogradov, Sergei; Gladstone, David J; Jarvis, Lesley A; Pogue, Brian W

2016-05-21

Ionizing radiation delivered by a medical linear accelerator (LINAC) generates Cherenkov emission within the treated tissue. A fraction of this light, in the 600-900 nm wavelength region, propagates through centimeters of tissue and can be used to excite optical probes in vivo, enabling molecular sensing of tissue analytes. The success of isolating the emission signal from this Cherenkov excitation background is dependent on key factors such as: (i) the Stokes shift of the probe spectra; (ii) the excited state lifetime; (iii) the probe concentration; (iv) the depth below the tissue surface; and (v) the radiation dose used. Previous studies have exclusively focused on imaging phosphorescent dyes, rather than fluorescent dyes. However there are only a few biologically important phosphorescent dyes and yet in comparison there are thousands of biologically relevant fluorescent dyes. So in this study the focus was a study of efficacy of Cherenkov-excited luminescence using fluorescent commercial near-infrared probes, IRDye 680RD, IRDye 700DX, and IRDye 800CW, and comparing them to the well characterized phosphorescent probe Oxyphor PtG4, an oxygen sensitive dye. Each probe was excited by Cherenkov light from a 6 MV external radiation beam, and measured in continuous wave or time-gated modes. The detection was performed by spectrally resolving the luminescence signals, and measuring them with spectrometer-based separation on an ICCD detector. The results demonstrate that IRDye 700DX and PtG4 allowed for the maximal signal to noise ratio. In the case of the phosphorescent probe, PtG4, with emission decays on the microsecond (μs) time scale, time-gated acquisition was possible, and it allowed for higher efficacy in terms of the probe concentration and detection depth. Phantoms containing the probe at 5 mm depth could be detected at concentrations down to the nanoMolar range, and at depths into the tissue simulating phantom near 3 cm. In vivo studies showed that 5 nmol of dye was readily detected with radiation doses less than 5 cGy. Since concentration, radiation dose and depth each contribute to the level of the detected signal, it may be possible to improve any of these parameters at expense of the others. This paradigm of nanoMolar sensitivity for optical reporters in vivo introduces the concept of molecular sensing of tumors during therapy or diagnostically with biologically relevant concentrations of fluorescent reporters.

Comparison of Cherenkov excited fluorescence and phosphorescence molecular sensing from tissue with external beam irradiation

NASA Astrophysics Data System (ADS)

Lin, Huiyun; Zhang, Rongxiao; Gunn, Jason R.; Esipova, Tatiana V.; Vinogradov, Sergei; Gladstone, David J.; Jarvis, Lesley A.; Pogue, Brian W.

2016-05-01

Ionizing radiation delivered by a medical linear accelerator (LINAC) generates Cherenkov emission within the treated tissue. A fraction of this light, in the 600-900 nm wavelength region, propagates through centimeters of tissue and can be used to excite optical probes in vivo, enabling molecular sensing of tissue analytes. The success of isolating the emission signal from this Cherenkov excitation background is dependent on key factors such as: (i) the Stokes shift of the probe spectra; (ii) the excited state lifetime; (iii) the probe concentration; (iv) the depth below the tissue surface; and (v) the radiation dose used. Previous studies have exclusively focused on imaging phosphorescent dyes, rather than fluorescent dyes. However there are only a few biologically important phosphorescent dyes and yet in comparison there are thousands of biologically relevant fluorescent dyes. So in this study the focus was a study of efficacy of Cherenkov-excited luminescence using fluorescent commercial near-infrared probes, IRDye 680RD, IRDye 700DX, and IRDye 800CW, and comparing them to the well characterized phosphorescent probe Oxyphor PtG4, an oxygen sensitive dye. Each probe was excited by Cherenkov light from a 6 MV external radiation beam, and measured in continuous wave or time-gated modes. The detection was performed by spectrally resolving the luminescence signals, and measuring them with spectrometer-based separation on an ICCD detector. The results demonstrate that IRDye 700DX and PtG4 allowed for the maximal signal to noise ratio. In the case of the phosphorescent probe, PtG4, with emission decays on the microsecond (μs) time scale, time-gated acquisition was possible, and it allowed for higher efficacy in terms of the probe concentration and detection depth. Phantoms containing the probe at 5 mm depth could be detected at concentrations down to the nanoMolar range, and at depths into the tissue simulating phantom near 3 cm. In vivo studies showed that 5 nmol of dye was readily detected with radiation doses less than 5 cGy. Since concentration, radiation dose and depth each contribute to the level of the detected signal, it may be possible to improve any of these parameters at expense of the others. This paradigm of nanoMolar sensitivity for optical reporters in vivo introduces the concept of molecular sensing of tumors during therapy or diagnostically with biologically relevant concentrations of fluorescent reporters.

Broadly tunable terahertz difference-frequency generation in quantum cascade lasers on silicon

NASA Astrophysics Data System (ADS)

Jung, Seungyong; Kim, Jae Hyun; Jiang, Yifan; Vijayraghavan, Karun; Belkin, Mikhail A.

2018-01-01

We report broadly tunable terahertz (THz) sources based on intracavity Cherenkov difference-frequency generation in quantum cascade lasers transfer-printed on high-resistivity silicon substrates. Spectral tuning from 1.3 to 4.3 THz was obtained from a 2-mm long laser chip using a modified Littrow external cavity setup. The THz power output and the midinfrared-to-THz conversion efficiency of the devices transferred on silicon are dramatically enhanced, compared with the devices on a native semi-insulating InP substrate. Enhancement is particularly significant at higher THz frequencies, where the tail of the Reststrahlen band results in a strong absorption of THz light in the InP substrate.

THz-wave sensing via pump and signal wave detection interacted with evanescent THz waves.

PubMed

Akiba, Takuya; Kaneko, Naoya; Suizu, Koji; Miyamoto, Katsuhiko; Omatsu, Takashige

2013-09-15

We report a novel sensing technique that uses an evanescent terahertz (THz) wave, without detecting the THz wave directly. When a THz wave generated by Cherenkov phase matching via difference frequency generation undergoes total internal reflection, the evanescent THz wave is subject to a phase change and an amplitude decrease. The reflected THz wave, under the influence of the sample, interferes with the propagating THz wave and the changing electric field of the THz wave interacts with the electric field of the pump waves. We demonstrate a sensing technique for detecting changes in the electric field of near-infrared light, transcribed from changes in the electric field of a THz wave.

Optical frequency up-conversion by supercontinuum-free widely-tunable fiber-optic Cherenkov radiation

PubMed Central

Tu, Haohua; Boppart, Stephen A.

2010-01-01

Spectrally-isolated narrowband Cherenkov radiation from commercial nonlinear photonic crystal fibers is demonstrated as an ultrafast optical source with a visible tuning range of 485–690 nm, which complementarily extends the near-infrared tuning range of 690–1020 nm from the corresponding femtosecond Ti:sapphire pump laser. Pump-to-signal conversion efficiency routinely surpasses 10%, enabling multimilliwatt visible output across the entire tuning range. Appropriate selection of fiber parameters and pumping conditions efficiently suppresses the supercontinuum generation typically associated with Cherenkov radiation. PMID:19506636

Reversed Cherenkov emission of terahertz waves from an ultrashort laser pulse in a sandwich structure with nonlinear core and left-handed cladding.

PubMed

Bakunov, M I; Mikhaylovskiy, R V; Bodrov, S B; Luk'yanchuk, B S

2010-01-18

We propose a scheme for an experimental verification of the reversed Cherenkov effect in left-handed media. The scheme uses optical-to-terahertz conversion in a planar sandwichlike structure that consists of a nonlinear core cladded with a material that exhibits left-handedness at terahertz frequencies. The focused into a line femtosecond laser pulse propagates in the core and emits Cherenkov wedge of terahertz waves in the cladding. We developed a theory that describes terahertz generation in such a structure and calculated spatial distribution of the generated terahertz field, its energy spectrum, and optical-to-terahertz conversion efficiency. The proposed structure can be a useful tool for characterization of the electromagnetic properties of metamaterials in the terahertz frequency range.

Aspherical mirrors for the Gamma-ray Cherenkov Telescope, a Schwarschild-Couder prototype proposed for the future Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Dournaux, J. L.; Gironnet, J.; Huet, J. M.; Laporte, P.; Chadwick, P.; Dumas, D.; Pech, M.; Rulten, C. B.; Sayède, F.; Schmoll, J.; Sol, H.

2016-07-01

The Cherenkov Telescope Array (CTA) project, led by an international collaboration of institutes, aims to create the world's largest next generation Very High-Energy (VHE) gamma-ray telescope array, devoted to observations in a wide band of energy, from a few tens of GeV to more than 100 TeV. The Small-Sized Telescopes (SSTs) are dedicated to the highest energy range. Seventy SSTs are planned in the baseline array design with a required lifetime of about 30 years. The GCT (Gamma-ray Cherenkov Telescope) is one of the prototypes proposed for CTA's SST sub-array. It is based on a Schwarzschild-Couder dual-mirror optical design. This configuration has the benefit of increasing the field-of-view and decreasing the masses of the telescope and of the camera. But, in spite of these many advantages, it was never implemented before in ground-based Cherenkov astronomy because of the aspherical and highly curved shape required for the mirrors. The optical design of the GCT consists of a primary 4 meter diameter mirror, segmented in six aspherical petals, a secondary monolithic 2-meter mirror and a light camera. The reduced number of segments simplifies the alignment of the telescope but complicates the shape of the petals. This, combined with the strong curvature of the secondary mirror, strongly constrains the manufacturing process. The Observatoire de Paris implemented metallic lightweight mirrors for the primary and the secondary mirrors of GCT. This choice was made possible because of the relaxed requirements of optical Cherenkov telescopes compared to optical ones. Measurements on produced mirrors show that these ones can fulfill requirements in shape, PSF and reflectivity, with a clear competition between manufacturing cost and final performance. This paper describes the design of these mirrors in the context of their characteristics and how design optimization was used to produce a lightweight design. The manufacturing process used for the prototype and planned for the large scale production is presented as well as the performance, in terms of geometric and optical properties, of the produced mirrors. The alignment procedure of the mirrors is also detailed. This technique is finally compared to other manufacturing techniques based on composite glass mirrors within the framework of GCT mirrors specificities.

Studies of runaway electrons via Cherenkov effect in tokamaks

NASA Astrophysics Data System (ADS)

Zebrowski, J.; Jakubowski, L.; Rabinski, M.; Sadowski, M. J.; Jakubowski, M. J.; Kwiatkowski, R.; Malinowski, K.; Mirowski, R.; Mlynar, J.; Ficker, O.; Weinzettl, V.; Causa, F.; COMPASS; FTU Teams

2018-01-01

The paper concerns measurements of runaway electrons (REs) which are generated during discharges in tokamaks. The control of REs is an important task in experimental studies within the ITER-physics program. The NCBJ team proposed to study REs by means of Cherenkov-type detectors several years ago. The Cherenkov radiation, induced by REs in appropriate radiators, makes it possible to identify fast electron beams and to determine their spatial- and temporal-characteristics. The results of recent experimental studies of REs, performed in two tokamaks - COMPASS in Prague and FTU in Frascati, are summarized and discussed in this paper. Examples of the electron-induced signals, as recorded at different experimental conditions and scenarios, are presented. Measurements performed with a three-channel Cherenkov-probe in COMPASS showed that the first fast electron peaks can be observed already during the current ramp-up phase. A strong dependence of RE-signals on the radial position of the Cherenkov probe was observed. The most distinct electron peaks were recorded during the plasma disruption. The Cherenkov signals confirmed the appearance of post-disruptive RE beams in circular-plasma discharges with massive Ar-puffing. During experiments at FTU a clear correlation between the Cherenkov detector signals and the rotation of magnetic islands was identified.

Redshifted Cherenkov Radiation for in vivo Imaging: Coupling Cherenkov Radiation Energy Transfer to multiple Förster Resonance Energy Transfers

PubMed Central

Bernhard, Yann; Collin, Bertrand; Decréau, Richard A.

2017-01-01

Cherenkov Radiation (CR), this blue glow seen in nuclear reactors, is an optical light originating from energetic β-emitter radionuclides. CR emitter 90Y triggers a cascade of energy transfers in the presence of a mixed population of fluorophores (which each other match their respective absorption and emission maxima): Cherenkov Radiation Energy Transfer (CRET) first, followed by multiple Förster Resonance Energy transfers (FRET): CRET ratios were calculated to give a rough estimate of the transfer efficiency. While CR is blue-weighted (300–500 nm), such cascades of Energy Transfers allowed to get a) fluorescence emission up to 710 nm, which is beyond the main CR window and within the near-infrared (NIR) window where biological tissues are most transparent, b) to amplify this emission and boost the radiance on that window: EMT6-tumor bearing mice injected with both a radionuclide and a mixture of fluorophores having a good spectral overlap, were shown to have nearly a two-fold radiance boost (measured on a NIR window centered on the emission wavelength of the last fluorophore in the Energy Transfer cascade) compared to a tumor injected with the radionuclide only. Some CR embarked light source could be converted into a near-infrared radiation, where biological tissues are most transparent. PMID:28338043

From the speed of sound to the speed of light: Ultrasonic Cherenkov refractometry

NASA Astrophysics Data System (ADS)

Hallewell, G. D.

2017-12-01

Despite its success in the SLD CRID at the SLAC Linear Collider, ultrasonic measurement of Cherenkov radiator refractive index has been less fully exploited in more recent Cherenkov detectors employing gaseous radiators. This is surprising, since it is ideally suited to monitoring hydrostatic variations in refractive index as well as its evolution during the replacement of a light radiator passivation gas (e.g. N2, CO2) with a heavier fluorocarbon (e.g. C4F10[CF4]; mol. wt. 188[88]). The technique exploits the dependence of sound velocity on the molar concentrations of the two components at known temperature and pressure. The SLD barrel CRID used an 87%C5F12/13%N2 blend, mixed before injection into the radiator vessel: blend control based on ultrasonic mixture analysis maintained the β=1 Cherenkov ring angle to a long term variation better than ±0.3%, with refractivity monitored ultrasonically at multiple points within the radiator vessel. Recent advances using microcontroller-based electronics have led to ultrasonic instruments capable of simultaneously measuring gas flow and binary mixture composition in the fluorocarbon evaporative cooling systems of the ATLAS Inner Detector. Sound transit times are measured with multi-MHz transit time clocks in opposite directions in flowing gas for simultaneous measurement of flow rate and sound velocity. Gas composition is evaluated in real-time by comparison with a sound velocity/composition database. Such instruments could be incorporated into new and upgraded gas Cherenkov detectors for radiator gas mixture (and corresponding refractive index) measurement to a precision better than 10-3. They have other applications in binary gas analysis - including in Xenon-based anaesthesia. These possibilities are discussed.

Volcanoes muon imaging using Cherenkov telescopes

NASA Astrophysics Data System (ADS)

Catalano, O.; Del Santo, M.; Mineo, T.; Cusumano, G.; Maccarone, M. C.; Pareschi, G.

2016-01-01

A detailed understanding of a volcano inner structure is one of the key-points for the volcanic hazards evaluation. To this aim, in the last decade, geophysical radiography techniques using cosmic muon particles have been proposed. By measuring the differential attenuation of the muon flux as a function of the amount of rock crossed along different directions, it is possible to determine the density distribution of the interior of a volcano. Up to now, a number of experiments have been based on the detection of the muon tracks crossing hodoscopes, made up of scintillators or nuclear emulsion planes. Using telescopes based on the atmospheric Cherenkov imaging technique, we propose a new approach to study the interior of volcanoes detecting of the Cherenkov light produced by relativistic cosmic-ray muons that survive after crossing the volcano. The Cherenkov light produced along the muon path is imaged as a typical annular pattern containing all the essential information to reconstruct particle direction and energy. Our new approach offers the advantage of a negligible background and an improved spatial resolution. To test the feasibility of our new method, we have carried out simulations with a toy-model based on the geometrical parameters of ASTRI SST-2M, i.e. the imaging atmospheric Cherenkov telescope currently under installation onto the Etna volcano. Comparing the results of our simulations with previous experiments based on particle detectors, we gain at least a factor of 10 in sensitivity. The result of this study shows that we resolve an empty cylinder with a radius of about 100 m located inside a volcano in less than 4 days, which implies a limit on the magma velocity of 5 m/h.

Cherenkov radiation imaging of beta emitters: in vitro and in vivo results

NASA Astrophysics Data System (ADS)

Spinelli, Antonello E.; Boschi, Federico; D'Ambrosio, Daniela; Calderan, Laura; Marengo, Mario; Fenzi, Alberto; Menegazzi, Marta; Sbarbati, Andrea; Del Vecchio, Antonella; Calandrino, Riccardo

2011-08-01

The main purpose of this work was to investigate both in vitro and in vivo Cherenkov radiation (CR) emission coming from 18F and 32P. The main difference between 18F and 32P is mainly the number of the emitted light photons, more precisely the same activity of 32P emits more CR photons with respect to 18F. In vitro results obtained by comparing beta counter measurements with photons average radiance showed that Cherenkov luminescence imaging (CLI) allows quantitative tracer activity measurements. In order to investigate in vivo the CLI approach, we studied an experimental xenograft tumor model of mammary carcinoma (BB1 tumor cells). Cherenkov in vivo dynamic whole body images of tumor bearing mice were acquired and the tumor tissue time activity curves reflected the well-known physiological accumulation of 18F-FDG in malignant tissues with respect to normal tissues. The results presented here show that it is possible to use conventional optical imaging devices for in vitro or in vivo study of beta emitters.

EUSO-SPB2: second generation Extreme Universe Space Observatory (EUSO) on board a Super-Pressure Balloon (SPB), The University of Alabama in Huntsville, Co-I PROPOSAL

NASA Astrophysics Data System (ADS)

Reardon, Patrick

This is the Co-Investigator Proposal for EUSO-SPB2, second generation Extreme Universe Space Observatory on a Super-Pressure Balloon, being led by PI Angela V. Olinto at the University of Chicago. We propose to design, build, deploy, and publish the scientific results of a second generation of the Extreme Universe Space Observatory (EUSO), to be flown aboard a Super-Pressure Balloon (SBP). EUSO-SPB2 will monitor the night sky of the Southern hemisphere to study cosmic rays of very high to ultrahigh energies and pioneer the search for cosmogenic tau neutrinos from space. EUSO-SPB2 will be the first instrument to observe Cherenkov light from extensive air-showers high in the atmosphere. EUSOSPB2 will observe a large sample of cosmic rays from 0.1 to 1 EeV with the Cherenkov technique and will discriminate among the Cherenkov profiles of primary protons, heavy nuclei, and photons. It will also characterize the background for upward going showers initiated by the decay of tau leptons, which are expected to be produced by Earthskimming tau neutrinos. A coincidence veto will be developed for EUSO-SPB2 so it can characterize the background for Cherenkov signals from the neutrino produced tau leptons. EUSO-SPB2 will also use fluorescence observations to measure, for the first time, the evolution of nearly horizontal high altitude extensive air showers, which develop at the nearly constant low-density atmosphere. Such measurements will provide a unique channel to probe hadronic interaction models at ultrahigh energies, and may elucidate the reason why ultrahigh-energy cosmic ray (UHECR) showers observed by ground-based detectors contain more muons than expected from hadronic interaction models. EUSO-SPB2 is a pathfinder for the more ambitious space-based measurements by the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA), currently proposed for a NASA design study. POEMMA will combine the well-developed Orbiting Widefield Light-collectors (OWL) concept with the recently proposed CHerenkov from Astrophysical Neutrinos Telescope (CHANT) concept to form a multi-messenger probe of the most extreme environments in the universe. EUSO-SPB2 will inform the best strategy for future space missions such as POEMMA. EUSO-SPB2 will build upon the experience of flying EUSO-SPB1 in the Spring of 2017. A number of upgrades will render EUSO-SPB2 more powerful, including a Schmidt design telescope and a faster ultraviolet (UV) camera to increase exposure. The new instrument will detect Cherenkov and fluorescence signal from highly inclined UHECR events. Horizontal observations will lead to much larger acceptance with a distancedependent energy threshold. Depending on EUSO-SPB1 results, EUSO-SPB2 may also point closer to nadir in fluorescence. The combination of nadir (EUSO-SPB) and tilted (EUSO-SPB2) observations will explore the power of space observatories to observe UHECR of extreme energies. A long enough flight of EUSO-SPB2 observations will match and complement ground observations. EUSO-SPB2 addresses the fourth science goal of the 2011 NASA Strategic Plan, to “Discover how the universe works, explore how it began and evolved” and one of the “Physics of the Cosmos” questions in NASA’s 2010 Science Plan: “How do matter, energy, space, and time behave under the extraordinarily diverse conditions of the cosmos?” EUSO-SPB2 directly addresses the sixth question in the “Connecting Quarks with the Cosmos” report in its list of “Eleven Science Questions for the New Century,” which is “How do Cosmic Accelerators Work and What are They Accelerating?”

EUSO-SPB2: Second Generation Extreme Universe Space Observatory on a SuperPressure Balloon, Colorado School of Mines Co-I

NASA Astrophysics Data System (ADS)

Wiencke, Lawrence

This is a Co-Investigator Proposal for EUSO-SPB2, second generation Extreme Universe Space Observatory on a Super-Pressure Balloon. The PI is Angela V. Olinto (University of Chicago) Co-Is at Marshall Space Flight Center (Institution PI, M. Christl), Colorado School of Mines (Institution PI, L.Wiencke), University of Alabama Huntsville (Institution PI, P. Reardon), and Lehman College, CUNY (Institution PI, L. Anchordoqui). We propose to design, build, deploy, and publish the scientific results of a second generation of the Extreme Universe Space Observatory (EUSO), to be flown aboard a Super-Pressure Balloon (SBP). EUSO-SPB2 will monitor the night sky of the Southern hemisphere to study cosmic rays of very high to ultrahigh energies and pioneer the search for cosmogenic tau neutrinos from space. EUSO-SPB2 will be the first instrument to observe Cherenkov light from extensive airshowers high in the atmosphere. EUSO-SPB2 will observe a large sample of cosmic rays from 0.1 to 1 EeV with the Cherenkov technique and will discriminate among the Cherenkov profiles of primary protons, heavy nuclei, and photons. It will also characterize the background for upward going showers initiated by the decay of tau leptons, which are expected to be produced by Earth-skimming tau neutrinos. A coincidence veto will be developed for EUSO-SPB2 so it can characterize the background for Cherenkov signals from the neutrino produced tau leptons. EUSO-SPB2 will also use fluorescence observations to measure, for the first time, the evolution of nearly horizontal high altitude extensive air showers, which develop at the nearly constant low-density atmosphere. Such measurements will provide a unique channel to probe hadronic interaction models at ultrahigh energies, and may elucidate the reason why ultrahigh-energy cosmic ray (UHECR) showers observed by ground-based detectors contain more muons than expected from hadronic interaction models. EUSO-SPB2 is a pathfinder for the more ambitious space-based measurements by the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA), currently proposed for a NASA design study. POEMMA will combine the well-developed Orbiting Wide-field Light-collectors (OWL) concept with the recently proposed CHerenkov from Astrophysical Neutrinos Telescope (CHANT) concept to form a multi-messenger probe of the most extreme environments in the universe. EUSO-SPB2 will inform the best strategy for future space missions such as POEMMA. EUSO-SPB2 will build upon the experience of flying EUSO-SPB1 in the Spring of 2017. A number of upgrades will render EUSO-SPB2 more powerful, including a Schmidt design telescope and a faster ultraviolet (UV) camera to increase exposure. The new instrument will detect Cherenkov and fluorescence signal from highly inclined UHECR events. Horizontal observations will lead to much larger acceptance with a distancedependent energy threshold. Depending on EUSO-SPB1 results, EUSO-SPB2 may also point closer to nadir in fluorescence. Narir (EUSO-SPB) and tilted (EUSO-SPB2) observations will explore the power of space observatories to observe UHECR of extreme energies. A long enough flight of EUSO-SPB2 observations will match and complement ground observations. EUSO-SPB2 addresses the fourth science goal of the 2011 NASA Strategic Plan, to ``Discover how the universe works, explore how it began and evolved'' and one of the ``Physics of the Cosmos'' questions in NASA's 2010 Science Plan: ``How do matter, energy, space, and time behave under the extraordinarily diverse conditions of the cosmos?'' EUSO-SPB2 directly addresses the sixth question in the ``Connecting Quarks with the Cosmos'' report in its list of ``Eleven Science Questions for the Ne What are They Accelerating?''w Century,'' which is ``How do Cosmic Accelerators Work and What are they Accelerating?''

EUSO-SPB2: Second Generation Extreme Universe Space Observatory on a SuperPressure Balloon

NASA Astrophysics Data System (ADS)

Olinto, Angela

This is the lead Institution Co-Investigator Proposal for EUSO-SPB2, second generation Extreme Universe Space Observatory on a Super-Pressure Balloon. It is led by PI Angela V. Olinto at the University of Chicago with Co-Is at Marshall Space Flight Center (Institution PI, Mark Christl), Colorado School of Mines (Institution PI, Lawrence Wiencke), University of Alabama Huntsville (Institution PI, Patrick Reardon), and Lehman College, CUNY (Institution PI, Luis Anchordoqui). We propose to design, build, deploy, and publish the scientific results of a second generation of the Extreme Universe Space Observatory (EUSO), to be flown aboard a Super-Pressure Balloon (SBP). EUSO-SPB2 will monitor the night sky of the Southern hemisphere to study cosmic rays of very high to ultrahigh energies and pioneer the search for cosmogenic tau neutrinos from space. EUSO-SPB2 will be the first instrument to observe Cherenkov light from extensive airshowers high in the atmosphere. EUSO-SPB2 will observe a large sample of cosmic rays from 0.1 to 1 EeV with the Cherenkov technique and will discriminate among the Cherenkov profiles of primary protons, heavy nuclei, and photons. It will also characterize the background for upward going showers initiated by the decay of tau leptons, which are expected to be produced by Earth-skimming tau neutrinos. A coincidence veto will be developed for EUSO-SPB2 so it can characterize the background for Cherenkov signals from the neutrino produced tau leptons. EUSO-SPB2 will also use fluorescence observations to measure, for the first time, the evolution of nearly horizontal high altitude extensive air showers, which develop at the nearly constant low-density atmosphere. Such measurements will provide a unique channel to probe hadronic interaction models at ultrahigh energies, and may elucidate the reason why ultrahigh-energy cosmic ray (UHECR) showers observed by ground-based detectors contain more muons than expected from hadronic interaction models. EUSO-SPB2 is a pathfinder for the more ambitious space-based measurements by the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA), currently proposed for a NASA design study. POEMMA will combine the well-developed Orbiting Wide-field Light-collectors (OWL) concept with the recently proposed CHerenkov from Astrophysical Neutrinos Telescope (CHANT) concept to form a multi-messenger probe of the most extreme environments in the universe. EUSO-SPB2 will inform the best strategy for future space missions such as POEMMA. EUSO-SPB2 will build upon the experience of flying EUSO-SPB1 in the Spring of 2017. A number of upgrades will render EUSO-SPB2 more powerful, including a Schmidt design telescope and a faster ultraviolet (UV) camera to increase exposure. The new instrument will detect Cherenkov and fluorescence signal from highly inclined UHECR events. Horizontal observations will lead to much larger acceptance with a distancedependent energy threshold. Depending on EUSO-SPB1 results, EUSO-SPB2 may also point closer to nadir in fluorescence. The combination of nadir (EUSO-SPB) and tilted (EUSO-SPB2) observations will explore the power of space observatories to observe UHECR of extreme energies. A long enough flight of EUSO-SPB2 observations will match and complement ground observations. EUSO-SPB2 addresses the fourth science goal of the 2011 NASA Strategic Plan, to “Discover how the universe works, explore how it began and evolved” and one of the “Physics of the Cosmos” questions in NASA’s 2010 Science Plan : “How do matter, energy, space, and time behave under the extraordinarily diverse conditions of the cosmos?” EUSO-SPB2 directly addresses the sixth question in the “Connecting Quarks with the Cosmos” report in its list of “Eleven Science Questions for the New Century,” which is “How do Cosmic Accelerators Work and What are They Accelerating?”

Remote Cherenkov imaging-based quality assurance of a magnetic resonance image-guided radiotherapy system.

PubMed

Andreozzi, Jacqueline M; Mooney, Karen E; Brůža, Petr; Curcuru, Austen; Gladstone, David J; Pogue, Brian W; Green, Olga

2018-06-01

Tools to perform regular quality assurance of magnetic resonance image-guided radiotherapy (MRIgRT) systems should ideally be independent of interference from the magnetic fields. Remotely acquired optical Cherenkov imaging-based dosimetry measurements in water were investigated for this purpose, comparing measures of dose accuracy, temporal dynamics, and overall integrated IMRT delivery. A 40 × 30.5 × 37.5 cm 3 water tank doped with 1 g/L of quinine sulfate was imaged using an intensified charge-coupled device (ICCD) to capture the Cherenkov emission while being irradiated by a commercial MRIgRT system (ViewRay™). The ICCD was placed down-bore at the end of the couch, 4 m from treatment isocenter and behind the 5-Gauss line of the 0.35-T MRI. After establishing optimal camera acquisition settings, square beams of increasing size (4.2 × 4.2 cm 2 , 10.5 × 10.5 cm 2 , and 14.7 × 14.7 cm 2 ) were imaged at 0.93 frames per second, from an individual cobalt-60 treatment head, to develop projection measures related to percent depth dose (PDD) curves and cross beam profiles (CPB). These Cherenkov-derived measurements were compared to ionization chamber (IC) and radiographic film dosimetry data, as well as simulation data from the treatment planning system (TPS). An intensity-modulated radiotherapy (IMRT) commissioning plan from AAPM TG-119 (C4:C-Shape) was also imaged at 2.1 frames per second, and the single linear sum image from 509 s of plan delivery was compared to the dose volume prediction generated by the TPS using gamma index analysis. Analysis of standardized test target images (1024 × 1024 pixels) yielded a pixel resolution of 0.37 mm/pixel. The beam width measured from the Cherenkov image-generated projection CBPs was within 1 mm accuracy when compared to film measurements for all beams. The 502 point measurements (i.e., pixels) of the Cherenkov image-based projection percent depth dose curves (pPDDs) were compared to pPDDs simulated by the treatment planning system (TPS), with an overall average error of 0.60%, 0.56%, and 0.65% for the 4.2, 10.5, and 14.7 cm square beams, respectively. The relationships between pPDDs and central axis PDDs derived from the TPS were used to apply a weighting factor to the Cherenkov pPDD, so that the Cherenkov data could be directly compared to IC PDDs (average error of -0.07%, 0.10%, and -0.01% for the same sized beams, respectively). Finally, the composite image of the TG-119 C4 treatment plan achieved a 95.1% passing rate using 4%/4 mm gamma index agreement criteria between Cherenkov intensity and TPS dose volume data. This is the first examination of Cherenkov-generated pPDDs and pCBPs in an MR-IGRT system. Cherenkov imaging measurements were fast to acquire, and minimal error was observed overall. Cherenkov imaging also provided novel real-time data for IMRT QA. The strengths of this imaging are the rapid data capture ability providing real-time, high spatial resolution data, combined with the remote, noncontact nature of imaging. The biggest limitation of this method is the two-dimensional (2D) projection-based imaging of three-dimensional (3D) dose distributions through the transparent water tank. © 2018 American Association of Physicists in Medicine.

The single mirror small sized telescope for the Cherenkov telescope array

NASA Astrophysics Data System (ADS)

Heller, M.; Schioppa, E., Jr.; Porcelli, A.; Pujadas, I. Troyano; Ziętara, K.; Della Volpe, D.; Montaruli, T.; Cadoux, F.; Favre, Y.; Aguilar, J. A.; Christov, A.; Prandini, E.; Rajda, P.; Rameez, M.; Bilnik, W.; Błocki, J.; Bogacz, L.; Borkowski, J.; Bulik, T.; Frankowski, A.; Grudzińska, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.; Kasperek, J.; Lalik, K.; Lyard, E.; Mach, E.; Mandat, D.; Marszałek, A.; Miranda, L. D. Medina; Michałowski, J.; Moderski, R.; Neronov, A.; Niemiec, J.; Ostrowski, M.; Paśko, P.; Pech, M.; Schovanek, P.; Seweryn, K.; Sliusar, V.; Skowron, K.; Stawarz, Ł.; Stodulska, M.; Stodulski, M.; Walter, R.; Więcek, M.; Zagdański, A.; CTA Consortium

2017-01-01

The Small Size Telescope with Single Mirror (SST-1M) is one of the proposed types of Small Size Telescopes (SST) for the Cherenkov Telescope Array (CTA). About 70 SST telescopes will be part the CTA southern array which will also include Medium Sized Telescopes (MST) in its threshold configuration. Optimized for the detection of gamma rays in the energy range from 5 TeV to 300 TeV, the SST-1M uses a Davies-Cotton optics with a 4 m dish diameter with a field of view of 9°. The Cherenkov light resulting from the interaction of the gamma-rays in the atmosphere is focused onto a 88 cm side-to-side hexagonal photo-detection plane. The latter is composed of 1296 hollow light guides coupled to large area hexagonal silicon photomultipliers (SiPM). The SiPM readout is fully digital readout as for the trigger system. The compact and lightweight design of the SST-1M camera offiers very high performance ideal for gamma-ray observation requirement. In this contribution, the concept, design, performance and status of the first telescope prototype are presented.

Real-time {sup 90}Sr Counter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaneko, Naomi; Kawai, Hideyuki; Kodama, Satoshi

2015-07-01

Radioisotopes have been emitted around Japan due to a nuclear accident at the Fukushima Daiichi nuclear power station in March 2011. A problem is the contaminated water including the atomic nucleus which relatively has a long half- life time and soluble such as {sup 90}Sr, {sup 137}Cs. Internal exposures by {sup 90}Sr are more dangerous than {sup 137}Cs's because Sr has effective half-life time of 18 years and property of accumulation in a born. We have developed real-time {sup 90}Sr counter which is sensitive beta-ray of maximum kinematic energy of 2.28 MeV from {sup 90}Sr and insensitive of beta-ray ofmore » maximum kinematic energy of 1.17 MeV and gamma-ray from {sup 90}Sr by Cherenkov detection. This counter composes of Cerenkov counter, trigger scintillation counter and veto counter. Silica aerogel for Cherenkov counter can obtain refractive index between 1.017 and 1.049 easily. And wavelength shifting fiber (WLSF) is used as a light guide for extending effective area and producing lower cost. A mechanism of the identification of {sup 90}Sr is explained in following. In case of {sup 90}Sr, when the trigger counter reacts on the beta-ray from {sup 90}Sr, aerogel emits the Cherenkov light and WLSF reacts and read the Cherenkov light. On the other hand, in case of {sup 137}Cs, the trigger counter reacts on the beta-ray, aerogel stops the beta- ray and Cherenkov light is not emitted. Therefore, aerogel has a function as a radiator and shielding material. the gamma-ray is not reacted on the lower density detector. Cosmic rays would be also reacted by the veto counter. A prototype counter whose the effective area is 30 cm x 10 cm was obtained (2.0±1.2){sup 3} of mis-identification as {sup 137}Cs/{sup 90}Sr. Detection limit in the surface contamination inspection depends on measurement time and effective area mainly. The sensitivity of wide range, 10{sup -2} - 10{sup 4} Bq/cm{sup 2}, is obtained by adjustment of detection level in circuit of this counter. A lower radioactive sample (< 10{sup -2} Bq/cm{sup 2}) allows be detected significantly by heating treatment to evaporate water shielding the beta-rays. (authors)« less

The TAIGA timing array HiSCORE - first results

NASA Astrophysics Data System (ADS)

Tluczykont, M.; Budnev, N.; Astapov, I.; Barbashina, N.; Bogdanov, A.; Boreyko, V.; Brückner, M.; Chiavassa, A.; Chvalaev, O.; Gress, O.; Gress, T.; Grishin, O.; Dyachok, A.; Epimakhov, S.; Fedorov, O.; Gafarov, A.; Gorbunov, N.; Grebenyuk, V.; Grinuk, A.; Horns, D.; Kalinin, A.; Karpov, N.; Kalmykov, N.; Kazarina, Y.; Kiryuhin, S.; Kokoulin, R.; Kompaniets, K.; Konstantinov, A.; Korosteleva, E.; Kozhin, V.; Kravchenko, E.; Kunnas, M.; Kuzmichev, L.; Lemeshev, Yu.; Lubsandorzhiev, B.; Lubsandorzhiev, N.; Mirgazov, R.; Mirzoyan, R.; Monkhoev, R.; Nachtigall, R.; Osipova, E.; Pakhorukov, A.; Panasyuk, M.; Pankov, L.; Petrukhin, A.; Poleschuk, V.; Popova, E.; Porelli, A.; Postnikov, E.; Prosin, V.; Ptuskin, V.; Rubtsov, G.; Pushnin, A.; Samoliga, V.; Satunin, P.; Semeney, Yu.; Silaev, A.; Silaev, A.; Skurikhin, A.; Slunecka, M.; Sokolov, A.; Spiering, C.; Sveshnikova, L.; Tabolenko, V.; Tarashansky, B.; Tkachenko, A.; Tkachev, L.; Voronin, D.; Wischnewski, R.; Zagorodnikov, A.; Zurbanov, V.; Zhurov, D.; Yashin, I.

2017-03-01

Observations of gamma rays up to several 100 TeV are particularly important to spectrally resolve the cutoff regime of the long-sought Pevatrons, the cosmic-ray PeV accelerators. One component of the TAIGA hybrid detector is the TAIGA-HiSCORE timing array, which currently consists of 28 wide angle (0.6 sr) air Cherenkov timing stations distributed on an area of 0.25 km2. The HiSCORE concept is based on (non-imaging) air shower front sampling with Cherenkov light. First results are presented.

Detection of tau neutrinos by imaging air Cherenkov telescopes

NASA Astrophysics Data System (ADS)

Góra, D.; Bernardini, E.

2016-09-01

This paper investigates the potential to detect tau neutrinos in the energy range of 1-1000 PeV searching for very inclined showers with imaging Cherenkov telescopes. A neutrino induced tau lepton escaping from the Earth may decay and initiate an air shower which can be detected by a fluorescence or Cherenkov telescope. We present here a study of the detection potential of Earth-skimming neutrinos taking into account neutrino interactions in the Earth crust, local matter distributions at various detector sites, the development of tau-induced showers in air and the detection of Cherenkov photons with IACTs. We analyzed simulated shower images on the camera focal plane and implemented generic reconstruction chains based on Hillas parameters. We find that present IACTs can distinguish air showers induced by tau neutrinos from the background of hadronic showers in the PeV-EeV energy range. We present the neutrino trigger efficiency obtained for a few configurations being considered for the next-generation Cherenkov telescopes, i.e. the Cherenkov Telescope Array. Finally, for a few representative neutrino spectra expected from astrophysical sources, we compare the expected event rates at running IACTs to what is expected for the dedicated IceCube neutrino telescope.

An emerging population of BL Lacs with extreme properties: towards a class of EBL and cosmic magnetic field probes?

NASA Astrophysics Data System (ADS)

Bonnoli, G.; Tavecchio, F.; Ghisellini, G.; Sbarrato, T.

2015-07-01

High-energy observations of extreme BL Lac objects, such as 1ES 0229+200 or 1ES 0347-121, recently focused interest both for blazar and jet physics and for the implication on the extragalactic background light and intergalactic magnetic field estimate. However, the number of these extreme highly peaked BL Lac objects (EHBL) is still rather small. Aiming at increase their number, we selected a group of EHBL candidates starting from the BL Lac sample of Plotkin et al. (2011), considering those undetected (or only barely detected) by the Large Area Telescope onboard Fermi and characterized by a high X-ray versus radio flux ratio. We assembled the multiwavelength spectral energy distribution of the resulting nine sources, profiting of publicly available archival observations performed by Swift, GALEX, and Fermi satellites, confirming their nature. Through a simple one-zone synchrotron self-Compton model we estimate the expected very high energy flux, finding that in the majority of cases it is within the reach of present generation of Cherenkov arrays or of the forthcoming Cherenkov Telescope Array.

SU-F-T-684: Analysis of Cherenkov Excitation in Tissue and the Feasibility of Cherenkov Excited Photodynamic Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saunders, Sara L; Andreozzi, Jacqueline M; Pogue, Brian W

Purpose: The irradiation of photodynamic agents with radiotherapy beams has been demonstrated to enhance tumor killing in various studies, and one proposed mechanism is the optical fluence of Cherenkov emission activating the photosensitizer. This mechanism is explored in Monte Carlo simulations of fluence as well as laboratory measurements of fluence and radical oxygen species. Methods: Simulations were completed using GAMOS/GEANT4 with a 6 MV photon beam in tissue. The effects of blood vessel diameter, blood oxygen saturation, and beam size were examined, recording spectral fluence. Experiments were carried out in solutions of photosensitizer and phantoms. Results: Cherenkov produced by amore » 100×100um{sup 2} 6 MV beam resulted in fluence of less than 1 nJ/cm{sup 2}/Gy per 1 nm wavelength. At this microscopic level, differences in absorption of blood and water in the tissue affected the fluence spectrum, but variation in blood oxygenation had little effect. Light in tissue resulting from larger (10mm ×10mm) 6 MV beams had greater fluence due to light transport and elastic scattering of optical photons, but this transport process also resulted in higher absorption shifts. Therefore, the spectrum produced by a microscopic beam was weighted more heavily in UV/blue wavelengths than the spectrum at the macroscopic level. At the macroscopic level, the total fluence available for absorption by Verteporfin (BPD) in tissue approached uJ/cm{sup 2} for a high radiation dose, indicating that photodynamic activation seems unlikely. Tissue phantom confirmation of these light levels supported this observation, and photosensitization measurements with a radical oxygen species reporter are ongoing. Conclusion: Simulations demonstrated that fluence produced by Cherenkov in tissue by 6 MV photon beams at typical radiotherapy doses appears insufficient to activate photosensitizers to the level required for threshold effects, yet this disagrees with published biological experiments. Experimental validation in tissue phantoms and cell studies are ongoing to clarify this discrepancy. Funding from NIH grant R01CA109558.« less

Search for Indirect Signals of Dark Matter with The High Altitude Water Cherenkov (HAWC) Observatory

NASA Astrophysics Data System (ADS)

Baughman, Brian; Harding, Patrick; HAWC Collaboration

2015-04-01

The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view observatory sensitive to 100 GeV-100 TeV gamma rays and cosmic rays. Located at an elevation of 4100 m on the Sierra Negra volcano in Mexico, HAWC observes extensive air showers from gamma rays via their production of Cherenkov light within an array of water tanks. With a wide field-of-view observing 2/3 of the sky each day and a sensitivity of greater than 1 Crab per day, HAWC has the ability to probe a large fraction of the sky for the signals of TeV-mass dark matter. HAWC's sensitivity to dark matter for several astrophysical sources and some early limits from the built detector will be presented.

A Search for Microsecond Gamma Ray Bursts From Primordial Black Holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frank Krennrich

2004-08-12

The project is called SGARFACE (Short Gamma Ray Front Air Cherenkov Experiment) and is an atmospheric Cherenkov detector to provide sensitivity to short bursts of gamma rays of extraterrestrial origin. The detector is an addition to the Whipple 10m gamma ray telescope on Mt. Hopkins in southern Arizona and uses a digital trigger module for recognizing Cherenkov light flashes from gamma ray bursts. The digital trigger modules have been designed, tested and constructed at Iowa State University and have been installed at the Whipple 10m telescope. Operation of the experiment started in March 2003 and data collecting will likely continuemore » until spring of 2005. A final results paper addressing a search for primordial black holes is likely to be finished by summer of 2005.« less

Using Deep Learning for Gamma Ray Source Detection at the First G-APD Cherenkov Telescope (FACT)

NASA Astrophysics Data System (ADS)

Bieker, Jacob

2018-06-01

Finding gamma-ray sources is of paramount importance for Imaging Air Cherenkov Telescopes (IACT). This study looks at using deep neural networks on data from the First G-APD Cherenkov Telescope (FACT) as a proof-of-concept of finding gamma-ray sources with deep learning for the upcoming Cherenkov Telescope Array (CTA). In this study, FACT’s individual photon level observation data from the last 5 years was used with convolutional neural networks to determine if one or more sources were present. The neural networks used various architectures to determine which architectures were most successful in finding sources. Neural networks offer a promising method for finding faint and extended gamma-ray sources for IACTs. With further improvement and modifications, they offer a compelling method for source detection for the next generation of IACTs.

WE-AB-303-04: A Tissue Model of Cherenkov Emission From the Skin Surface During Megavoltage X-Ray Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiles, A. N.; Loyalka, S. K.; Izaguirre, E. W.

Purpose: To develop a tissue model of Cherenkov radiation emitted from the skin surface during external beam radiotherapy. Imaging Cherenkov radiation emitted from human skin allows visualization of the beam position and potentially surface dose estimates, and our goal is to characterize the optical properties of these emissions. Methods: We developed a Monte Carlo model of Cherenkov radiation generated in a semi-infinite tissue slab by megavoltage x-ray beams with optical transmission properties determined by a two-layered skin model. We separate the skin into a dermal and an epidermal layer in our model, where distinct molecular absorbers modify the Cherenkov intensitymore » spectrum in each layer while we approximate the scattering properties with Mie and Rayleigh scattering from the highly structured molecular organization found in human skin. Results: We report on the estimated distributions of the Cherenkov wavelength spectrum, emission angles, and surface distribution for the modeled irradiated skin surface. The expected intensity distribution of Cherenkov radiation emitted from skin shows a distinct intensity peak around 475 nm, the blue region of the visible spectrum, between a pair of optical absorption bands in hemoglobin and a broad plateau beginning near 600 nm and extending to at least 700 nm where melanin and hemoglobin absorption are both low. We also find that the Cherenkov intensity decreases with increasing angle from the surface normal, the majority being emitted within 20 degrees of the surface normal. Conclusion: Our estimate of the spectral distribution of Cherenkov radiation emitted from skin indicates an advantage to using imaging devices with long wavelength spectral responsivity. We also expect the most efficient imaging to be near the surface normal where the intensity is greatest; although for contoured surfaces, the relative intensity across the surface may appear to vary due to decreasing Cherenkov intensity with increased angle from the skin normal. This research was supported in part by a GAANN Fellowship from the Department of Education.« less

Real-time in vivo Cherenkoscopy imaging during external beam radiation therapy.

PubMed

Zhang, Rongxiao; Gladstone, David J; Jarvis, Lesley A; Strawbridge, Rendall R; Jack Hoopes, P; Friedman, Oscar D; Glaser, Adam K; Pogue, Brian W

2013-11-01

Cherenkov radiation is induced when charged particles travel through dielectric media (such as biological tissue) faster than the speed of light through that medium. Detection of this radiation or excited luminescence during megavoltage external beam radiotherapy (EBRT) can allow emergence of a new approach to superficial dose estimation, functional imaging, and quality assurance for radiation therapy dosimetry. In this letter, the first in vivo Cherenkov images of a real-time Cherenkoscopy during EBRT are presented. The imaging system consisted of a time-gated intensified charge coupled device (ICCD) coupled with a commercial lens. The ICCD was synchronized to the linear accelerator to detect Cherenkov photons only during the 3.25-μs radiation bursts. Images of a tissue phantom under irradiation show that the intensity of Cherenkov emission is directly proportional to radiation dose, and images can be acquired at 4.7 frames/s with SNR>30. Cherenkoscopy was obtained from the superficial regions of a canine oral tumor during planned, Institutional Animal Care and Use Committee approved, conventional (therapeutically appropriate) EBRT irradiation. Coregistration between photography and Cherenkoscopy validated that Cherenkov photons were detected from the planned treatment region. Real-time images correctly monitored the beam field changes corresponding to the planned dynamic wedge movement, with accurate extent of overall beam field, and expected cold and hot regions.

The Atmospheric Monitoring Strategy for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Daniel, M. K.; CTA Consortium

2015-04-01

The Imaging Atmospheric Cherenkov Technique (IACT) is unusual in astronomy as the atmosphere actually forms an intrinsic part of the detector system, with telescopes indirectly detecting very high energy particles by the generation and transport of Cherenkov photons deep within the atmosphere. This means that accurate measurement, characterisation and monitoring of the atmosphere is at the very heart of successfully operating an IACT system. The Cherenkov Telescope Array (CTA) will be the next generation IACT observatory with an ambitious aim to improve the sensitivity of an order of magnitude over current facilities, along with corresponding improvements in angular and energy resolution and extended energy coverage, through an array of Large (23 m), Medium (12 m) and Small (4 m) sized telescopes spread over an area of order ~km2. Whole sky coverage will be achieved by operating at two sites: one in the northern hemisphere and one in the southern hemisphere. This proceedings will cover the characterisation of the candidate sites and the atmospheric calibration strategy. CTA will utilise a suite of instrumentation and analysis techniques for atmospheric modelling and monitoring regarding pointing forecasts, intelligent pointing selection for the observatory operations and for offline data correction.

Camera selection for real-time in vivo radiation treatment verification systems using Cherenkov imaging.

PubMed

Andreozzi, Jacqueline M; Zhang, Rongxiao; Glaser, Adam K; Jarvis, Lesley A; Pogue, Brian W; Gladstone, David J

2015-02-01

To identify achievable camera performance and hardware needs in a clinical Cherenkov imaging system for real-time, in vivo monitoring of the surface beam profile on patients, as novel visual information, documentation, and possible treatment verification for clinicians. Complementary metal-oxide-semiconductor (CMOS), charge-coupled device (CCD), intensified charge-coupled device (ICCD), and electron multiplying-intensified charge coupled device (EM-ICCD) cameras were investigated to determine Cherenkov imaging performance in a clinical radiotherapy setting, with one emphasis on the maximum supportable frame rate. Where possible, the image intensifier was synchronized using a pulse signal from the Linac in order to image with room lighting conditions comparable to patient treatment scenarios. A solid water phantom irradiated with a 6 MV photon beam was imaged by the cameras to evaluate the maximum frame rate for adequate Cherenkov detection. Adequate detection was defined as an average electron count in the background-subtracted Cherenkov image region of interest in excess of 0.5% (327 counts) of the 16-bit maximum electron count value. Additionally, an ICCD and an EM-ICCD were each used clinically to image two patients undergoing whole-breast radiotherapy to compare clinical advantages and limitations of each system. Intensifier-coupled cameras were required for imaging Cherenkov emission on the phantom surface with ambient room lighting; standalone CMOS and CCD cameras were not viable. The EM-ICCD was able to collect images from a single Linac pulse delivering less than 0.05 cGy of dose at 30 frames/s (fps) and pixel resolution of 512 × 512, compared to an ICCD which was limited to 4.7 fps at 1024 × 1024 resolution. An intensifier with higher quantum efficiency at the entrance photocathode in the red wavelengths [30% quantum efficiency (QE) vs previous 19%] promises at least 8.6 fps at a resolution of 1024 × 1024 and lower monetary cost than the EM-ICCD. The ICCD with an intensifier better optimized for red wavelengths was found to provide the best potential for real-time display (at least 8.6 fps) of radiation dose on the skin during treatment at a resolution of 1024 × 1024.

Monte Carlo performance studies for the site selection of the Cherenkov Telescope Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hassan, T.; Arrabito, L.; Bernlöhr, K.

The Cherenkov Telescope Array (CTA) represents the next generation of ground-based instruments for very-high-energy (VHE) gamma-ray astronomy, aimed at improving on the sensitivity of current-generation experiments by an order of magnitude and providing coverage over four decades of energy. The current CTA design consists of two arrays of tens of imaging atmospheric Cherenkov Telescopes, comprising Small, Medium and Large-Sized Telescopes, with one array located in each of the Northern and Southern Hemispheres. To study the effect of the site choice on the overall CTA performance and support the site evaluation process, detailed Monte Carlo simulations have been performed. These resultsmore » show the impact of different site-related attributes such as altitude, night-sky background and local geomagnetic field on CTA performance for the observation of VHE gamma rays.« less

Monte Carlo performance studies for the site selection of the Cherenkov Telescope Array

DOE PAGES

Hassan, T.; Arrabito, L.; Bernlöhr, K.; ...

2017-05-03

The Cherenkov Telescope Array (CTA) represents the next generation of ground-based instruments for very-high-energy (VHE) gamma-ray astronomy, aimed at improving on the sensitivity of current-generation experiments by an order of magnitude and providing coverage over four decades of energy. The current CTA design consists of two arrays of tens of imaging atmospheric Cherenkov Telescopes, comprising Small, Medium and Large-Sized Telescopes, with one array located in each of the Northern and Southern Hemispheres. To study the effect of the site choice on the overall CTA performance and support the site evaluation process, detailed Monte Carlo simulations have been performed. These resultsmore » show the impact of different site-related attributes such as altitude, night-sky background and local geomagnetic field on CTA performance for the observation of VHE gamma rays.« less

Prototyping the graphical user interface for the operator of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Sadeh, I.; Oya, I.; Schwarz, J.; Pietriga, E.

2016-07-01

The Cherenkov Telescope Array (CTA) is a planned gamma-ray observatory. CTA will incorporate about 100 imaging atmospheric Cherenkov telescopes (IACTs) at a Southern site, and about 20 in the North. Previous IACT experiments have used up to five telescopes. Subsequently, the design of a graphical user interface (GUI) for the operator of CTA involves new challenges. We present a GUI prototype, the concept for which is being developed in collaboration with experts from the field of Human-Computer Interaction (HCI). The prototype is based on Web technology; it incorporates a Python web server, Web Sockets and graphics generated with the d3.js Javascript library.

Searches for magnetic monopoles with IceCube

NASA Astrophysics Data System (ADS)

Pollmann, Anna

2018-01-01

Particles that carry a magnetic monopole charge are proposed by various theories which go beyond the Standard Model of particle physics. The expected mass of magnetic monopoles varies depending on the theory describing its origin, generally the monopole mass far exceeds those which can be created at accelerators. Magnetic monopoles gain kinetic energy in large scale galactic magnetic fields and, depending on their mass, can obtain relativistic velocities. IceCube is a high energy neutrino detector using the clear ice at the South Pole as a detection medium. As monopoles pass through this ice they produce optical light by a variety of mechanisms. With increasing velocity, they produce light by catalysis of baryon decay, luminescence in the ice associated with electronic excitations, indirect and direct Cherenkov light from the monopole track, and Cherenkov light from cascades induced by pair creation and photonuclear reactions. By searching for this light, current best limits for the monopole flux over a broad range of velocities was achieved using the IceCube detector. A review of these magnetic monopole searches is presented.

Mass dependence of spectral and angular distributions of Cherenkov radiation from relativistic isotopes in solid radiators and its possible application as mass selector

NASA Astrophysics Data System (ADS)

Bogdanov, O. V.; Rozhkova, E. I.; Pivovarov, Yu. L.; Kuzminchuk-Feuerstein, N.

2018-02-01

The first proof of principle experiment with a prototype of a Time-of-Flight (TOF) - Cherenkov detector of relativistic heavy ions (RHI) exploiting a liquid Iodine Naphthalene radiator has been performed at Cave C at GSI (Darmstadt, Germany). A conceptual design for a liquid Cherenkov detector was proposed as a prototype for the future TOF measurements at the Super-FRS by detection of total number of Cherenkov photons. The ionization energy loss of RHI in a liquid radiator decreases only slightly this number, while in a solid radiator changes sufficiently not the total number of ChR photons, but ChR angular and spectral distributions. By means of computer simulations, we showed that these distributions are very sensitive to the isotope mass, due to different stopping powers of isotopes with initial equal relativistic factors. The results of simulations for light (Li, Be) and heavy (Xe) isotopes at 500-1000 MeV/u are presented indicating the possibility to use the isotopic effect in ChR of RHI as the mass selector.

The large-area hybrid-optics RICH detector for the CLAS12 spectrometer

NASA Astrophysics Data System (ADS)

Mirazita, M.; Angelini, G.; Balossino, I.; Barion, L.; Bailey, K.; Benmokhtar, F.; Brooks, W.; Cisbani, E.; Contalbrigo, M.; Cuevas, C.; Hafidi, K.; Kim, A.; Kubarovsky, V.; Lucherini, V.; Malaguti, R.; Montgomery, R.; Movsisyan, A.; Musico, P.; O'Connor, T.; Orecchini, D.; Pappalardo, L.; Perrino, R.; Pisano, S.; Raydo, B.; Rossi, P.; Squerzanti, S.; Tomassini, S.; Turisini, M.

2017-12-01

A large area imaging Cherenkov detector is under construction to provide hadron identification in the momentum range between 3 and 8 GeV/c for the CLAS12 exeperiment at the new 12 GeV electron beam of the Jefferson Laboratory (JLab). The detector adopts a hybrid optics solution with aerogel radiator, light planar and spherical mirrors and highly-segmented photon detectors. Cherenkov photons will be imaged either directly (for forward tracks) or after two mirror reflections (large angle tracks). The status of the detector construction is here reported.

Status and Aims of the DUMAND Neutrino Project: the Ocean as a Neutrino Detector

DOE R&D Accomplishments Database

Roberts, A.; Blood, H.; Learned, J.; Reines, F.

1976-07-01

The possibility of using the ocean as a neutrino detector is considered. Neutrino-produced interactions result in charged particles that generate Cherenkov radiation in the water, which can be detected by light-gathering equipment and photomultipliers. The properties of the ocean as seen from this standpoint are critically examined, and the advantages and disadvantages pointed out. Possible uses for such a neutrino detector include (1) the detection of neutrinos emitted in gravitational collapse of stars (supernova production), not only in our own galaxy, but in other galaxies up to perhaps twenty-million light-years away, (2) the extension of high-energy neutrino physics, as currently practiced up to 200 GeV at high-energy accelerators, to energies up to 50 times higher, using neutrinos generated in the atmosphere by cosmic rays, and (3) the possible detection of neutrinos produced by cosmic-ray interactions outside the earth`s atmosphere. The technology for such an undertaking seems to be within reach.

Electromagnetic field of a bunch intersecting a dielectric plate in a waveguide

NASA Astrophysics Data System (ADS)

Alekhina, Tatiana Yu; Tyukhtin, Andrey V.

2014-05-01

The electromagnetic field (EMF) of a bunch moving uniformly and traversing a dielectric plate located in a waveguide is investigated. The main attention is focused on the case when Cherenkov radiation is generated in the plate. Analysis of the field components of the mode is performed with methods of the complex variable function theory. An algorithm of computation using the exact expressions for the EMF is also presented. Consideration of the EMF structure for different time moments is given. It is shown that Cherenkov-transition radiation (CTR) is generated in the vacuum area after the plate under certain conditions. Results obtained might be of interest for development of new methods of generation of electromagnetic radiation.

A simulation study on few parameters of Cherenkov photons in extensive air showers of different primaries incident at various zenith angles over a high altitude observation level

NASA Astrophysics Data System (ADS)

Das, G. S.; Hazarika, P.; Goswami, U. D.

2018-07-01

We have studied the distribution patterns of lateral density, arrival time and angular position of Cherenkov photons generated in Extensive Air Showers (EASs) initiated by γ-ray, proton and iron primaries incident with various energies and at various zenith angles. This study is the extension of our earlier work [1] to cover a wide energy range of ground based γ-ray astronomy with a wide range of zenith angles (≤40°) of primary particles, as well as the extension to study the angular distribution patterns of Cherenkov photons in EASs. This type of study is important for distinguishing the γ-ray initiated showers from the hadronic showers in the ground based γ-ray astronomy, where Atmospheric Cherenkov Technique (ACT) is being used. Importantly, such study gives an insight on the nature of γ-ray and hadronic showers in general. In this work, the CORSIKA 6.990 simulation code is used for generation of EASs. Similarly to the case of Ref. [1], this study also revealed that, the lateral density and arrival time distributions of Cherenkov photons vary almost in accordance with the functions: ρch(r) =ρ0e-βr and tch(r) =t0eΓ/rλ respectively by taking different values of the parameters of functions for the type, energy and zenith angle of the primary particle. The distribution of Cherenkov photon's angular positions with respect to shower axis shows distinctive features depending on the primary type, its energy and the zenith angle. As a whole this distribution pattern for the iron primary is noticeably different from those for γ-ray and proton primaries. The value of the angular position at which the maximum number of Cherenkov photons are concentrated, increases with increase in energy of vertically incident primary, but for inclined primary it lies within a small value (≤1°) for almost all energies and primary types. No significant difference in the results obtained by using the high energy hadronic interaction models, viz., QGSJETII and EPOS has been observed.

Experimental evaluation of models for predicting Cherenkov light intensities from short-cooled nuclear fuel assemblies

NASA Astrophysics Data System (ADS)

Branger, E.; Grape, S.; Jansson, P.; Jacobsson Svärd, S.

2018-02-01

The Digital Cherenkov Viewing Device (DCVD) is a tool used by nuclear safeguards inspectors to verify irradiated nuclear fuel assemblies in wet storage based on the recording of Cherenkov light produced by the assemblies. One type of verification involves comparing the measured light intensity from an assembly with a predicted intensity, based on assembly declarations. Crucial for such analyses is the performance of the prediction model used, and recently new modelling methods have been introduced to allow for enhanced prediction capabilities by taking the irradiation history into account, and by including the cross-talk radiation from neighbouring assemblies in the predictions. In this work, the performance of three models for Cherenkov-light intensity prediction is evaluated by applying them to a set of short-cooled PWR 17x17 assemblies for which experimental DCVD measurements and operator-declared irradiation data was available; (1) a two-parameter model, based on total burnup and cooling time, previously used by the safeguards inspectors, (2) a newly introduced gamma-spectrum-based model, which incorporates cycle-wise burnup histories, and (3) the latter gamma-spectrum-based model with the addition to account for contributions from neighbouring assemblies. The results show that the two gamma-spectrum-based models provide significantly higher precision for the measured inventory compared to the two-parameter model, lowering the standard deviation between relative measured and predicted intensities from 15.2 % to 8.1 % respectively 7.8 %. The results show some systematic differences between assemblies of different designs (produced by different manufacturers) in spite of their similar PWR 17x17 geometries, and possible ways are discussed to address such differences, which may allow for even higher prediction capabilities. Still, it is concluded that the gamma-spectrum-based models enable confident verification of the fuel assembly inventory at the currently used detection limit for partial defects, being a 30 % discrepancy between measured and predicted intensities, while some false detection occurs with the two-parameter model. The results also indicate that the gamma-spectrum-based prediction methods are accurate enough that the 30 % discrepancy limit could potentially be lowered.

Prism-coupled Cherenkov phase-matched terahertz wave generation using a DAST crystal.

PubMed

Suizu, Koji; Shibuya, Takayuki; Uchida, Hirohisa; Kawase, Kodo

2010-02-15

Terahertz (THz) wave generation based on nonlinear frequency conversion is a promising method for realizing a tunable monochromatic high-power THz-wave source. Unfortunately, many nonlinear crystals have strong absorption in the THz frequency region. This limits efficient and widely tunable THz-wave generation. The Cherenkov phase-matching method is one of the most promising techniques for overcoming these problems. Here, we propose a prism-coupled Cherenkov phase-matching (PCC-PM) method, in which a prism with a suitable refractive index at THz frequencies is coupled to a nonlinear crystal. This has the following advantages. Many crystals can be used as THz-wave emitters; the phase-matching condition inside the crystal does not have to be observed; the absorption of the crystal does not prevent efficient generation of radiation; and pump sources with arbitrary wavelengths can be employed. Here we demonstrate PCC-PM THz-wave generation using the organic crystal 4-dimethylamino-N-metyl-4-stilbazolium tosylate (DAST) and a Si prism coupler. We obtain THz-wave radiation with tunability of approximately 0.1 to 10 THz and with no deep absorption features resulting from the absorption spectrum of the crystal. The obtained spectra did not depend on the pump wavelength in the range 1300 to 1450 nm. This simple technique shows promise for generating THz radiation using a wide variety of nonlinear crystals.

Detection of Cherenkov Photons with Multi-Anode Photomultipliers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salazar, H.; Moreno, E.; Murrieta, T.

2006-09-25

The present paper describes the laboratory course given at the X Mexican Workshop on Particles and Fields. We describe the setup and procedure used to measure the Cherenkov circles produced by cosmic muons upon traversal of a simple glass radiator system. The main purpose of this exercise is to introduce the students to work with multi-anode photomultipliers such as the one used for this experiment (Hamamatsu R5900-M64), with which measurements requiring position sensitive detection of single photons can be successfully performed. We present a short introduction to multi-anode photomultipliers (MAPMT) and describe the setup and the procedure used to measuremore » the response of a MAPMT to a uniform source of light. Finally, we describe the setup and procedure used to measure the Cherenkov circles produced by cosmic muons upon traversal of a simple glass radiator system.« less

NECTAR: New electronics for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Naumann, Christopher Lindsay; Bolmont, J.; Corona, P.; Delagnes, E.; Dzahini, D.; Feinstein, F.; Gascon, D.; Glicenstein, J.-F.; Nayman, P.; Rarbi, F.; Ribo, M.; Sanuy, A.; Siero, X.; Tavernet, J.-P.; Toussenel, F.; Vincent, P.; Vorobiov, S.

2012-12-01

The international CTA consortium is currently in the preparatory phase for the development of the next-generation Cherenkov Telescope Array (CTA [1]), based on the return of experience from the three major current-generation arrays H.E.S.S., MAGIC and VERITAS. To achieve an unprecedented sensitivity and energy range for TeV gamma rays, a new kind of flexible and powerful yet inexpensive front-end hardware will be required for the order of 105 channels of photodetectors in up to 100 telescopes. One possible solution is the NECTAr (New Electronics for the Cherenkov Telescope Array) system, based on the integration of as much as possible of the front-end electronics (amplifiers, fast analogue samplers, memory and ADCs) into a single ASIC for very fast readout performance and a significant reduction of the cost and the lower consumption per channel, while offering a high degree of flexibility both for the triggering and the readout of the telescope. The current status of its development is presented, along with newest results from measurements and simulation studies.

EUSO-SPB2: Second Generation Extreme Universe Space Observatory (EUSO) on Board a Super-Pressure Balloon (SPB)

NASA Astrophysics Data System (ADS)

Anchordoqui, Luis

This is a Co-Investigator Proposal for EUSO-SPB2 being led by PI Angela V. Olinto at the University of Chicago as the lead Institution. This is the Lehman College (City University of New York) Task Statement. We propose to design, build, deploy, and publish the scientific results of a second generation of the Extreme Universe Space Observatory (EUSO), to be flown aboard a Super-Pressure Balloon (SBP). EUSO-SPB2 will monitor the night sky of the Southern hemisphere to study cosmic rays of very high to ultrahigh energies and pioneer the search for cosmogenic tau neutrinos from space. EUSO-SPB2 will be the first instrument to observe Cherenkov light from extensive airshowers high in the atmosphere. EUSO-SPB2 will observe a large sample of cosmic rays from 0.1 to 1 EeV with the Cherenkov technique and will discriminate among the Cherenkov profiles of primary protons, heavy nuclei, and photons. It will also characterize the background for upward going showers initiated by the decay of tau leptons, which are expected to be produced by Earth-skimming tau neutrinos. A coincidence veto will be developed for EUSO-SPB2 so it can characterize the background for Cherenkov signals from the neutrino produced tau leptons. EUSO-SPB2 will also use fluorescence observations to measure, for the first time, the evolution of nearly horizontal high altitude extensive air showers, which develop at the nearly constant low-density atmosphere. Such measurements will provide a unique channel to probe hadronic interaction models at ultrahigh energies, and may elucidate the reason why ultrahigh-energy cosmic ray (UHECR) showers observed by ground-based detectors contain more muons than expected from hadronic interaction models. EUSO-SPB2 is a pathfinder for the more ambitious space-based measurements by the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA), currently proposed for a NASA design study. POEMMA will combine the well-developed Orbiting Wide-field Light-collectors (OWL) concept with the recently proposed CHerenkov from Astrophysical Neutrinos Telescope (CHANT) concept to form a multi-messenger probe of the most extreme environments in the universe. EUSO-SPB2 will inform the best strategy for future space missions such as POEMMA. EUSO-SPB2 will build upon the experience of flying EUSO-SPB in the Spring of 2017. A number of upgrades will render EUSO-SPB2 more powerful, including a Schmidt design telescope and a faster ultraviolet (UV) camera to increase exposure. The new instrument will detect Cherenkov and fluorescence signal from highly inclined UHECR events. Horizontal observations will lead to much larger acceptance with a distancedependent energy threshold. Depending on EUSO-SPB1 results, EUSO-SPB2 may also point closer to nadir in fluorescence. The combination of nadir (EUSO-SPB) and tilted (EUSO-SPB2) observations will explore the power of space observatories to observe UHECR of extreme energies. A long enough flight of EUSO-SPB2 observations will match and complement ground observations. EUSO-SPB2 addresses the fourth science goal of the 2011 NASA Strategic Plan, to “Discover how the universe works, explore how it began and evolved”• and one of the “Physics of the Cosmos” questions in NASA’s 2010 Science Plan : “How do matter, energy, space, and time behave under the extraordinarily diverse conditions of the cosmos?”• EUSO-SPB2 directly addresses the sixth question in the “Connecting Quarks with the Cosmos” report in its list of “Eleven Science Questions for the New Century,”• which is “How do Cosmic Accelerators Work and What are They Accelerating?” Upcoming measurements of EUSO-SPB2 are essential to achieve the ambitious recommendations of the U.S. HEP Snowmass planning process: “The Bright Side of the Cosmic Frontier: Cosmic Probes of Fundamental Physics.”

EUSO-SPB2: second generation Extreme Universe Space Observatory (EUSO) on board a Super-Pressure Balloon (SPB), NASA/MSFC Co-I

NASA Astrophysics Data System (ADS)

Christl, Mark

This is a Co-Investigator Proposal for EUSO-SPB2 being led by PI Angela V. Olinto at the University of Chicago as the lead Institution. This is the NASA/Marshall Space Flight Center Task Statement. We propose to design, build, deploy, and publish the scientific results of a second generation of the Extreme Universe Space Observatory (EUSO), to be flown aboard a Super-Pressure Balloon (SPB). EUSO-SPB2 will monitor the night sky of the Southern hemisphere to study cosmic rays of very high to ultrahigh energies and pioneer the search for cosmogenic tau neutrinos from space. EUSO-SPB2 will be the first instrument to observe Cherenkov light from extensive airshowers high in the atmosphere. EUSO-SPB2 will observe a large sample of cosmic rays from 0.1 to 1 EeV with the Cherenkov technique and will discriminate among the Cherenkov profiles of primary protons, heavy nuclei, and photons. It will also characterize the background for upward going showers initiated by the decay of tau leptons, which are expected to be produced by Earth-skimming tau neutrinos. A fast coincidence test will be developed for EUSO-SPB2 so it can characterize the background for Cherenkov signals from the neutrino produced tau leptons. EUSO-SPB2 will also use fluorescence observations to measure, for the first time, the evolution of nearly horizontal high altitude extensive air showers, which develop at the nearly constant low-density atmosphere. Such measurements will provide a unique channel to probe hadronic interaction models at ultrahigh energies, and may elucidate the reason why ultrahigh-energy cosmic ray (UHECR) showers observed by ground-based detectors contain more muons than expected from hadronic interaction models. EUSO-SPB2 is a pathfinder for the more ambitious space-based measurements by the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA), currently proposed for a NASA design study. POEMMA will combine the well-developed Orbiting Wide-field Light-collectors (OWL) concept with the recently proposed CHerenkov from Astrophysical Neutrinos Telescope (CHANT) concept to form a multi-messenger probe of the most extreme environments in the universe. EUSO-SPB2 will inform the best strategy for future space missions such as POEMMA. EUSO-SPB2 will build upon the experience of flying EUSO-SPB1 in the Spring of 2017. A number of upgrades will render EUSO-SPB2 more powerful, including a Schmidt design telescope and a faster ultraviolet (UV) camera to increase exposure. The new instrument will detect Cherenkov and fluorescence signal from highly inclined UHECR events. Horizontal observations will lead to much larger acceptance with a distancedependent energy threshold. Depending on EUSO-SPB1 results, EUSO-SPB2 may also point closer to nadir in fluorescence. The combination of nadir (EUSO-SPB) and tilted (EUSO-SPB2) observations will explore the power of space observatories to observe UHECR of extreme energies. A long enough flight of EUSO-SPB2 observations will match and complement ground observations. EUSO-SPB2 addresses the fourth science goal of the 2011 NASA Strategic Plan, to “Discover how the universe works, explore how it began and evolved” and one of the “Physics of the Cosmos” questions in NASA’s 2010 Science Plan: “How do matter, energy, space, and time behave under the extraordinarily diverse conditions of the cosmos?” EUSO-SPB2 directly addresses the sixth question in the “Connecting Quarks with the Cosmos” report in its list of “Eleven Science Questions for the New Century,” which is “How do Cosmic Accelerators Work and What are They Accelerating?” Upcoming measurements of EUSO-SPB2 are essential to achieve the ambitious recommendations of the U.S. HEP Snowmass planning process: “The Bright Side of the Cosmic Frontier: Cosmic Probes of Fundamental Physics.”

TU-AB-BRA-12: Quality Assurance of An Integrated Magnetic Resonance Image Guided Adaptive Radiotherapy Machine Using Cherenkov Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreozzi, J; Bruza, P; Saunders, S

Purpose: To investigate the viability of using Cherenkov imaging as a fast and robust method for quality assurance tests in the presence of a magnetic field, where other instruments can be limited. Methods: Water tank measurements were acquired from a clinically utilized adaptive magnetic resonance image guided radiation therapy (MR-IGRT) machine with three multileaf-collimator equipped 60Co sources. Cherenkov imaging used an intensified charge coupled device (ICCD) camera placed 3.5m from the treatment isocenter, looking down the bore of the 0.35T MRI into a water tank. Images were post-processed to make quantitative comparison between Cherenkov light intensity with both film andmore » treatment planning system predictions, in terms of percent depth dose curves as well as lateral beam profile measurements. A TG-119 commissioning test plan (C4: C-Shape) was imaged in real-time at 6.33 frames per second to investigate the temporal and spatial resolution of the Cherenkov imaging technique. Results: A .33mm/pixel Cherenkov image resolution was achieved across 1024×1024 pixels in this setup. Analysis of the Cherenkov image of a 10.5×10.5cm treatment beam in the water tank successfully measured the beam width at the depth of maximum dose within 1.2% of the film measurement at the same point. The percent depth dose curve for the same beam was on average within 2% of ionization chamber measurements for corresponding depths between 3–100mm. Cherenkov video of the TG-119 test plan provided qualitative agreement with the treatment planning system dose predictions, and a novel temporal verification of the treatment. Conclusions: Cherenkov imaging was successfully used to make QA measurements of percent depth dose curves and cross beam profiles of MRI-IGRT radiotherapy machines after only several seconds of beam-on time and data capture; both curves were extracted from the same data set. Video-rate imaging of a dynamic treatment plan provided new information regarding temporal dose deposition. This study has been funded by NIH grants R21EB17559 and R01CA109558, as well as Norris Cotton Cancer Center Pilot funding.« less

Characterization of Multianode Photomultiplier Tubes for a Cherenkov Detector

NASA Astrophysics Data System (ADS)

Benninghoff, Morgen; Turisini, Matteo; Kim, Andrey; Benmokhtar, Fatiha; Kubarovsky, Valery; Duquesne University Collaboration; Jefferson Lab Collaboration

2017-09-01

In the Fall of 2017, Jefferson Lab's CLAS12 (CEBAF Large Acceptance Spectrometer) detector is expecting the addition of a RICH (ring imaging Cherenkov) detector which will allow enhanced particle identification in the momentum range of 3 to 8 GeV/c. RICH detectors measure the velocity of charged particles through the detection of produced Cherenkov radiation and the reconstruction of the angle of emission. The emitted Cherenkov photons are detected by a triangular-shaped grid of 391 multianode photomultiplier tubes (MAPMTs) made by Hamamatsu. The custom readout electronics consist of MAROC (multianode read out chip) boards controlled by FPGA (Field Programmable Gate Array) boards, and adapters used to connect the MAROC boards and MAPMTs. The focus of this project is the characterization of the MAPMTs with the new front end electronics. To perform these tests, a black box setup with a picosecond diode laser was constructed with low and high voltage supplies. A highly automated procedure was developed to acquire data at different combinations of high voltage values, light intensities and readout electronics settings. Future work involves using the collected data in calibration procedures and analyzing that data to resolve the best location for each MAPMT. SULI, NSF.

The Cherenkov Telescope Array: Exploring the Very-high-energy Sky from ESO's Paranal Site

NASA Astrophysics Data System (ADS)

Hofmann, W.

2017-06-01

The Cherenkov Telescope Array (CTA) is a next-generation observatory for ground-based very-high-energy gamma-ray astronomy, using the imaging atmospheric Cherenkov technique to detect and reconstruct gamma-ray induced air showers. The CTA project is planning to deploy 19 telescopes on its northern La Palma site, and 99 telescopes on its southern site at Paranal, covering the 20 GeV to 300 TeV energy domain and offering vastly improved performance compared to currently operating Cherenkov telescopes. The combination of three different telescope sizes (23-, 12- and 4-metre) allows cost-effective coverage of the wide energy range. CTA will be operated as a user facility, dividing observation time between a guest observer programme and large Key Science Projects (KSPs), and the data will be made public after a one-year proprietary period. The history of the project, the implementation of the arrays, and some of the major science goals and KSPs, are briefly summarised.

A site evaluation campaign for a ground based atmospheric Cherenkov telescope in Romania

NASA Astrophysics Data System (ADS)

Radu, Aurelian Andrei; Angelescu, Tatiana; Curtef, Valentin; Delia, Florin; Felea, Daniel; Goia, Ioana; Haşegan, Dumitru; Lucaschi, Bogdan; Manea, Ancuta; Popa, Vlad; Raliţă, Ioan; Văcăreanu, Radu

2012-07-01

Around the world, several scientific projects share the interest of a global network of small Cherenkov telescopes for monitoring observations of the brightest blazars—the DWARF network. A small, ground based, imaging atmospheric Cherenkov telescope of last generation is intended to be installed and operated in Romania as a component of the DWARF network. To prepare the construction of the observatory, two support projects have been initiated. Within the framework of these projects, we have assessed a number of possible sites where to settle the observatory. In this paper we submit a brief report on the general characteristics of the best four sites selected after the local infrastructure, the nearby facilities and the social impact criteria have been applied.

Single photon detection imaging of Cherenkov light emitted during radiation therapy

NASA Astrophysics Data System (ADS)

Adamson, Philip M.; Andreozzi, Jacqueline M.; LaRochelle, Ethan; Gladstone, David J.; Pogue, Brian W.

2018-03-01

Cherenkov imaging during radiation therapy has been developed as a tool for dosimetry, which could have applications in patient delivery verification or in regular quality audit. The cameras used are intensified imaging sensors, either ICCD or ICMOS cameras, which allow important features of imaging, including: (1) nanosecond time gating, (2) amplification by 103-104, which together allow for imaging which has (1) real time capture at 10-30 frames per second, (2) sensitivity at the level of single photon event level, and (3) ability to suppress background light from the ambient room. However, the capability to achieve single photon imaging has not been fully analyzed to date, and as such was the focus of this study. The ability to quantitatively characterize how a single photon event appears in amplified camera imaging from the Cherenkov images was analyzed with image processing. The signal seen at normal gain levels appears to be a blur of about 90 counts in the CCD detector, after going through the chain of photocathode detection, amplification through a microchannel plate PMT, excitation onto a phosphor screen and then imaged on the CCD. The analysis of single photon events requires careful interpretation of the fixed pattern noise, statistical quantum noise distributions, and the spatial spread of each pulse through the ICCD.

A Water Cherenkov Detector prototype for the HAWC Gamma-Ray Observatory

NASA Astrophysics Data System (ADS)

Longo, Megan; Mostafa, Miguel; Salesa Greus, Francisco; Warner, David

2011-10-01

A full-size Water Cherenkov Detector (WCD) prototype for the High Altitude Water Cherenkov (HAWC) gamma-ray Observatory was deployed, and is currently being operated at Colorado State University (CSU). The HAWC Observatory will consist of 300 WCDs at the very high altitude (4100m) site in Sierra Negra, Mexico. Each WCD will have 4 baffled upward-facing Photomultiplier Tubes (PMTs) anchored to the bottom of a self made multilayer hermetic plastic bag containing 200,000 liters of purified water, inside a 5m deep by 7.3m diameter steel container. The full size WCD at CSU is the only full size prototype outside of the HAWC site. It is equipped with seven HAWC PMTs and has scintillators both under and above the volume of water. It has been in operation since March 1, 2011. This prototype also has the same laser calibration system that the detectors deployed at the HAWC site will have. The CSU WCD serves as a testbed for the different subsystems before deployment at high altitude, and for optimizing the location of the PMTs, the design of the light collectors, deployment procedures, etc. Simulations of the light inside the detectors and the expected signals in the PMTs can also be benchmarked with this prototype.

Simulating the optical performance of a small-sized telescope with secondary optics for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Rulten, Cameron; Zech, Andreas; Okumura, Akira; Laporte, Philippe; Schmoll, Jürgen

2016-09-01

The Gamma-ray Cherenkov Telescope (GCT) is a small-sized telescope (SST) that represents one of three novel designs that are based on Schwarzschild-Couder optics and are proposed for use within the Cherenkov Telescope Array (CTA). The GAmma-ray Telescope Elements (GATE) program has led an effort to build a prototype of the GCT at the Paris Observatory in Meudon, France. The mechanical structure of the prototype, known as the SST-GATE prototype telescope, is now complete along with the successful installation of the camera. We present the results of extensive simulation work to determine the optical performance of the SST-GATE prototype telescope. Using the ROBAST software and assuming an ideal optical system, we find the radius of the encircled point spread function (θ80) of the SST-GATE to be ∼1.3 arcmin (∼0.02°) for an on-axis (θfield =0∘) observation and ∼3.6 arcmin (∼0.06°) for an observation at the edge of the field of view (θfield = 4 .4∘). In addition, this research highlights the shadowing that results from the stopping of light rays by various telescope components such as the support masts and trusses. It is shown that for on-axis observations the effective collection area decreases by approximately 1 m2 as a result of shadowing components other than the secondary mirror. This is a similar loss (∼11%) to that seen with the current generation of conventional Davies-Cotton (DC) Cherenkov telescopes. An extensive random tolerance analysis was also performed and it was found that certain parameters, especially the secondary mirror z-position and the tip and tilt rotations of the mirrors, are critical in order to contain θ80 within the pixel limit radius for all field angles. In addition, we have studied the impact upon the optical performance of introducing a hole in the center of the secondary mirror for use with pointing and alignment instruments. We find that a small circular area (radius < 150 mm) at the center of the secondary mirror can be used for instrumentation without any significant impact upon optical performance. Finally, we studied the impact of reducing the size of the primary mirror for the prototype telescope and found that this comes at the cost of poorer image quality and light collection efficiency for all field angles, but at a significant cost saving for a one-off prototype.

The Potential of Spaced-based High-Energy Neutrino Measurements via the Airshower Cherenkov Signal

NASA Technical Reports Server (NTRS)

Krizmanic, John F.; Mitchell, John W.

2011-01-01

Future space-based experiments, such as (Orbiting Wide-angle Light Collectors (OWL) and JEM-EUSO, view large atmospheric and terrestrial neutrino targets. With energy thresholds slightly above 10(exp 19) eV for observing airshowers via air fluorescence, the potential for observing the cosmogenic neutrino flux associated with the GZK effect is limited. However, the forward Cherenkov signal associated with the airshower can be observed at much lower energies. A simulation was developed to determine the Cherenkov signal strength and spatial extent at low-Earth orbit for upward-moving airshowers. A model of tau neutrino interactions in the Earth was employed to determine the event rate of interactions that yielded a tau lepton which would induce an upward-moving airshower observable by a space-based instrument. The effect of neutrino attenuation by the Earth forces the viewing of the Earth's limb to observe the vT-induced Cherenkov airshower signal at above the OWL Cherenkov energy threshold of approximately 10(exp 16.5) eV for limb-viewed events. Furthermore, the neutrino attenuation limits the effective terrestrial neutrino target area to approximately 3 x 10(exp 5) square km at 10(exp 17) eV, for an orbit of 1000 km and an instrumental full Field-of-View of 45 deg. This translates into an observable cosmogenic neutrino event rate of approx. l/year based upon two different models of the cosmogenic neutrino flux, assuming neutrino oscillations and a 10% duty cycle for observation.

The new ATLAS/LUCID detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruschi, Marco

The new ATLAS luminosity monitor has many innovative aspects implemented. Its photomultipliers tubes are used as detector elements by using the Cherenkov light produced by charged particles above threshold crossing the quartz windows. The analog shaping of the readout chain has been improved, in order to cope with the 25 ns bunch spacing of the LHC machine. The main readout card is a quite general processing unit based on 12 bit - 500 MS/s Flash ADC and on FPGAs, delivering the processed data to 1.3 Gb/s optical links. The article will describe all these aspects and will outline future perspectivesmore » of the card for next generation high energy physics experiments. (authors)« less

Design and performance of SiPM-based readout of PbF 2 crystals for high-rate, precision timing applications

DOE PAGES

Kaspar, J.; Fienberg, A. T.; Hertzog, D. W.; ...

2017-01-11

Here, we have developed a custom amplifier board coupled to a large-format 16-channel Hamamatsu silicon photomultiplier device for use as the light sensor for the electromagnetic calorimeters in the Muon g-2 experiment at Fermilab. The calorimeter absorber is an array of lead-fluoride crystals, which produces short-duration Cherenkov light. The detector sits in the high magnetic field of the muon storage ring. The SiPMs selected, and their accompanying custom electronics, must preserve the short pulse shape, have high quantum efficiency, be non-magnetic, exhibit gain stability under varying rate conditions, and cover a fairly large fraction of the crystal exit surface area.more » We describe an optimized design that employs the new-generation of thru-silicon via devices. As a result, the performance is documented in a series of bench and beam tests.« less

High sensitivity optical molecular imaging system

NASA Astrophysics Data System (ADS)

An, Yu; Yuan, Gao; Huang, Chao; Jiang, Shixin; Zhang, Peng; Wang, Kun; Tian, Jie

2018-02-01

Optical Molecular Imaging (OMI) has the advantages of high sensitivity, low cost and ease of use. By labeling the regions of interest with fluorescent or bioluminescence probes, OMI can noninvasively obtain the distribution of the probes in vivo, which play the key role in cancer research, pharmacokinetics and other biological studies. In preclinical and clinical application, the image depth, resolution and sensitivity are the key factors for researchers to use OMI. In this paper, we report a high sensitivity optical molecular imaging system developed by our group, which can improve the imaging depth in phantom to nearly 5cm, high resolution at 2cm depth, and high image sensitivity. To validate the performance of the system, special designed phantom experiments and weak light detection experiment were implemented. The results shows that cooperated with high performance electron-multiplying charge coupled device (EMCCD) camera, precision design of light path system and high efficient image techniques, our OMI system can simultaneously collect the light-emitted signals generated by fluorescence molecular imaging, bioluminescence imaging, Cherenkov luminance and other optical imaging modality, and observe the internal distribution of light-emitting agents fast and accurately.

Monte Carlo studies of medium-size telescope designs for the Cherenkov Telescope Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, M. D.; Jogler, T.; Dumm, J.

In this paper, we present studies for optimizing the next generation of ground-based imaging atmospheric Cherenkov telescopes (IACTs). Results focus on mid-sized telescopes (MSTs) for CTA, detecting very high energy gamma rays in the energy range from a few hundred GeV to a few tens of TeV. We describe a novel, flexible detector Monte Carlo package, FAST (FAst Simulation for imaging air cherenkov Telescopes), that we use to simulate different array and telescope designs. The simulation is somewhat simplified to allow for efficient exploration over a large telescope design parameter space. We investigate a wide range of telescope performance parametersmore » including optical resolution, camera pixel size, and light collection area. In order to ensure a comparison of the arrays at their maximum sensitivity, we analyze the simulations with the most sensitive techniques used in the field, such as maximum likelihood template reconstruction and boosted decision trees for background rejection. Choosing telescope design parameters representative of the proposed Davies–Cotton (DC) and Schwarzchild–Couder (SC) MST designs, we compare the performance of the arrays by examining the gamma-ray angular resolution and differential point-source sensitivity. We further investigate the array performance under a wide range of conditions, determining the impact of the number of telescopes, telescope separation, night sky background, and geomagnetic field. We find a 30–40% improvement in the gamma-ray angular resolution at all energies when comparing arrays with an equal number of SC and DC telescopes, significantly enhancing point-source sensitivity in the MST energy range. Finally, we attribute the increase in point-source sensitivity to the improved optical point-spread function and smaller pixel size of the SC telescope design.« less

Monte Carlo studies of medium-size telescope designs for the Cherenkov Telescope Array

DOE PAGES

Wood, M. D.; Jogler, T.; Dumm, J.; ...

2015-06-07

In this paper, we present studies for optimizing the next generation of ground-based imaging atmospheric Cherenkov telescopes (IACTs). Results focus on mid-sized telescopes (MSTs) for CTA, detecting very high energy gamma rays in the energy range from a few hundred GeV to a few tens of TeV. We describe a novel, flexible detector Monte Carlo package, FAST (FAst Simulation for imaging air cherenkov Telescopes), that we use to simulate different array and telescope designs. The simulation is somewhat simplified to allow for efficient exploration over a large telescope design parameter space. We investigate a wide range of telescope performance parametersmore » including optical resolution, camera pixel size, and light collection area. In order to ensure a comparison of the arrays at their maximum sensitivity, we analyze the simulations with the most sensitive techniques used in the field, such as maximum likelihood template reconstruction and boosted decision trees for background rejection. Choosing telescope design parameters representative of the proposed Davies–Cotton (DC) and Schwarzchild–Couder (SC) MST designs, we compare the performance of the arrays by examining the gamma-ray angular resolution and differential point-source sensitivity. We further investigate the array performance under a wide range of conditions, determining the impact of the number of telescopes, telescope separation, night sky background, and geomagnetic field. We find a 30–40% improvement in the gamma-ray angular resolution at all energies when comparing arrays with an equal number of SC and DC telescopes, significantly enhancing point-source sensitivity in the MST energy range. Finally, we attribute the increase in point-source sensitivity to the improved optical point-spread function and smaller pixel size of the SC telescope design.« less

Cherenkov excited phosphorescence-based pO2 estimation during multi-beam radiation therapy: phantom and simulation studies

NASA Astrophysics Data System (ADS)

Holt, Robert W.; Zhang, Rongxiao; Esipova, Tatiana V.; Vinogradov, Sergei A.; Glaser, Adam K.; Gladstone, David J.; Pogue, Brian W.

2014-09-01

Megavoltage radiation beams used in External Beam Radiotherapy (EBRT) generate Cherenkov light emission in tissues and equivalent phantoms. This optical emission was utilized to excite an oxygen-sensitive phosphorescent probe, PtG4, which has been developed specifically for NIR lifetime-based sensing of the partial pressure of oxygen (pO2). Phosphorescence emission, at different time points with respect to the excitation pulse, was acquired by an intensifier-gated CCD camera synchronized with radiation pulses delivered by a medical linear accelerator. The pO2 distribution was tomographically recovered in a tissue-equivalent phantom during EBRT with multiple beams targeted from different angles at a tumor-like anomaly. The reconstructions were tested in two different phantoms that have fully oxygenated background, to compare a fully oxygenated and a fully deoxygenated inclusion. To simulate a realistic situation of EBRT, where the size and location of the tumor is well known, spatial information of a prescribed region was utilized in the recovery estimation. The phantom results show that region-averaged pO2 values were recovered successfully, differentiating aerated and deoxygenated inclusions. Finally, a simulation study was performed showing that pO2 in human brain tumors can be measured to within 15 mmHg for edge depths less than 10-20 mm using the Cherenkov Excited Phosphorescence Oxygen imaging (CEPhOx) method and PtG4 as a probe. This technique could allow non-invasive monitoring of pO2 in tumors during the normal process of EBRT, where beams are generally delivered from multiple angles or arcs during each treatment fraction.

SiPM detectors for the ASTRI project in the framework of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Billotta, Sergio; Marano, Davide; Bonanno, Giovanni; Belluso, Massimiliano; Grillo, Alessandro; Garozzo, Salvatore; Romeo, Giuseppe; Timpanaro, Maria Cristina; Maccarone, Maria Concetta C.; Catalano, Osvaldo; La Rosa, Giovanni; Sottile, Giuseppe; Impiombato, Domenico; Gargano, Carmelo; Giarrusso, Salavtore

2014-07-01

The Cherenkov Telescope Array (CTA) is a worldwide new generation project aimed at realizing an array of a hundred ground based gamma-ray telescopes. ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is the Italian project whose primary target is the development of an end-to-end prototype, named ASTRI SST-2M, of the CTA small size class of telescopes devoted to investigation of the highest energy region, from 1 to 100 TeV. Next target is the implementation of an ASTRI/CTA mini-array based on seven identical telescopes. Silicon Photo-Multipliers (SiPMs) are the semiconductor photosensor devices designated to constitute the camera detection system at the focal plane of the ASTRI telescopes. SiPM photosensors are suitable for the detection of the Cherenkov flashes, since they are very fast and sensitive to the light in the 300-700nm wavelength spectrum. Their drawbacks compared to the traditional photomultiplier tubes are high dark count rates, after-pulsing and optical cross-talk contributions, and intrinsic gains strongly dependent on temperature. Nonetheless, for a single pixel, the dark count rate is well below the Night Sky Background, the effects of cross-talk and afterpulses are typically lower than 20%, and the gain can be kept stable against temperature variations by means of adequate bias voltage compensation strategies. This work presents and discusses some experimental results from a large set of measurements performed on the SiPM sensors to be used for the ASTRI SST-2M prototype camera and on recently developed detectors demonstrating outstanding performance for the future evolution of the project in the ASTRI/CTA mini-array.

Cherenkov excited phosphorescence-based pO2 estimation during multi-beam radiation therapy: phantom and simulation studies.

PubMed

Holt, Robert W; Zhang, Rongxiao; Esipova, Tatiana V; Vinogradov, Sergei A; Glaser, Adam K; Gladstone, David J; Pogue, Brian W

2014-09-21

Megavoltage radiation beams used in External Beam Radiotherapy (EBRT) generate Cherenkov light emission in tissues and equivalent phantoms. This optical emission was utilized to excite an oxygen-sensitive phosphorescent probe, PtG4, which has been developed specifically for NIR lifetime-based sensing of the partial pressure of oxygen (pO2). Phosphorescence emission, at different time points with respect to the excitation pulse, was acquired by an intensifier-gated CCD camera synchronized with radiation pulses delivered by a medical linear accelerator. The pO2 distribution was tomographically recovered in a tissue-equivalent phantom during EBRT with multiple beams targeted from different angles at a tumor-like anomaly. The reconstructions were tested in two different phantoms that have fully oxygenated background, to compare a fully oxygenated and a fully deoxygenated inclusion. To simulate a realistic situation of EBRT, where the size and location of the tumor is well known, spatial information of a prescribed region was utilized in the recovery estimation. The phantom results show that region-averaged pO2 values were recovered successfully, differentiating aerated and deoxygenated inclusions. Finally, a simulation study was performed showing that pO2 in human brain tumors can be measured to within 15 mmHg for edge depths less than 10-20 mm using the Cherenkov Excited Phosphorescence Oxygen imaging (CEPhOx) method and PtG4 as a probe. This technique could allow non-invasive monitoring of pO2 in tumors during the normal process of EBRT, where beams are generally delivered from multiple angles or arcs during each treatment fraction.

Performance verification of the FlashCam prototype camera for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Werner, F.; Bauer, C.; Bernhard, S.; Capasso, M.; Diebold, S.; Eisenkolb, F.; Eschbach, S.; Florin, D.; Föhr, C.; Funk, S.; Gadola, A.; Garrecht, F.; Hermann, G.; Jung, I.; Kalekin, O.; Kalkuhl, C.; Kasperek, J.; Kihm, T.; Lahmann, R.; Marszalek, A.; Pfeifer, M.; Principe, G.; Pühlhofer, G.; Pürckhauer, S.; Rajda, P. J.; Reimer, O.; Santangelo, A.; Schanz, T.; Schwab, T.; Steiner, S.; Straumann, U.; Tenzer, C.; Vollhardt, A.; Wolf, D.; Zietara, K.; CTA Consortium

2017-12-01

The Cherenkov Telescope Array (CTA) is a future gamma-ray observatory that is planned to significantly improve upon the sensitivity and precision of the current generation of Cherenkov telescopes. The observatory will consist of several dozens of telescopes with different sizes and equipped with different types of cameras. Of these, the FlashCam camera system is the first to implement a fully digital signal processing chain which allows for a traceable, configurable trigger scheme and flexible signal reconstruction. As of autumn 2016, a prototype FlashCam camera for the medium-sized telescopes of CTA nears completion. First results of the ongoing system tests demonstrate that the signal chain and the readout system surpass CTA requirements. The stability of the system is shown using long-term temperature cycling.

The ANTARES optical beacon system

NASA Astrophysics Data System (ADS)

Ageron, M.; Aguilar, J. A.; Albert, A.; Ameli, F.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardellier-Desages, F.; Aslanides, E.; Aubert, J.-J.; Auer, R.; Barbarito, E.; Basa, S.; Battaglieri, M.; Becherini, Y.; Beltramelli, J.; Bertin, V.; Bigi, A.; Billault, M.; Blaes, R.; de Botton, N.; Bouwhuis, M. C.; Bradbury, S. M.; Bruijn, R.; Brunner, J.; Burgio, G. F.; Busto, J.; Cafagna, F.; Caillat, L.; Calzas, A.; Capone, A.; Caponetto, L.; Carmona, E.; Carr, J.; Cartwright, S. L.; Castel, D.; Castorina, E.; Cavasinni, V.; Cecchini, S.; Ceres, A.; Charvis, P.; Chauchot, P.; Chiarusi, T.; Circella, M.; Colnard, C.; Compère, C.; Coniglione, R.; Cottini, N.; Coyle, P.; Cuneo, S.; Cussatlegras, A.-S.; Damy, G.; van Dantzig, R.; de Bonis, G.; de Marzo, C.; de Vita, R.; Dekeyser, I.; Delagnes, E.; Denans, D.; Deschamps, A.; Destelle, J.-J.; Dinkespieler, B.; Distefano, C.; Donzaud, C.; Drogou, J.-F.; Druillole, F.; Durand, D.; Ernenwein, J.-P.; Escoffier, S.; Falchini, E.; Favard, S.; Fehr, F.; Feinstein, F.; Ferry, S.; Fiorello, C.; Flaminio, V.; Fratini, K.; Fuda, J.-L.; Galeotti, S.; Gallone, J.-M.; Giacomelli, G.; Girard, N.; Gojak, C.; Goret, Ph.; Graf, K.; Hallewell, G.; Harakeh, M. N.; Hartmann, B.; Heijboer, A.; Heine, E.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; Hoffman, C.; Hogenbirk, J.; Hubbard, J. R.; Jaquet, M.; Jaspers, M.; de Jong, M.; Jouvenot, F.; Kalantar-Nayestanaki, N.; Kappes, A.; Karg, T.; Katz, U.; Keller, P.; Kok, E.; Kok, H.; Kooijman, P.; Kopper, C.; Korolkova, E. V.; Kouchner, A.; Kretschmer, W.; Kruijer, A.; Kuch, S.; Kudryavstev, V. A.; Lagier, P.; Lahmann, R.; Lamanna, G.; Lamare, P.; Lambard, G.; Languillat, J.-C.; Laschinsky, H.; Lavalle, J.; Le Guen, Y.; Le Provost, H.; Le van Suu, A.; Lefèvre, D.; Legou, T.; Lelaizant, G.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Louis, F.; Lucarelli, F.; Lyashuk, V.; Marcelin, M.; Margiotta, A.; Masullo, R.; Mazéas, F.; Mazure, A.; McMillan, J. E.; Megna, R.; Melissas, M.; Migneco, E.; Milovanovic, A.; Mongelli, M.; Montaruli, T.; Morganti, M.; Moscoso, L.; Musumeci, M.; Naumann-Godo, M.; Naumann, C.; Niess, V.; Noble, T.; Olivetto, C.; Ostasch, R.; Palanque-Delabrouille, N.; Payre, P.; Peek, H.; Perez, A.; Petta, C.; Piattelli, P.; Pillet, R.; Pineau, J.-P.; Poinsignon, J.; Popa, V.; Pradier, T.; Racca, C.; Randazzo, N.; van Randwijk, J.; Real, D.; van Rens, B.; Réthoré, F.; Rewiersma, P.; Riccobene, G.; Rigaud, V.; Ripani, M.; Roca, V.; Roda, C.; Rolin, J. F.; Rose, H. J.; Rostovtsev, A.; Roux, J.; Ruppi, M.; Russo, G. V.; Rusydi, G.; Salesa, F.; Salomon, K.; Sapienza, P.; Schmitt, F.; Schuller, J.-P.; Shanidze, R.; Sokalski, I.; Spona, T.; Spurio, M.; van der Steenhoven, G.; Stolarczyk, T.; Streeb, K.; Sulak, L.; Taiuti, M.; Tamburini, C.; Tao, C.; Terreni, G.; Thompson, L. F.; Urbano, F.; Valdy, P.; Valente, V.; Vallage, B.; Vaudaine, G.; Venekamp, G.; Verlaat, B.; Vernin, P.; de Vries-Uiterweerd, G.; van Wijk, R.; Wijnker, G.; de Witt Huberts, P.; Wobbe, G.; de Wolf, E.; Yao, A.-F.; Zaborov, D.; Zaccone, H.; Zornoza, J. D.; Zúñiga, J.

2007-08-01

ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three-dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular, when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented.

Design and development of a Gadolinium-doped water Cherenkov detector

NASA Astrophysics Data System (ADS)

Poudyal, Nabin

This thesis describes a research and development project for neutron capture and detection in Gadolinium doped water. The Sanford Underground Research Facility (SURF) is exploring rare event physics, such as neutrinoless double beta decay (MAJORANA Project) and dark-matter detection (LUX experiment). The success of these experiments requires a careful study and understanding of background radiation, including flux and energy spectrum. The background radiation from surface contamination, radioactive decays of U-238, Th-232, Rn-222 in the surrounding rocks and muon induced neutrons have a large impact on the success of rare-event physics. The main objective of this R&D project is to measure the neutron flux contributing to ongoing experiments at SURF and suppress it by identification and capture method. For this purpose, we first modeled and designed a detector with Geant4 software. The approximate dimension of the detector is determined. The neutron capture percentage of the detector is estimated using Monte Carlo. The energy response of the detector is simulated. Next, we constructed the experimental detector, an acrylic rectangular tank (60cm x 30cm x 30cm), filled with Gadolinium-doped deionized water. The tank is coated with high efficient reflector and then taped with black electrical tape to make it opaque. The voltage dividers attached to PMTs are covered with mu-metal. Two 5-inch Hamamatsu Photomultiplier tubes were attached on both sides facing the tank to collect the Cherenkov light produced in the water. The detector utilizes the principle of Cherenkov light emission by a charged particle moving through a water at a speed higher than the speed of light in the water, hence it has an inherent energy threshold of Cherenkov photon production. This property reduces the lower energy backgrounds. Event data are obtained using the Data Acquisition hardware, Flash Analog to digital converter, along with Multi Instance Data Acquisition software. Post-experimental analysis was performed using ROOT software. Position calibration of the detector shows that the detector is position independent. We have designed and constructed the Gd-doped neutron detector which successfully detects the neutrons with low cost and high efficiency.

Performance of the CAPRICE98 balloon-borne gas-RICH detector

NASA Astrophysics Data System (ADS)

Bergström, D.; Boezio, M.; Carlson, P.; Francke, T.; Grinstein, S.; Weber, N.; Suffert, M.; Hof, M.; Kremer, J.; Menn, W.; Simon, M.; Stephens, S. A.; Ambriola, M.; Bellotti, R.; Cafagna, F.; Castellano, M.; Ciacio, F.; Circella, M.; De Marzo, C.; Finetti, N.; Papini, P.; Piccardi, S.; Spillantini, P.; Bartalucci, S.; Ricci, M.; Bidoli, V.; Casolino, M.; De Pascale, M. P.; Morselli, A.; Picozza, P.; Sparvoli, R.; Barbiellini, G.; Schiavon, P.; Vacchi, A.; Zampa, N.; Mitchell, J. W.; Ormes, J. F.; Streitmatter, R. E.; Bravar, U.; Stochaj, S. J.

2001-05-01

A RICH counter using a gas radiator of C 4F 10 and a photosensitive MWPC with pad readout has been developed, tested in particle beam at CERN and used in the CAPRICE98 balloon-borne experiment. The MWPC was operated with a TMAE and ethane mixture at atmospheric pressure and used a cathode pad plane to give an unambiguous image of the Cherenkov light. The induced signals in the pad plane were read out using the AMPLEX chip and CRAMS. The good efficiency of the Cherenkov light collection, the efficient detection of the weak signal from single UV photons together with a low noise level in the electronics of the RICH detector, resulted in a large number of detected photoelectrons per event. For β≃1 charge one particles, an average of 12 photoelectrons per event were detected. The reconstructed Cherenkov angle of 50 mrad for a β≃1 particle had a resolution of 1.2 mrad (rms). The RICH was flown with the CAPRICE98 magnetic spectrometer and was the first RICH counter ever used in a balloon-borne experiment capable of identifying charge one particles at energies above 5 GeV. The RICH provided an identification of cosmic ray antiprotons up to the highest energies ever studied (about 50 GeV of total energy). The spectrometer was flown on 28-29 May 1998 from Fort Sumner, New Mexico, USA.

Search for neutrino generated air shower candidates with energy ≥ 1019 eV and Zenith angle θ

NASA Astrophysics Data System (ADS)

Knurenko, Stanislav; Petrov, Igor; Sabourov, Artem

2017-06-01

The description of the methodology and results of searching for air showers generated by neutral particles such as high energy gamma quanta and astroneutrinos are presented. For this purpose, we conducted a comprehensive analysis of the data: the electron, the muon and the EAS Cerenkov light, and their response time in scintillation and Cherenkov detectors. Air showers with energy more than 5·1018 eV and zenith angle θ ≥ 55∘ are selected and analyzed. Search results indicate a lack of air shower events formed by gamma-rays or high-energy neutrinos, but it does not mean that such air showers do not exist in nature; for example, experiments that recorded showers having a marked low muon content, i.e., "Muonless", are likely to be candidates for showers produced by neutral primary particles.

Ring Imaging Cerenkov Detector for CLAS12

NASA Astrophysics Data System (ADS)

Muhoza, Mireille; Aaron, Elise; Smoot, Waymond; Benmokhtar, Fatiha

2017-09-01

The CLAS12 detector at Thomas Jefferson National Accelerator Facility (TJNAF) is undergoing an upgrade. One of the additions to this detector is a Ring Imaging Cherenkov (RICH) detector to improve particle identification in the 3-8 GeV/c momentum range. Approximately 400 multi anode photomultiplier tubes (MAPMTs) will be used to detect Cherenkov Radiation in the single photoelectron spectra (SPS). Detector tests are taking place at Jefferson Lab, while analysis software development is ongoing at Duquesne. I will be summarizing the work done at Duquesne on the Database development and the analysis of the ADC and TDCs for the Hamamatsu Multi-Anode PMTs that are used for Cerenkov light radiation. National Science Foundation, Award 1615067.

Aerogel mass production for the CLAS12 RICH: Novel characterization methods and optical performance

NASA Astrophysics Data System (ADS)

Contalbrigo, M.; Balossino, I.; Barion, L.; Barnyakov, A. Yu.; Battaglia, G.; Danilyuk, A. F.; Katcin, A. A.; Kravchenko, E. A.; Mirazita, M.; Movsisyan, A.; Orecchini, D.; Pappalardo, L. L.; Squerzanti, S.; Tomassini, S.; Turisini, M.

2017-12-01

A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capabilities in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the Jefferson Lab upgraded 12 GeV continuous electron beam accelerator facility. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely-packed and highly-segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The status of the aerogel mass-production and the assessment studies of the aerogel optical performance are here reported.

Radiation of a resonant medium excited by few-cycle optical pulses at superluminal velocity

NASA Astrophysics Data System (ADS)

Arkhipov, R. M.; Pakhomov, A. V.; Arkhipov, M. V.; Babushkin, I.; Tolmachev, Yu A.; Rosanov, N. N.

2017-05-01

Recent progress in generation of optical pulses of durations comparable to one optical cycle has presented great opportunities for studies of the fundamental processes in matter as well as time-resolved spectroscopy of ultrafast processes in nonlinear media. It opened up a new area of research in modern ultrafast nonlinear optics and led to appearance of the attosecond science. In parallel, a new research area related to emission from resonant media excited by superluminally propagating ultrashort bursts of electromagnetic radiation has been actively developed over the last few years. In this paper, we review our recent results on theoretical analysis of the Cherenkov-type radiation of a resonant medium excited by few-cycle optical pulses propagating at superluminal velocity. This situation can be realized when an electromagnetic pulse with a plane wavefront incidents on a straight string of resonant atoms or a spot of light rotates at very large angular frequency and excites a distant circular string of resonant dipoles. Theoretical analysis revealed some unusual and remarkable features of the Cherenkov radiation generated in this case. This radiation arises in a transient regime which leads to the occurrence of new frequencies in the radiation spectrum. Analysis of the characteristics of this radiation can be used for the study of the resonant structure properties. In addition, a nonlinear resonant medium excited at superluminal velocity can emit unipolar optical pulses, which can be important in ultrafast control of wave-packet dynamics of matter. Specifics of the few-cycle pulse-driven optical response of a resonant medium composed of linear and nonlinear oscillators is discussed.

Astronomía gamma con telescopios Cherenkov: hacia un observatorio astronómico abierto a la comunidad

NASA Astrophysics Data System (ADS)

Rovero, A. C.

Gamma-ray astronomy is opening the way to a universe far more energetic than anyone could have imagined half a century ago. The understanding of the processes of nature which carry a large portion of the energy in the universe, has astrophysical and cosmological implications. The next gen- eration of Cherenkov telescopes, an order of magnitude more sensitive and with higher resolution than the current systems, will mean a significant step forward for ground-based gamma-ray astronomy. This paper presents the current status of this field as well as the next generation of telescopes in this energy range, which are being designed for the first international observa- tory open to the astronomical community. The Cherenkov Telescope Array project and the Argentine sites proposed for the southern observatory are described in this paper. FULL TEXT IN SPANISH

The single mirror small size telescope (SST-1M) of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Aguilar, J. A.; Bilnik, W.; Borkowski, J.; Cadoux, F.; Christov, A.; della Volpe, D.; Favre, Y.; Heller, M.; Kasperek, J.; Lyard, E.; Marszałek, A.; Moderski, R.; Montaruli, T.; Porcelli, A.; Prandini, E.; Rajda, P.; Rameez, M.; Schioppa, E., Jr.; Troyano Pujadas, I.; Zietara, K.; Blocki, J.; Bogacz, L.; Bulik, T.; Frankowski, A.; Grudzinska, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.; Lalik, K.; Mach, E.; Mandat, D.; Michałowski, J.; Neronov, A.; Niemiec, J.; Ostrowski, M.; Paśko, P.; Pech, M.; Schovanek, P.; Seweryn, K.; Skowron, K.; Sliusar, V.; Stawarz, L.; Stodulska, M.; Stodulski, M.; Toscano, S.; Walter, R.; WiÈ©cek, M.; Zagdański, A.

2016-07-01

The Small Size Telescope with Single Mirror (SST-1M) is one of the proposed types of Small Size Telescopes (SST) for the Cherenkov Telescope Array (CTA). The CTA south array will be composed of about 100 telescopes, out of which about 70 are of SST class, which are optimized for the detection of gamma rays in the energy range from 5 TeV to 300 TeV. The SST-1M implements a Davies-Cotton optics with a 4 m dish diameter with a field of view of 9°. The Cherenkov light produced in atmospheric showers is focused onto a 88 cm wide hexagonal photo-detection plane, composed of 1296 custom designed large area hexagonal silicon photomultipliers (SiPM) and a fully digital readout and trigger system. The SST-1M camera has been designed to provide high performance in a robust as well as compact and lightweight design. In this contribution, we review the different steps that led to the realization of the telescope prototype and its innovative camera.

Cherenkov Telescope Array: the next-generation gamma ray observatory

NASA Astrophysics Data System (ADS)

Ebr, Jan

2017-08-01

The Cherenkov Telescope Array (CTA) is a project to build the next generation ground-based observatory for gamma-ray astronomy at very-high energies in the range from 20 GeV to 300 TeV, which will both surpass the sensitivity of existing instruments in their energy domains and extend the limits of the observed energy spectrum. It will probe some of the most energetic processes in the Universe and provide insight into topics such as the acceleration of charged cosmic rays and their role in galaxy evolution, processes in relativistic jets, wind and explosions and the nature and distribution of dark matter. The CTA Observatory will consist of more than a hundred imaging atmospheric Cherenkov telescopes (IACT) of three different size classes, installed at two premier astronomical locations, one in each hemisphere. It is foreseen that the telescopes will use a variety of optical designs including parabolic primary mirrors, variations of the Davies-Cotton design and two-mirror setups such as the Schwarzschild-Couder telescope, and several camera designs, using both photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs) for detection of the nanosecond-scale Cherenkov flashes. Each telescope will feature a precise but lightweight and agile mount, allowing even the largest telescopes to change targets within 20 seconds, with systems of sensors and actuators actively controlling the shape of the reflecting surfaces. As an integral part, the Observatory will feature extensive calibration facilities, closely monitoring both the detectors themselves and the surrounding atmosphere. Several telescope prototypes already exist and the installation works at the northern site have started.

An innovative bolometric Cherenkov-light detector for a double beta decay search

DOE PAGES

Novati, V.; Artusa, D. R.; Avignone, F. T.; ...

2017-10-31

Here, we present here an innovative cryogenic light detector capable to measure a few tens of eV signal thanks to the amplification assisted by the Neganov-Luke effect. The thermal signal boost in the presence of an electric field allows us to improve the signal-to-noise ratio reaching a baseline noise of around 20 eV. This device - coupled to an enriched 130TeO 2 bolometer (435 g) - registered 160 eV Cherenkov light signal induced by 2615 keV 208 Tl with a signal to noise ratio about 6:1. Since α particles emitted in decays of natural radionuclides do not produce the Cherenkovmore » radiation, we were then able to achieve an efficient α/γ separation in the region of interest for neutrinoless double beta decay of 130 Te (Q-value is 2527 keV). Specifically, a rejection factor of 99.9% for α particles was obtained with a 98.3% acceptance of β/γ events. The achieved α rejection efficiency is required to reduce the dominant α background in the follow-up of the CUORE experiment (CUPID), a ton-scale bolometric search with particle identification.« less

An innovative bolometric Cherenkov-light detector for a double beta decay search

DOE Office of Scientific and Technical Information (OSTI.GOV)

Novati, V.; Artusa, D. R.; Avignone, F. T.

Here, we present here an innovative cryogenic light detector capable to measure a few tens of eV signal thanks to the amplification assisted by the Neganov-Luke effect. The thermal signal boost in the presence of an electric field allows us to improve the signal-to-noise ratio reaching a baseline noise of around 20 eV. This device - coupled to an enriched 130TeO 2 bolometer (435 g) - registered 160 eV Cherenkov light signal induced by 2615 keV 208 Tl with a signal to noise ratio about 6:1. Since α particles emitted in decays of natural radionuclides do not produce the Cherenkovmore » radiation, we were then able to achieve an efficient α/γ separation in the region of interest for neutrinoless double beta decay of 130 Te (Q-value is 2527 keV). Specifically, a rejection factor of 99.9% for α particles was obtained with a 98.3% acceptance of β/γ events. The achieved α rejection efficiency is required to reduce the dominant α background in the follow-up of the CUORE experiment (CUPID), a ton-scale bolometric search with particle identification.« less

Broadly tunable terahertz generation in mid-infrared quantum cascade lasers.

PubMed

Vijayraghavan, Karun; Jiang, Yifan; Jang, Min; Jiang, Aiting; Choutagunta, Karthik; Vizbaras, Augustinas; Demmerle, Frederic; Boehm, Gerhard; Amann, Markus C; Belkin, Mikhail A

2013-01-01

Room temperature, broadly tunable, electrically pumped semiconductor sources in the terahertz spectral range, similar in operation simplicity to diode lasers, are highly desired for applications. An emerging technology in this area are sources based on intracavity difference-frequency generation in dual-wavelength mid-infrared quantum cascade lasers. Here we report terahertz quantum cascade laser sources based on an optimized non-collinear Cherenkov difference-frequency generation scheme that demonstrates dramatic improvements in performance. Devices emitting at 4 THz display a mid-infrared-to-terahertz conversion efficiency in excess of 0.6 mW W(-2) and provide nearly 0.12 mW of peak power output. Devices emitting at 2 and 3 THz fabricated on the same chip display 0.09 and 0.4 mW W(-2) conversion efficiencies at room temperature, respectively. High terahertz-generation efficiency and relaxed phase-matching conditions offered by the Cherenkov scheme allowed us to demonstrate, for the first time, an external-cavity terahertz quantum cascade laser source tunable between 1.70 and 5.25 THz.

Radiotherapy-induced Cherenkov luminescence imaging in a human body phantom.

PubMed

Ahmed, Syed Rakin; Jia, Jeremy Mengyu; Bruza, Petr; Vinogradov, Sergei; Jiang, Shudong; Gladstone, David J; Jarvis, Lesley A; Pogue, Brian W

2018-03-01

Radiation therapy produces Cherenkov optical emission in tissue, and this light can be utilized to activate molecular probes. The feasibility of sensing luminescence from a tissue molecular oxygen sensor from within a human body phantom was examined using the geometry of the axillary lymph node region. Detection of regions down to 30-mm deep was feasible with submillimeter spatial resolution with the total quantity of the phosphorescent sensor PtG4 near 1 nanomole. Radiation sheet scanning in an epi-illumination geometry provided optimal coverage, and maximum intensity projection images provided illustration of the concept. This work provides the preliminary information needed to attempt this type of imaging in vivo. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Design and Fabrication of Cherenkov Counters for the Detection of SNM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erickson, Anna S.; Lanza, Richard; Galaitsis, Anthony

2011-12-13

The need for large-size detectors for long-range active interrogation (AI) detection of SNM has generated interest in water-based detector technologies. Water Cherenkov Detectors (WCD) were selected for this research because of their transportability, scalability, and an inherent energy threshold. The detector design and analysis was completed using the Geant4 toolkit. It was demonstrated both computationally and experimentally that it is possible to use WCD to detect and characterize gamma rays. Absolute efficiency of the detector (with no energy cuts applied) was determined to be around 30% for a {sup 60}Co source.

Development of a digital astronomical intensity interferometer: laboratory results with thermal light

NASA Astrophysics Data System (ADS)

Matthews, Nolan; Kieda, David; LeBohec, Stephan

2018-06-01

We present measurements of the second-order spatial coherence function of thermal light sources using Hanbury-Brown and Twiss interferometry with a digital correlator. We demonstrate that intensity fluctuations between orthogonal polarizations, or at detector separations greater than the spatial coherence length of the source, are uncorrelated but can be used to reduce systematic noise. The work performed here can readily be applied to existing and future Imaging Air-Cherenkov Telescopes used as star light collectors for stellar intensity interferometry to measure spatial properties of astronomical objects.

Light propagation and fluorescence quantum yields in liquid scintillators

NASA Astrophysics Data System (ADS)

Buck, C.; Gramlich, B.; Wagner, S.

2015-09-01

For the simulation of the scintillation and Cherenkov light propagation in large liquid scintillator detectors a detailed knowledge about the absorption and emission spectra of the scintillator molecules is mandatory. Furthermore reemission probabilities and quantum yields of the scintillator components influence the light propagation inside the liquid. Absorption and emission properties are presented for liquid scintillators using 2,5-Diphenyloxazole (PPO) and 4-bis-(2-Methylstyryl)benzene (bis-MSB) as primary and secondary wavelength shifter. New measurements of the quantum yields for various aromatic molecules are shown.

Ionic liquids as solvents for Čerenkov counting and the effect of a wavelength shifter.

PubMed

Mirenda, M; Rodrigues, D; Ferreyra, C; Arenillas, P; Sarmiento, G P; Krimer, N; Japas, M L

2018-04-01

We study the wavelength shift of the Čerenkov light - generated in the ionic liquid (BMIMCl) - caused by the addition of the highly fluorescent ionic liquid (BMIMHPTS). 18 F and 32 P efficiencies increases up to 124% and 14%, respectively, compared with the values obtained with pure BMIMCl. With this improvement, ionic liquid mixtures become a good alternative - when using the TDCR-Cherenkov technique - to standardize radionuclides having electron emissions energies close to the threshold energy in water (∼ 260keV). As an advantage compared with other solvents, the Ionic liquid mixture can be reused, in the case of short-lived radionuclides, by simply removing all water content in a vacuum oven. Copyright © 2017 Elsevier Ltd. All rights reserved.

Composite panels for optical mirrors for Cherenkov Telescopes: development of the cold glass slumping technology

NASA Astrophysics Data System (ADS)

Canestrari, R.; Motta, G.; Pareschi, G.; Basso, S.; Doro, M.; Giro, E.; Lessio, L.

2010-07-01

In the last decade a new window for ground-based high energy astrophysics has been opened. It explores the energy band from about 100 GeV to 10 TeV making use of Imaging Atmospheric Cherenkov Telescopes (IACTs). Research in Very High Energy (VHE) gamma-ray astronomy is improving rapidly and thanks to the newest facilities as MAGIC, HESS and VERITAS astronomers and particle physicists are obtaining surprising implications in the theoretical models. New projects have been started as the European Cherenkov Telescope Array (CTA) and the U.S. Advanced Gamma-ray Imaging System (AGIS). The aim is to enhance both the sensitivity and the energy band coverage to perform imaging, photometry and spectroscopy of sources. In this framework, tens of thousands of optical mirror panels have to be manufactured, tested and mounted into the telescopes. Because of this high number of mirrors it is mandatory to develop a technique easily transferable to industrial mass production, but keeping the technical and cost-effectiveness requirements of the next generation of TeV telescopes. In this context the Astronomical Observatory of Brera (INAF-OAB) is investigating a technique for the manufacturing of stiff and lightweight glass mirror panels with modest angular resolution. These panels have a composite sandwich-like structure with two thin glass skins on both sides of a core material; the reflecting skin is optically shaped using an ad-hoc slumping procedure. The technology here presented is particularly attractive for the mass production of cost-effective mirror segments with long radius of curvature like those required in the primary mirrors of the next generation of Cherenkov telescopes. In this paper we present and discuss some relevant results we have obtained from the latest panels realized.

The DIRC front-end electronics chain for BaBar

NASA Astrophysics Data System (ADS)

Bailly, P.; Chauveau, J.; Del Buono, L.; Genat, J. F.; Lebbolo, H.; Roos, L.; Zhang, B.; Beigbeder, C.; Bernier, R.; Breton, D.; Caceres, T.; Chase, R.; Ducorps, A.; Hrisoho, A.; Imbert, P.; Sen, S.; Tocut, V.; Truong, K.; Wormser, G.; Zomer, F.; Bonneaud, G.; Dohou, F.; Gastaldi, F.; Matricon, P.; Renard, C.; Thiebaux, C.; Vasileiadis, G.; Verderi, M.; Oxoby, G.; Va'Vra, J.; Warner, D.; Wilson, R. J.

1999-08-01

The detector of Internally Reflected Cherenkov light (DIRC) of the BaBar detector (SLAC Stanford, USA) measures better than 1 ns the arrival time of Cherenkov photoelectrons, detected in a 11 000 phototubes array and their amplitude spectra. It mainly comprises of 64-channel DIRC Front-End Boards (DFB) equipped with eight full-custom Analog chips performing zero-cross discrimination with 2 mV threshold and pulse shaping, four full-custom Digital TDC chips for timing measurements with 500 ps binning and a readout logic selecting hits in the trigger window, and DIRC Crate Controller cards (DCC) serializing the data collected from up to 16 DFBs onto a 1.2 Gb/s optical link. Extensive test of the pre-production chips have been performed as well as system tests.

Next generation gamma-ray Cherenkov detectors for the National Ignition Facility.

PubMed

Herrmann, H W; Kim, Y H; McEvoy, A M; Zylstra, A B; Young, C S; Lopez, F E; Griego, J R; Fatherley, V E; Oertel, J A; Stoeffl, W; Khater, H; Hernandez, J E; Carpenter, A; Rubery, M S; Horsfield, C J; Gales, S; Leatherland, A; Hilsabeck, T; Kilkenny, J D; Malone, R M; Hares, J D; Milnes, J; Shmayda, W T; Stoeckl, C; Batha, S H

2016-11-01

The newest generation of Gas Cherenkov Detector (GCD-3) employed in Inertial Confinement Fusion experiments at the Omega Laser Facility has provided improved performance over previous generations. Comparison of reaction histories measured using two different deuterium-tritium fusion products, namely gamma rays using GCD and neutrons using Neutron Temporal Diagnostic (NTD), have provided added credibility to both techniques. GCD-3 is now being brought to the National Ignition Facility (NIF) to supplement the existing Gamma Reaction History (GRH-6m) located 6 m from target chamber center (TCC). Initially it will be located in a reentrant well located 3.9 m from TCC. Data from GCD-3 will inform the design of a heavily-shielded "Super" GCD to be located as close as 20 cm from TCC. It will also provide a test-bed for faster optical detectors, potentially lowering the temporal resolution from the current ∼100 ps state-of-the-art photomultiplier tubes (PMT) to ∼10 ps Pulse Dilation PMT technology currently under development.

Neutrino astronomy at the South Pole: Latest results from the IceCube neutrino observatory and its future development

NASA Astrophysics Data System (ADS)

Toscano, S.; IceCube Collaboration

2017-12-01

The IceCube Neutrino Observatory is a cubic-kilometer neutrino telescope located at the geographic South Pole. Buried deep under the Antarctic ice sheet, an array of 5160 Digital Optical Modules (DOMs) is used to capture the Cherenkov light emitted by relativistic particles generated from neutrino interactions. The main goal of IceCube is the detection of astrophysical neutrinos. In 2013 the IceCube neutrino telescope discovered a high-energy diffuse flux of neutrino events with energy ranging from tens of TeV up to few PeV of cosmic origin. Meanwhile, different analyses confirm the discovery and search for possible correlations with astrophysical sources. However, the source of these neutrinos remains a mystery, since no counterparts have been identified yet. In this contribution we give an overview of the detection principles of IceCube, the most recent results, and the plans for a next-generation neutrino detector, dubbed IceCube-Gen2.

Noise characterization of broadband fiber Cherenkov radiation as a visible-wavelength source for optical coherence tomography and two-photon fluorescence microscopy.

PubMed

Tu, Haohua; Zhao, Youbo; Liu, Yuan; Liu, Yuan-Zhi; Boppart, Stephen

2014-08-25

Optical sources in the visible region immediately adjacent to the near-infrared biological optical window are preferred in imaging techniques such as spectroscopic optical coherence tomography of endogenous absorptive molecules and two-photon fluorescence microscopy of intrinsic fluorophores. However, existing sources based on fiber supercontinuum generation are known to have high relative intensity noise and low spectral coherence, which may degrade imaging performance. Here we compare the optical noise and pulse compressibility of three high-power fiber Cherenkov radiation sources developed recently, and evaluate their potential to replace the existing supercontinuum sources in these imaging techniques.

Electro-Optic Generation and Detection of Femtosecond Electromagnetic Pulses

DTIC Science & Technology

1991-11-20

electromagnetic pulses from an electro - optic crystal following their generation by electro - optic Cherenkov radiation, and their subsequent propagation and detection...in free space; (4) The measurement of subpicosecond electrical response of a new organic electrooptic material (polymer); (5) The observation of terahertz transition radiation from the surfaces of electro - optic crystals.

Evaluation of the night sky quality at El Leoncito and LEO++ in Argentina

NASA Astrophysics Data System (ADS)

Aubé, Martin; García, Beatriz; Fortin, Nicolas; Turcotte, Sara; Mancilla, Alexis; Maya, Javier

2015-08-01

Light pollution is a growing concern at many levels, but especially for the astronomical community. Artificial lighting veil celestial objects and disturbs the measurement of night time atmospheric phenomena. This is what motivates our sky brightness measurement experiment in Argentina. Our goal was to determine the quality of two Argentinian observation sites: LEO++ and El Leoncito. Both sites were candidates to host the Cherenkov Telescope Array (CTA). This project consists of an arrangement of many telescopes that can measure high-energy gamma ray emissions via their Cherenkov radiation produced when entering the earth's atmosphere. Even if the two argentinian sites has been excluded from the final CTA site competition, they are still of great interest for other astronomical projects. Especially the El Leoncito site which already hots the CASLEO astronomical complex. In this presentation, we describe the measurement methods used to determine the sky quality. We compared our results with different renowned astronomical sites (Kitt Peak, Arizona, USA, and Mont-Mégantic, Canada). Amongst our results, we found that LEO++ is a high quality site, however there are a lot of aerosols that can interfere with the measurements. El Leoncito shows very low sky brightness levels, which are optimal for low light level detection.

An all-sky, three-flavor search for neutrinos from gamma-ray bursts with the icecube neutrino observatory

NASA Astrophysics Data System (ADS)

Hellauer, Robert Eugene, III

Ultra high energy cosmic rays (UHECRs), defined by energy greater than 10. 18 eV, have been observed for decades, but their sources remain unknown. Protons and heavy ions, which comprise cosmic rays, interact with galactic and intergalactic magnetic fields and, consequently, do not point back to their sources upon measurement. Neutrinos, which are inevitably produced in photohadronic interactions, travel unimpeded through the universe and disclose the directions of their sources. Among the most plausible candidates for the origins of UHECRs is a class of astrophysical phenomena known as gamma-ray bursts (GRBs). GRBs are the most violent and energetic events witnessed in the observable universe. The IceCube Neutrino Observatory, located in the glacial ice 1450 m to 2450 m below the South Pole surface, is the largest neutrino detector in operation. IceCube detects charged particles, such as those emitted in high energy neutrino interactions in the ice, by the Cherenkov light radiated by these particles. The measurement of neutrinos of 100 TeV energy or greater in IceCube correlated with gamma-ray photons from GRBs, measured by spacecraft detectors, would provide evidence of hadronic interaction in these powerful phenomena and confirm their role in ultra high energy cosmic ray production. This work presents the first IceCube GRB-neutrino coincidence search optimized for charged-current interactions of electron and tau neutrinos as well as neutral-current interactions of all neutrino flavors, which produce nearly spherical Cherenkov light showers in the ice. These results for three years of data are combined with the results of previous searches over four years of data optimized for charged-current muon neutrino interactions, which produce extended Cherenkov light tracks. Several low significance events correlated with GRBs were detected, but are consistent with the background expectation from atmospheric muons and neutrinos. The combined results produce limits that place the strongest constraints thus far on models of neutrino and UHECR production in GRB fireballs.

Systematics for T2K/Hyper-K (Review Talk)

NASA Astrophysics Data System (ADS)

Shah, Raj

Hyper-Kamiokande is a proposed next generation underground water Cherenkov detector. Presented here is a review of sensitivities and dominant uncertainties associated with measurements of CP violation and non-maximal mixing in the 2-3 sector.

Camera Development for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Moncada, Roberto Jose

2017-01-01

With the Cherenkov Telescope Array (CTA), the very-high-energy gamma-ray universe, between 30 GeV and 300 TeV, will be probed at an unprecedented resolution, allowing deeper studies of known gamma-ray emitters and the possible discovery of new ones. This exciting project could also confirm the particle nature of dark matter by looking for the gamma rays produced by self-annihilating weakly interacting massive particles (WIMPs). The telescopes will use the imaging atmospheric Cherenkov technique (IACT) to record Cherenkov photons that are produced by the gamma-ray induced extensive air shower. One telescope design features dual-mirror Schwarzschild-Couder (SC) optics that allows the light to be finely focused on the high-resolution silicon photomultipliers of the camera modules starting from a 9.5-meter primary mirror. Each camera module will consist of a focal plane module and front-end electronics, and will have four TeV Array Readout with GSa/s Sampling and Event Trigger (TARGET) chips, giving them 64 parallel input channels. The TARGET chip has a self-trigger functionality for readout that can be used in higher logic across camera modules as well as across individual telescopes, which will each have 177 camera modules. There will be two sites, one in the northern and the other in the southern hemisphere, for full sky coverage, each spanning at least one square kilometer. A prototype SC telescope is currently under construction at the Fred Lawrence Whipple Observatory in Arizona. This work was supported by the National Science Foundation's REU program through NSF award AST-1560016.

RICH Detector for Jefferson Labs CLAS12

NASA Astrophysics Data System (ADS)

Trotta, Richard; Torisky, Ben; Benmokhtar, Fatiha

2015-10-01

Jefferson Lab (Jlab) is performing a large-scale upgrade to its Continuous Electron Beam Accelerator Facility (CEBAF) up to 12GeV beams. The Large Acceptance Spectrometer (CLAS12) in Hall B is being upgraded and a new hybrid Ring Imaging Cherenkov (RICH) detector is being developed to provide better kaon - pion separation throughout the 3 to 8 GeV/c momentum range. This detector will be used for a variety of Semi-Inclusive Deep Inelastic Scattering experiments. Cherenkov light can be accurately detected by a large array of sophisticated Multi-Anode Photomultiplier Tubes (MA-PMT) and heavier particles, like kaons, will span the inner radii. We are presenting our work on the creation of the RICH's geometry within the CLAS12 java framework. This development is crucial for future calibration, reconstructions and analysis of the detector.

Evidence for a mixed mass composition at the 'ankle' in the cosmic-ray spectrum

NASA Astrophysics Data System (ADS)

Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Al Samarai, I.; Albuquerque, I. F. M.; Allekotte, I.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Biermann, P. L.; Billoir, P.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; Dallier, R.; D'Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; Debatin, J.; del Peral, L.; Deligny, O.; Di Giulio, C.; Di Matteo, A.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D'Olivo, J. C.; Dorofeev, A.; dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; García, B.; Garcia-Pinto, D.; Gaté, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Głas, D.; Glaser, C.; Glass, H.; Golup, G.; Gómez Berisso, M.; Gómez Vitale, P. F.; González, N.; Gookin, B.; Gordon, J.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Hasankiadeh, Q.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Johnsen, J. A.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A.; LaHurd, D.; Latronico, L.; Lauscher, M.; Lautridou, P.; Lebrun, P.; Legumina, R.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; López, R.; López Casado, A.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Mariş, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martínez Bravo, O.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Messina, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Mockler, D.; Molina-Bueno, L.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafá, M.; Müller, G.; Muller, M. A.; Müller, S.; Naranjo, I.; Navas, S.; Nellen, L.; Neuser, J.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, H.; Núñez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Pȩkala, J.; Pelayo, R.; Peña-Rodriguez, J.; Pereira, L. A. S.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollant, R.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Reinert, D.; Revenu, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Rogozin, D.; Rosado, J.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sanabria Gomez, J. D.; Sánchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sarmiento-Cano, C.; Sato, R.; Scarso, C.; Schauer, M.; Scherini, V.; Schieler, H.; Schmidt, D.; Scholten, O.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Stanca, D.; Stanič, S.; Stasielak, J.; Strafella, F.; Suarez, F.; Suarez Durán, M.; Sudholz, T.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Taborda, O. A.; Tapia, A.; Tepe, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Torri, M.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valbuena-Delgado, A.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Villaseñor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczyński, H.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yang, L.; Yelos, D.; Younk, P.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zuccarello, F.; Pierre Auger Collaboration

2016-11-01

We report a first measurement for ultrahigh energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the 'ankle' at lg ⁡ (E /eV) = 18.5- 19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A > 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavored as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.

Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum

DOE PAGES

Aab, Alexander

2016-09-28

Here, we report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' atmore » $$\\lg(E/{\\rm eV})=18.5-19.0$$ differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass $A > 4$. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.« less

Search for point sources of high energy neutrinos with Amanda

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahrens, J.

2002-08-01

Report of search for likely point sources for neutrinos observed by the Amanda detector. Places intensity limits on observable point sources. This paper describes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector, an array of 302 photomultiplier tubes, used for the detection of Cherenkov light from upward traveling neutrino-induced muons, buried deep in ice at the South Pole. The absolute pointing accuracy and angular resolution were studied by using coincident events between the AMANDA detector and two independent telescopes on the surface, the GASP air Cherenkov telescope and the SPASE extensive air shower array. Using datamore » collected from April to October of 1997 (130.1 days of livetime), a general survey of the northern hemisphere revealed no statistically significant excess of events from any direction. The sensitivity for a flux of muon neutrinos is based on the effective detection area for through-going muons. Averaged over the Northern sky, the effective detection area exceeds 10,000 m{sup 2} for E{sub {mu}} {approx} 10 TeV. Neutrinos generated in the atmosphere by cosmic ray interactions were used to verify the predicted performance of the detector. For a source with a differential energy spectrum proportional to E{sub {nu}}{sup -2} and declination larger than +40{sup o}, we obtain E{sup 2} (dN{sub {nu}}/dE) {le} 10{sup -6} GeV cm{sup -2} s{sup -1} for an energy threshold of 10 GeV.« less

DIRC Dreams: Research Directions for the Next Generation of Internally Reflected Imaging Counters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratcliff, Blair N.

1999-08-17

Some conceptual design features of the total internally reflecting,imaging Cherenkov counter (DIRC) are described. Limits of the DIRC approach to particle identification, and a few features of alternative DIRC designs, are briefly explored.

Enriched TeO 2 bolometers with active particle discrimination: Towards the CUPID experiment

DOE PAGES

Artusa, D. R.; Avignone, F. T.; Beeman, J. W.; ...

2017-04-01

We present the performances of two 92% enriched 130TeO2 crystals operated as thermal bolometers in view of a next generation experiment to search for neutrinoless double beta decay of 130Te. The crystals, 435 g each, show an energy resolution, evaluated at the 2615 keV γ-line of 208Tl, of 6.5 and 4.3 keV FWHM. The only observable internal radioactive contamination arises from 238U (15 and 8 μBq/kg, respectively). The internal activity of the most problematic nuclei for neutrinoless double beta decay, 226Ra and 228Th, are both evaluated as <3.1 μBq/kg for one crystal and <2.3 μBq/kg for the second. Thanks tomore » the readout of the weak Cherenkov light emitted by β/γ particles by means of Neganov–Luke bolometric light detectors we were able to perform an event-by-event identification of β/γ events with a 95% acceptance level, while establishing a rejection factor of 98.21% and 99.99% for α particles.« less

Enriched TeO 2 bolometers with active particle discrimination: Towards the CUPID experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Artusa, D. R.; Avignone, F. T.; Beeman, J. W.

We present the performances of two 92% enriched 130TeO2 crystals operated as thermal bolometers in view of a next generation experiment to search for neutrinoless double beta decay of 130Te. The crystals, 435 g each, show an energy resolution, evaluated at the 2615 keV γ-line of 208Tl, of 6.5 and 4.3 keV FWHM. The only observable internal radioactive contamination arises from 238U (15 and 8 μBq/kg, respectively). The internal activity of the most problematic nuclei for neutrinoless double beta decay, 226Ra and 228Th, are both evaluated as <3.1 μBq/kg for one crystal and <2.3 μBq/kg for the second. Thanks tomore » the readout of the weak Cherenkov light emitted by β/γ particles by means of Neganov–Luke bolometric light detectors we were able to perform an event-by-event identification of β/γ events with a 95% acceptance level, while establishing a rejection factor of 98.21% and 99.99% for α particles.« less

Focal Plane Detectors for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Otte, A. N.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Horan, D.; Mukherjee, R.; Smith, A.; Tajima, H.; Wagner, R. G.; Williams, D. A.

2008-12-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. Design goals are ten times better sensitivity, higher angular resolution, and a lower energy threshold than existing Cherenkov telescopes. Simulations show that a substantial improvement in angular resolution may be achieved if the pixel diameter is reduced to the order of 0.05 deg, i.e. two to three times smaller than the pixel diameter of current Cherenkov telescope cameras. At these dimensions, photon detectors with smaller physical dimensions can be attractive alternatives to the classical photomultiplier tube (PMT). Furthermore, the operation of an experiment with the size of AGIS requires photon detectors that are among other things more reliable, more durable, and possibly higher efficiency photon detectors. Alternative photon detectors we are considering for AGIS include both silicon photomultipliers (SiPMs) and multi-anode photomultipliers (MAPMTs). Here we present results from laboratory testing of MAPMTs and SiPMs along with results from the first incorporation of these devices into cameras on test bed Cherenkov telescopes.

Reconstructing the direction of reactor antineutrinos via electron scattering in Gd-doped water Cherenkov detectors

DOE PAGES

Hellfeld, D.; Bernstein, A.; Dazeley, S.; ...

2017-01-01

The potential of elastic antineutrino-electron scattering (ν¯ e + e – → ν¯ e + e –) in a Gd-doped water Cherenkov detector to determine the direction of a nuclear reactor antineutrino flux was investigated using the recently proposed WATCHMAN antineutrino experiment as a baseline model. The expected scattering rate was determined assuming a 13 km standoff from a 3.758 GWt light water nuclear reactor. Background was estimated via independent simulations and by appropriately scaling published measurements from similar detectors. Many potential backgrounds were considered, including solar neutrinos, misidentified reactor-based inverse beta decay interactions, cosmogenic radionuclide and water-borne radon decays,more » and gamma rays from the photomultiplier tubes, detector walls, and surrounding rock. The detector response was modeled using a GEANT4-based simulation package. The results indicate that with the use of low radioactivity PMTs and sufficient fiducialization, water-borne radon and cosmogenic radionuclides pose the largest threats to sensitivity. The directional sensitivity was then analyzed as a function of radon contamination, detector depth, and detector size. Lastly, the results provide a list of theoretical conditions that, if satisfied in practice, would enable nuclear reactor antineutrino directionality in a Gd-doped water Cherenkov detector approximately 10 km from a large power reactor.« less

The Cherenkov Surface Detector of the Pierre Auger Observatory

NASA Astrophysics Data System (ADS)

Billoir, Pierre

2014-12-01

The Pierre Auger Observatory detects the atmospheric showers induced by cosmic rays of ultra-high energy (UHE). It is the first one to use the hybrid technique. A set of telescopes observes the fluorescence of the nitrogen molecules on clear moonless nights, giving access to the longitudinal profile of the shower. These telescopes surround a giant array of 1600 water Cherenkov tanks (covering more than 3000 km2), which works continuously and samples the particles reaching the ground (mainly muons, photons and electrons/positrons); the light produced within the water is recorded into FADC (Fast Analog to Digital Convertes) traces. A subsample of hybrid events provides a cross calibration of the two components. We describe the structure of the Cherenkov detectors, their sensitivity to different particles and the information they can give on the direction of origin, the energy and the nature of the primary UHE object; we discuss also their discrimination power for rare events (UHE photons or neutrinos). To cope with the variability of weather conditions and the limitations of the communication system, the procedures for trigger and real time calibration have been shared between local processors and a central acquisition system. The overall system has been working almost continuously for 10 years, while being progressively completed and increased by the creation of a dense "infill" subarray.

Supernova remnants and pulsar wind nebulae with Imaging Atmospheric Cherenkov Telescopes (IACTs)

NASA Astrophysics Data System (ADS)

Eger, Peter

2015-08-01

The observation of very-high-energy (VHE, E > 100 GeV) gamma rays is an excellent tool to study the most energetic and violent environments in the Galaxy. This energy range is only accessible with ground-based instruments such as Imaging Atmospheric Cherenkov Telescopes (IACTs) that reconstruct the energy and direction of the primary gamma ray by observing the Cherenkov light from the induced extended air showers in Earths atmosphere. The main goals of Galactic VHE gamma-ray science are the identification of individual sources of cosmic rays (CRs), such as supernova remnants (SNRs), and the study of other extreme astrophysical objects at the highest energies, such as gamma-ray binaries and pulsar wind nebulae (PWNe). One of the main challenges is the discrimination between leptonic and hadronic gamma-ray production channels. To that end, the gamma-ray signal from each individual source needs to be brought into context with the multi-wavelength environment of the astrophysical object in question, particularly with observations tracing the density of the surrounding interstellar medium, or synchrotron radiation from relativistic electrons. In this review presented at the European Cosmic Ray Symposium 2014 (ECRS2014), the most recent developments in the field of Galactic VHE gamma-ray science are highlighted, with particular emphasis on SNRs and PWNe.

Optimal strategies for observation of active galactic nuclei variability with Imaging Atmospheric Cherenkov Telescopes

NASA Astrophysics Data System (ADS)

Giomi, Matteo; Gerard, Lucie; Maier, Gernot

2016-07-01

Variable emission is one of the defining characteristic of active galactic nuclei (AGN). While providing precious information on the nature and physics of the sources, variability is often challenging to observe with time- and field-of-view-limited astronomical observatories such as Imaging Atmospheric Cherenkov Telescopes (IACTs). In this work, we address two questions relevant for the observation of sources characterized by AGN-like variability: what is the most time-efficient way to detect such sources, and what is the observational bias that can be introduced by the choice of the observing strategy when conducting blind surveys of the sky. Different observing strategies are evaluated using simulated light curves and realistic instrument response functions of the Cherenkov Telescope Array (CTA), a future gamma-ray observatory. We show that strategies that makes use of very small observing windows, spread over large periods of time, allows for a faster detection of the source, and are less influenced by the variability properties of the sources, as compared to strategies that concentrate the observing time in a small number of large observing windows. Although derived using CTA as an example, our conclusions are conceptually valid for any IACTs facility, and in general, to all observatories with small field of view and limited duty cycle.

Comparación del funcionamiento entre PMT y SiPM para la detección de Cherenkov atmosférico en el Complejo Astronómico El Leoncito

NASA Astrophysics Data System (ADS)

Yelós, L. D.; Suarez, F.; García, B.

2017-10-01

Most recent discoveries in gamma ray astronomy with energies around 50 GeV to 30 TeV, were achieved with ground Cherenkov Telescopes, traditionally composed of a parabolic mirror and a single or an array of photo multiplier tubes (PMTs) in their focus. The same detectors (or similar) are used in most astrophysics experiments. Recently, a new detector, the silicon photo-multiplier (SiPM), is progressively replacing the PMTs due to their technical advantages. However some limitations in their functioning make them more complex to use than PMTs and forces their characterization for each project. This work describes the characterization of SiPM from SensL (model MicroFC-SMA-30035) and a PMT from Hamamatsu (model R1463), both detectors are possible options to be used in an array of three Cherenkov telescopes at CASLEO. Additionally, we include the results of the operation of both detectors under controlled laboratory conditions that simulate expected conditions at field. Laboratory test were run in a darkbox with a data acquisition system, a personalized data analyze system with ROOT libraries, temperature control and monitoring, polarization control, a controlled light source, and humidity monitoring.

An Educational MONTE CARLO Simulation/Animation Program for the Cosmic Rays Muons and a Prototype Computer-Driven Hardware Display.

ERIC Educational Resources Information Center

Kalkanis, G.; Sarris, M. M.

1999-01-01

Describes an educational software program for the study of and detection methods for the cosmic ray muons passing through several light transparent materials (i.e., water, air, etc.). Simulates muons and Cherenkov photons' paths and interactions and visualizes/animates them on the computer screen using Monte Carlo methods/techniques which employ…

Muon reconstruction in the Daya Bay water pools

DOE PAGES

Hackenburg, R. W.

2017-08-12

Muon reconstruction in the Daya Bay water pools would serve to verify the simulated muon fluxes and offer the possibility of studying cosmic muons in general. This reconstruction is, however, complicated by many optical obstacles and the small coverage of photomultiplier tubes (PMTs) as compared to other large water Cherenkov detectors. The PMTs’ timing information is useful only in the case of direct, unreflected Cherenkov light. This requires PMTs to be added and removed as an hypothesized muon trajectory is iteratively improved, to account for the changing effects of obstacles and direction of light. Therefore, muon reconstruction in the Dayamore » Bay water pools does not lend itself to a general fitting procedure employing smoothly varying functions with continuous derivatives. Here, we describe an algorithm which overcomes these complications. It employs the method of Least Mean Squares to determine an hypothesized trajectory from the PMTs’ charge-weighted positions. This initially hypothesized trajectory is then iteratively refined using the PMTs’ timing information. Reconstructions with simulated data reproduce the simulated trajectory to within about 5° in direction and about 45 cm in position at the pool surface, with a bias that tends to pull tracks away from the vertical by about 3°.« less

Muon reconstruction in the Daya Bay water pools

NASA Astrophysics Data System (ADS)

Hackenburg, R. W.

2017-11-01

Muon reconstruction in the Daya Bay water pools would serve to verify the simulated muon fluxes and offer the possibility of studying cosmic muons in general. This reconstruction is, however, complicated by many optical obstacles and the small coverage of photomultiplier tubes (PMTs) as compared to other large water Cherenkov detectors. The PMTs' timing information is useful only in the case of direct, unreflected Cherenkov light. This requires PMTs to be added and removed as an hypothesized muon trajectory is iteratively improved, to account for the changing effects of obstacles and direction of light. Therefore, muon reconstruction in the Daya Bay water pools does not lend itself to a general fitting procedure employing smoothly varying functions with continuous derivatives. Here, an algorithm is described which overcomes these complications. It employs the method of Least Mean Squares to determine an hypothesized trajectory from the PMTs' charge-weighted positions. This initially hypothesized trajectory is then iteratively refined using the PMTs' timing information. Reconstructions with simulated data reproduce the simulated trajectory to within about 5°in direction and about 45 cm in position at the pool surface, with a bias that tends to pull tracks away from the vertical by about 3°.

Next Generation Gamma-Ray Cherenkov Detectors for the National Ignition Facility

DOE PAGES

Herrmann, Hans W.; Kim, Yong Ho; McEvoy, Aaron Matthew; ...

2016-10-19

The newest generation of Gas Cherenkov Detector (GCD-3) employed in Inertial Confinement Fusion experiments at the Omega Laser Facility has provided improved performance over previous generations. Comparison of reaction histories measured using two different deuterium-tritium fusion products, namely gamma rays using GCD and neutrons using Neutron Temporal Diagnostic (NTD), have provided added credibility to both techniques. GCD-3 is now being brought to the National Ignition Facility (NIF) to supplement the existing Gamma Reaction History (GRH-6m) located 6 m from target chamber center (TCC). Initially it will be located in a reentrant well located 3.9 m from TCC. Data from GCD-3more » will inform the design of a heavily-shielded “Super” GCD to be located as close as 20 cm from TCC. In conclusion, it will also provide a test-bed for faster optical detectors, potentially lowering the temporal resolution from the current ~100 ps state-of-the-art photomultiplier tubes (PMT) to ~10 ps Pulse Dilation PMT technology currently under development.« less

Mechanisms of phosphenes in irradiated patients

PubMed Central

Mathis, Thibaud; Vignot, Stephane; Leal, Cecila; Caujolle, Jean-Pierre; Maschi, Celia; Mauget-Faÿsse, Martine; Kodjikian, Laurent; Baillif, Stéphanie; Herault, Joel; Thariat, Juliette

2017-01-01

Anomalous visual perceptions have been reported in various diseases of the retina and visual pathways or can be experienced under specific conditions in healthy individuals. Phosphenes are perceptions of light in the absence of ambient light, occurring independently of the physiological and classical photonic stimulation of the retina. They are a frequent symptom in patients irradiated in the region of the central nervous system (CNS), head and neck and the eyes. Phosphenes have historically been attributed to complex physical phenomena such as Cherenkov radiation. While phosphenes are related to Cherenkov radiation under high energy photon/electron irradiation conditions, physical phenomena are unlikely to be responsible for light flashes at energies used for ocular proton therapy. Phosphenes may involve a direct role for ocular photoreceptors and possible interactions between cones and rods. Other mechanisms involving the retinal ganglion cells or ultraweak biophoton emission and rhodopsin bleaching after exposure to free radicals are also likely to be involved. Despite their frequency as shown in our preliminary observations, phosphenes have been underreported probably because their mechanism and impact are poorly understood. Recently, phosphenes have been used to restore the vision and whether they might predict vision loss after therapeutic irradiation is a current field of investigation. We have reviewed and also investigated here the mechanisms related to the occurrence of phosphenes in irradiated patients and especially in patients irradiated by proton therapy for ocular tumors. PMID:28969095

Development of sampling calorimeter with segmented lead glass absorber

NASA Astrophysics Data System (ADS)

Terada, R.; Takeshita, T.; Itoh, H.; Kanzaki, I.

2018-02-01

Sampling calorimeter is indispensable for physics measurement at collider experiment with PFA. Uncertainty of deposit energy at absorber layer degrades energy resolution. This problem will be solved by using lead glass as absorber, which is clear and heavy. High energy particles produce Cherenkov lights whose light yield corresponds to the track length in the lead glass. This information from the absorber will improve the energy resolution of the calorimeter. Performance of this calorimeter prototype tested for electrons at ELPH beam at Tohoku University has been described. We discuss the problems and its capabilities.

Measurement of the dependence of the light yields of linear alkylbenzene-based and EJ-301 scintillators on electron energy

NASA Astrophysics Data System (ADS)

Wan Chan Tseung, H.; Kaspar, J.; Tolich, N.

2011-10-01

An experimental test of the electron energy scale linearities of SNO+ and EJ-301 scintillators was carried out using a Compton spectrometer with electrons in the energy range 0.09-3 MeV. The linearity of the apparatus was explicitly demonstrated. It was found that the response of both types of scintillators with respect to electrons becomes non-linear below ˜0.4 MeV. An explanation is given in terms of Cherenkov light absorption and re-emission by the scintillators.

The Gamma-ray Cherenkov Telescope, an end-to end Schwarzschild-Couder telescope prototype proposed for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Dournaux, J. L.; Abchiche, A.; Allan, D.; Amans, J. P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J.-J.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Dangeon, L.; Daniel, M. K.; De Franco, A.; De Frondat, F.; Dumas, D.; Ernenwein, J. P.; Fasola, G.; Funk, S.; Gironnet, J.; Graham, J. A.; Greenshaw, T.; Hameau, B.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J. M.; Jégouzo, I.; Jogler, T.; Kawashima, T.; Kraush, M.; Lapington, J. S.; Laporte, P.; Lefaucheur, J.; Markoff, S.; Melse, T.; Mohrmann, L.; Molyneux, P.; Nolan, S. J.; Okumura, A.; Osborne, J. P.; Parsons, R. D.; Rosen, S.; Ross, D.; Rowell, G.; Rulten, C. B.; Sato, Y.; Sayède, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Sol, H.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Tibaldo, L.; Trichard, C.; Vink, J.; Watson, J. J.; White, R.; Yamane, N.; Zech, A.; Zink, A.

2016-08-01

The GCT (Gamma-ray Cherenkov Telescope) is a dual-mirror prototype of Small-Sized-Telescopes proposed for the Cherenkov Telescope Array (CTA) and made by an Australian-Dutch-French-German-Indian-Japanese-UK-US consortium. The integration of this end-to-end telescope was achieved in 2015. On-site tests and measurements of the first Cherenkov images on the night sky began on November 2015. This contribution describes the telescope and plans for the pre-production and a large scale production within CTA.

PPO-ethanol system as wavelength shifter for the Cherenkov counting technique using a liquid scintillation counter

NASA Astrophysics Data System (ADS)

Takiue, Makoto; Fujii, Haruo; Ishikawa, Hiroaki

1984-12-01

2, 5-diphenyloxazole (PPO) has been proposed as a wavelength shifter for Cherenkov counting. Since PPO is not incorporated with water, we have introduced the fluor into water in the form of micelle using a PPO-ethanol system. This technique makes it possible to obtain a high Cherenkov counting efficiency under stable sample conditions, attributed to the proper spectrometric features of the PPO. The 32P Cherenkov counting efficiency (68.4%) obtained from this technique is large as that measured with a conventional Cherenkov technique.

The wide-aperture gamma-ray telescope TAIGA-HiSCORE in the Tunka Valley: Design, composition and commissioning

NASA Astrophysics Data System (ADS)

Gress, O.; Astapov, I.; Budnev, N.; Bezyazeekov, P.; Bogdanov, A.; Boreyko, V.; Brückner, M.; Chiavassa, A.; Chvalaev, O.; Dyachok, A.; Gress, T.; Epimakhov, S.; Fedoseev, E.; Gafarov, A.; Gorbunov, N.; Grebenyuk, V.; Grinuk, A.; Grishin, O.; Horns, D.; Ivanova, A.; Kalinin, A.; Karpov, N.; Kalmykov, N.; Kazarina, Yu.; Kirichkov, N.; Kiryuhin, S.; Kokoulin, R.; Komponiest, K.; Korosteleva, E.; Kozhin, V.; Kunnas, M.; Kuzmichev, L.; Lenok, V.; Lubsandorzhiev, B.; Lubsandorzhiev, N.; Mirgazov, R.; Mirzoyan, R.; Monkhoev, R.; Nachtigall, R.; Pakhorukov, A.; Panasyuk, M.; Pankov, L.; Petrukhin, A.; Platonov, V.; Poleschuk, V.; Popova, E.; Porelli, A.; Prosin, V.; Rubtsov, G.; Pushnin, A.; Samoliga, V.; Saunkin, A.; Semeney, Yu.; Shaibonov(ju), B.; Silaev, A.; Silaev(ju), A.; Skurikhin, A.; Slucka, V.; Spiering, C.; Sveshnikova, L.; Tabolenko, V.; Tarashchansky, B.; Tkachenko, A.; Tkachev, L.; Tluczykont, M.; Voronin, D.; Wischnewski, R.; Zagorodnikov, A.; Zurbanov, V.; Yashin, I.

2017-02-01

The new TAIGA-HiSCORE non-imaging Cherenkov array aims to detect air showers induced by gamma rays above 30 TeV and to study cosmic rays above 100 TeV. TAIGA-HiSCORE is made of integrating air Cherenkov detector stations with a wide field of view (0.6 sr), placed at a distance of about 100 m. They cover an area of initially ∼0.25 km2 (prototype array), and of ∼5 km2 at the final phase of the experiment. Each station includes 4 PMTs with 20 or 25 cm diameter, equipped with light guides shaped as Winstone cones. We describe the design, specifications of the read-out, DAQ and control and monitoring systems of the array. The present 28 detector stations of the TAIGA-HiSCORE engineering setup are in operation since September 2015.

Searches for relativistic magnetic monopoles in IceCube

DOE PAGES

Aartsen, M. G.; Abraham, K.; Ackermann, M.; ...

2016-03-10

Various extensions of the Standard Model motivate the existence of stable magnetic monopoles that could have been created during an early high-energy epoch of the Universe. These primordial magnetic monopoles would be gradually accelerated by cosmic magnetic fields and could reach high velocities that make them visible in Cherenkov detectors such as IceCube. Equivalently to electrically charged particles, magnetic monopoles produce direct and indirect Cherenkov light while traversing through matter at relativistic velocities. This paper describes searches for relativistic ((Formula presented.)) and mildly relativistic ((Formula presented.)) monopoles, each using one year of data taken in 2008/2009 and 2011/2012, respectively. Nomore » monopole candidate was detected. For a velocity above (Formula presented.) the monopole flux is constrained down to a level of (Formula presented.). This is an improvement of almost two orders of magnitude over previous limits.« less

Searches for relativistic magnetic monopoles in IceCube

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aartsen, M. G.; Abraham, K.; Ackermann, M.

Various extensions of the Standard Model motivate the existence of stable magnetic monopoles that could have been created during an early high-energy epoch of the Universe. These primordial magnetic monopoles would be gradually accelerated by cosmic magnetic fields and could reach high velocities that make them visible in Cherenkov detectors such as IceCube. Equivalently to electrically charged particles, magnetic monopoles produce direct and indirect Cherenkov light while traversing through matter at relativistic velocities. This paper describes searches for relativistic ((Formula presented.)) and mildly relativistic ((Formula presented.)) monopoles, each using one year of data taken in 2008/2009 and 2011/2012, respectively. Nomore » monopole candidate was detected. For a velocity above (Formula presented.) the monopole flux is constrained down to a level of (Formula presented.). This is an improvement of almost two orders of magnitude over previous limits.« less

The large-area hybrid-optics RICH detector for the CLAS12 spectrometer

DOE PAGES

Mirazita, M.; Angelini, G.; Balossino, I.; ...

2017-01-16

A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forwardmore » tracks) or after two mirror reflections (large angle tracks). Finally, the preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here.« less

The ASTRI SST-2M prototype for the Cherenkov Telescope Array: prototype technologies goals and strategies for the future SST

NASA Astrophysics Data System (ADS)

Marchiori, Gianpietro; Busatta, Andrea; Giacomel, Stefano; Folla, Ivan; Valsecchi, Marco; Canestrari, Rodolfo; Bonnoli, Giacomo; Cascone, Enrico; Conconi, Paolo; Fiorini, Mauro; Giro, Enrico; La Palombara, Nicola; Pareschi, Giovanni; Perri, Luca; Rodeghiero, Gabriele; Sironi, Giorgia; Stringhetti, Luca; Toso, Giorgio; Tosti, Gino; Pellicciari, Carlo

2014-07-01

The Cherenkov Telescope Array (CTA) observatory will represent the next generation of Imaging Atmospheric Cherenkov Telescope. Using a combination of large-, medium-, and small-scale telescopes (LST, MST, SST, respectively), it will explore the Very High Energy domain from a few tens of GeVup to about few hundreds of TeV with unprecedented sensitivity, angular resolution and imaging quality. In this framework, the Italian ASTRI program, led by the Italian National Institute of Astrophysics (INAF) developed a 4-meter class telescope, which will adopt an aplanatic, wide-field, double-reflection optical layout in a Schwarzschild- Couder configuration. Within this program INAF assigned to the consortium between Galbiati Group and EIE Group the construction, assembly and tests activities of the prototype named ASTRI SST-2M. On the basis of the lesson learnt from the prototype, other telescopes will be produced, starting from a re-design phase, in order to optimize performances and the overall costs and production schedule for the CTA-SST telescope. This paper will firstly give an overview of the concept for the SST prototype mount structure. In this contest, the technologies adopted for the design, manufacturing and tests of the entire system will be presented. Moreover, a specific focus on the challenges of the prototype and the strategies associated with it will be provided, in order to outline the near future performance goals for this type of Cherenkov telescopes employed for Gamma ray science.

The possibilities of Cherenkov telescopes to perform cosmic-ray muon imaging of volcanoes

NASA Astrophysics Data System (ADS)

Carbone, Daniele; Catalano, Osvaldo; Cusumano, Giancarlo; Del Santo, Melania; Maccarone, Maria Concetta; Mineo, Teresa; Pareschi, Giovanni; Vercellone, Stefano; Zuccarello, Luciano

2016-04-01

Volcanic activity is regulated by the interaction of gas-liquid flow with conduit geometry. Hence, the quantitative understanding of the inner shallow structure of a volcano is mandatory to forecast the occurrence of dangerous stages of activity and mitigate volcanic hazards. Among the techniques used to investigate the underground structure of a volcano, muon imaging offers some advantages, as it provides a fine spatial resolution, and does not require neither spatially dense measurements in active zones, nor the implementation of cost demanding energizing systems, as when electric or active seismic sources are utilized. The principle of muon radiography is essentially the same as X-ray radiography: muons are more attenuated by higher density parts inside the target and thus information about its inner structure are obtained from the differential muon absorption. Up-to-date, muon imaging of volcanic structures has been mainly accomplished with detectors that employ planes of scintillator strips. These telescopes are exposed to different types of background noise (accidental coincidence of vertical shower particles, horizontal high-energy electrons, flux of upward going particles), whose amplitude is high relative to the tiny flux of interest. An alternative technique is based on the detection of the Cherenkov light produced by muons. The latter can be imaged as an annular pattern that contains the information needed to reconstruct both direction and energy of the particle. Cherenkov telescopes have never been utilized to perform muon imaging of volcanoes. Nonetheless, thanks to intrinsic features, they offer the possibility to detect the through-target muon flux with negligible levels of background noise. Under some circumstances, they would also provide a better spatial resolution and acceptance than scintillator-based telescopes. Furthermore, contrarily to the latter systems, Cherenkov detectors allow in-situ measurements of the open-sky energy spectrum of atmospheric muons, that is needed to asses a reference model of the through-target integrated flux. Here we describe our plans for the production of a Cherenkov telescope with suitable characteristics for installation in the summit zone of Etna volcano.

The modified scheme of optimized in simulations Cherenkov type high-power microwave oscillator without guiding magnetic field

NASA Astrophysics Data System (ADS)

Guo, Li M.; Shu, T.; Li, Zhi Q.; Ju, Jin C.

2017-12-01

The compactness and miniaturization of high-power-microwave (HPM) systems are drawing more and more attention. Based on this demand, HPM generators without a guiding magnetic field are being developed. This paper presents an X-band Cherenkov type HPM oscillator without the guiding magnetic field. By particle-in-cell codes, this oscillator achieves an efficiency of 40% in simulation. When the diode voltage and current are 620 kV and 9.0 kA, respectively, a TEM mode microwave is generated with a power of 2.2 GW and a frequency of 9.1 GHz. In this oscillator, electrons are modulated in both longitudinal and radial directions, and the radial modulation has a significant effect on the energy conversion efficiency. As analyzed in this paper, the different radial modulation effects depend on the phase matching differences of the microwave and electrons. The modified scheme of simulations achieves a structure with an efficient longitudinal beam-wave interaction and optimized radial modulation.

Information and Communications Technology (ICT) Infrastructure for the ASTRI SST-2M telescope prototype for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Gianotti, F.; Tacchini, A.; Leto, G.; Martinetti, E.; Bruno, P.; Bellassai, G.; Conforti, V.; Gallozzi, S.; Mastropietro, M.; Tanci, C.; Malaguti, G.; Trifoglio, M.

2016-08-01

The Cherenkov Telescope Array (CTA) represents the next generation of ground-based observatories for very high energy gamma-ray astronomy. The CTA will consist of two arrays at two different sites, one in the northern and one in the southern hemisphere. The current CTA design foresees, in the southern site, the installation of many tens of imaging atmospheric Cherenkov telescopes of three different classes, namely large, medium and small, so defined in relation to their mirror area; the northern hemisphere array would consist of few tens of the two larger telescope types. The Italian National Institute for Astrophysics (INAF) is developing the Cherenkov Small Size Telescope ASTRI SST- 2M end-to-end prototype telescope within the framework of the International Cherenkov Telescope Array (CTA) project. The ASTRI prototype has been installed at the INAF observing station located in Serra La Nave on Mt. Etna, Italy. Furthermore a mini-array, composed of nine of ASTRI telescopes, has been proposed to be installed at the Southern CTA site. Among the several different infrastructures belonging the ASTRI project, the Information and Communication Technology (ICT) equipment is dedicated to operations of computing and data storage, as well as the control of the entire telescope, and it is designed to achieve the maximum efficiency for all performance requirements. Thus a complete and stand-alone computer centre has been designed and implemented. The goal is to obtain optimal ICT equipment, with an adequate level of redundancy, that might be scaled up for the ASTRI mini-array, taking into account the necessary control, monitor and alarm system requirements. In this contribution we present the ICT equipment currently installed at the Serra La Nave observing station where the ASTRI SST-2M prototype will be operated. The computer centre and the control room are described with particular emphasis on the Local Area Network scheme, the computing and data storage system, and the telescope control and monitoring.

Characterization and commissioning of the SST-1M camera for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Aguilar, J. A.; Bilnik, W.; Błocki, J.; Bogacz, L.; Borkowski, J.; Bulik, T.; Cadoux, F.; Christov, A.; Curyło, M.; della Volpe, D.; Dyrda, M.; Favre, Y.; Frankowski, A.; Grudnik, Ł.; Grudzińska, M.; Heller, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.; Kasperek, J.; Lalik, K.; Lyard, E.; Mach, E.; Mandat, D.; Marszałek, A.; Medina Miranda, L. D.; Michałowski, J.; Moderski, R.; Montaruli, T.; Neronov, A.; Niemiec, J.; Ostrowski, M.; Paśko, P.; Pech, M.; Porcelli, A.; Prandini, E.; Rajda, P.; Rameez, M.; Schioppa, E., Jr.; Schovanek, P.; Seweryn, K.; Skowron, K.; Sliusar, V.; Sowiński, M.; Stawarz, Ł.; Stodulska, M.; Stodulski, M.; Toscano, S.; Troyano Pujadas, I.; Walter, R.; Wiȩcek, M.; Zagdański, A.; Ziȩtara, K.; Żychowski, P.

2017-02-01

The Cherenkov Telescope Array (CTA), the next generation very high energy gamma-rays observatory, will consist of three types of telescopes: large (LST), medium (MST) and small (SST) size telescopes. The SSTs are dedicated to the observation of gamma-rays with energy between a few TeV and a few hundreds of TeV. The SST array is expected to have 70 telescopes of different designs. The single-mirror small size telescope (SST-1 M) is one of the proposed telescope designs under consideration for the SST array. It will be equipped with a 4 m diameter segmented mirror dish and with an innovative camera based on silicon photomultipliers (SiPMs). The challenge is not only to build a telescope with exceptional performance but to do it foreseeing its mass production. To address both of these challenges, the camera adopts innovative solutions both for the optical system and readout. The Photo-Detection Plane (PDP) of the camera is composed of 1296 pixels, each made of a hollow, hexagonal light guide coupled to a hexagonal SiPM designed by the University of Geneva and Hamamatsu. As no commercial ASIC would satisfy the CTA requirements when coupled to such a large sensor, dedicated preamplifier electronics have been designed. The readout electronics also use an innovative approach in gamma-ray astronomy by adopting a fully digital approach. All signals coming from the PDP are digitized in a 250 MHz Fast ADC and stored in ring buffers waiting for a trigger decision to send them to the pre-processing server where calibration and higher level triggers will decide whether the data are stored. The latest generation of FPGAs is used to achieve high data rates and also to exploit all the flexibility of the system. As an example each event can be flagged according to its trigger pattern. All of these features have been demonstrated in laboratory measurements on realistic elements and the results of these measurements will be presented in this contribution.

NECTAr: New electronics for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Vorobiov, S.; Bolmont, J.; Corona, P.; Delagnes, E.; Feinstein, F.; Gascón, D.; Glicenstein, J.-F.; Naumann, C. L.; Nayman, P.; Sanuy, A.; Toussenel, F.; Vincent, P.

2011-05-01

The European astroparticle physics community aims to design and build the next generation array of Imaging Atmospheric Cherenkov Telescopes (IACTs), that will benefit from the experience of the existing H.E.S.S. and MAGIC detectors, and further expand the very-high energy astronomy domain. In order to gain an order of magnitude in sensitivity in the 10 GeV to >100TeV range, the Cherenkov Telescope Array (CTA) will employ 50-100 mirrors of various sizes equipped with 1000-4000 channels per camera, to be compared with the 6000 channels of the final H.E.S.S. array. A 3-year program, started in 2009, aims to build and test a demonstrator module of a generic CTA camera. We present here the NECTAr design of front-end electronics for the CTA, adapted to the trigger and data acquisition of a large IACTs array, with simple production and maintenance. Cost and camera performances are optimized by maximizing integration of the front-end electronics (amplifiers, fast analog samplers, ADCs) in an ASIC, achieving several GS/s and a few μs readout dead-time. We present preliminary results and extrapolated performances from Monte Carlo simulations.

A Cherenkov-emission Microwave Source*

NASA Astrophysics Data System (ADS)

Lai, C. H.; Yoshii, J.; Katsouleas, T.; Hairapetian1, G.; Joshi, C.; Mori, W.

1996-11-01

In an unmagnetized plasma, there is no Cherenkov emission because the phase velocity vf of light is greater than c. In a magnetized plasma, the situation is completely changed. There is a rich variety of plasma modes with phase velocities vf 2 c which can couple to a fast particle. In the magnetized plasma, a fast particle, a particle beam, or even a short laser pulse excites a Cherenkov wake that has both electrostatic and electromagnetic components. Preliminary simulations indicate that at the vacuum/plasma boundary, the wake couples to a vacuum microwave with an amplitude equal to the electromagnetic component in the plasma. For a weakly magnetized plasma, the amplitude of the out-coupled radiation is approximately wc/wp times the amplitude of the wake excited in the plasma by the beam, and the frequency is approximately wp. Since plasma wakes as high as a few GeV/m are produced in current experiments, the potential for a high-power (i.e., GWatt) coherent microwave to THz source exists. In this talk, a brief overview of the scaling laws will be presented, followed by 1-D and 2-D PIC simulations. Prospects for a tuneable microwave source experiment based on this mechanism at the UCLA plasma wakefield accelerator facility will be discussed. *Work supported by AFOSR Grant #F4 96200-95-0248 and DOE Grant # DE-FG03-92ER40745. 1Now at Hughes Research Laboratories, Malibu, CA 90265

Studies on a silicon-photomultiplier-based camera for Imaging Atmospheric Cherenkov Telescopes

NASA Astrophysics Data System (ADS)

Arcaro, C.; Corti, D.; De Angelis, A.; Doro, M.; Manea, C.; Mariotti, M.; Rando, R.; Reichardt, I.; Tescaro, D.

2017-12-01

Imaging Atmospheric Cherenkov Telescopes (IACTs) represent a class of instruments which are dedicated to the ground-based observation of cosmic VHE gamma ray emission based on the detection of the Cherenkov radiation produced in the interaction of gamma rays with the Earth atmosphere. One of the key elements of such instruments is a pixelized focal-plane camera consisting of photodetectors. To date, photomultiplier tubes (PMTs) have been the common choice given their high photon detection efficiency (PDE) and fast time response. Recently, silicon photomultipliers (SiPMs) are emerging as an alternative. This rapidly evolving technology has strong potential to become superior to that based on PMTs in terms of PDE, which would further improve the sensitivity of IACTs, and see a price reduction per square millimeter of detector area. We are working to develop a SiPM-based module for the focal-plane cameras of the MAGIC telescopes to probe this technology for IACTs with large focal plane cameras of an area of few square meters. We will describe the solutions we are exploring in order to balance a competitive performance with a minimal impact on the overall MAGIC camera design using ray tracing simulations. We further present a comparative study of the overall light throughput based on Monte Carlo simulations and considering the properties of the major hardware elements of an IACT.

A Major Upgrade of the H.E.S.S. Cherenkov Cameras

NASA Astrophysics Data System (ADS)

Lypova, Iryna; Giavitto, Gianluca; Ashton, Terry; Balzer, Arnim; Berge, David; Brun, Francois; Chaminade, Thomas; Delagnes, Eric; Fontaine, Gerard; Füßling, Matthias; Giebels, Berrie; Glicenstein, Jean-Francois; Gräber, Tobias; Hinton, Jim; Jahnke, Albert; Klepser, Stefan; Kossatz, Marko; Kretzschmann, Axel; Lefranc, Valentin; Leich, Holger; Lüdecke, Hartmut; Manigot, Pascal; Marandon, Vincent; Moulin, Emmanuel; de Naurois, Mathieu; Nayman, Patrick; Ohm, Stefan; Penno, Marek; Ross, Duncan; Salek, David; Schade, Markus; Schwab, Thomas; Simoni, Rachel; Stegmann, Christian; Steppa, Constantin; Thornhill, Julian; Toussnel, Francois

2017-03-01

The High Energy Stereoscopic System (H.E.S.S.) is an array of imaging atmospheric Cherenkov telescopes (IACTs) located in Namibia. It was built to detect Very High Energy (VHE, >100 GeV) cosmic gamma rays, and consists of four 12 m diameter Cherenkov telescopes (CT1-4), built in 2003, and a larger 28 m telescope (CT5), built in 2012. The larger mirror surface of CT5 permits to lower the energy threshold of the array down to 30 GeV. The cameras of CT1-4 are currently undergoing an extensive upgrade, with the goals of reducing their failure rate, reducing their readout dead time and improving the overall performance of the array. The entire camera electronics has been renewed from ground-up, as well as the power, ventilation and pneumatics systems, and the control and data acquisition software. Technical solutions forseen for the next-generation Cherenkov Telescope Array (CTA) observatory have been introduced, most notably the readout is based on the NECTAr analog memory chip. The camera control subsystems and the control software framework also pursue an innovative design, increasing the camera performance, robustness and flexibility. The CT1 camera has been upgraded in July 2015 and is currently taking data; CT2-4 will upgraded in Fall 2016. Together they will assure continuous operation of H.E.S.S at its full sensitivity until and possibly beyond the advent of CTA. This contribution describes the design, the testing and the in-lab and on-site performance of all components of the newly upgraded H.E.S.S. camera.

Visual sensations induced by Cherenkov radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

McNulty, P.J.; Pease, V.P.; Bond, V.P.

1975-08-01

Pulses of relativistic singly charged particles entering the eyeball induce a variety of visual phenomena by means of Cerenkov radiation generated during their passage through the vitreous. These phenomena are similar in appearance to many of the visual sensations experienced by Apollo astronauts exposed to the cosmic rays in deep space. (auth)

EFFECT OF CHERENKOV LIGHT POLARIZATION ON TOTAL REFLECTION COUNTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dowell, J.D.; Duteil, P.; Leontic, B.

1963-01-01

A rugged total internal reflection counter with a 3- to 5cm thick compact radiator was used at the CERN proton synchrotron for beam analysis. The threshold behavior of this counter was compared when filled with glycerol and with turpentine. Turpentine is optically active and rotates the plane of polarization about 7 un. Concent 85% /cm. Figures illustrate the effect of this polarization rotation. (A.G.W.)

Ceramic Electron Multiplier

DOE PAGES

Comby, G.

1996-10-01

The Ceramic Electron Multipliers (CEM) is a compact, robust, linear and fast multi-channel electron multiplier. The Multi Layer Ceramic Technique (MLCT) allows to build metallic dynodes inside a compact ceramic block. The activation of the metallic dynodes enhances their secondary electron emission (SEE). The CEM can be used in multi-channel photomultipliers, multi-channel light intensifiers, ion detection, spectroscopy, analysis of time of flight events, particle detection or Cherenkov imaging detectors. (auth)

Gamma-ray Monitoring of Active Galactic Nuclei with HAWC

NASA Astrophysics Data System (ADS)

Lauer, Robert; HAWC Collaboration

2016-03-01

Active Galactic Nuclei (AGN) are extra-galactic sources that can exhibit extreme flux variability over a wide range of wavelengths. TeV gamma rays have been observed from about 60 AGN and can help to diagnose emission models and to study cosmic features like extra-galactic background light or inter-galactic magnetic fields. The High Altitude Water Cherenkov (HAWC) observatory is a new extensive air shower array that can complement the pointed TeV observations of imaging air Cherenkov telescopes. HAWC is optimized for studying gamma rays with energies between 100 GeV and 100 TeV and has an instantaneous field of view of ~2 sr and a duty cycle >95% that allow us to scan 2/3 of the sky every day. By performing an unbiased monitoring of TeV emissions of AGN over most of the northern and part of the southern sky, HAWC can provide crucial information and trigger follow-up observations in collaborations with pointed TeV instruments. Furthermore, HAWC coverage of AGN is complementary to that provided by the Fermi satellite at lower energies. In this contribution, we will present HAWC flux light curves of TeV gamma rays from various sources, notably the bright AGN Markarian 421 and Markarian 501, and highlight recent results from multi-wavelengths and multi-instrument studies.

Performance of a Mach-Zehnder based analogue data recording system for use with the Gas Cherenkov Detector on the NIF

NASA Astrophysics Data System (ADS)

Carpenter, A. C.; Herrmann, H. W.; Beeman, B. V.; Lopez, F. E.; Hernandez, J. E.

2016-09-01

This paper covers the performance of a high speed analogue data transmission system. This system uses multiple Mach- Zehnder optical modulators to transmit and record fusion burn history data for the Gas Cherenkov Detector (GCD) on the National Ignition Facility. The GCD is designed to measure the burn duration of high energy gamma rays generated by Deuterium-Tritium (DT) interactions in the NIF. The burn duration of DT fusion can be as short as 10ps and the optical photons generated in the gas Cherenkov cell are measured using a vacuum photodiode with a FWHM of 55ps. A recording system with a 3dB bandwidth of ≥10GHz and a signal to noise ratio of ≥5 for photodiode output voltage of 50mV is presented. The data transmission system uses two or three Mach-Zehnder modulators and an RF amplifier to transmit data optically. This signal is received and recorded by optical to electrical converts and a high speed digital oscilloscope placed outside of the NIF Target Bay. Electrical performance metrics covered include signal to noise ratio (SNR), signal to peak to peak noise ratio, single shot dynamic range, shot to shot dynamic range, system bandwidth, scattering parameters, are shown. Design considerations such as self-test capabilities, the NIF radiation environment, upgrade compatibility, Mach-Zehnder (MZ) biasing, maintainability, and operating considerations for the use of MZs are covered. This data recording system will be used for the future upgrade of the GCD to be used with a Pulse Dilation PMT, currently under development.

Research on mutual influence of Cherenkov-type probes within the ISTTOK tokamak chamber

NASA Astrophysics Data System (ADS)

Jakubowski, L.; Plyusnin, V. V.; Malinowski, K.; Sadowski, M. J.; Zebrowski, J.; Rabinski, M.; Fernandes, H.; Silva, C.; Figueiredo, H.; Jakubowski, M. J.

2014-12-01

The paper describes an influence of a Cherenkov-type probe, which is used for measurements of fast electron streams inside the ISTTOK chamber, on other probes and behaviour of a plasma ring. The reported study shows that such a probe situated near the plasma column has a strong influence on signals from another Cherenkov probe, and can cause a considerable reduction of electron-induced signals. This effect does not depend on positions of the probes in relation to the limiter. Measurements of hard X-ray (HXR) emission show that the deeply immersed Cherenkov probe can also influence on the limiter . Under specific experimental conditions such a Cherenkov probe can play the role of a new limiter and change the plasma configuration.

Very-high-energy gamma-ray observations of pulsar wind nebulae and cataclysmic variable stars with MAGIC and development of trigger systems for IACTs

NASA Astrophysics Data System (ADS)

Lopez-Coto, Ruben

2015-07-01

The history of astronomy is as ancient as the reach of our written records. All the human civilizations have been interested in the study and interpretation of the night sky and its objects and phenomena. These observations were performed with the naked eye until the beginning of the 17th century, when Galileo Galilei started to use an instrument recently developed called telescope. Since then, the range of accessible wavelengths has been increasing, with a burst in the 20th century with the developing of instruments to observe them: antennas (radio and submillimeter), telescopes (optical, IR) and satellites (UV, X-rays and soft gamma rays). The last wavelength range accessed was the Very-High-Energy (VHE) gamma rays. At this range fluxes are so low that it is not possible to use space-based instruments with typical collection areas of O(1) m2. We must resort to the imaging atmospheric Cherenkov technique, which is based on the detection of the flashes of Cherenkov light that VHE gamma rays produce when they interact with the Earth's atmosphere. The field is very young, with the first source discovered in 1989 by the pioneering Whipple telescope. It is very dynamic with more than 150 sources detected to date, most of them by MAGIC, HESS and VERITAS, that make up the current generation of instruments. Finally, the field is also very promising, with the preparation of a next generation of imaging atmospheric Cherenkov telescopes: CTA, that is expected to start full operation in 2020. The work presented in this thesis comprises my efforts to take the ground-based γ-ray astronomy one step forward. Part I of the thesis is an introduction to the non- thermal universe, the imaging atmospheric Cherenkov technique and the Imaging Atmospheric Cherenkov Telescopes (IACTs) MAGIC and CTA. Part II deals with several ways to reduce the trigger threshold of IACTs. This includes the simula- tion, characterization and test of an analog trigger especially designed to achieve the lowest possible energy threshold with the LSTs of CTA. Together with this work, the trigger of the MAGIC telescopes was improved. We have simulated, tested and commissioned a new concept of stereoscopic trigger. This new system, that uses the information of the position of the showers on each of the MAGIC cameras, is dubbed "Topo-trigger". The scientific fraction of the thesis deals with galactic sources observed with the MAGIC telescopes. In Part III, I talk about the analysis of the VHE γ-ray emission of Pulsar Wind Nebulae (PWNe): the discovery of VHE γ-ray emission from the puzzling PWN 3C 58, the likely remnant of the SN 1181 AD and the weakest PWN detected at VHE to date; the characterization of the VHE tail of the Crab nebula by observing it at the highest zenith angles; and the search for an additional inverse Compton component during the Crab nebula flares reported by Fermi-LAT in the synchrotron regime. Part IV is concerned with searches for VHE γ-ray emission of cataclysmic variable stars. I studied, on a multiwavelength context, the VHE γ-ray nature of the previously claimed pulsed γ-ray emission of the cataclysmic variable AE Aqr. I also performed observations of novae and a dwarf nova to pinpoint the ac- celeration mechanisms taking place in this kind of objects and to discover a putative hadronic component of the soft γ-ray emission. A conclusion chapter summarizes all the work performed and lists prospects related with the topics treated in this thesis.

Test of the CLAS12 RICH large-scale prototype in the direct proximity focusing configuration

DOE PAGES

Anefalos Pereira, S.; Baltzell, N.; Barion, L.; ...

2016-02-11

A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c up to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Laboratory. The adopted solution foresees a novel hybrid optics design based on aerogel radiator, composite mirrors and high-packed and high-segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). We report here the results of the tests of a large scale prototype of the RICH detector performed withmore » the hadron beam of the CERN T9 experimental hall for the direct detection configuration. As a result, the tests demonstrated that the proposed design provides the required pion-to-kaon rejection factor of 1:500 in the whole momentum range.« less

The search for TeV-scale dark matter with the HAWC observatory

DOE PAGES

Harding, J. Patrick

2015-01-01

The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to 100 GeV - 100 TeV gamma rays and cosmic rays. Located at an elevation of 4100 m on the Sierra Negra mountain in Mexico, HAWC observes extensive air showers from gamma and cosmic rays with an array of water tanks which produce Cherenkov light in the presence of air showers. With a field-of-view capable of observing 2/3 of the sky each day, and a sensitivity of 1 Crab/day, HAWC will be able to map out the sky in gamma and cosmic rays in detail. In thismore » paper, we discuss the capabilities of HAWC to map out the directions and spectra of TeV gamma rays and cosmic rays coming from sources of dark matter annihilation. We discuss the HAWC sensitivity to multiple extended sources of dark matter annihilation and the possibility of HAWC observations of annihilations in nearby dark matter subhalos.« less

Very-high-energy gamma rays from a distant quasar: how transparent is the universe?

PubMed

Albert, J; Aliu, E; Anderhub, H; Antonelli, L A; Antoranz, P; Backes, M; Baixeras, C; Barrio, J A; Bartko, H; Bastieri, D; Becker, J K; Bednarek, W; Berger, K; Bernardini, E; Bigongiari, C; Biland, A; Bock, R K; Bonnoli, G; Bordas, P; Bosch-Ramon, V; Bretz, T; Britvitch, I; Camara, M; Carmona, E; Chilingarian, A; Commichau, S; Contreras, J L; Cortina, J; Costado, M T; Covino, S; Curtef, V; Dazzi, F; De Angelis, A; De Cea Del Pozo, E; de Los Reyes, R; De Lotto, B; De Maria, M; De Sabata, F; Mendez, C Delgado; Dominguez, A; Dorner, D; Doro, M; Errando, M; Fagiolini, M; Ferenc, D; Fernández, E; Firpo, R; Fonseca, M V; Font, L; Galante, N; López, R J García; Garczarczyk, M; Gaug, M; Goebel, F; Hayashida, M; Herrero, A; Höhne, D; Hose, J; Hsu, C C; Huber, S; Jogler, T; Kneiske, T M; Kranich, D; La Barbera, A; Laille, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; López, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Meyer, M; Miranda, J M; Mirzoyan, R; Mizobuchi, S; Moles, M; Moralejo, A; Nieto, D; Nilsson, K; Ninkovic, J; Otte, N; Oya, I; Panniello, M; Paoletti, R; Paredes, J M; Pasanen, M; Pascoli, D; Pauss, F; Pegna, R G; Perez-Torres, M A; Persic, M; Peruzzo, L; Piccioli, A; Prada, F; Prandini, E; Puchades, N; Raymers, A; Rhode, W; Ribó, M; Rico, J; Rissi, M; Robert, A; Rügamer, S; Saggion, A; Saito, T Y; Salvati, M; Sanchez-Conde, M; Sartori, P; Satalecka, K; Scalzotto, V; Scapin, V; Schmitt, R; Schweizer, T; Shayduk, M; Shinozaki, K; Shore, S N; Sidro, N; Sierpowska-Bartosik, A; Sillanpää, A; Sobczynska, D; Spanier, F; Stamerra, A; Stark, L S; Takalo, L; Tavecchio, F; Temnikov, P; Tescaro, D; Teshima, M; Tluczykont, M; Torres, D F; Turini, N; Vankov, H; Venturini, A; Vitale, V; Wagner, R M; Wittek, W; Zabalza, V; Zandanel, F; Zanin, R; Zapatero, J

2008-06-27

The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Because high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts.

Cherenkov neutron detector for fusion reaction and runaway electron diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheon, MunSeong, E-mail: munseong@nfri.re.kr; Kim, Junghee

2015-08-15

A Cherenkov-type neutron detector was newly developed and neutron measurement experiments were performed at Korea Superconducting Tokamak Advanced Research. It was shown that the Cherenkov neutron detector can monitor the time-resolved neutron flux from deuterium-fueled fusion plasmas. Owing to the high temporal resolution of the detector, fast behaviors of runaway electrons, such as the neutron spikes, could be observed clearly. It is expected that the Cherenkov neutron detector could be utilized to provide useful information on runaway electrons as well as fusion reaction rate in fusion plasmas.

Cherenkov Water Detectors in Particle Physics and Cosmic Rays

NASA Astrophysics Data System (ADS)

Petrukhin, A. A.; Yashin, I. I.

2017-12-01

Among various types of Cherenkov detectors (solid, liquid and gaseous) created for different studies, the most impressive development was gained by water detectors: from the first detector with a volume of several liters in which the Cherenkov radiation was discovered, to the IceCube detector with a volume of one cubic kilometer. The review of the development of Cherenkov water detectors for various purposes and having different locations - ground-based, underground and underwater-is presented in the paper. The prospects of their further development are also discussed.

Angular distribution of Cherenkov radiation from relativistic heavy ions taking into account deceleration in the radiator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogdanov, O. V., E-mail: bov@tpu.ru; Fiks, E. I.; Pivovarov, Yu. L.

2012-09-15

Numerical methods are used to study the dependence of the structure and the width of the angular distribution of Vavilov-Cherenkov radiation with a fixed wavelength in the vicinity of the Cherenkov cone on the radiator parameters (thickness and refractive index), as well as on the parameters of the relativistic heavy ion beam (charge and initial energy). The deceleration of relativistic heavy ions in the radiator, which decreases the velocity of ions, modifies the condition of structural interference of the waves emitted from various segments of the trajectory; as a result, a complex distribution of Vavilov-Cherenkov radiation appears. The main quantitymore » is the stopping power of a thin layer of the radiator (average loss of the ion energy), which is calculated by the Bethe-Bloch formula and using the SRIM code package. A simple formula is obtained to estimate the angular distribution width of Cherenkov radiation (with a fixed wavelength) from relativistic heavy ions taking into account the deceleration in the radiator. The measurement of this width can provide direct information on the charge of the ion that passes through the radiator, which extends the potentialities of Cherenkov detectors. The isotopic effect (dependence of the angular distribution of Vavilov-Cherenkov radiation on the ion mass) is also considered.« less

Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

NASA Astrophysics Data System (ADS)

Actis, M.; Agnetta, G.; Aharonian, F.; Akhperjanian, A.; Aleksić, J.; Aliu, E.; Allan, D.; Allekotte, I.; Antico, F.; Antonelli, L. A.; Antoranz, P.; Aravantinos, A.; Arlen, T.; Arnaldi, H.; Artmann, S.; Asano, K.; Asorey, H.; Bähr, J.; Bais, A.; Baixeras, C.; Bajtlik, S.; Balis, D.; Bamba, A.; Barbier, C.; Barceló, M.; Barnacka, A.; Barnstedt, J.; Barres de Almeida, U.; Barrio, J. A.; Basso, S.; Bastieri, D.; Bauer, C.; Becerra, J.; Becherini, Y.; Bechtol, K.; Becker, J.; Beckmann, V.; Bednarek, W.; Behera, B.; Beilicke, M.; Belluso, M.; Benallou, M.; Benbow, W.; Berdugo, J.; Berger, K.; Bernardino, T.; Bernlöhr, K.; Biland, A.; Billotta, S.; Bird, T.; Birsin, E.; Bissaldi, E.; Blake, S.; Blanch, O.; Bobkov, A. A.; Bogacz, L.; Bogdan, M.; Boisson, C.; Boix, J.; Bolmont, J.; Bonanno, G.; Bonardi, A.; Bonev, T.; Borkowski, J.; Botner, O.; Bottani, A.; Bourgeat, M.; Boutonnet, C.; Bouvier, A.; Brau-Nogué, S.; Braun, I.; Bretz, T.; Briggs, M. S.; Brun, P.; Brunetti, L.; Buckley, J. H.; Bugaev, V.; Bühler, R.; Bulik, T.; Busetto, G.; Buson, S.; Byrum, K.; Cailles, M.; Cameron, R.; Canestrari, R.; Cantu, S.; Carmona, E.; Carosi, A.; Carr, J.; Carton, P. H.; Casiraghi, M.; Castarede, H.; Catalano, O.; Cavazzani, S.; Cazaux, S.; Cerruti, B.; Cerruti, M.; Chadwick, P. M.; Chiang, J.; Chikawa, M.; Cieślar, M.; Ciesielska, M.; Cillis, A.; Clerc, C.; Colin, P.; Colomé, J.; Compin, M.; Conconi, P.; Connaughton, V.; Conrad, J.; Contreras, J. L.; Coppi, P.; Corlier, M.; Corona, P.; Corpace, O.; Corti, D.; Cortina, J.; Costantini, H.; Cotter, G.; Courty, B.; Couturier, S.; Covino, S.; Croston, J.; Cusumano, G.; Daniel, M. K.; Dazzi, F.; de Angelis, A.; de Cea Del Pozo, E.; de Gouveia Dal Pino, E. M.; de Jager, O.; de La Calle Pérez, I.; de La Vega, G.; de Lotto, B.; de Naurois, M.; de Oña Wilhelmi, E.; de Souza, V.; Decerprit, B.; Deil, C.; Delagnes, E.; Deleglise, G.; Delgado, C.; Dettlaff, T.; di Paolo, A.; di Pierro, F.; Díaz, C.; Dick, J.; Dickinson, H.; Digel, S. W.; Dimitrov, D.; Disset, G.; Djannati-Ataï, A.; Doert, M.; Domainko, W.; Dorner, D.; Doro, M.; Dournaux, J.-L.; Dravins, D.; Drury, L.; Dubois, F.; Dubois, R.; Dubus, G.; Dufour, C.; Durand, D.; Dyks, J.; Dyrda, M.; Edy, E.; Egberts, K.; Eleftheriadis, C.; Elles, S.; Emmanoulopoulos, D.; Enomoto, R.; Ernenwein, J.-P.; Errando, M.; Etchegoyen, A.; Falcone, A. D.; Farakos, K.; Farnier, C.; Federici, S.; Feinstein, F.; Ferenc, D.; Fillin-Martino, E.; Fink, D.; Finley, C.; Finley, J. P.; Firpo, R.; Florin, D.; Föhr, C.; Fokitis, E.; Font, Ll.; Fontaine, G.; Fontana, A.; Förster, A.; Fortson, L.; Fouque, N.; Fransson, C.; Fraser, G. W.; Fresnillo, L.; Fruck, C.; Fujita, Y.; Fukazawa, Y.; Funk, S.; Gäbele, W.; Gabici, S.; Gadola, A.; Galante, N.; Gallant, Y.; García, B.; García López, R. J.; Garrido, D.; Garrido, L.; Gascón, D.; Gasq, C.; Gaug, M.; Gaweda, J.; Geffroy, N.; Ghag, C.; Ghedina, A.; Ghigo, M.; Gianakaki, E.; Giarrusso, S.; Giavitto, G.; Giebels, B.; Giro, E.; Giubilato, P.; Glanzman, T.; Glicenstein, J.-F.; Gochna, M.; Golev, V.; Gómez Berisso, M.; González, A.; González, F.; Grañena, F.; Graciani, R.; Granot, J.; Gredig, R.; Green, A.; Greenshaw, T.; Grimm, O.; Grube, J.; Grudzińska, M.; Grygorczuk, J.; Guarino, V.; Guglielmi, L.; Guilloux, F.; Gunji, S.; Gyuk, G.; Hadasch, D.; Haefner, D.; Hagiwara, R.; Hahn, J.; Hallgren, A.; Hara, S.; Hardcastle, M. J.; Hassan, T.; Haubold, T.; Hauser, M.; Hayashida, M.; Heller, R.; Henri, G.; Hermann, G.; Herrero, A.; Hinton, J. A.; Hoffmann, D.; Hofmann, W.; Hofverberg, P.; Horns, D.; Hrupec, D.; Huan, H.; Huber, B.; Huet, J.-M.; Hughes, G.; Hultquist, K.; Humensky, T. B.; Huppert, J.-F.; Ibarra, A.; Illa, J. M.; Ingjald, J.; Inoue, Y.; Inoue, S.; Ioka, K.; Jablonski, C.; Jacholkowska, A.; Janiak, M.; Jean, P.; Jensen, H.; Jogler, T.; Jung, I.; Kaaret, P.; Kabuki, S.; Kakuwa, J.; Kalkuhl, C.; Kankanyan, R.; Kapala, M.; Karastergiou, A.; Karczewski, M.; Karkar, S.; Karlsson, N.; Kasperek, J.; Katagiri, H.; Katarzyński, K.; Kawanaka, N.; Kȩdziora, B.; Kendziorra, E.; Khélifi, B.; Kieda, D.; Kifune, T.; Kihm, T.; Klepser, S.; Kluźniak, W.; Knapp, J.; Knappy, A. R.; Kneiske, T.; Knödlseder, J.; Köck, F.; Kodani, K.; Kohri, K.; Kokkotas, K.; Komin, N.; Konopelko, A.; Kosack, K.; Kossakowski, R.; Kostka, P.; Kotuła, J.; Kowal, G.; Kozioł, J.; Krähenbühl, T.; Krause, J.; Krawczynski, H.; Krennrich, F.; Kretzschmann, A.; Kubo, H.; Kudryavtsev, V. A.; Kushida, J.; La Barbera, N.; La Parola, V.; La Rosa, G.; López, A.; Lamanna, G.; Laporte, P.; Lavalley, C.; Le Flour, T.; Le Padellec, A.; Lenain, J.-P.; Lessio, L.; Lieunard, B.; Lindfors, E.; Liolios, A.; Lohse, T.; Lombardi, S.; Lopatin, A.; Lorenz, E.; Lubiński, P.; Luz, O.; Lyard, E.; Maccarone, M. C.; Maccarone, T.; Maier, G.; Majumdar, P.; Maltezos, S.; Małkiewicz, P.; Mañá, C.; Manalaysay, A.; Maneva, G.; Mangano, A.; Manigot, P.; Marín, J.; Mariotti, M.; Markoff, S.; Martínez, G.; Martínez, M.; Mastichiadis, A.; Matsumoto, H.; Mattiazzo, S.; Mazin, D.; McComb, T. J. L.; McCubbin, N.; McHardy, I.; Medina, C.; Melkumyan, D.; Mendes, A.; Mertsch, P.; Meucci, M.; Michałowski, J.; Micolon, P.; Mineo, T.; Mirabal, N.; Mirabel, F.; Miranda, J. M.; Mirzoyan, R.; Mizuno, T.; Moal, B.; Moderski, R.; Molinari, E.; Monteiro, I.; Moralejo, A.; Morello, C.; Mori, K.; Motta, G.; Mottez, F.; Moulin, E.; Mukherjee, R.; Munar, P.; Muraishi, H.; Murase, K.; Murphy, A. Stj.; Nagataki, S.; Naito, T.; Nakamori, T.; Nakayama, K.; Naumann, C.; Naumann, D.; Nayman, P.; Nedbal, D.; Niedźwiecki, A.; Niemiec, J.; Nikolaidis, A.; Nishijima, K.; Nolan, S. J.; Nowak, N.; O'Brien, P. T.; Ochoa, I.; Ohira, Y.; Ohishi, M.; Ohka, H.; Okumura, A.; Olivetto, C.; Ong, R. A.; Orito, R.; Orr, M.; Osborne, J. P.; Ostrowski, M.; Otero, L.; Otte, A. N.; Ovcharov, E.; Oya, I.; Oziȩbło, A.; Paiano, S.; Pallota, J.; Panazol, J. L.; Paneque, D.; Panter, M.; Paoletti, R.; Papyan, G.; Paredes, J. M.; Pareschi, G.; Parsons, R. D.; Paz Arribas, M.; Pedaletti, G.; Pepato, A.; Persic, M.; Petrucci, P. O.; Peyaud, B.; Piechocki, W.; Pita, S.; Pivato, G.; Płatos, Ł.; Platzer, R.; Pogosyan, L.; Pohl, M.; Pojmański, G.; Ponz, J. D.; Potter, W.; Prandini, E.; Preece, R.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quel, E.; Quirrenbach, A.; Rajda, P.; Rando, R.; Rataj, M.; Raue, M.; Reimann, C.; Reimann, O.; Reimer, A.; Reimer, O.; Renaud, M.; Renner, S.; Reymond, J.-M.; Rhode, W.; Ribó, M.; Ribordy, M.; Rico, J.; Rieger, F.; Ringegni, P.; Ripken, J.; Ristori, P.; Rivoire, S.; Rob, L.; Rodriguez, S.; Roeser, U.; Romano, P.; Romero, G. E.; Rosier-Lees, S.; Rovero, A. C.; Roy, F.; Royer, S.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Russo, F.; Ryde, F.; Sacco, B.; Saggion, A.; Sahakian, V.; Saito, K.; Saito, T.; Sakaki, N.; Salazar, E.; Salini, A.; Sánchez, F.; Sánchez Conde, M. Á.; Santangelo, A.; Santos, E. M.; Sanuy, A.; Sapozhnikov, L.; Sarkar, S.; Scalzotto, V.; Scapin, V.; Scarcioffolo, M.; Schanz, T.; Schlenstedt, S.; Schlickeiser, R.; Schmidt, T.; Schmoll, J.; Schroedter, M.; Schultz, C.; Schultze, J.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schweizer, T.; Seiradakis, J.; Selmane, S.; Seweryn, K.; Shayduk, M.; Shellard, R. C.; Shibata, T.; Sikora, M.; Silk, J.; Sillanpää, A.; Sitarek, J.; Skole, C.; Smith, N.; Sobczyńska, D.; Sofo Haro, M.; Sol, H.; Spanier, F.; Spiga, D.; Spyrou, S.; Stamatescu, V.; Stamerra, A.; Starling, R. L. C.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Steiner, S.; Stergioulas, N.; Sternberger, R.; Stinzing, F.; Stodulski, M.; Straumann, U.; Suárez, A.; Suchenek, M.; Sugawara, R.; Sulanke, K. H.; Sun, S.; Supanitsky, A. D.; Sutcliffe, P.; Szanecki, M.; Szepieniec, T.; Szostek, A.; Szymkowiak, A.; Tagliaferri, G.; Tajima, H.; Takahashi, H.; Takahashi, K.; Takalo, L.; Takami, H.; Talbot, R. G.; Tam, P. H.; Tanaka, M.; Tanimori, T.; Tavani, M.; Tavernet, J.-P.; Tchernin, C.; Tejedor, L. A.; Telezhinsky, I.; Temnikov, P.; Tenzer, C.; Terada, Y.; Terrier, R.; Teshima, M.; Testa, V.; Tibaldo, L.; Tibolla, O.; Tluczykont, M.; Todero Peixoto, C. J.; Tokanai, F.; Tokarz, M.; Toma, K.; Torres, D. F.; Tosti, G.; Totani, T.; Toussenel, F.; Vallania, P.; Vallejo, G.; van der Walt, J.; van Eldik, C.; Vandenbroucke, J.; Vankov, H.; Vasileiadis, G.; Vassiliev, V. V.; Vegas, I.; Venter, L.; Vercellone, S.; Veyssiere, C.; Vialle, J. P.; Videla, M.; Vincent, P.; Vink, J.; Vlahakis, N.; Vlahos, L.; Vogler, P.; Vollhardt, A.; Volpe, F.; von Gunten, H. P.; Vorobiov, S.; Wagner, S.; Wagner, R. M.; Wagner, B.; Wakely, S. P.; Walter, P.; Walter, R.; Warwick, R.; Wawer, P.; Wawrzaszek, R.; Webb, N.; Wegner, P.; Weinstein, A.; Weitzel, Q.; Welsing, R.; Wetteskind, H.; White, R.; Wierzcholska, A.; Wilkinson, M. I.; Williams, D. A.; Winde, M.; Wischnewski, R.; Wiśniewski, Ł.; Wolczko, A.; Wood, M.; Xiong, Q.; Yamamoto, T.; Yamaoka, K.; Yamazaki, R.; Yanagita, S.; Yoffo, B.; Yonetani, M.; Yoshida, A.; Yoshida, T.; Yoshikoshi, T.; Zabalza, V.; Zagdański, A.; Zajczyk, A.; Zdziarski, A.; Zech, A.; Ziȩtara, K.; Ziółkowski, P.; Zitelli, V.; Zychowski, P.

2011-12-01

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.

Development of the quality control system of the readout electronics for the large size telescope of the Cherenkov Telescope Array observatory

NASA Astrophysics Data System (ADS)

Konno, Y.; Kubo, H.; Masuda, S.; Paoletti, R.; Poulios, S.; Rugliancich, A.; Saito, T.

2016-07-01

The Cherenkov Telescope Array (CTA) is the next generation VHE γ-ray observatory which will improve the currently available sensitivity by a factor of 10 in the range 100 GeV to 10 TeV. The array consists of different types of telescopes, called large size telescope (LST), medium size telescope (MST) and small size telescope (SST). A LST prototype is currently being built and will be installed at the Observatorio Roque de los Muchachos, island of La Palma, Canary islands, Spain. The readout system for the LST prototype has been designed and around 300 readout boards will be produced in the coming months. In this note we describe an automated quality control system able to measure basic performance parameters and quickly identify faulty boards.

Simulated gamma-ray pulse profile of the Crab pulsar with the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Burtovoi, A.; Zampieri, L.

2016-07-01

We present simulations of the very high energy (VHE) gamma-ray light curve of the Crab pulsar as observed by the Cherenkov Telescope Array (CTA). The CTA pulse profile of the Crab pulsar is simulated with the specific goal of determining the accuracy of the position of the interpulse. We fit the pulse shape obtained by the Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) telescope with a three-Gaussian template and rescale it to account for the different CTA instrumental and observational configurations. Simulations are performed for different configurations of CTA and for the ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) mini-array. The northern CTA configuration will provide an improvement of a factor of ˜3 in accuracy with an observing time comparable to that of MAGIC (73 h). Unless the VHE spectrum above 1 TeV behaves differently from what we presently know, unreasonably long observing times are required for a significant detection of the pulsations of the Crab pulsar with the high-energy-range sub-arrays. We also found that an independent VHE timing analysis is feasible with Large Size Telescopes. CTA will provide a significant improvement in determining the VHE pulse shape parameters necessary to constrain theoretical models of the gamma-ray emission of the Crab pulsar. One of such parameters is the shift in phase between peaks in the pulse profile at VHE and in other energy bands that, if detected, may point to different locations of the emission regions.

A Cherenkov-emission Microwave Source.*

NASA Astrophysics Data System (ADS)

Lai, C. H.; Yoshii, J.; Katsouleas, T.; Hairapetian, G.; Joshi, C.; Mori, W.

1996-11-01

In an unmagnetized plasma, there is no Cherenkov emission because the phase velocity ν_φ of light is greater than c. In a magnetized plasma, the situation is completely changed. There is a rich variety of plasma modes with phase velocities ν_φ <= c which can couple to a fast particle. In the magnetized plasma, a fast particle, a particle beam, or even a short laser pulse excites a Cherenkov wake that has both electrostatic and electromagnetic components. Preliminary simulations indicate that at the vacuum/plasma boundary, the wake couples to a vacuum microwave with an amplitude equal to the electromagnetic component in the plasma. For a weakly magnetized plasma, the amplitude of the out-coupled radiation is approximately ωc / ωp times the amplitude of the wake excited in the plasma by the beam, and the frequency is approximately ω_p. Since plasma wakes as high as a few GeV/m are produced in current experiments, the potential for a high-power (i.e., GWatt) coherent microwave to THz source exists. In this talk, a brief overview of the scaling laws will be presented, followed by 1-D and 2-D PIC simulations. Prospects for a tuneable microwave source experiment based on this mechanism at the UCLA plasma wakefield accelerator facility will be discussed. Work supported by AFOSR Grant #F4 96200-95-0248 and DOE Grant # DE-FG03-92ER40745. ^1Now at Hughes Research Laboratories, Malibu, CA 90265.

Performance of the Gamma-ray Cherenkov Telescope structure: a dual-mirror telescope prototype proposed for the future Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Dournaux, J. L.; Amans, J. P.; Dangeon, L.; Fasola, G.; Gironnet, J.; Huet, J. M.; Laporte, P.; Abchiche, A.; Barkaoui, S.; Bousquet, J. J.; Buchholtz, G.; Dumas, D.; Gaudemard, J.; Jégouzo, I.; Poinsignon, P.; Vergne, L.; Sol, H.

2016-07-01

The Cherenkov Telescope Array (CTA) project aims to create the next generation Very High-Energy (VHE) gamma-ray telescope array. It will be devoted to the observation of gamma rays from 20 GeV to above 100 TeV. Because of this wide energy band, three classes of telescopes, associated with different energy ranges and different mirror sizes, are defined. The Small Size Telescopes (SSTs) are associated with the highest energy range. Seventy of these telescopes are foreseen on the Southern site of the CTA. The large number of telescopes constrains their mechanical structure because easy maintenance and reduced cost per telescope are needed. Moreover, of course, the design shall fulfill the required performance and lifetime in the environment conditions of the site. The Observatoire de Paris started design studies in 2011 of the mechanical structure of the GCT (Gamma-ray Cherenkov Telescope), a four-meter prototype telescope for the SSTs of CTA, from optical and preliminary mechanical designs made by the University of Durham. At the end of 2014 these studies finally resulted in a lightweight ( 8 tons) and stiff design. This structure was based on the dual-mirror Schwarzschild-Couder (SC) optical design, which is an interesting and innovative alternative to the one-mirror Davies-Cotton design commonly used in ground-based Cherenkov astronomy. The benefits of such a design are many since it enables a compact structure, lightweight camera and a good angular resolution across the entire field-of-view. The mechanical structure was assembled on the Meudon site of the Observatoire de Paris in spring 2015. The secondary mirror, panels of the primary mirror and the Telescope Control System were successfully implemented afterwards leading now to a fully operational telescope. This paper focuses on the mechanics of the telescope prototype. It describes the mechanical structure and presents its performance identified from computations or direct measurements. Upgrades of the design in the context of the preproduction and the large scale CTA production are also discussed.

Optical response of highly reflective film used in the water Cherenkov muon veto of the XENON1T dark matter experiment

NASA Astrophysics Data System (ADS)

Geis, Ch.; Grignon, C.; Oberlack, U.; Ramírez García, D.; Weitzel, Q.

2017-06-01

The XENON1T experiment is the most recent stage of the XENON Dark Matter Search, aiming for the direct detection of dark matter candidates, such as the Weakly Interacting Massive Particles (WIMPs). The projected sensitivity for the spin-independent WIMP-nucleon elastic scattering cross-section is σ ≈ 2 × 10-47 cm2 for a WIMP mass of mχ = 50 GeV/c2. To reach its projected sensitivity, the background has to be reduced by two orders of magnitude compared to its predecessor XENON100. This requires a water Cherenkov muon veto surrounding the XENON1T TPC, both to shield external backgrounds and to tag muon-induced energetic neutrons through detection of a passing muon or the secondary shower induced by a muon interacting in the surrounding rock. The muon veto is instrumented with 84 8'' PMTs with high quantum efficiency (QE) in the Cherenkov regime and the walls of the watertank are clad with the highly reflective DF2000MA foil by 3M. Here, we present a study of the reflective properties of this foil, as well as the measurement of its wavelength shifting (WLS) properties. Furthermore, we present the impact of reflectance and WLS on the detection efficiency of the muon veto, through the use of a Monte Carlo simulation carried out with the Geant4 toolkit. The measurements yield a specular reflectance of ≈100% for wavelengths larger than 400 nm, while ≈90% of the incoming light below 370 nm is absorbed by the foil. Approximately 3-7.5% of the light hitting the foil within the wavelength range 250 nm <= λ <= 390 nm is used for the WLS process. The intensity of the emission spectrum of the WLS light is slightly dependent on the absorbed wavelength and shows the shape of a rotational-vibrational fluorescence spectrum, peaking at around λ ≈ 420 nm. Adjusting the reflectance values to the measured ones in the Monte Carlo simulation originally used for the muon veto design, the veto detection efficiency remains unchanged. Including the wavelength shifting in the Monte Carlo simulation leads to an increase of the efficiency of approximately 0.5%.

Cherenkov and Scintillation Properties of Cubic Zirconium

NASA Technical Reports Server (NTRS)

Christl, M.J.; Adams, J.H.; Parnell, T.A.; Kuznetsov, E.N.

2008-01-01

Cubic zirconium (CZ) is a high index of refraction (n =2.17) material that we have investigated for Cherenkov counter applications. Laboratory and proton accelerator tests of an 18cc sample of CZ show that the expected fast Cherenkov response is accompanied by a longer scintillation component that can be separated by pulse shaping. This presents the possibility of novel particle spectrometers which exploits both properties of CZ. Other high index materials being examined for Cherenkov applications will be discussed. Results from laboratory tests and an accelerator exposure will be presented and a potential application in solar energetic particle instruments will be discussed

Development of FARICH detector for particle identification system at accelerators

NASA Astrophysics Data System (ADS)

Finogeev, D. A.; Kurepin, A. B.; Razin, V. I.; Reshetin, A. I.; Usenko, E. A.; Barnyakov, A. Yu.; Barnyakov, M. Yu.; Bobrovnikov, V. S.; Buzykaev, A. R.; Kasyanenko, P. V.; Kononov, S. A.; Kravchenko, E. A.; Kuyanov, I. A.; Onuchin, A. P.; Ovtin, I. V.; Podgornov, N. A.; Talyshev, A. A.; Danilyuk, A. F.

2018-01-01

Aerogel has been successfully used as a radiator in Cherenkov detectors. In 2004, a multilayer aerogel providing Cherenkov ring focusing was proposed and produced. FARICH (Focusing Aerogel Rich Imaging CHerenkov) detectors such as ARICH for Belle-II (KEK, Japan), Forward RICH for PANDA detector (FAIR, Germany), and FARICH for the Super Charm-Tau factory project (BINP, Novosibirsk) have been developed based on this aerogel. Prototypes of FARICH detector based on MRS APD and Philips DPC photosensors were developed and tested in the framework of this project. An angular resolution for Cherenkov rings of 3.6 mrad was achieved.

A measurement of the cosmic ray spectrum and composition at the knee

NASA Astrophysics Data System (ADS)

Fowler, J. W.; Fortson, L. F.; Jui, C. C. H.; Kieda, D. B.; Ong, R. A.; Pryke, C. L.; Sommers, P.

2001-03-01

The energy spectrum and primary composition of cosmic rays with energy between 3×10 14 and 3×10 16 eV have been studied using the CASA-BLANCA detector. CASA consisted of 957 surface scintillation stations; BLANCA consisted of 144 angle-integrating Cherenkov light detectors located at the same site. CASA measured the charged particle distribution of air showers, while BLANCA measured the lateral distribution of Cherenkov light. The data are interpreted using the predictions of the CORSIKA air shower simulation coupled with four different hadronic interaction codes. The differential flux of cosmic rays measured by BLANCA exhibits a knee in the range of 2-3 PeV with a width of approximately 0.5 decades in primary energy. The power law indices of the differential flux below and above the knee are -2.72±0.02 and -2.95±0.02, respectively. We present our data both as a mean depth of shower maximum and as a mean nuclear mass. A multi-component fit using four elemental species suggests the same composition trends exhibited by the mean quantities, and also indicates that QGSJET and VENUS are the preferred hadronic interaction models. We find that an initially mixed composition turns lighter between 1 and 3 PeV, and then becomes heavier with increasing energies above 3 PeV.

The gamma-ray Cherenkov telescope for the Cherenkov telescope array

NASA Astrophysics Data System (ADS)

Tibaldo, L.; Abchiche, A.; Allan, D.; Amans, J.-P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J.-J.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Daniel, M. K.; De Franco, A.; De Frondat, F.; Dournaux, J.-L.; Dumas, D.; Ernenwein, J.-P.; Fasola, G.; Funk, S.; Gironnet, J.; Graham, J. A.; Greenshaw, T.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J.-M.; Jankowsky, D.; Jegouzo, I.; Jogler, T.; Kraus, M.; Lapington, J. S.; Laporte, P.; Lefaucheur, J.; Markoff, S.; Melse, T.; Mohrmann, L.; Molyneux, P.; Nolan, S. J.; Okumura, A.; Osborne, J. P.; Parsons, R. D.; Rosen, S.; Ross, D.; Rowell, G.; Rulten, C. B.; Sato, Y.; Sayède, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Sol, H.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Trichard, C.; Vink, J.; Watson, J. J.; White, R.; Yamane, N.; Zech, A.; Zink, A.; Zorn, J.; CTA Consortium

2017-01-01

The Cherenkov Telescope Array (CTA) is a forthcoming ground-based observatory for very-high-energy gamma rays. CTA will consist of two arrays of imaging atmospheric Cherenkov telescopes in the Northern and Southern hemispheres, and will combine telescopes of different types to achieve unprecedented performance and energy coverage. The Gamma-ray Cherenkov Telescope (GCT) is one of the small-sized telescopes proposed for CTA to explore the energy range from a few TeV to hundreds of TeV with a field of view ≳ 8° and angular resolution of a few arcminutes. The GCT design features dual-mirror Schwarzschild-Couder optics and a compact camera based on densely-pixelated photodetectors as well as custom electronics. In this contribution we provide an overview of the GCT project with focus on prototype development and testing that is currently ongoing. We present results obtained during the first on-telescope campaign in late 2015 at the Observatoire de Paris-Meudon, during which we recorded the first Cherenkov images from atmospheric showers with the GCT multi-anode photomultiplier camera prototype. We also discuss the development of a second GCT camera prototype with silicon photomultipliers as photosensors, and plans toward a contribution to the realisation of CTA.

Design Concepts for the Cherenkov Telescope Array CTA: An Advanced Facility for Ground-Based High-Energy Gamma-Ray Astronomy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Actis, M

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTAmore » is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.« less

Atmospheric neutrinos and proton decay in Super-Kamiokande and Hyper-Kamiokande

NASA Astrophysics Data System (ADS)

Li, Zepeng; Super-Kamiokande Collaboration; Hyper-Kamiokande Collaboration

2017-06-01

Super-Kamiokande is a 50 kton water Cherenkov detector, which has been in operation since 1996. Super-Kamiokande atmospheric neutrino data have a preference for the normal neutrino mass hierarchy (Δχ2 = χNH2- χIH2 = - 4.3) when the constraints from reactor neutrino experiments are included. The search for tau neutrino appearance from neutrino oscillations has resulted in a 4.6σ exclusion of the hypothesis of no tau appearance. Hyper-Kamiokande is a proposed next-generation water Cherenkov detector, which will be a natural extension of Super-Kamiokande. The proposed experiment will have two cylindrical tanks containing 520 kton of water in total. Hyper-K will search for CP violation using the neutrino beam from J-PARC, and will have a broad physics program including studies of atmospheric neutrinos, supernova burst neutrinos, geo-neutrinos and searches for proton decay.

Candidates to replace R-12 as a radiator gas in Cherenkov detectors

NASA Astrophysics Data System (ADS)

Harvey, Allan H.; Paulechka, Eugene; Egan, Patrick F.

2018-06-01

Dichlorodifluoromethane (R-12) has been widely used as a radiator gas in pressure threshold Cherenkov detectors for high-energy particle physics. However, that compound is becoming unavailable due to the Montreal Protocol. To find a replacement with suitably high refractive index, we use a combination of theory and experiment to examine the polarizability and refractivity of several non-ozone-depleting compounds. Our measurements show that the fourth-generation refrigerants R-1234yf (2,3,3,3-tetrafluoropropene) and R-1234ze(E) (trans-1,3,3,3-tetrafluoropropene) have sufficient refractivity to replace R-12 in this application. If the slight flammability of these compounds is a problem, two nonflammable alternatives are R-218 (octafluoropropane), which has a high Global Warming Potential, and R-13I1 (trifluoroiodomethane), which has low Ozone Depletion Potential and Global Warming Potential but may not be sufficiently inert.

Transmission of light in deep sea water at the site of the ANTARES neutrino telescope

NASA Astrophysics Data System (ADS)

ANTARES Collaboration; Aguilar, J. A.; Albert, A.; Amram, P.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardellier-Desages, F. E.; Aslanides, E.; Aubert, J.-J.; Azoulay, R.; Bailey, D.; Basa, S.; Battaglieri, M.; Becherini, Y.; Bellotti, R.; Beltramelli, J.; Bertin, V.; Billault, M.; Blaes, R.; Blanc, F.; Bland, R. W.; de Botton, N.; Boulesteix, J.; Bouwhuis, M. C.; Brooks, C. B.; Bradbury, S. M.; Bruijn, R.; Brunner, J.; Bugeon, F.; Burgio, G. F.; Cafagna, F.; Calzas, A.; Caponetto, L.; Carmona, E.; Carr, J.; Cartwright, S. L.; Cecchini, S.; Charvis, P.; Circella, M.; Colnard, C.; Compère, C.; Croquette, J.; Cooper, S.; Coyle, P.; Cuneo, S.; Damy, G.; van Dantzig, R.; Deschamps, A.; de Marzo, C.; Destelle, J.-J.; de Vita, R.; Dinkelspiler, B.; Dispau, G.; Drougou, J.-F.; Druillole, F.; Engelen, J.; Favard, S.; Feinstein, F.; Ferry, S.; Festy, D.; Fopma, J.; Fuda, J.-L.; Gallone, J.-M.; Giacomelli, G.; Girard, N.; Goret, P.; Gournay, J.-F.; Hallewell, G.; Hartmann, B.; Heijboer, A.; Hello, Y.; Hernández-Rey, J. J.; Herrouin, G.; Hößl, J.; Hoffmann, C.; Hubbard, J. R.; Jaquet, M.; de Jong, M.; Jouvenot, F.; Kappes, A.; Karg, T.; Karkar, S.; Karolak, M.; Katz, U.; Keller, P.; Kooijman, P.; Korolkova, E. V.; Kouchner, A.; Kretschmer, W.; Kudryavtsev, V. A.; Lafoux, H.; Lagier, P.; Lamare, P.; Languillat, J.-C.; Laubier, L.; Legou, T.; Le Guen, Y.; Le Provost, H.; Le van Suu, A.; Lo Nigro, L.; Lo Presti, D.; Loucatos, S.; Louis, F.; Lyashuk, V.; Magnier, P.; Marcelin, M.; Margiotta, A.; Maron, C.; Massol, A.; Mazéas, F.; Mazeau, B.; Mazure, A.; McMillan, J. E.; Michel, J.-L.; Millot, C.; Milovanovic, A.; Montanet, F.; Montaruli, T.; Morel, J.-P.; Moscoso, L.; Nezri, E.; Niess, V.; Nooren, G. J.; Ogden, P.; Olivetto, C.; Palanque-Delabrouille, N.; Payre, P.; Petta, C.; Pineau, J.-P.; Poinsignon, J.; Popa, V.; Potheau, R.; Pradier, T.; Racca, C.; Randazzo, N.; Real, D.; van Rens, B. A. P.; Réthoré, F.; Ripani, M.; Roca-Blay, V.; Romeyer, A.; Rollin, J.-F.; Romita, M.; Rose, H. J.; Rostovtsev, A.; Ruppi, M.; Russo, G. V.; Sacquin, Y.; Saouter, S.; Schuller, J.-P.; Schuster, W.; Sokalski, I.; Suvorova, O.; Spooner, N. J. C.; Spurio, M.; Stolarczyk, T.; Stubert, D.; Taiuti, M.; Thompson, L. F.; Tilav, S.; Usik, A.; Valdy, P.; Vallage, B.; Vaudaine, G.; Vernin, P.; Virieux, J.; Vladimirsky, E.; de Vries, G.; de Witt Huberts, P.; de Wolf, E.; Zaborov, D.; Zaccone, H.; Zakharov, V.; Zavatarelli, S.; de Zornoza, J. D.; Zúñiga, J.

2005-02-01

The ANTARES neutrino telescope is a large photomultiplier array designed to detect neutrino-induced upward-going muons by their Cherenkov radiation. Understanding the absorption and scattering of light in the deep Mediterranean is fundamental to optimising the design and performance of the detector. This paper presents measurements of blue and UV light transmission at the ANTARES site taken between 1997 and 2000. The derived values for the scattering length and the angular distribution of particulate scattering were found to be highly correlated, and results are therefore presented in terms of an absorption length λabs and an effective scattering length λscteff. The values for blue (UV) light are found to be λabs ≃ 60(26) m, λscteff≃265(122)m, with significant (˜15%) time variability. Finally, the results of ANTARES simulations showing the effect of these water properties on the anticipated performance of the detector are presented.

Rise Time of the Simulated VERITAS 12 m Davies-Cotton Reflector

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, Richard J.

The Very Energetic Radiation Imaging Telescope Array System (VERITAS) will utilise Imaging Atmospheric Cherenkov Telescopes (IACTs) based on a Davies-Cotton design with f-number f/1.0 to detect cosmic gamma-rays. Unlike a parabolic reflector, light from the Davies-Cotton does not arrive isochronously at the camera. Here the effect of the telescope geometry on signal rise-time is examined. An almost square-pulse arrival time profile with a rise time of 1.7 ns is found analytically and confirmed through simulation.

Simultaneous measurements of water optical properties by AC9 transmissometer and ASP-15 inherent optical properties meter in Lake Baikal

NASA Astrophysics Data System (ADS)

Balkanov, V.; Belolaptikov, I.; Bezrukov, L.; Budnev, N.; Capone, A.; Chensky, A.; Danilchenko, I.; Domogatsky, G.; Dzhilkibaev, Zh.-A.; Fialkovsky, S.; Gaponenko, O.; Gress, O.; Gress, T.; Il'Yasov, R.; Klabukov, A.; Klimov, A.; Klimushin, S.; Konischev, K.; Koshechkin, A.; Kuznetzov, Vy.; Kuzmichev, L.; Kulepov, V.; Lubsandorzhiev, B.; Masullo, R.; Migneco, E.; Mikheyev, S.; Milenin, M.; Mirgazov, R.; Moseiko, N.; Osipova, E.; Panfilov, A.; Pan'kov, L.; Parfenov, Yu.; Pavlov, A.; Petruccetti, M.; Pliskovsky, E.; Pokhil, P.; Poleschuk, V.; Popova, E.; Prosin, V.; Riccobene, G.; Rozanov, M.; Rubtzov, V.; Semeney, Yu.; Spiering, Ch.; Streicher, O.; Tarashansky, B.; Vasiljev, R.; Wischnewski, R.; Yashin, I.; Zhukov, V.

2003-02-01

Measurements of optical properties in media enclosing Cherenkov neutrino telescopes are important not only at the moment of the selection of an adequate site, but also for the continuous characterization of the medium as a function of time. Over the two last decades, the Baikal collaboration has been measuring the optical properties of the deep water in Lake Baikal (Siberia) where, since April 1998, the neutrino telescope NT-200 is in operation. Measurements have been made with custom devices. The NEMO Collaboration, aiming at the construction of a km3 Cherenkov neutrino detector in the Mediterranean Sea, has developed an experimental setup for the measurement of oceanographic and optical properties of deep sea water. This setup is based on a commercial transmissometer. During a joint campaign of the two collaborations in March and April 2001, light absorption, scattering and attenuation in water have been measured. The results are compatible with previous ones reported by the Baikal Collaboration and show convincing agreement between the two experimental techniques.

Evaluating the Radiation Damage to Quartz Rods in the ATLAS Zero Degree Calorimeter

NASA Astrophysics Data System (ADS)

Goodale, Kathryn

2017-09-01

At the Large Hadron Collider, the ATLAS experiment studies particle collisions to explore the fundamental particles of nature. A key instrumentation technology used by the ATLAS experiment are calorimeters for particle energy measurements. UIUC is developing a new Zero-Degree Calorimeter; a hadronic calorimeter located at zero-degrees from the collision axis. It consists of alternating layers of tungsten and oil; passive and active layers, respectively. The passive layers cause intense showers of secondary particles. These particles then produce Cherenkov radiation in the active layer. The oil in the active layer is replaced at a constant rate allowing for very high radiation doses in the detector without deteriorating the radiator material. The active layer includes wavelength shifters that absorb and re-emit isotropically the Cherenkov radiation. In this way, some of the photons arrive at two, hollow quartz rods which are filled by a second stage wavelength shifter. Here the light is absorbed and re-directed to a Silicon Photomultiplier for detection. In this paper, the impact of ionizing radiation on quartz rods will be discussed and the results from attenuation measurements will be presented.

Transparency of the Universe to gamma-rays

NASA Astrophysics Data System (ADS)

De Angelis, A.; Galanti, G.; Roncadelli, M.

2013-07-01

Using the most recent observational data concerning the extragalactic background light and the radio background for a source at an arbitrary redshift in the range zs ≤ 3, we compute the energy E0 of an observed γ-ray photon in the range 10 ≤ E0 ≤ 1013 GeV such that the resulting optical depth τγ(E0, zs) takes the values 1, 2, 3 and 4.6 corresponding to an observed flux dimming of e-1 ≃ 0.37, e-2 ≃ 0.14, e-3 ≃ 0.05 and e-4.6 ≃ 0.01, respectively. Below a distance D ≃ 8 kpc, we find that τγ(E0, DH0/c) < 1 for any value of E0. In the limiting case of a local Universe (zs ≃ 0), we compare our result with the one derived in 1997 by Coppi and Aharonian. The present achievement is of paramount relevance for the planned ground-based detectors like Cherenkov Telescope Array, High Altitude Water Cherenkov Experiment and Hundred Square-km Cosmic ORigin Explorer.

On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform

NASA Astrophysics Data System (ADS)

Brown, Anthony M.

2018-01-01

Recent advances in unmanned aerial vehicle (UAV) technology have made UAVs an attractive possibility as an airborne calibration platform for astronomical facilities. This is especially true for arrays of telescopes spread over a large area such as the Cherenkov Telescope Array (CTA). In this paper, the feasibility of using UAVs to calibrate CTA is investigated. Assuming a UAV at 1km altitude above CTA, operating on astronomically clear nights with stratified, low atmospheric dust content, appropriate thermal protection for the calibration light source and an onboard photodiode to monitor its absolute light intensity, inter-calibration of CTA's telescopes of the same size class is found to be achievable with a 6 - 8 % uncertainty. For cross-calibration of different telescope size classes, a systematic uncertainty of 8 - 10 % is found to be achievable. Importantly, equipping the UAV with a multi-wavelength calibration light source affords us the ability to monitor the wavelength-dependent degradation of CTA telescopes' optical system, allowing us to not only maintain this 6 - 10 % uncertainty after the first few years of telescope deployment, but also to accurately account for the effect of multi-wavelength degradation on the cross-calibration of CTA by other techniques, namely with images of air showers and local muons. A UAV-based system thus provides CTA with several independent and complementary methods of cross-calibrating the optical throughput of individual telescopes. Furthermore, housing environmental sensors on the UAV system allows us to not only minimise the systematic uncertainty associated with the atmospheric transmission of the calibration signal, it also allows us to map the dust content above CTA as well as monitor the temperature, humidity and pressure profiles of the first kilometre of atmosphere above CTA with each UAV flight.

The design and performance of a prototype water Cherenkov optical time-projection chamber

NASA Astrophysics Data System (ADS)

Oberla, Eric; Frisch, Henry J.

2016-04-01

A first experimental test of tracking relativistic charged particles by 'drifting' Cherenkov photons in a water-based optical time-projection chamber (OTPC) has been performed at the Fermilab Test Beam Facility. The prototype OTPC detector consists of a 77 cm long, 28 cm diameter, 40 kg cylindrical water mass instrumented with a combination of commercial 5.1 × 5.1cm2 micro-channel plate photo-multipliers (MCP-PMT) and 6.7 × 6.7cm2 mirrors. Five MCP-PMTs are installed in two columns along the OTPC cylinder in a small-angle stereo configuration. A mirror is mounted opposite each MCP-PMT on the inner surface of the detector cylinder, effectively increasing the photo-detection efficiency and providing a time-resolved image of the Cherenkov light on the opposing wall. Each MCP-PMT is coupled to an anode readout consisting of thirty 50 Ω microstrips. A 180-channel data acquisition system digitizes the MCP-PMT signals on one end of the microstrips using the PSEC4 waveform sampling-and-digitizing chip operating at a sampling rate of 10.24 Gigasamples-per-second. The single-ended microstrip readout determines the time and position of a photon arrival at the face of the MCP-PMT by recording both the direct signal and the pulse reflected from the unterminated far end of the strip. The detector was installed on the Fermilab MCenter secondary beam-line behind a steel absorber where the primary flux is multi-GeV muons. Approximately 80 Cherenkov photons are detected for a through-going muon track in a total event duration of 2 ns. By measuring the time-of-arrival and the position of individual photons at the surface of the detector to ≤ 100 ps and a few mm, respectively, we have measured a spatial resolution of 15 mm for each MCP-PMT track segment, and, from linear fits over the entire track length of 40 cm, an angular resolution on the track direction of 60 mrad.

Cherenkov water detector NEVOD

NASA Astrophysics Data System (ADS)

Petrukhin, A. A.

2015-05-01

A unique multipurpose Cherenkov water detector, the NEVOD facility, uses quasispherical measuring modules to explore all the basic components of cosmic rays on Earth's surface, including neutrinos. Currently, the experimental complex includes the Cherenkov water detector, a calibration telescope system, and a coordinate detector. This paper traces the basic development stages of NEVOD, examines research directions, presents the results obtained, including the search for the solution to the 'muon puzzle', and discusses possible future development prospects.

Angular width of the Cherenkov radiation with inclusion of multiple scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jian, E-mail: jzheng@ustc.edu.cn

2016-06-15

Visible Cherenkov radiation can offer a method of the measurement of the velocity of charged particles. The angular width of the radiation is important since it determines the resolution of the velocity measurement. In this article, the angular width of Cherenkov radiation with inclusion of multiple scattering is calculated through the path-integral method, and the analytical expressions are presented. The condition that multiple scattering processes dominate the angular distribution is obtained.

Underground Prototype Water Cherenkov Muon Detector with the Tibet Air Shower Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amenomori, M.; Nanjo, H.; Bi, X. J.

2008-12-24

We are planning to build a 10,000 m{sup 2} water-Cherenkov-type muon detector (MD) array under the Tibet air shower (AS) array. The Tibet AS+MD array will have the sensitivity to detect gamma rays in the 100 TeV region by an order of the magnitude better than any other previous existing detectors in the world. In the late fall of 2007, a prototype water Cherenkov muon detector of approximately 100 m{sup 2} was constructed under the existing Tibet AS array. The preliminary data analysis is in good agreement with our MC simulation. We are now ready for further expanding the undergroundmore » water Cherenkov muon detector.« less

The upgrade of the H.E.S.S. cameras

NASA Astrophysics Data System (ADS)

Giavitto, Gianluca; Ashton, Terry; Balzer, Arnim; Berge, David; Brun, Francois; Chaminade, Thomas; Delagnes, Eric; Fontaine, Gerard; Füßling, Matthias; Giebels, Berrie; Glicenstein, Jean-Francois; Gräber, Tobias; Hinton, Jim; Jahnke, Albert; Klepser, Stefan; Kossatz, Marko; Kretzschmann, Axel; Lefranc, Valentin; Leich, Holger; Lüdecke, Hartmut; Lypova, Iryna; Manigot, Pascal; Marandon, Vincent; Moulin, Emmanuel; Naurois, Mathieu de; Nayman, Patrick; Ohm, Stefan; Penno, Marek; Ross, Duncan; Salek, David; Schade, Markus; Schwab, Thomas; Simoni, Rachel; Stegmann, Christian; Steppa, Constantin; Thornhill, Julian; Toussnel, Francois

2017-12-01

The High Energy Stereoscopic System (HESS) is an array of imaging atmospheric Cherenkov telescopes (IACTs) located in the Khomas highland in Namibia. It was built to detect Very High Energy (VHE > 100 GeV) cosmic gamma rays. Since 2003, HESS has discovered the majority of the known astrophysical VHE gamma-ray sources, opening a new observational window on the extreme non-thermal processes at work in our universe. HESS consists of four 12-m diameter Cherenkov telescopes (CT1-4), which started data taking in 2002, and a larger 28-m telescope (CT5), built in 2012, which lowers the energy threshold of the array to 30 GeV . The cameras of CT1-4 are currently undergoing an extensive upgrade, with the goals of reducing their failure rate, reducing their readout dead time and improving the overall performance of the array. The entire camera electronics has been renewed from ground-up, as well as the power, ventilation and pneumatics systems, and the control and data acquisition software. Only the PMTs and their HV supplies have been kept from the original cameras. Novel technical solutions have been introduced, which will find their way into some of the Cherenkov cameras foreseen for the next-generation Cherenkov Telescope Array (CTA) observatory. In particular, the camera readout system is the first large-scale system based on the analog memory chip NECTAr, which was designed for CTA cameras. The camera control subsystems and the control software framework also pursue an innovative design, exploiting cutting-edge hardware and software solutions which excel in performance, robustness and flexibility. The CT1 camera has been upgraded in July 2015 and is currently taking data; CT2-4 have been upgraded in fall 2016. Together they will assure continuous operation of HESS at its full sensitivity until and possibly beyond the advent of CTA. This contribution describes the design, the testing and the in-lab and on-site performance of all components of the newly upgraded HESS camera.

The cosmic ray proton, helium and CNO fluxes in the 100 TeV energy region from TeV muons and EAS atmospheric Cherenkov light observations of MACRO and EAS-TOP

NASA Astrophysics Data System (ADS)

Aglietta, M.; Alessandro, B.; Antonioli, P.; Arneodo, F.; Bergamasco, L.; Bertaina, M.; Castagnoli, C.; Castellina, A.; Chiavassa, A.; Cini, G.; D'Ettorre Piazzoli, B.; Di Sciascio, G.; Fulgione, W.; Galeotti, P.; Ghia, P. L.; Iacovacci, M.; Mannocchi, G.; Morello, C.; Navarra, G.; Saavedra, O.; Stamerra, A.; Trinchero, G. C.; Valchierotti, S.; Vallania, P.; Vernetto, S.; Vigorito, C.; Ambrosio, M.; Antolini, R.; Baldini, A.; Barbarino, G. C.; Barish, B. C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Caruso, R.; Cecchini, S.; Cei, F.; Chiarella, V.; Chiarusi, T.; Choudhary, B. C.; Coutu, S.; Cozzi, M.; De Cataldo, G.; Dekhissi, H.; De Marzo, C.; De Mitri, I.; Derkaoui, J.; De Vincenzi, M.; Di Credico, A.; Erriquez, O.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Grillo, A.; Guarino, F.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Iarocci, E.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D. S.; Lipari, P.; Longley, N. P.; Longo, M. J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M. N.; Michael, D. G.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolò, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patera, V.; Patrizii, L.; Pazzi, R.; Peck, C. W.; Perrone, L.; Petrera, S.; Popa, V.; Rainò, A.; Reynoldson, J.; Ronga, F.; Satriano, C.; Scapparone, E.; Scholberg, K.; Sciubba, A.; Sioli, M.; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J. L.; Sulak, L. R.; Surdo, A.; Tarlé, G.; Togo, V.; Vakili, M.; Walter, C. W.; Webb, R.; EAS-TOP Collaboration

2004-06-01

The primary cosmic ray (CR) proton, helium and CNO fluxes in the energy range 80-300 TeV are studied at the National Gran Sasso Laboratories by means of EAS-TOP (Campo Imperatore, 2005 m a.s.l.) and MACRO (deep underground, 3100 m w.e., the surface energy threshold for a muon reaching the detector being Eμth≈1.3 TeV). The measurement is based on: (a) the selection of primaries based on their energy/nucleon (i.e., with energy/nucleon sufficient to produce a muon with energy larger than 1.3 TeV) and the reconstruction of the shower geometry by means of the muons recorded by MACRO in the deep underground laboratories; (b) the detection of the associated atmospheric Cherenkov light (C.l.) signals by means of the C.l. detector of EAS-TOP. The C.l. density at core distance r>100 m is directly related to the total primary energy E0. Proton and helium ("p + He") and proton, helium and CNO ("p + He + CNO") primaries are thus selected at E0≃80 TeV, and at E0≃250 TeV, respectively. Their flux is measured: J p+ He(80 TeV)=(1.8±0.4)×10 -6 m -2 s -1 sr -1 TeV -1, and J p+ He+ CNO(250 TeV)=(1.1±0.3)×10 -7 m -2 s -1 sr -1 TeV -1, their relative weights being: J p+ He/J p+ He+ CNO(250 TeV)=0.78±0.17 . By using the measurements of the proton spectrum obtained from the direct experiments and hadron flux data in the atmosphere, we obtain for the relative weights of the three components at 250 TeV: Jp: JHe: JCNO=(0.20±0.08):(0.58±0.19):(0.22±0.17). This corresponds to the dominance of helium over proton primaries at 100-1000 TeV, and a possible non-negligible contribution from CNO. The lateral distribution of Cherenkov light in Extensive Air Showers (EASs), which is related to the rate of energy deposit of the primary in the atmosphere, is measured for a selected proton and helium primary beam, and good agreement is found when compared with the one calculated with the CORSIKA/QGSJET simulation model.

Gamma ray measurements at OMEGA with the newest gas Cherenkov Detector “GCD-3”

DOE Office of Scientific and Technical Information (OSTI.GOV)

McEvoy, A. M.; Herrmann, H. W.; Kim, Y.

Initial results from the newest Gas Cherenkov Detector (GCD-3) are reported demonstrating improved performance over previous GCD iterations. Increased shielding and lengthening of the Cherenkov photon optical path have resulted in a diminished precursor signal with increased temporal separation between the precursor and the primary DT Cherenkov signal. Design changes resulted in a measured GCD-3 sensitivity comparable to GCD-1 at identical 100 psia CO 2 operation. All metal gasket seals and pressure vessel certification to 400 psia operation allow for a GCD-3 lower Cherenkov threshold of 1.8 MeV using the fluorinated gas C 2F 6 as compared to the 6.3more » MeV lower limit of GCD-1 and GCD-2. Calibration data will be used to benchmark GEANT4 and ACCEPT detector models. Lastly, the GCD-3 acts as a prototype for the Super GCD being fielded at the National Ignition Facility (NIF) as part of the National Diagnostics Plan and will be installed at NIF in early 2016.« less

Gamma ray measurements at OMEGA with the newest gas Cherenkov Detector “GCD-3”

DOE PAGES

McEvoy, A. M.; Herrmann, H. W.; Kim, Y.; ...

2016-05-26

Initial results from the newest Gas Cherenkov Detector (GCD-3) are reported demonstrating improved performance over previous GCD iterations. Increased shielding and lengthening of the Cherenkov photon optical path have resulted in a diminished precursor signal with increased temporal separation between the precursor and the primary DT Cherenkov signal. Design changes resulted in a measured GCD-3 sensitivity comparable to GCD-1 at identical 100 psia CO 2 operation. All metal gasket seals and pressure vessel certification to 400 psia operation allow for a GCD-3 lower Cherenkov threshold of 1.8 MeV using the fluorinated gas C 2F 6 as compared to the 6.3more » MeV lower limit of GCD-1 and GCD-2. Calibration data will be used to benchmark GEANT4 and ACCEPT detector models. Lastly, the GCD-3 acts as a prototype for the Super GCD being fielded at the National Ignition Facility (NIF) as part of the National Diagnostics Plan and will be installed at NIF in early 2016.« less

The Calibration Units of the KM3NeT neutrino telescope

NASA Astrophysics Data System (ADS)

Baret, B.; Keller, P.; Clark, M. Lindsey

2016-04-01

KM3NeT is a network of deep-sea neutrino telescopes to be deployed in the Mediterranean Sea that will perform neutrino astronomy and oscillation studies. It consists of three-dimensional arrays of thousands of optical modules that detect the Cherenkov light induced by charged particles resulting from the interaction of a neutrino with the surrounding medium. The performance of the neutrino telescope relies on the precise timing and positioning calibration of the detector elements. Other environmental conditions which may affect light and sound transmission, such as water temperature and salinity, must also be continuously monitored. This contribution describes the technical design of the first Calibration Unit, to be deployed on the French site as part of KM3NeT Phase 1.

Distribution of secondary particles intensities over Earth's surface: Effect of the geomagnetic field

NASA Astrophysics Data System (ADS)

Bobik, P.; Kudela, K.; Pastircak, B.; Santangelo, A.; Bertaina, M.; Shinozaki, K.; Fenu, F.; Szabelski, J.; Urbar, J.

2012-10-01

We use the CORSIKA package (Heck et al., 1998) and AMS-01 flight data (Alcaraz et al., 2000) to evaluate the distribution of secondary particles in the Earth atmosphere. Distribution covers all longitudes and latitudes of STS-91 Space Shuttle flight trajectory to Mir Space Station. Moreover distribution covers all depth in the atmosphere in the evaluated area. We show distributions for e-, e+, μ+, μ-, gammas, hadrons and Cherenkov light from primary protons and helium component of cosmic rays flux. Our results compare favorably with other estimates made by different techniques. We also estimate an UV light production (300-400 nm) by electron component of secondaries at the top of the atmosphere and at ISS orbit.

Results on the Performance of a Broad Band Focussing Cherenkov Counter

DOE R&D Accomplishments Database

Cester, R.; Fitch, V. L.; Montag, A.; Sherman, S.; Webb, R. C.; Witherell, M. S.

1980-01-01

The field of ring imaging (broad band differential) Cherenkov detectors has become a very active area of interest in detector development at several high energy physics laboratories. Our group has previously reported on a method of Cherenkov ring imaging for a counter with large momentum and angular acceptance using standard photo multipliers. Recently, we have applied this technique to the design of a set of Cherenkov counters for use in a particle search experiment at Fermi National Accelerator Laboratory (FNAL). This new detector operates over the range 0.998 < ..beta.. < 1.000 in velocity with a delta..beta.. approx. 2 x 10{sup -4}. The acceptance in angle is +- 14 mrad in the horizontal and +- 28 mrad in the vertical. We report here on the performance of this counter.

Color quench correction for low level Cherenkov counting.

PubMed

Tsroya, S; Pelled, O; German, U; Marco, R; Katorza, E; Alfassi, Z B

2009-05-01

The Cherenkov counting efficiency varies strongly with color quenching, thus correction curves must be used to obtain correct results. The external (152)Eu source of a Quantulus 1220 liquid scintillation counting (LSC) system was used to obtain a quench indicative parameter based on spectra area ratio. A color quench correction curve for aqueous samples containing (90)Sr/(90)Y was prepared. The main advantage of this method over the common spectra indicators is its usefulness also for low level Cherenkov counting.

From MAGIC to CTA: the INAF participation to Cherenkov Telescopes experiments for very high energy astrophysics .

NASA Astrophysics Data System (ADS)

Antonelli, L. A.; INAF MAGIC Collaboration

The next decade can be considered the "golden age" of the Gamma Ray Astronomy with the two satellites for Gamma Ray Astronomy (AGILE and GLAST) in orbit. Therefore, thanks to many other X-ray experiments already in orbit (e.g. Swift, Chandra, NewtonXMM, etc.) it will be possible to image the Universe for the first time all over the electromagnetic spectrum almost contemporarily. The new generations of ground-based very high gamma-ray instruments are ready to extend the observed band also to the very high frequencies. Scientists from the Italian National Institute for Astrophysics (INAF) are involved in many, both space- and ground- based gamma ray experiments, and recently such an involvement has been largely improved in the field of the Imaging Atmospheric Cherenkov Telescopes (IACT). INAF is now member of the MAGIC collaboration and is participating to the realization of the second MAGIC telescope. MAGIC, as well other IACT experiments, is not operated as an observatory so a proper guest observer program does not exist. A consortium of European scientists (including INAF scientists) is thus now thinking to the design of a new research infrastructure: the Cherenkov Telescope Array (CTA). CTA is conceived to provide 10 times the sensitivity of current instruments, combined with increased flexibility and increased coverage from some 10 GeV to some 100 TeV. CTA will be operated as an observatory to serve a wider community of astronomer and astroparticle physicists.

Gamma rays from dark matter annihilation in three-loop radiative neutrino mass generation models

NASA Astrophysics Data System (ADS)

Chowdhury, Talal Ahmed; Nasri, Salah

2018-07-01

We present the Sommerfeld enhanced Dark Matter (DM) annihilation into gamma ray for a class of three-loop radiative neutrino mass models with large electroweak multiplets where the DM mass is in O(TeV) range. We show that in this model, the DM annihilation rate becomes more prominent for larger multiplets and it is already within the reach of currently operating Imaging Atmospheric Cherenkov telescopes (IACTs), High Energy Stereoscopic System (H.E.S.S.). Furthermore, Cherenkov Telescope Array (CTA), which will begin operating in 2030, will improve this sensitivity by a factor of O (10) and may exclude a large portion of parameter space of this radiative neutrino mass model with larger electroweak multiplet. This implies that the only viable option is the model with lowest electroweak multiplets i.e. singlets of SU(2)L where the DM annihilation rate is not Sommerfeld enhanced and hence it is not yet constrained by the indirect detection limits from H.E.S.S. or future CTA.

A programmable systolic array correlator as a trigger processor for electron pairs in rich (ring image Cherenkov) counters

NASA Astrophysics Data System (ADS)

Männer, R.

1989-12-01

This paper describes a systolic array processor for a ring image Cherenkov counter which is capable of identifying pairs of electron circles with a known radius and a certain minimum distance within 15 μs. The processor is a very flexible and fast device. It consists of 128 x 128 processing elements (PEs), where one PE is assigned to each pixel of the image. All PEs run synchronously at 40 MHz. The identification of electron circles is done by correlating the detector image with the proper circle circumference. Circle centers are found by peak detection in the correlation result. A second correlation with a circle disc allows circles of closed electron pairs to be rejected. The trigger decision is generated if a pseudo adder detects at least two remaining circles. The device is controlled by a freely programmable sequencer. A VLSI chip containing 8 x 8 PEs is being developed using a VENUS design system and will be produced in 2μ CMOS technology.

A Monte Carlo study of different detector geometries for HAWC

NASA Astrophysics Data System (ADS)

Gebauer, Iris

Compared to other parts of astronomy the study of the universe at energies above 100GeV is a relatively new field. Pointed instruments presently achieve the highest sensitivities. They have detected gamma-rays from at least 10 sources, but they are only able to monitor a relatively small fraction of the sky. The detection of exciting phenomena such as Gamma-ray Bursts (GRBs) requires a highly sensitive detector capable of continuously monitoring the entire overhead sky. Such an instrument could make an unbiased study of the entire field of view. With sufficient sensitivity it could detect short transients (~ 15 minutes) and study the time structure of Active galactic nuclei (AGN) flares at energies unattainable to space-based instruments. This thesis describes the design and performance of the next generation water Cherenkov detector HAWC (High Altitude Water Cherenkov). Focussing on the performance in background-rejection and sensitivity to point sources, two possible detector geometries, different in the way the photomultipliers (PMTs) are separated from each other, are compared.

Towards a flexible array control and operation framework for CTA

NASA Astrophysics Data System (ADS)

Birsin, E.; Colomé, J.; Hoffmann, D.; Koeppel, H.; Lamanna, G.; Le Flour, T.; Lopatin, A.; Lyard, E.; Melkumyan, D.; Oya, I.; Panazol, J.-L.; Schlenstedt, S.; Schmidt, T.; Schwanke, U.; Stegmann, C.; Walter, R.; Wegner, P.; CTA Consortium

2012-12-01

The Cherenkov Telescope Array (CTA) [1] will be the successor to current Imaging Atmospheric Cherenkov Telescopes (IACT) like H.E.S.S., MAGIC and VERITAS. CTA will improve in sensitivity by about an order of magnitude compared to the current generation of IACTs. The energy range will extend from well below 100 GeV to above 100 TeV. To accomplish these goals, CTA will consist of two arrays, one in each hemisphere, consisting of 50-80 telescopes and composed of three different telescope types with different mirror sizes. It will be the first open observatory for very high energy γ-ray astronomy. The Array Control working group of CTA is currently evaluating existing technologies which are best suited for a project like CTA. The considered solutions comprise the ALMA Common Software (ACS), the OPC Unified Architecture (OPC UA) and the Data Distribution Service (DDS) for bulk data transfer. The first applications, like an automatic observation scheduler and the control software for some prototype instrumentation have been developed.

New electronics for the Cherenkov Telescope Array (NECTAr)

NASA Astrophysics Data System (ADS)

Naumann, C. L.; Delagnes, E.; Bolmont, J.; Corona, P.; Dzahini, D.; Feinstein, F.; Gascón, D.; Glicenstein, J.-F.; Guilloux, F.; Nayman, P.; Rarbi, F.; Sanuy, A.; Tavernet, J.-P.; Toussenel, F.; Vincent, P.; Vorobiov, S.

2012-12-01

The international CTA consortium has recently entered into its preparatory phase towards the construction of the next-generation Cherenkov Telescope Array CTA. This experiment will be a successor, and based on the return of experience from the three major current-generation arrays H.E.S.S., MAGIC and VERITAS, and aims to significantly improve upon the sensitivity as well as the energy range of its highly successful predecessors. Construction is planned to begin by 2013, and when finished, CTA will be able to explore the highest-energy gamma ray sky in unprecedented detail. To achieve this increase in sensitivity and energy range, CTA will employ the order of 100 telescopes of three different sizes on two sites, with around 1000-4000 channels per camera, depending on the telescope size. To equip and reliably operate the order of 100000 channels of photodetectors (compared to 6000 of the H.E.S.S. array), a new kind of flexible and powerful yet inexpensive front-end hardware will be required. One possible solution is pursued by the NECTAr (New Electronics for the Cherenkov Telescope Array) project. Its main feature is the integration of as much as possible of the front-end electronics (amplifiers, fast analogue samplers, memory and ADCs) into a single ASIC, which will allow very fast readout performances while significantly reducing the cost and the power consumption per channel. Also included is a low-cost FPGA for digital treatment and online data processing, as well as an Ethernet connection. Other priorities of NECTAr are the modularity of the system, a high degree of flexibility in the trigger system as well as the possibility of flexible readout modes to optimise the signal-to-noise ratio while at the same time allowing a significant reduction of data rates, both of which could improve the sensitivity of CTA compared to current detection systems. This paper gives an overview over the development work for the Nectar system, with particular focus on its main component, the NECTAr ASIC.

The Advanced Gamma-ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Buckley, James

2008-04-01

We describe a concept for a ˜km^2 ground-based gamma-ray experiment (AGIS) comprised of an array of ˜100 imaging atmospheric Cherenkov telescopes achieving a sensitivity an order of magnitude better than the current generation of space or ground-based instruments in the energy range of 40 GeV to ˜100 TeV. We present the scientific drivers for AGIS including the prospects for contributions to understanding extragalactic sources such as nearby galaxies, active galaxies, galaxy clusters and GRB; galactic sources such as X-ray binaries, supernova remnants, and pulsar wind nebulae; as well as probes of fundamental physics including indirectly detecting dark matter and probing TeV-scale physics. With the current generation of atmospheric Cherenkov telescope arrays, TeV astronomy has become well established, with the number TeV gamma-ray sources now nearing 100, including many unidentified and serendipitous sources. Improvements in the instantaneous field of view, angular resolution, effective area and energy resolution of AGIS are certain to provide great scientific returns in high energy astrophysics as well as opening up new discovery space. Here we present an overview of the ongoing design studies for AGIS including the optimization of array parameters as well as an overview of the technical drivers for the observatory.

First results from HAWC: monitoring the TeV gamma-ray sky

NASA Astrophysics Data System (ADS)

Lauer, Robert J.

2015-03-01

The High Altitude Water Cherenkov (HAWC) Observatory is a wide-field gamma-ray detector sensitive to primary energies between 100 GeV and 100 TeV. The array is being built at an altitude of 4100 m a.s.l. on the Sierra Negra volcano near Puebla, Mexico. Data taking has already started while construction continues, with the completion projected for early 2015. The design is optimized to detect extended air showers induced by gamma rays that pass through the array and to reconstruct the directions and energies of the primary photons. With a duty cycle close to 100% and a daily coverage of ~8 sr of the sky, HAWC will perform a survey of TeV emissions from many different sources. The northern active galactic nuclei will be monitored for up to 6 hours each day, providing unprecedented light curve coverage at energies comparable to those of imaging air Cherenkov telescopes. HAWC has been in scientific operation with more than 100 detector modules since August 2013. Here we present a preliminary look at the first results and discuss the efforts to integrate HAWC in multi-wavelength studies of extragalactic jets.

Search for relativistic magnetic monopoles with the AMANDA-II neutrino telescope

NASA Astrophysics Data System (ADS)

Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Benzvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bissok, M.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Böser, S.; Botner, O.; Bradley, L.; Braun, J.; Buitink, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Davis, J. C.; de Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Feusels, T.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Karg, T.; Karle, A.; Kelley, J. L.; Kemming, N.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Knops, S.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Lauer, R.; Lehmann, R.; Lennarz, D.; Lünemann, J.; Madsen, J.; Majumdar, P.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Matusik, M.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Ono, M.; Panknin, S.; Paul, L.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Roucelle, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schlenstedt, S.; Schmidt, T.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Voge, M.; Voigt, B.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.

2010-10-01

We present the search for Cherenkov signatures from relativistic magnetic monopoles in data taken with the AMANDA-II detector, a neutrino telescope deployed in the Antarctic ice cap at the Geographic South Pole. The non-observation of a monopole signal in data collected during the year 2000 improves present experimental limits on the flux of relativistic magnetic monopoles: Our flux limit varies between 3.8×10-17 cm-2 s-1 sr-1 (for monopoles moving at the vacuum speed of light) and 8.8×10-16 cm-2 s-1 sr-1 (for monopoles moving at a speed β= v/ c=0.76, just above the Cherenkov threshold in ice). These limits apply to monopoles that are energetic enough to penetrate the Earth and enter the detector from below the horizon. The limit obtained for monopoles reaching the detector from above the horizon is less stringent by roughly an order of magnitude, due to the much larger background from down-going atmospheric muons. This looser limit is however valid for a larger class of magnetic monopoles, since the monopoles are not required to pass through the Earth.

Cherenkov imaging method for rapid optimization of clinical treatment geometry in total skin electron beam therapy

PubMed Central

Zhang, Rongxiao; Gladstone, David J.; Williams, Benjamin B.; Glaser, Adam K.; Pogue, Brian W.; Jarvis, Lesley A.

2016-01-01

Purpose: A method was developed utilizing Cherenkov imaging for rapid and thorough determination of the two gantry angles that produce the most uniform treatment plane during dual-field total skin electron beam therapy (TSET). Methods: Cherenkov imaging was implemented to gather 2D measurements of relative surface dose from 6 MeV electron beams on a white polyethylene sheet. An intensified charge-coupled device camera time-gated to the Linac was used for Cherenkov emission imaging at sixty-two different gantry angles (1° increments, from 239.5° to 300.5°). Following a modified Stanford TSET technique, which uses two fields per patient position for full body coverage, composite images were created as the sum of two beam images on the sheet; each angle pair was evaluated for minimum variation across the patient region of interest. Cherenkov versus dose correlation was verified with ionization chamber measurements. The process was repeated at source to surface distance (SSD) = 441, 370.5, and 300 cm to determine optimal angle spread for varying room geometries. In addition, three patients receiving TSET using a modified Stanford six-dual field technique with 6 MeV electron beams at SSD = 441 cm were imaged during treatment. Results: As in previous studies, Cherenkov intensity was shown to directly correlate with dose for homogenous flat phantoms (R2 = 0.93), making Cherenkov imaging an appropriate candidate to assess and optimize TSET setup geometry. This method provided dense 2D images allowing 1891 possible treatment geometries to be comprehensively analyzed from one data set of 62 single images. Gantry angles historically used for TSET at their institution were 255.5° and 284.5° at SSD = 441 cm; however, the angles optimized for maximum homogeneity were found to be 252.5° and 287.5° (+6° increase in angle spread). Ionization chamber measurements confirmed improvement in dose homogeneity across the treatment field from a range of 24.4% at the initial angles, to only 9.8% with the angles optimized. A linear relationship between angle spread and SSD was observed, ranging from 35° at 441 cm, to 39° at 300 cm, with no significant variation in percent-depth dose at midline (R2 = 0.998). For patient studies, factors influencing in vivo correlation between Cherenkov intensity and measured surface dose are still being investigated. Conclusions: Cherenkov intensity correlates to relative dose measured at depth of maximum dose in a uniform, flat phantom. Imaging of phantoms can thus be used to analyze and optimize TSET treatment geometry more extensively and rapidly than thermoluminescent dosimeters or ionization chambers. This work suggests that there could be an expanded role for Cherenkov imaging as a tool to efficiently improve treatment protocols and as a potential verification tool for routine monitoring of unique patient treatments. PMID:26843259

Cherenkov imaging method for rapid optimization of clinical treatment geometry in total skin electron beam therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreozzi, Jacqueline M., E-mail: Jacqueline.M.Andreozzi.th@dartmouth.edu, E-mail: Lesley.A.Jarvis@hitchcock.org; Glaser, Adam K.; Zhang, Rongxiao

2016-02-15

Purpose: A method was developed utilizing Cherenkov imaging for rapid and thorough determination of the two gantry angles that produce the most uniform treatment plane during dual-field total skin electron beam therapy (TSET). Methods: Cherenkov imaging was implemented to gather 2D measurements of relative surface dose from 6 MeV electron beams on a white polyethylene sheet. An intensified charge-coupled device camera time-gated to the Linac was used for Cherenkov emission imaging at sixty-two different gantry angles (1° increments, from 239.5° to 300.5°). Following a modified Stanford TSET technique, which uses two fields per patient position for full body coverage, compositemore » images were created as the sum of two beam images on the sheet; each angle pair was evaluated for minimum variation across the patient region of interest. Cherenkov versus dose correlation was verified with ionization chamber measurements. The process was repeated at source to surface distance (SSD) = 441, 370.5, and 300 cm to determine optimal angle spread for varying room geometries. In addition, three patients receiving TSET using a modified Stanford six-dual field technique with 6 MeV electron beams at SSD = 441 cm were imaged during treatment. Results: As in previous studies, Cherenkov intensity was shown to directly correlate with dose for homogenous flat phantoms (R{sup 2} = 0.93), making Cherenkov imaging an appropriate candidate to assess and optimize TSET setup geometry. This method provided dense 2D images allowing 1891 possible treatment geometries to be comprehensively analyzed from one data set of 62 single images. Gantry angles historically used for TSET at their institution were 255.5° and 284.5° at SSD = 441 cm; however, the angles optimized for maximum homogeneity were found to be 252.5° and 287.5° (+6° increase in angle spread). Ionization chamber measurements confirmed improvement in dose homogeneity across the treatment field from a range of 24.4% at the initial angles, to only 9.8% with the angles optimized. A linear relationship between angle spread and SSD was observed, ranging from 35° at 441 cm, to 39° at 300 cm, with no significant variation in percent-depth dose at midline (R{sup 2} = 0.998). For patient studies, factors influencing in vivo correlation between Cherenkov intensity and measured surface dose are still being investigated. Conclusions: Cherenkov intensity correlates to relative dose measured at depth of maximum dose in a uniform, flat phantom. Imaging of phantoms can thus be used to analyze and optimize TSET treatment geometry more extensively and rapidly than thermoluminescent dosimeters or ionization chambers. This work suggests that there could be an expanded role for Cherenkov imaging as a tool to efficiently improve treatment protocols and as a potential verification tool for routine monitoring of unique patient treatments.« less

Design of Cherenkov bars for the optical part of the time-of-flight detector in Geant4.

PubMed

Nozka, L; Brandt, A; Rijssenbeek, M; Sykora, T; Hoffman, T; Griffiths, J; Steffens, J; Hamal, P; Chytka, L; Hrabovsky, M

2014-11-17

We present the results of studies devoted to the development and optimization of the optical part of a high precision time-of-flight (TOF) detector for the Large Hadron Collider (LHC). This work was motivated by a proposal to use such a detector in conjunction with a silicon detector to tag and measure protons from interactions of the type p + p → p + X + p, where the two outgoing protons are scattered in the very forward directions. The fast timing detector uses fused silica (quartz) bars that emit Cherenkov radiation as a relativistic particle passes through and the emitted Cherenkov photons are detected by, for instance, a micro-channel plate multi-anode Photomultiplier Tube (MCP-PMT). Several possible designs are implemented in Geant4 and studied for timing optimization as a function of the arrival time, and the number of Cherenkov photons reaching the photo-sensor.

Spallation backgrounds in Super-Kamiokande are made in muon-induced showers

NASA Astrophysics Data System (ADS)

Li, Shirley Weishi; Beacom, John F.

2015-05-01

Crucial questions about solar and supernova neutrinos remain unanswered. Super-Kamiokande has the exposure needed for progress, but detector backgrounds are a limiting factor. A leading component is the beta decays of isotopes produced by cosmic-ray muons and their secondaries, which initiate nuclear spallation reactions. Cuts of events after and surrounding muon tracks reduce this spallation decay background by ≃ 90 % (at a cost of ≃ 20 % deadtime), but its rate at 6-18 MeV is still dominant. A better way to cut this background was suggested in a Super-Kamiokande paper by Bays et al. [Phys. Rev. D 85, 052007 (2012)] on a search for the diffuse supernova neutrino background. They found that spallation decays above 16 MeV were preceded near the same location by a peak in the apparent Cherenkov light profile from the muon; a more aggressive cut was applied to a limited section of the muon track, leading to decreased background without increased deadtime. We put their empirical discovery on a firm theoretical foundation. We show that almost all spallation decay isotopes are produced by muon-induced showers and that these showers are rare enough and energetic enough to be identifiable. This is the first such demonstration for any detector. We detail how the physics of showers explains the peak in the muon Cherenkov light profile and other Super-K observations. Our results provide a physical basis for practical improvements in background rejection that will benefit multiple studies. For solar neutrinos, in particular, it should be possible to dramatically reduce backgrounds at energies as low as 6 MeV.

AMS results on the fluxes of light nuclei in cosmic rays

NASA Astrophysics Data System (ADS)

Bertucci, Bruna; AMS Collaboration

2017-01-01

AMS-02 is a wide acceptance high-energy physics experiment installed on the International Space Station in May 2011 and it has been operating continuously since then. AMS-02 is able to separate cosmic rays light nuclei species (1 <= Z <= 8) with contaminations less than 10-3 thanks to the redundant measurement of the particle charge in eight silicon tracker layers, four scintillator planes and the Ring Imaging Cherenkov detector. The accurate measure of their spectrum in the GeV-TeV range is performed by the magnetic spectrometer with a maximum detectable rigidity of 2-3 TV. Precise measurements from AMS will be presented, including proton, helium, boron to carbon flux ratio, and highlights of ongoing analyses discussed. On behalf of the AMS Collaboration.

Scintillating glasses for total absorption dual readout calorimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonvicini, V.; Driutti, A.; Cauz, D.

2012-01-01

Scintillating glasses are a potentially cheaper alternative to crystal - based calorimetry with common problems related to light collection, detection and processing. As such, their use and development are part of more extensive R&D aimed at investigating the potential of total absorption, combined with the readout (DR) technique, for hadron calorimetry. A recent series of measurements, using cosmic and particle beams from the Fermilab test beam facility and scintillating glass with the characteristics required for application of the DR technique, serve to illustrate the problems addressed and the progress achieved by this R&D. Alternative solutions for light collection (conventional andmore » silicon photomultipliers) and signal processing are compared, the separate contributions of scintillation and Cherenkov processes to the signal are evaluated and results are compared to simulation.« less

Relativistic twistron based on backward-wave oscillator with modulating reflector and an efficiency of 56%

NASA Astrophysics Data System (ADS)

Totmeninov, E. M.; Pegel, I. V.; Tarakanov, V. P.

2017-06-01

Using numerical simulation, the operating mode of a relativistic Cherenkov microwave generator of the twistronic type has been demonstrated. The generator includes an electrodynamic system based on a backward-wave oscillator and modulating reflector with nonmonotonous, highly nonuniform energy exchange along the length of the system. The efficiency of power conversion from the electron beam to electromagnetic radiation is 56%, and the electronic efficiency is 66%. For an accelerating voltage of 340 kV and an electron beam current of 3.3 kA, the simulated generation power is 630 MW at a frequency of 9.7 GHz and a guiding magnetic field of 2.2 T.

Simultaneous operation and control of about 100 telescopes for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Wegner, P.; Colomé, J.; Hoffmann, D.; Houles, J.; Köppel, H.; Lamanna, G.; Le Flour, T.; Lopatin, A.; Lyard, E.; Melkumyan, D.; Oya, I.; Panazol, L.-I.; Punch, M.; Schlenstedt, S.; Schmidt, T.; Stegmann, C.; Schwanke, U.; Walter, R.; Consortium, CTA

2012-12-01

The Cherenkov Telescope Array (CTA) project is an initiative to build the next generation ground-based very high energy (VHE) gamma-ray instrument. Compared to current imaging atmospheric Cherenkov telescope experiments CTA will extend the energy range and improve the angular resolution while increasing the sensitivity up to a factor of 10. With about 100 separate telescopes it will be operated as an observatory open to a wide astrophysics and particle physics community, providing a deep insight into the non-thermal high-energy universe. The CTA Array Control system (ACTL) is responsible for several essential control tasks supporting the evaluation and selection of proposals, as well as the preparation, scheduling, and finally the execution of observations with the array. A possible basic distributed software framework for ACTL being considered is the ALMA Common Software (ACS). The ACS framework follows a container component model and contains a high level abstraction layer to integrate different types of device. To achieve a low-level consolidation of connecting control hardware, OPC UA (OPen Connectivity-Unified Architecture) client functionality is integrated directly into ACS, thus allowing interaction with other OPC UA capable hardware. The CTA Data Acquisition System comprises the data readout of all cameras and the transfer of the data to a camera server farm, thereby using standard hardware and software technologies. CTA array control is also covering conceptions for a possible array trigger system and the corresponding clock distribution. The design of the CTA observations scheduler is introducing new algorithmic technologies to achieve the required flexibility.

Software design and code generation for the engineering graphical user interface of the ASTRI SST-2M prototype for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Tanci, Claudio; Tosti, Gino; Antolini, Elisa; Gambini, Giorgio F.; Bruno, Pietro; Canestrari, Rodolfo; Conforti, Vito; Lombardi, Saverio; Russo, Federico; Sangiorgi, Pierluca; Scuderi, Salvatore

2016-08-01

ASTRI is an on-going project developed in the framework of the Cherenkov Telescope Array (CTA). An end- to-end prototype of a dual-mirror small-size telescope (SST-2M) has been installed at the INAF observing station on Mt. Etna, Italy. The next step is the development of the ASTRI mini-array composed of nine ASTRI SST-2M telescopes proposed to be installed at the CTA southern site. The ASTRI mini-array is a collaborative and international effort carried on by Italy, Brazil and South-Africa and led by the Italian National Institute of Astrophysics, INAF. To control the ASTRI telescopes, a specific ASTRI Mini-Array Software System (MASS) was designed using a scalable and distributed architecture to monitor all the hardware devices for the telescopes. Using code generation we built automatically from the ASTRI Interface Control Documents a set of communication libraries and extensive Graphical User Interfaces that provide full access to the capabilities offered by the telescope hardware subsystems for testing and maintenance. Leveraging these generated libraries and components we then implemented a human designed, integrated, Engineering GUI for MASS to perform the verification of the whole prototype and test shared services such as the alarms, configurations, control systems, and scientific on-line outcomes. In our experience the use of code generation dramatically reduced the amount of effort in development, integration and testing of the more basic software components and resulted in a fast software release life cycle. This approach could be valuable for the whole CTA project, characterized by a large diversity of hardware components.

Model analysis for the MAGIC telescope

NASA Astrophysics Data System (ADS)

Mazin, D.; Bigongiari, C.; Goebel, F.; Moralejo, A.; Wittek, W.

The MAGIC Collaboration operates the 17m imaging Cherenkov telescope on the Canary island La Palma. The main goal of the experiment is an energy threshold below 100 GeV for primary gamma rays. The new analysis technique (model analysis) takes advantage of the high resolution (both in space and time) camera by fitting the averaged expected templates of the shower development to the measured shower images in the camera. This approach allows to recognize and reconstruct images just above the level of the night sky background light fluctuations. Progress and preliminary results of the model analysis technique will be presented.

Underwater acoustic positioning system for the SMO and KM3NeT - Italia projects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viola, S.; Barbagallo, G.; Cacopardo, G.

In the underwater neutrino telescopes, the positions of the Cherenkov light sensors and their movements must be known with an accuracy of few tens of centimetres. In this work, the activities of the SMO and KM3NeT-Italia teams for the development of an acoustic positioning system for KM3NeT-Italia project are presented. The KM3NeT-Italia project foresees the construction, within two years, of 8 towers in the view of the several km{sup 3}-scale neutrino telescope KM3NeT.

Gas Ring-Imagining Cherenkov (GRINCH) Detector for the Super BigBite Spectrometer at Jefferson Lab

NASA Astrophysics Data System (ADS)

Averett, Todd; Wojtsekhowski, Bogdan; Amidouch, Abdellah; Danagoulian, Samuel; Niculescu, Gabriel; Niculescu, Ioana; Jefferson Lab SBS Collaboration Collaboration

2017-01-01

A new gas Cherenkov detector is under construction for the upcoming SuperBigBite spectrometer research program in Hall A at Jefferson Lab. The existing BigBite spectrometer is being upgraded to handle expected increases in event rate and background rate due to the increased luminosity required for the experimental program. The detector will primarily be used to separate good electron events from significant pion and electromagnetic contamination. In contrast to typical gas Cherenkov detectors that use large-diameter photomultiplier tubes and charge integrating ADCs, this detector uses an array of 510 small-diameter tubes that are more than 25x less sensitive to background. Cherenkov radiation clusters will be identified in this array using fast TDCs and a narrow timing window relative to typical ADC gates. In addition, a new FPGA-based DAQ system is being tested to provide a PID trigger using real-time cluster finding. Details of the detector and current status of the project will be presented.

Calibration of the Cherenkov telescope array using cosmic ray electrons

NASA Astrophysics Data System (ADS)

Parsons, R. D.; Hinton, J. A.; Schoorlemmer, H.

2016-11-01

Cosmic ray electrons represent a background for gamma-ray observations with Cherenkov telescopes, initiating air-showers which are difficult to distinguish from photon-initiated showers. This similarity, however, and the presence of cosmic ray electrons in every field observed, makes them potentially very useful for calibration purposes. Here we study the precision with which the relative energy scale and collection area/efficiency for photons can be established using electrons for a major next generation instrument such as CTA. We find that variations in collection efficiency on hour timescales can be corrected to better than 1%. Furthermore, the break in the electron spectrum at ∼ 0.9 TeV can be used to calibrate the energy scale at the 3% level on the same timescale. For observations on the order of hours, statistical errors become negligible below a few TeV and allow for an energy scale cross-check with instruments such as CALET and AMS. Cosmic ray electrons therefore provide a powerful calibration tool, either as an alternative to intensive atmospheric monitoring and modelling efforts, or for independent verification of such procedures.

An image-based array trigger for imaging atmospheric Cherenkov telescope arrays

NASA Astrophysics Data System (ADS)

Dickinson, Hugh; Krennrich, Frank; Weinstein, Amanda; Eisch, Jonathan; Byrum, Karen; Anderson, John; Drake, Gary

2018-05-01

It is anticipated that forthcoming, next generation, atmospheric Cherenkov telescope arrays will include a number of medium-sized telescopes that are constructed using a dual-mirror Schwarzschild-Couder configuration. These telescopes will sample a wide (8 °) field of view using a densely pixelated camera comprising over 104 individual readout channels. A readout frequency congruent with the expected single-telescope trigger rates would result in substantial data rates. To ameliorate these data rates, a novel, hardware-level Distributed Intelligent Array Trigger (DIAT) is envisioned. A copy of the DIAT operates autonomously at each telescope and uses reduced resolution imaging data from a limited subset of nearby telescopes to veto events prior to camera readout and any subsequent network transmission of camera data that is required for centralized storage or aggregation. We present the results of Monte-Carlo simulations that evaluate the efficacy of a "Parallax width" discriminator that can be used by the DIAT to efficiently distinguish between genuine gamma-ray initiated events and unwanted background events that are initiated by hadronic cosmic rays.

Lorentz-invariant formulation of Cherenkov radiation by tachyons

NASA Technical Reports Server (NTRS)

Jones, F. C.

1972-01-01

Previous treatments of Cherenkov radiation, electromagnetic and gravitational, by tachyons were in error because the prescription employed to cut off the divergent integral over frequency is not a Lorentz invariant procedure. The resulting equation of motion for the tachyon is therefore not covariant. The proper procedure requires an extended, deformable distribution of charge or mass and yields a particularly simple form for the tachyon's world line, one that could be deduced from simple invariance considerations. It is shown that Cherenkov radiation by tachyons implys their ultimate annihilation with an antitachyon and demonstrates a disturbing property of tachyons, namely the impossibility of specifying arbitrary Cauchy data even in a purely classical theory.

Cherenkov detectors for spatial imaging applications using discrete-energy photons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, Paul B.; Erickson, Anna S., E-mail: erickson@gatech.edu

Cherenkov detectors can offer a significant advantage in spatial imaging applications when excellent timing response, low noise and cross talk, large area coverage, and the ability to operate in magnetic fields are required. We show that an array of Cherenkov detectors with crude energy resolution coupled with monochromatic photons resulting from a low-energy nuclear reaction can be used to produce a sharp image of material while providing large and inexpensive detector coverage. The analysis of the detector response to relative transmission of photons with various energies allows for reconstruction of material's effective atomic number further aiding in high-Z material identification.

Cherenkov imaging for Total Skin Electron Therapy (TSET)

NASA Astrophysics Data System (ADS)

Xie, Yunhe; Petroccia, Heather; Maity, Amit; Miao, Tianshun; Zhu, Yihua; Bruza, Petr; Pogue, Brian W.; Andreozzi, Jacqueline M.; Plastaras, John P.; Dong, Lei; Zhu, Timothy C.

2018-03-01

Total Skin Electron Therapy (TSET) utilizes high-energy electrons to treat cancers on the entire body surface. The otherwise invisible radiation beam can be observed via the optical Cherenkov photons emitted from interaction between the high-energy electron beam and tissue. Using a specialized camera-system, the Cherenkov emission can thus be used to evaluate the dose uniformity on the surface of the patient in real-time. Each patient was also monitored during TSET via in-vivo detectors (IVD) in nine locations. Patients undergoing TSET in various conditions (whole body and half body) were imaged and analyzed, and the viability of the system to provide clinical feedback was established.

Cherenkov imaging during volumetric modulated arc therapy for real-time radiation beam tracking and treatment response monitoring

NASA Astrophysics Data System (ADS)

Andreozzi, Jacqueline M.; Zhang, Rongxiao; Glaser, Adam K.; Gladstone, David J.; Jarvis, Lesley A.; Pogue, Brian W.

2016-03-01

External beam radiotherapy utilizes high energy radiation to target cancer with dynamic, patient-specific treatment plans. The otherwise invisible radiation beam can be observed via the optical Cherenkov photons emitted from interaction between the high energy beam and tissue. Using a specialized camera-system, the Cherenkov emission can thus be used to track the radiation beam on the surface of the patient in real-time, even for complex cases such as volumetric modulated arc therapy (VMAT). Two patients undergoing VMAT of the head and neck were imaged and analyzed, and the viability of the system to provide clinical feedback was established.

Effect of Vavilov–Cherenkov radiation cone transformation upon entry of a relativistic electron into a substance layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kishchin, I. A.; Kubankin, A. S., E-mail: kubankin@bsu.edu.ru; Nikulicheva, T. B.

Transformation of the Vavilov–Cherenkov radiation cone under grazing interaction of a relativistic electron with a layer of substance is theoretically studied. It is shown that this effect can occur when the electron enters the substance layer.

Light flavour hadron production in pp collisions at \\sqrt{s} = 13 TeV with ALICE

NASA Astrophysics Data System (ADS)

Tonatiuh Jiménez Bustamante, Raúl; ALICE Collaboration

2017-04-01

The ALICE detector has excellent Particle IDentification (PID) capabilities in the central barrel (|η| < 0.9). This allows identified hadron production to be measured over a wide transverse momentum (pT) range, using different sub-detectors and techniques: their specific energy loss (dE/dx), the velocity determination via time-of-flight measurement, the Cherenkov angle or their characteristic weak decay topology. Results on identified light flavour hadron production at mid-rapidity measured by ALICE in proton-proton collisions at \\sqrt{s} = 13 TeV are presented and compared with previous measurements performed at lower energies. The results cover a wide range of particle species including long-lived hadrons, resonances and multi-strange baryons over the pT range from 150 MeV/c up to 20 GeV/c, depending on the particle species.

Research and design progress of the Jinping Neutrino Experiment

NASA Astrophysics Data System (ADS)

Wang, Zhe

2018-01-01

Thanks to the 2400 m overburden and the long distance to commercial reactors, the China Jinping Underground Laboratory (CJPL) is an ideal site for low background neutrino experiments. The Jinping Neutrino Experiment will perform an in-depth research on solar neutrinos, geo-neutrinos and supernova relic neutrinos. Many efforts were devoted to the R&D of the experimental proposal. A new type of liquid scintillator, with high light-yield and Cherenkov and scintillation separation capability, is being developed. The assay and selection of low radioactive stainless-steel (SST) was carried out. A wide field-of-view of 90 degree and high-geometry-efficiency of 98% light concentrator is developed. At the same time, a 1-ton prototype is constructed and placed underground at Jinping laboratory. The simulation and analysis software, electromagnetic calorimeter function, rock damage zone simulation will also be introduced briefly.

Cosmic Ray Observation at Mount Chacaltaya for beyond the Knee Region

NASA Astrophysics Data System (ADS)

Tsunesada, Y.; Kakimoto, F.; Furuhata, F.; Matsumoto, H.; Sugawara, T.; Wakamatsu, H.; Gotoh, E.; Nakatani, H.; Nishi, K.; Tajima, N.; Yamada, Y.; Shimoda, S.; Yoshii, H.; Kaneko, T.; Ogio, S.; Matsubara, Y.; Kadota, K.; Tokuno, H.; Mizumoto, Y.; Shirasaki, Y.; Toyoda, Y.; Burgoa, O.; Flores, V.; Miranda, P.; Salinas, J.; Velarde, A.

We have installed a new air shower array at Mount Chacaltaya (5,200m above sea level) to observe primary cosmic rays with energies greater than 1015 eV. In our previous experiments, we measured energy spectrum and nuclear composition of primary cosmic rays around the knee region. Above all, we obtained the cosmic ray composition with three independent techniques, namely from the equi-intensity cuts, the arrival time distributions of Cherenkov lights associated with air showers, and the lateral distributions of Cherenkov photons around the shower axis. All the results from these experiments are in agreement and show that the average mass of cosmic ray nuclei increases with energies below and above the knee, and dominated by heavier nuclei as iron at 1016 eV. This result is consistent with the confinement and rigidity dependent acceleration models, and suggests that the cosmic ray origins are supernova remnants of massive population as Wolf-Rayet stars. It is of quite interest whether the mass of cosmic ray nuclei continues to increase with energies, or decreases by contributions of lighter components expected from the extra-galactic cosmic ray models. In this paper, we describe the characteristics of the new array and preliminary results from the first observation.

Readout and Data Acquisition for a Liquid Radiator Radiation Exposure Test

NASA Astrophysics Data System (ADS)

Lantz, Chad

2017-09-01

The ATLAS Zero Degree Calorimeter (ZDC) prototype is a tungsten-sampling, oil/quartz radiating calorimeter placed on each side of the interaction point. The ZDC is used in heavy ion runs for centrality measurements. The UIUC group develops a ZDC that is significantly more radiation hard than the currently employed detector. The current ZDC uses scintillating quartz rods placed directly in the beamline whose optical transmission is known to degrade as a function of radiation dosage. Our prototype uses organic wavelength shifters (WLS) dissolved in oil in two stages to take Cherenkov light produced in the oil by the particle shower and guide it to a photodetector. This design allows the quartz rods be located away from the beam center to experience a lower radiation dose, and the oil containing WLS can be replaced periodically to negate radiation damage. Quantum dots are studied as a more radiation hard alternative to WLS. This increase in radiation hardness will allow ATLAS to operate the ZDC after the luminosity upgrades planned for the LHC. A test setup has been developed for the study of radiation hardness of liquid Cherenkov radiators and wavelength shifters. The setup will be described in this presentation with a focus on the readout electronics and data acquisition.

Data acquisition architecture and online processing system for the HAWC gamma-ray observatory

NASA Astrophysics Data System (ADS)

Abeysekara, A. U.; Alfaro, R.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Ayala Solares, H. A.; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Becerra Gonzalez, J.; Belmont-Moreno, E.; BenZvi, S. Y.; Berley, D.; Bonilla Rosales, M.; Braun, J.; Caballero-Lopez, R. A.; Caballero-Mora, K. S.; Carramiñana, A.; Castillo, M.; Cotti, U.; Cotzomi, J.; de la Fuente, E.; De León, C.; DeYoung, T.; Diaz-Cruz, J.; Diaz Hernandez, R.; Díaz-Vélez, J. C.; Dingus, B. L.; DuVernois, M. A.; Ellsworth, R. W.; Fiorino, D. W.; Fraija, N.; Galindo, A.; Garfias, F.; González, M. M.; Goodman, J. A.; Grabski, V.; Gussert, M.; Hampel-Arias, Z.; Harding, J. P.; Hui, C. M.; Hüntemeyer, P.; Imran, A.; Iriarte, A.; Karn, P.; Kieda, D.; Kunde, G. J.; Lara, A.; Lauer, R. J.; Lee, W. H.; Lennarz, D.; León Vargas, H.; Linares, E. C.; Linnemann, J. T.; Longo Proper, M.; Luna-García, R.; Malone, K.; Marinelli, A.; Marinelli, S. S.; Martinez, O.; Martínez-Castro, J.; Martínez-Huerta, H.; Matthews, J. A. J.; McEnery, J.; Mendoza Torres, E.; Miranda-Romagnoli, P.; Moreno, E.; Mostafá, M.; Nellen, L.; Newbold, M.; Noriega-Papaqui, R.; Oceguera-Becerra, T.; Patricelli, B.; Pelayo, R.; Pérez-Pérez, E. G.; Pretz, J.; Rivière, C.; Rosa-González, D.; Ruiz-Velasco, E.; Ryan, J.; Salazar, H.; Salesa Greus, F.; Sanchez, F. E.; Sandoval, A.; Schneider, M.; Silich, S.; Sinnis, G.; Smith, A. J.; Sparks Woodle, K.; Springer, R. W.; Taboada, I.; Toale, P. A.; Tollefson, K.; Torres, I.; Ukwatta, T. N.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Wisher, I. G.; Wood, J.; Yapici, T.; Yodh, G. B.; Younk, P. W.; Zaborov, D.; Zepeda, A.; Zhou, H.

2018-04-01

The High Altitude Water Cherenkov observatory (HAWC) is an air shower array devised for TeV gamma-ray astronomy. HAWC is located at an altitude of 4100 m a.s.l. in Sierra Negra, Mexico. HAWC consists of 300 Water Cherenkov Detectors, each instrumented with 4 photomultiplier tubes (PMTs). HAWC re-uses the Front-End Boards from the Milagro experiment to receive the PMT signals. These boards are used in combination with Time to Digital Converters (TDCs) to record the time and the amount of light in each PMT hit (light flash). A set of VME TDC modules (128 channels each) is operated in a continuous (dead time free) mode. The TDCs are read out via the VME bus by Single-Board Computers (SBCs), which in turn are connected to a gigabit Ethernet network. The complete system produces ≈500 MB/s of raw data. A high-throughput data processing system has been designed and built to enable real-time data analysis. The system relies on off-the-shelf hardware components, an open-source software technology for data transfers (ZeroMQ) and a custom software framework for data analysis (AERIE). Multiple trigger and reconstruction algorithms can be combined and run on blocks of data in a parallel fashion, producing a set of output data streams which can be analyzed in real time with minimal latency (<5 s). This paper provides an overview of the hardware set-up and an in-depth description of the software design, covering both the TDC data acquisition system and the real-time data processing system. The performance of these systems is also discussed.

The central pixel of the MAGIC telescope for optical observations

NASA Astrophysics Data System (ADS)

Lucarelli, F.; Barrio, J. A.; Antoranz, P.; Asensio, M.; Camara, M.; Contreras, J. L.; Fonseca, M. V.; Lopez, M.; Miranda, J. M.; Oya, I.; Reyes, R. De Los; Firpo, R.; Sidro, N.; Goebel, F.; Lorenz, E.; Otte, N.

2008-05-01

The MAGIC telescope has been designed for the observation of Cherenkov light generated in Extensive Air Showers initiated by cosmic particles. However, its 17 m diameter mirror and optical design makes the telescope suitable for direct optical observations as well. In this paper, we report about the development of a system based on the use of a dedicated photo-multiplier (PMT) for optical observations. This PMT is installed in the centre of the MAGIC camera (the so-called central pixel). An electro-to-optical system has been developed in order to transmit the PMT output signal by an optical fibre to the counting room, where it is digitized and stored for off-line analysis. The performance of the system using the optical pulsation of the Crab nebula as calibration source is presented. The time required for a 5σ detection of the Crab pulsar in the optical band is less than 20 s. The central pixel will be mainly used to perform simultaneous observations of the Crab pulsar both in the optical and γ-ray regimes. It will also allow for periodic testing of the precision of the MAGIC timing system using the Crab rotational optical pulses as a very precise timing reference.

Characterization benches for neutrino telescope Optical Modules at the APC laboratory

NASA Astrophysics Data System (ADS)

Avgitas, Theodore; Creusot, Alexandre; Kouchner, Antoine

2016-04-01

As has been demonstrated by the first generation of neutrino telescopes Antares and IceCube, precise knowledge of the photon detection efficiency of optical modules is of fundamental importance for the understanding of the instrument and accurate event reconstruction. Dedicated test benches have been developed to measure all related quantities for the Digital Optical Modules of the KM3NeT neutrino telescope being currently deployed in the Mediterranean sea. The first bench is a black box with robotic arms equipped with a calibrated single photon source or laser which enable a precise mapping of the detection efficiency at arbitrary incident angles as well as precise measurements of the time delays induced by the photodetection chain. These measurement can be incorporated and compared to full GEANT MonteCarlo simulations of the optical modules. The second bench is a 2 m×2 m ×2 m water tank equipped with muon hodoscopes on top and bottom. It enables to study and measure the angular dependence of the DOM's detection efficiency of the Cherenkov light produced in water by relativistic muons, thus reproducing in situ detection conditions. We describe these two benches and present their first results and status.

A program to study antiprotons in the cosmic rays: Arizona collaboration

NASA Technical Reports Server (NTRS)

Bowen, Theodore

1987-01-01

The Low Energy AntiProton (LEAP) experiment was designed to measure the primary antiproton flux in the 200 MeV to 1 GeV kinetic energy range. A superconducting magnetic spectrometer, a time-of-flight (TOF) detector, and a Cherenkov counter are the main components of LEAP. An additional scintillation detector was designed and constructed to detect the passage of particles through the bottom of the Cherenkov counter. The LEAP package was launched on August 22, 1987, and enjoyed a 27 hour flight, with 23 hours of data at high altitude. Preliminary plans for data analysis include using the Micro-Vax at the University of Arizona for data reduction of the Cherenkov and S2 signals.

Updates on Software development for a RICH detector

NASA Astrophysics Data System (ADS)

Voloshin, Andrew; Benmokhtar, Fatiha; Lendacky, Andrew; Goodwill, Justin

2017-01-01

The CLAS12 detector at Thomas Jefferson National Accelerator Facility (TJNAF) is undergoing an upgrade. One of the improvements is the addition of a Ring Imaging Cherenkov (RICH) detector to improve particle identification in the 3-8 GeV/c momentum range. Approximately 400 multi anode photomultiplier tubes (MAPMTs) are going to be used to detect Cherenkov Radiation in the single photoelectron spectra (SPS). Software development for slow control as well as online monitoring is under development. I will be presenting my work on the development of a java based programs for a monitor and explain its interaction with a Mysql database where the MAPMTs information is stored as well as the techniques used to visualize Cherenkov rings.

Cherenkov radiation conversion and collection considerations for a gamma bang time/reaction history diagnostic for the NIF.

PubMed

Herrmann, Hans W; Mack, Joseph M; Young, Carlton S; Malone, Robert M; Stoeffl, Wolfgang; Horsfield, Colin J

2008-10-01

Bang time and reaction history measurements are fundamental components of diagnosing inertial confinement fusion (ICF) implosions and will be essential contributors to diagnosing attempts at ignition on the National Ignition Facility (NIF). Fusion gammas provide a direct measure of fusion interaction rate without being compromised by Doppler spreading. Gamma-based gas Cherenkov detectors that convert fusion gamma rays to optical Cherenkov photons for collection by fast recording systems have been developed and fielded at Omega. These systems have established their usefulness in illuminating ICF physics in several experimental campaigns. Bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF system design requirements. A comprehensive, validated numerical study of candidate systems is providing essential information needed to make a down selection based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF logistics. This paper presents basic design considerations arising from the two-step conversion process from gamma rays to relativistic electrons to UV/visible Cherenkov radiation.

Calibration of Cherenkov detectors for monoenergetic photon imaging in active interrogation applications

NASA Astrophysics Data System (ADS)

Rose, P. B.; Erickson, A. S.

2015-11-01

Active interrogation of cargo containers using monoenergetic photons offers a rapid and low-dose approach to search for shielded special nuclear materials. Cherenkov detectors can be used for imaging of the cargo provided that gamma ray energies used in interrogation are well resolved, as the case in 11B(d,n-γ)12C reaction resulting in 4.4 MeV and 15.1 MeV photons. While an array of Cherenkov threshold detectors reduces low energy background from scatter while providing the ability of high contrast transmission imaging, thus confirming the presence of high-Z materials, these detectors require a special approach to energy calibration due to the lack of resolution. In this paper, we discuss the utility of Cherenkov detectors for active interrogation with monoenergetic photons as well as the results of computational and experimental studies of their energy calibration. The results of the studies with sources emitting monoenergetic photons as well as complex gamma ray spectrum sources, for example 232Th, show that calibration is possible as long as the energies of photons of interest are distinct.

Modeling the Effects of Mirror Misalignment in a Ring Imaging Cherenkov Detector

NASA Astrophysics Data System (ADS)

Hitchcock, Tawanda; Harton, Austin; Garcia, Edmundo

2012-03-01

The Very High Momentum Particle Identification Detector (VHMPID) has been proposed for the ALICE experiment at the Large Hadron Collider (LHC). This detector upgrade is considered necessary to study jet-matter interaction at high energies. The VHMPID identifies charged hadrons in the 5 GeV/c to 25 GeV/c momentum range. The Cherenkov photons emitted in the VHMPID radiator are collected by spherical mirrors and focused onto a photo-detector plane forming a ring image. The radius of this ring is related to the Cherenkov angle, this information coupled with the particle momentum allows the particle identification. A major issue in the RICH detector is that environmental conditions can cause movements in mirror position. In addition, chromatic dispersion causes the refractive index to shift, altering the Cherenkov angle. We are modeling a twelve mirror RICH detector taking into account the effects of mirror misalignment and chromatic dispersion using a commercial optical software package. This will include quantifying the effects of both rotational and translational mirror misalignment for the initial assembly of the module and later on particle identification.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baird, K.; SLD Collaboration

The authors have measured production fractions and spectra for {pi}{sup {+-}}, K{sup {+-}} and p, and production spectra for K{sup 0} and {Lambda}{sup 0} in both hadronic Z{sup 0} decays and a Z{sup 0} {yields} light quark (uds) subset at SLD. The SLD Cherenkov Ring Imaging Detector was used to identify charged hadrons. The CCD vertex detector was used to select the enriched uds sample. For the global sample, the results are consistent with previous experiments. The authors observe a clear flavor dependence in production spectra, but only a small effect in hadron fractions and {xi} = ln(1/x{sub p}) peakmore » positions.« less

On constraining the speed of gravitational waves following GW150914

NASA Astrophysics Data System (ADS)

Blas, D.; Ivanov, M. M.; Sawicki, I.; Sibiryakov, S.

2016-05-01

We point out that the observed time delay between the detection of the signal at the Hanford and Livingston LIGO sites from the gravitational wave event GW150914 places an upper bound on the speed of propagation of gravitational waves, c gw ≲ 1.7 in the units of speed of light. Combined with the lower bound from the absence of gravitational Cherenkov losses by cosmic rays that rules out most of subluminal velocities, this gives a model-independent double-sided constraint 1 ≲ c gw ≲ 1.7. We compare this result to model-specific constraints from pulsar timing and cosmology.

The Cosmic Ray Energy Spectrum and Related Measurements with the Pierre Auger Observatory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abraham, : J.; Abreu, P.; Aglietta, M.

2009-06-01

These are presentations to be presented at the 31st International Cosmic Ray Conference, in Lodz, Poland during July 2009. It consists of the following presentations: (1) Measurement of the cosmic ray energy spectrum above 10{sup 18} eV with the Pierre Auger Observatory; (2) The cosmic ray flux observed at zenith angles larger than 60 degrees with the Pierre Auger Observatory; (3) Energy calibration of data recorded with the surface detectors of the Pierre Auger Observatory; (4) Exposure of the Hybrid Detector of The Pierre Auger Observatory; and (5) Energy scale derived from Fluorescence Telescopes using Cherenkov Light and Shower Universality.

MO-A-BRD-06: In Vivo Cherenkov Video Imaging to Verify Whole Breast Irradiation Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, R; Glaser, A; Jarvis, L

Purpose: To show in vivo video imaging of Cherenkov emission (Cherenkoscopy) can be acquired in the clinical treatment room without affecting the normal process of external beam radiation therapy (EBRT). Applications of Cherenkoscopy, such as patient positioning, movement tracking, treatment monitoring and superficial dose estimation, were examined. Methods: In a phase 1 clinical trial, including 12 patients undergoing post-lumpectomy whole breast irradiation, Cherenkov emission was imaged with a time-gated ICCD camera synchronized to the radiation pulses, during 10 fractions of the treatment. Images from different treatment days were compared by calculating the 2-D correlations corresponding to the averaged image. Anmore » edge detection algorithm was utilized to highlight biological features, such as the blood vessels. Superficial dose deposited at the sampling depth were derived from the Eclipse treatment planning system (TPS) and compared with the Cherenkov images. Skin reactions were graded weekly according to the Common Toxicity Criteria and digital photographs were obtained for comparison. Results: Real time (fps = 4.8) imaging of Cherenkov emission was feasible and feasibility tests indicated that it could be improved to video rate (fps = 30) with system improvements. Dynamic field changes due to fast MLC motion were imaged in real time. The average 2-D correlation was about 0.99, suggesting the stability of this imaging technique and repeatability of patient positioning was outstanding. Edge enhanced images of blood vessels were observed, and could serve as unique biological markers for patient positioning and movement tracking (breathing). Small discrepancies exists between the Cherenkov images and the superficial dose predicted from the TPS but the former agreed better with actual skin reactions than did the latter. Conclusion: Real time Cherenkoscopy imaging during EBRT is a novel imaging tool that could be utilized for patient positioning, movement tracking, treatment monitoring, superficial dose and skin reaction estimation and prediction.« less

MO-AB-BRA-08: Rapid Treatment Field Uniformity Optimization for Total Skin Electron Beam Therapy Using Cherenkov Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreozzi, J; Zhang, R; Glaser, A

Purpose: To evaluate treatment field heterogeneity resulting from gantry angle choice in total skin electron beam therapy (TSEBT) following a modified Stanford dual-field technique, and determine a relationship between source to surface distance (SSD) and optimized gantry angle spread. Methods: Cherenkov imaging was used to image 62 treatment fields on a sheet of 1.2m x 2.2m x 1.2cm polyethylene following standard TSEBT setup at our institution (6 MeV, 888 MU/min, no spoiler, SSD=441cm), where gantry angles spanned from 239.5° to 300.5° at 1° increments. Average Cherenkov intensity and coefficient of variation in the region of interest were compared for themore » set of composite Cherenkov images created by summing all unique combinations of angle pairs to simulate dual-field treatment. The angle pair which produced the lowest coefficient of variation was further studied using an ionization chamber. The experiment was repeated at SSD=300cm, and SSD=370.5cm. Cherenkov imaging was also implemented during TSEBT of three patients. Results: The most uniform treatment region from a symmetric angle spread was achieved using gantry angles +/−17.5° about the horizontal axis at SSD=441cm, +/−18.5° at SSD=370.5cm, and +/−19.5° at SSD=300cm. Ionization chamber measurements comparing the original treatment spread (+/−14.5°) and the optimized angle pair (+/−17.5°) at SSD=441cm showed no significant deviation (r=0.999) in percent depth dose curves, and chamber measurements from nine locations within the field showed an improvement in dose uniformity from 24.41% to 9.75%. Ionization chamber measurements correlated strongly (r=0.981) with Cherenkov intensity measured concurrently on the flat Plastic Water phantom. Patient images and TLD results also showed modest uniformity improvements. Conclusion: A decreasing linear relationship between optimal angle spread and SSD was observed. Cherenkov imaging offers a new method of rapidly analyzing and optimizing TSEBT setup geometry by providing a 2D image of the treatment plane as a sum of the two fields. This study has been funded by NIH grants R21EB17559 and R01CA109558 as well as Norris Cotton Cancer Center Pilot funding.« less

Extragalactic photon-ALP conversion at CTA energies

DOE PAGES

Kartavtsev, A.; Raffelt, G.; Vogel, H.

2017-01-12

Magnetic fields in extragalactic space between galaxy clusters may induce conversions between photons and axion-like particles (ALPs), thereby shielding the photons from absorption on the extragalactic background light. For TeV gamma rays, the oscillation length (l osc) of the photon-ALP system becomes inevitably of the same order as the coherence length of the magnetic field l and the length over which the field changes significantly (transition length l t) due to refraction on background photons. We derive exact statistical evolution equations for the mean and variance of the photon and ALP transfer functions in the non-adiabatic regime (l osc ~more » l >> l t). We also make analytical predictions for the transfer functions in the quasi-adiabatic regime (l osc

Study on 3-inch Hamamatsu photomultipliers

NASA Astrophysics Data System (ADS)

Giordano, Valentina; Aiello, Sebastiano; Leonora, Emanuele

2016-07-01

Several kinds of photomultipliers are widely used in astroparticle physics detectors to measure Cherenkov light in media like water or ice. In neutrino telescopes the key element of the detector is the optical module, which consists of one or more photodetectors inside a transparent pressure-resistant glass sphere. It serves as mechanical protection while ensuring good light transmission. The KM3NeT collaboration has developed an innovative design of an optical module composed by 31 photomultipliers (PMTs) of 3-inch diameter housed in a 17-inch glass shpere. The performance of the telescope is largely dependent on the presence on noise pulses present on the anode of the photomultipliers. A study was conducted of noise pulses of Hamamatsu 3-inch diameter photomultipliers measuring time and charge distributions of dark pulses, pre-pulses, delayed pulses and after-pulses, focusing in particular on analysis on multiple afterpulses. Effects of the Earth's magnetic field on 3-inch PMTs were also studied.

The laser calibration system of the TOP detector

NASA Astrophysics Data System (ADS)

Tamponi, Umberto

2017-12-01

The TOP detector of the Belle II Experiment at KEK is a particle identification detector, devoted mainly to the separation of charged pions and kaons. The Cherenkov photons produced in fused silica bars are detected by an array of micro-cannel plate photomultipliers, and the position and time of arrival of the photoelectrons are used to identify the particle. In order to achieve a time resolution of less than 100 ps, the performance of electronics and PMTs must be continuously monitored by a high resolution laser calibration system. Here we report about the design, characterization, construction and installation of this light distribution system consisting of a picosecond laser source, a printed light circuit (PLC), long single mode fibers coupled to bundles of multimode fibers terminated with graded index microlenses, to provide illumination of all the PMT pixels with time jitter less than 50 ps.

Measurement of light yield dependence on electron energy for SNO+ scintillator

NASA Astrophysics Data System (ADS)

Wan Chan Tseung, Hok

2011-10-01

SNO+ is a multi-purpose neutrino experiment whose reach extends to the following areas of neutrino physics: neutrinoless double beta decay (with Nd-loaded scintillator), geo-neutrinos, reactor and low-energy solar neutrinos, as well as supernova neutrinos. It is a ~780-tonne liquid scintillator detector currently under construction at the SNOLAB facility in Sudbury, Ontario,Canada. The scintillator to be used in SNO+ is linear alkylbenzene (LAB) with ~2 g/L of PPO (2,5-diphenyloxazole). In this talk, we describe an experiment to test the linearity of the response of LAB-PPO with respect to electrons. We find that below ~0.4 MeV, the energy scale of LAB-PPO becomes non-linear. An explanation is given in terms of Cherenkov light absorption and re-emission by the scintillator. This research has been supported under DOE Grant No. DE-FG02-97ER41020.

Scintillation Detector for the Measurement of Ultra-Heavy Cosmic Rays on the Super-TIGER Experiment

NASA Technical Reports Server (NTRS)

Link, Jason

2011-01-01

We discuss the design and construction of the scintillation detectors for the Super-TIGER experiment. Super-TIGER is a large-area (5.4sq m) balloon-borne experiment designed to measure the abundances of cosmic-ray nuclei between Z= 10 and Z=56. It is based on the successful TIGER experiment that flew in Antarctica in 2001 and 2003. Super-TIGER has three layers of scintillation detectors, two Cherenkov detectors and a scintillating fiber hodoscope. The scintillation detector employs four wavelength shifter bars surrounding the edges of the scintillator to collect the light from particles traversing the detector. PMTs are optically coupled at both ends of the bars for light collection. We report on laboratory performance of the scintillation counters using muons. In addition we discuss the design challenges and detector response over this broad charge range including the effect of scintilator saturation.

Underground neutrino detectors for particle and astroparticle Science: The Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER)

NASA Astrophysics Data System (ADS)

Rubbia, André

2009-06-01

The current focus of the CERN program is the Large Hadron Collider (LHC), however, CERN is engaged in long baseline neutrino physics with the CNGS project and supports T2K as recognized CERN RE13, and for good reasons: a number of observed phenomena in high-energy physics and cosmology lack their resolution within the Standard Model of particle physics; these puzzles include the origin of neutrino masses, CP-violation in the leptonic sector, and baryon asymmetry of the Universe. They will only partially be addressed at LHC. A positive measurement of sin2 2θ13 > 0.01 would certainly give a tremendous boost to neutrino physics by opening the possibility to study CP violation in the lepton sector and the determination of the neutrino mass hierarchy with upgraded conventional super-beams. These experiments (so called 'Phase II') require, in addition to an upgraded beam power, next generation very massive neutrino detectors with excellent energy resolution and high detection efficiency in a wide neutrino energy range, to cover 1st and 2nd oscillation maxima, and excellent particle identification and p0 background suppression. Two generations of large water Cherenkov detectors at Kamioka (Kamiokande and Super-Kamiokande) have been extremely successful. And there are good reasons to consider a third generation water Cherenkov detector with an order of magnitude larger mass than Super-Kamiokande for both non-accelerator (proton decay, supernovae,...) and accelerator-based physics. On the other hand, a very massive underground liquid Argon detector of about 100 kton could represent a credible alternative for the precision measurements of 'Phase II' and aim at significantly new results in neutrino astroparticle and non-accelerator-based particle physics (e.g. proton decay).

Optimization of the design of Gas Cherenkov Detectors for ICF diagnosis

NASA Astrophysics Data System (ADS)

Liu, Bin; Hu, Huasi; Han, Hetong; Lv, Huanwen; Li, Lan

2018-07-01

A design method, which combines a genetic algorithm (GA) with Monte-Carlo simulation, is established and applied to two different types of Cherenkov detectors, namely, Gas Cherenkov Detector (GCD) and Gamma Reaction History (GRH). For accelerating the optimization program, open Message Passing Interface (MPI) is used in the Geant4 simulation. Compared with the traditional optical ray-tracing method, the performances of these detectors have been improved with the optimization method. The efficiency for GCD system, with a threshold of 6.3 MeV, is enhanced by ∼20% and time response improved by ∼7.2%. For the GRH system, with threshold of 10 MeV, the efficiency is enhanced by ∼76% in comparison with previously published results.

Cut-off characterisation of energy spectra of bright fermi sources: Current instrument limits and future possibilities

NASA Astrophysics Data System (ADS)

Romoli, C.; Taylor, A. M.; Aharonian, F.

2017-02-01

In this paper some of the brightest GeV sources observed by the Fermi-LAT were analysed, focusing on their spectral cut-off region. The sources chosen for this investigation were the brightest blazar flares of 3C 454.3 and 3C 279 and the Vela pulsar with a reanalysis with the latest Fermi-LAT software. For the study of the spectral cut-off we first explored the Vela pulsar spectrum, whose statistics in the time interval of the 3FGL catalog allowed strong constraints to be obtained on the parameters. We subsequently performed a new analysis of the flaring blazar SEDs. For these sources we obtained constraints on the cut-off parameters under the assumption that their underlying spectral distribution is described by a power-law with a stretched exponential cut-off. We then highlighted the significant potential improvements on such constraints by observations with next generation ground based Cherenkov telescopes, represented in our study by the Cherenkov Telescope Array (CTA). Adopting currently available simulations for this future observatory, we demonstrate the considerable improvement in cut-off constraints achievable by observations with this new instrument when compared with that achievable by satellite observations.

The presence of two electron beams in a Cherenkov maser and their different behavior for generation and amplification of THz electromagnetic waves

NASA Astrophysics Data System (ADS)

Hajijamali-Arani, Zeinab; Jazi, Bahram

2017-04-01

The wave propagation in a cylindrical metallic waveguide including a dielectric tube is investigated. Two electron beams with opposite velocities are injected in the system as energy sources. It is shown that one of the electron beams is responsible for Cherenkov radiation, the other one is as the stabilizer. The dispersion relation of the waves, impedance of the waves, operating frequency of the system and time growth rate of THz waves are investigated. The effects of relative permittivity constant of dielectric tube, the geometrical dimensions, and the accelerating voltage on time growth rate are investigated. The effective factors on the frequency spectra of the waveguide will be presented too. It is obtained that the time growth rate of the waves increases with increasing the dielectric permittivity and thickness of the dielectric tube. In addition, with increasing the accelerating voltage the time growth rate has opposite behavior in some of the branches of the dispersion graphs. The power obtained in the excitation process for one branch of the dispersion graphs is presented. The graph of variations of transported power with respect to the wave frequency is plotted.

Dark matter signals from Draco and Willman 1: prospects for MAGIC II and CTA

NASA Astrophysics Data System (ADS)

Bringmann, Torsten; Doro, Michele; Fornasa, Mattia

2009-01-01

The next generation of ground-based Imaging Air Cherenkov Telescopes will play an important role in indirect dark matter searches. In this article, we consider two particularly promising candidate sources for dark matter annihilation signals, the nearby dwarf galaxies Draco and Willman 1, and study the prospects of detecting such a signal for the soon-operating MAGIC II telescope system as well as for the planned installation of CTA, taking special care of describing the experimental features that affect the detectional prospects. For the first time in such studies, we fully take into account the effect of internal bremsstrahlung, which has recently been shown to considerably enhance, in some cases, the gamma-ray flux in the high energies domain where Atmospheric Cherenkov Telescopes operate, thus leading to significantly harder annihilation spectra than traditionally considered. While the detection of the spectral features introduced by internal bremsstrahlung would constitute a smoking gun signature for dark matter annihilation, we find that for most models the overall flux still remains at a level that will be challenging to detect, unless one adopts somewhat favorable descriptions of the smooth dark matter distribution in the dwarfs.

The software system for the Control and Data Acquisition for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Wegner, P.; FüBling, M.; Oya, I.; Hagge, L.; Schwanke, U.; Schwarz, J.; Tosti, G.; Conforti, V.; Lyard, E.; Walter, R.; Oliveira Antonino, P.; Morgenstern, A.

2016-10-01

The Cherenkov Telescope Array (CTA), as the next generation ground-based very high-energy gamma-ray observatory, is defining new areas beyond those related to physics. It is also creating new demands on the control and data acquisition system. CTA will consist of two installations, one in each hemisphere, containing tens of telescopes of different sizes. The ACTL (array control and data acquisition) system will consist of the hardware and software that is necessary to control and monitor the CTA array, as well as to time-stamp, read-out, filter and store the scientific data at aggregated rates of a few GB/s. The ACTL system must implement a flexible software architecture to permit the simultaneous automatic operation of multiple sub-arrays of telescopes with a minimum personnel effort on site. In addition ACTL must be able to modify the observation schedule on timescales of a few tens of seconds, to account for changing environmental conditions or to prioritize incoming scientific alerts from time-critical transient phenomena such as gamma-ray bursts. This contribution summarizes the status of the development of the software architecture and the main design choices and plans.

H.E.S.S. and CTA, present and perspectives in ground-based gamma-ray astronomy

NASA Astrophysics Data System (ADS)

Sol, H.

2016-12-01

Very high energy (VHE) gamma-ray astronomy emerged as a new branch of astronomy about ten years ago with the major discoveries achieved by the High Energy Stereocopic System (H.E.S.S.) operating in Namibia, quickly followed by the Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC) in the Canary Islands and the Very Energetic Radiation Imaging Telescope Array System (VERITAS) in the USA. These experiments succeeded to start exploring the cosmos at TeV energies, with the present detection of 178 sources in this range, mostly pulsar wind nebulae, supernova remnants, binary systems, blazars, and a variety of other types of sources. Based on these promizing results, the scientific community soon defined a next generation global project with significantly improved performance, the Cherenkov Telescope Array (CTA), in order to implement an open observatory at extreme energies, allowing a deep analysis of the sky in the highest part of the electromagnetic spectrum, from 20 GeV to 300 TeV. The CTA preparation phase is now completed. Production of the first telescopes should start in 2017 for deployment in 2018, in the perspective of an array fully operational at the horizon 2022.

Focal Plane Detectors for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Wagner, Robert G.; AGIS Photodetector Group; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Horan, D.; Mukherjee, R.; Tajima, H.; Williams, D.

2008-03-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. It is being designed to achieve a significant improvement in sensitivity compared to current Imaging Air Cherenkov Telescope (IACT) Arrays. One of the main requirements in order that AGIS fulfill this goal will be to achieve higher angular resolution than current IACTs. Simulations show that a substantial improvement in angular resolution may be achieved if the pixel size is reduced to less than 0.05 deg, i.e. two to three times smaller than the pixel size of current IACT cameras. With finer pixelation and the plan to deploy on the order of 100 telescopes in the AGIS array, the channel count will exceed 1,000,000 imaging pixels. High uniformity and long mean time-to-failure will be important aspects of a successful photodetector technology choice. Here we present alternatives being considered for AGIS, including both silicon photomultipliers (SiPMs) and multi-anode photomultipliers (MAPMTs). Results from laboratory testing of MAPMTs and SiPMs are presented along with results from the first incorporation of these devices in cameras on test bed Cherenkov telescopes.

LUNASKA experiments using the Australia Telescope Compact Array to search for ultrahigh energy neutrinos and develop technology for the lunar Cherenkov technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

James, C. W.; Protheroe, R. J.; Ekers, R. D.

2010-02-15

We describe the design, performance, sensitivity and results of our recent experiments using the Australia Telescope Compact Array (ATCA) for lunar Cherenkov observations with a very wide (600 MHz) bandwidth and nanosecond timing, including a limit on an isotropic neutrino flux. We also make a first estimate of the effects of small-scale surface roughness on the effective experimental aperture, finding that contrary to expectations, such roughness will act to increase the detectability of near-surface events over the neutrino energy-range at which our experiment is most sensitive (though distortions to the time-domain pulse profile may make identification more difficult). The aimmore » of our 'Lunar UHE Neutrino Astrophysics using the Square Kilometre Array' (LUNASKA) project is to develop the lunar Cherenkov technique of using terrestrial radio telescope arrays for ultrahigh energy (UHE) cosmic ray (CR) and neutrino detection, and, in particular, to prepare for using the Square Kilometre Array (SKA) and its path-finders such as the Australian SKA Pathfinder (ASKAP) and the Low Frequency Array (LOFAR) for lunar Cherenkov experiments.« less

Enhanced UV light detection using a p-terphenyl wavelength shifter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joosten, Sylvester J.; Kaczanowicz, Ed; Ungaro, Maurizio

Here, UV-glass photomultiplier tubes (PMTs) have poor photon detection efficiency for wavelengths belowmore » $$300\\,\\text{nm}$$ due to the opaqueness of the window material. Costly quartz PMTs could be used to enhance the efficiency below $$300\\,\\text{nm}$$. A less expensive solution that dramatically improves this efficiency is the application of a thin film of a p-terphenyl (PT) wavelength shifter on UV-glass PMTs. This improvement was quantified for Photonis XP4500B PMTs for wavelengths between $$200\\,\\text{nm}$$ and $$400\\,\\text{nm}$$. The gain factor ranges up to 5.4 $$\\pm$$ 0.5 at a wavelength of $$215\\,\\text{nm}$$, with a material load of $$110\\pm10\\,\\mu\\text{g}/\\text{cm}^2$$ ($$894\\,\\text{nm}$$). The wavelength shifter was found to be fully transparent for wavelengths greater than $$300\\,\\text{nm}$$. The resulting gain in detection efficiency, when used in a typical Cherenkov counter, was estimated to be of the order of 40%. Consistent coating quality was assured by a rapid gain testing procedure using narrow-band UV LEDs. Based on these results, 200 Photonis XP4500B PMTs were treated with PT for the upgraded low-threshold Cherenkov counter (LTCC) to be used in the CEBAF Large Acceptance Spectrometer upgraded detector (CLAS12) at the Thomas Jefferson National Accelerator Facility.« less

Vavilov–Cherenkov radiation when cosmic rays pass through the relic photon gas and when fast charged particles traverse an optical laser beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chefranov, S. G., E-mail: schefranov@mail.ru

2016-07-15

Using a new [9, 10] quantum theory of Vavilov–Cherenkov radiation (VCR) based on Abraham’s theory, we show that a threshold VCR effect can be excited by the relic photon gas when relativistic charged cosmic-ray particles with γ ≥ γ{sub th} ≈ 1.9 × 10{sup 10} (where γ{sup –2} = 1–v{sup 2}/c{sup 2}, v is the particle speed, and c is the speed of light in a vacuum) pass through it. This is compatible with the well-known GZK cutoff [7, 8] at γ ≈ 10{sup 11}. We have obtained the condition γ > γ{sub th} ≈ 2.1 × 10{sup 2} formore » the appearance of VCR when a sufficiently fast charged particle (an electron, a proton, or a nucleus) passes through intense laser radiation. This condition ensures that VCR can be observed experimentally (e.g., on the Large Hadron Collider) without invoking any additional conditions required from the currently existing estimate of γth > 8.8 × 10{sup 4} [13] based on the now universally accepted quantum theory of VCR, which follows from Minkowski’s theory (and which gives an estimate of γ > 10{sup 21} when excited by the relic photon gas).« less

Evaluation of novel PMTs of worldwide best parameters for the CTA project

NASA Astrophysics Data System (ADS)

Mirzoyan, R.; Müller, D.; Hose, J.; Menzel, U.; Nakajima, D.; Takahashi, M.; Teshima, M.; Toyama, T.; Yamamoto, T.

2017-02-01

Photomultiplier Tubes (PMT) are the most widespread detectors for measuring fast and faint light signals. About six years ago, we started an improvement program for the PMT candidates for the Cherenkov Telescope Array (CTA) project in cooperation with the companies Hamamatsu Photonics K.K. (Japan) and Electron Tubes Enterprises Ltd. (England). CTA is the next major Imaging Atmospheric Cherenkov Telescopes array for ground-based high energy gamma-ray astrophysics. A total of ∼ 100 telescopes of sizes of 23 m, 12 m and 4 m in diameter will be built in northern and southern hemispheres. For CTA we need PMTs with the highest quantum efficiency and photoelectron collection efficiency, short pulse width of a few ns, low transit time spread and very low afterpulsing. The manufacturers were able to produce 1.5‧ PMTs of enhanced peak quantum efficiency of ∼ 40 % . These collect up to 95-98% of photoelectrons onto the first dynode for the wavelengths ≥ 400 nm . A pulse width of ≤ 3 ns has been achieved at the selected operational gain of 40k. The afterpulsing for a threshold of ≥ 4 photoelectrons is dramatically reduced, down to the level of 0.02%. We will report on the measurements of 1.5‧ PMTs from Hamamatsu and Electron Tubes Enterprises as candidate PMTs for the CTA project. The novel 1.5‧ PMTs have the worldwide best parameters.

Enhanced UV light detection using a p-terphenyl wavelength shifter

DOE PAGES

Joosten, Sylvester J.; Kaczanowicz, Ed; Ungaro, Maurizio; ...

2017-07-25

Here, UV-glass photomultiplier tubes (PMTs) have poor photon detection efficiency for wavelengths belowmore » $$300\\,\\text{nm}$$ due to the opaqueness of the window material. Costly quartz PMTs could be used to enhance the efficiency below $$300\\,\\text{nm}$$. A less expensive solution that dramatically improves this efficiency is the application of a thin film of a p-terphenyl (PT) wavelength shifter on UV-glass PMTs. This improvement was quantified for Photonis XP4500B PMTs for wavelengths between $$200\\,\\text{nm}$$ and $$400\\,\\text{nm}$$. The gain factor ranges up to 5.4 $$\\pm$$ 0.5 at a wavelength of $$215\\,\\text{nm}$$, with a material load of $$110\\pm10\\,\\mu\\text{g}/\\text{cm}^2$$ ($$894\\,\\text{nm}$$). The wavelength shifter was found to be fully transparent for wavelengths greater than $$300\\,\\text{nm}$$. The resulting gain in detection efficiency, when used in a typical Cherenkov counter, was estimated to be of the order of 40%. Consistent coating quality was assured by a rapid gain testing procedure using narrow-band UV LEDs. Based on these results, 200 Photonis XP4500B PMTs were treated with PT for the upgraded low-threshold Cherenkov counter (LTCC) to be used in the CEBAF Large Acceptance Spectrometer upgraded detector (CLAS12) at the Thomas Jefferson National Accelerator Facility.« less

Design, optimization and characterization of the light concentrators of the single-mirror small size telescopes of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Aguilar, J. A.; Basili, A.; Boccone, V.; Cadoux, F.; Christov, A.; della Volpe, D.; Montaruli, T.; Płatos, Ł.; Rameez, M.

2015-01-01

The focal-plane cameras of γ -ray telescopes frequently use light concentrators in front of the light sensors. The purpose of these concentrators is to increase the effective area of the camera as well as to reduce the stray light coming at large incident angles. These light concentrators are usually based on the Winston cone design. In this contribution we present the design of a hexagonal hollow light concentrator with a lateral profile optimized using a cubic Bézier function to achieve a higher collection efficiency in the angular region of interest. The design presented here is optimized for a Davies-Cotton telescope with a primary mirror of about 4 m in diameter and a focal length of 5.6 m. The described concentrators are part of an innovative camera made up of silicon-photomultiplier sensors, although a similar approach can be used for other sizes of single-mirror telescopes with different camera sensors, including photomultipliers. The challenge of our approach is to achieve a cost-effective design suitable for standard industrial production of both the plastic concentrator substrate and the reflective coating. At the same time we maximize the optical performance. In this paper we also describe the optical set-up to measure the absolute collection efficiency of the light concentrators and demonstrate our good understanding of the measured data using a professional ray-tracing simulation.

Reversed Cherenkov-transition radiation in a waveguide partly filled with a left-handed medium

NASA Astrophysics Data System (ADS)

Alekhina, Tatiana Yu.; Tyukhtin, Andrey V.

2018-04-01

We analyze the electromagnetic field of a charged particle that moves uniformly in a circular waveguide and crosses a boundary between a vacuum area and an area filled with a left-handed medium exhibiting resonant frequency dispersion. The investigation of the waveguide mode components is performed analytically and numerically. The reversed Cherenkov radiation in the filled area of the waveguide and the reversed Cherenkov-transition radiation (RCTR) in the vacuum area are analyzed. The conditions for the excitation of RCTR are obtained. It is shown that the number of modes of RCTR is always finite; in particular, under certain conditions, the RCTR is composed of the first waveguide mode only. Plots of the typical fields of the excited waveguide mode are presented.

TAIGA experiment: present status and perspectives

NASA Astrophysics Data System (ADS)

Budnev, N.; Astapov, I.; Bezyazeekov, P.; Boreyko, V.; Borodin, A.; Brückner, M.; Chiavassa, A.; Gafarov, A.; Grebenyuk, V.; Gress, O.; Gress, T.; Grinyuk, A.; Grishin, O.; Dyachok, A.; Fedorov, O.; Haungs, A.; Horns, D.; Huege, T.; Ivanova, A.; Kalmykov, N.; Kazarina, Y.; Kindin, V.; Kiryuhin, S.; Kokoulin, R.; Kompaniets, K.; Kostunin, D.; Korosteleva, E.; Kozhin, V.; Kravchenko, E.; Kunnas, M.; Kuzmichev, L.; Lemeshev, Yu.; Lenok, V.; Lubsandorzhiev, B.; Lubsandorzhiev, N.; Mirgazov, R.; Mirzoyan, R.; Monkhoev, R.; Nachtigall, R.; Osipova, E.; Pakhorukov, A.; Panasyuk, M.; Pankov, L.; Poleschuk, V.; Popesku, M.; Popova, E.; Porelli, A.; Postnikov, E.; Prosin, V.; Ptuskin, V.; Petrukhin, A.; Pushnin, A.; Rjabov, E.; Rubtsov, G.; Sagan, Y.; Samoliga, V.; Semeney, Yu.; Sidorenkov, A.; Schröder, F.; Silaev, A.; Silaev (junior, A.; Skurikhin, A.; Slunecka, M.; Sokolov, A.; Spiering, C.; Sveshnikova, L.; Tabolenko, V.; Tarashansky, B.; Tkachenko, A.; Tkachev, L.; Tluczykont, M.; Wischnewski, R.; Yashin, I.; Zagorodnikov, A.; Zhurov, D.; Zurbanov, V.

2017-08-01

The TAIGA observatory addresses ground-based gamma-ray astronomy at energies from a few TeV to several PeV, as well as cosmic ray physics from 100 TeV to several EeV . TAIGA will be located in the Tunka valley, ~ 50 km West from Lake Baikal. The different detectors of the TAIGA will be grouped in 6 arrays to measure Cherenkov and radio emission as well as electron and muon components of atmospheric showers. The combination of the wide angle Cherenkov detectors of the TAIGA-HiSCORE array and the 4-m Imaging Atmospheric Cherenkov Telescopes of the TAIGA-IACT array with their FoV of 10×10 degrees and underground muon detectors offers a very cost effective way to construct a 5 km2 array for gamma-ray astronomy.

Seeing Stars - Intensity Interferometry in the Laboratory & on the Ground

NASA Astrophysics Data System (ADS)

Carlile, Colin; Dravins, Dainis

2018-04-01

In many ways it is a golden age for astronomy. Spectacular new discoveries, for example the detection of gravitational waves, are very dependent upon instrumental development. The specific instrument development we propose, Intensity Interferometry (II), aims toimprove the spatial resolution of optical telescopes by 100x to 50µas [1]. This is impractical to achieve by increasing the size of telescopes or by extending the capabilities of phase interferometry. II, if implemented on the Cherenkov Telescope Array (CTA) currently being installed in La Palma and Paranal, would record the light intensity – the photon train - from many different telescopes, up to 2 km apart, on a nanosecond timescale and compare them. The signal from the many pairs of telescopes would quantify the degree of correlation by extracting the second-order correlation function, and thus create an image. This is not a real space image. However we can invert the data by Fourier Transform and create a real image. The more telescopes, the better resolved and more physical is the image, enabling the study of sunspots on nearby stars; orbiting binary stars; or exoplanets traversing the disc of their own star. We understand the Sun well but we have little experimental knowledge of how representative it is of main sequence stars. To test the II method, at Lund Observatory we have set up a laboratory analogue comprising ten small telescopes observing an artificial star created by light from a laser. The method has been shown to work [2] and the telescope array has now been extended to two dimensions. We are in discussion with other groups to explore the possibility of implementing this method on real telescopes observing actual stars. We plan to do this with the prototype Small Size Telescopes being built by groups in Europe, and ultimately with the CTA itself. A Science Working Group for II has now been set up within the CTA Consortium, of which Lund University is an integral part. A Letter of Intent has been sent to CTA expressing these intentions. An attractive aspect of II is its complementarity to the principle goal of CTA - the exploration of high energy cosmic rays via the Cherenkov light they generate in the atmosphere. This can only be observed under the most demanding atmospheric conditions whereas II can be recorded when conditions are poor: with a bright Moon, during periods of turbulence; in hazy conditions; or after dusk and before dawn. Two further advantages of implementing an II option on CTA are the minimal marginal costs incurred to an already 400M€ investment and, secondly, that even a few telescopes would produce unique scientific results even in the early days when the CTA array is far from complete. [1] Dainis Dravins and Colin Carlile, SPIE Newsroom (2016), http://spie.org/newsroom/6504-kilometer-baseline-optical-intensity-interferometry-for-stellar-surface-observations [2] D. Dravins, T. Lagadec, P.D. Nuñez, Nature Communications 6, 6852 (2015)

Circular-Polarization-Selective Transmission Induced by Spin-Orbit Coupling in a Helical Tape Waveguide

NASA Astrophysics Data System (ADS)

Liu, Yahong; Guo, Qinghua; Liu, Hongchao; Liu, Congcong; Song, Kun; Yang, Biao; Hou, Quanwen; Zhao, Xiaopeng; Zhang, Shuang; Navarro-Cía, Miguel

2018-05-01

Spin-orbit coupling of light, describing the interaction between the polarization (spin) and spatial degrees of freedom (orbit) of light, plays an important role in subwavelength scale systems and leads to many interesting phenomena, such as the spin Hall effect of light. Here, based on the spin-orbit coupling, we design and fabricate a helical tape waveguide (HTW), which can realize a circular-polarization-selective process. When the incident circularly polarized wave is of the same handedness as the helix of the HTW, a nearly complete transmission is observed; in contrast, a counterrotating circular polarization of incident wave results in a much lower transmission or is even totally blocked by the HTW. Indeed, both simulations and experiments reveal that the blocked component of power leaks through the helical aperture of the HTW and forms a conical beam analogous to helical Cherenkov radiation due to the conversion from the spin angular momentum to the orbital angular momentum. Our HTW structure demonstrates its potential as a polarization selector in a broadband frequency range.

A swimming pool array for ultra high energy showers

NASA Astrophysics Data System (ADS)

Yodh, Gaurang B.; Shoup, Anthony; Barwick, Steve; Goodman, Jordan A.

1992-11-01

A very preliminary design concept for an array using water Cherenkov counters, built out of commercially available backyard swimming pools, to sample the electromagnetic and muonic components of ultra high energy showers at large lateral distances is presented. The expected performance of the pools is estimated using the observed lateral distributions by scintillator and water Cherenkov arrays at energies above 1019 eV and simulations.

BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET

NASA Astrophysics Data System (ADS)

Brunner, S. E.; Schaart, D. R.

2017-06-01

Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ˜10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ˜2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite trend.

BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET.

PubMed

Brunner, S E; Schaart, D R

2017-06-07

Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ∼10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ∼2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm 3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite trend.

Modeling the low-light response of photomultiplier tubes

NASA Astrophysics Data System (ADS)

Maxwell, Patrick; Niculescu, Ioana

2017-09-01

A number of crucial experiments exploring the intricate tomography of protons and neutrons will be carried out in Hall A at Jefferson Lab using the SuperBigBite Spectrometer (SBS), a large acceptance magnetic spectrometer sporting 0.5% momentum and 0.5 mr angular resolution. As part of the standard SBS detector package the Gas Ring Imaging Cherenkov (GRINCH) detector will help identify particles produced in the experiments. To determine which photomultiplier (PMT) tubes would be used in GRINCH, more than 900 29 mm 9125B PMTs were tested. Two models, were used to fit test data. For the parameters relevant to this study, results from both models were found to be equivalent, and will be discussed here.

Terahertz generation in mid-infrared quantum cascade lasers with a dual-upper-state active region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujita, Kazuue, E-mail: kfujita@crl.hpk.co.jp; Hitaka, Masahiro; Ito, Akio

2015-06-22

We report the performance of room temperature terahertz sources based on intracavity difference-frequency generation in mid-infrared quantum cascade lasers with a dual-upper-state (DAU) active region. DAU active region design is theoretically expected to produce larger optical nonlinearity for terahertz difference-frequency generation, compared to the active region designs of the bound-to-continuum type used previously. Fabricated buried heterostructure devices with a two-section buried distributed feedback grating and the waveguide designed for Cherenkov difference-frequency phase-matching scheme operate in two single-mode mid-infrared wavelengths at 10.7 μm and 9.7 μm and produce terahertz output at 2.9 THz with mid-infrared to terahertz conversion efficiency of 0.8 mW/W{sup 2}more » at room temperature.« less

Science with the Advanced Gamma Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Coppi, Paolo

2009-05-01

We present the scientific drivers for the Advanced Gamma Ray Imaging System (AGIS), a concept for the next-generation ground- based gamma-ray experiment, comprised of an array of ˜100 imaging atmospheric Cherenkov telescopes. Design requirements for AGIS include achieving a sensitivity an order of magnitude better than the current generation of space or ground-based instruments in the energy range of 40 GeV to ˜100 TeV. We present here an overview of the scientific goals of AGIS, including the prospects for understanding VHE phenomena in the vicinity of accreting black holes, particle acceleration in a variety of astrophysical environments, indirect detection of dark matter, study of cosmological background radiation fields, and particle physics beyond the standard model.

Design and fabrication of a window for the gas Cherenkov detector 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fatherley, V. E., E-mail: vef@lanl.gov; Bingham, D. A.; Cartelli, M. D.

2016-11-15

The gas Cherenkov detector 3 was designed at Los Alamos National Laboratory for use in inertial confinement fusion experiments at both the Omega Laser Facility and the National Ignition Facility. This instrument uses a low-Z gamma-to-electron convertor plate and high pressure gas to convert MeV gammas into UV/visible Cherenkov photons for fast optical detection. This is a follow-on diagnostic from previous versions, with two notable differences: the pressure of the gas is four times higher, and it allows the use of fluorinated gas, requiring metal seals. These changes force significant changes in the window component, having a unique set ofmore » requirements and footprint limitations. The selected solution for this component, a sapphire window brazed into a stainless steel flange housing, is described.« less

Design and fabrication of a window for the Gas Cherenkov Detector 3

DOE PAGES

Fatherley, Valerie E.; Bingham, David A.; Cartelli, Myles Derrick; ...

2016-08-23

The gas Cherenkov detector 3 was designed at Los Alamos National Laboratory for use in inertial confinement fusion experiments at both the Omega Laser Facility and the National Ignition Facility. This instrument uses a low-Z gamma-to-electron convertor plate and high pressure gas to convert MeV gammas into UV/visible Cherenkov photons for fast optical detection. This is a follow-on diagnostic from previous versions, with two notable differences: the pressure of the gas is four times higher, and it allows the use of fluorinated gas, requiring metal seals. These changes force significant changes in the window component, having a unique set ofmore » requirements and footprint limitations. Finally, the selected solution for this component, a sapphire window brazed into a stainless steel flange housing, is described.« less

NASA Tech Briefs, April 2010

NASA Technical Reports Server (NTRS)

2010-01-01

Topics covered include: Active and Passive Hybrid Sensor; Quick-Response Thermal Actuator for Use as a Heat Switch; System for Hydrogen Sensing; Method for Detecting Perlite Compaction in Large Cryogenic Tanks; Using Thin-Film Thermometers as Heaters in Thermal Control Applications; Directional Spherical Cherenkov Detector; AlGaN Ultraviolet Detectors for Dual-Band UV Detection; K-Band Traveling-Wave Tube Amplifier; Simplified Load-Following Control for a Fuel Cell System; Modified Phase-meter for a Heterodyne Laser Interferometer; Loosely Coupled GPS-Aided Inertial Navigation System for Range Safety; Sideband-Separating, Millimeter-Wave Heterodyne Receiver; Coaxial Propellant Injectors With Faceplate Annulus Control; Adaptable Diffraction Gratings With Wavefront Transformation; Optimizing a Laser Process for Making Carbon Nanotubes; Thermogravimetric Analysis of Single-Wall Carbon Nanotubes; Robotic Arm Comprising Two Bending Segments; Magnetostrictive Brake; Low-Friction, Low-Profile, High-Moment Two-Axis Joint; Foil Gas Thrust Bearings for High-Speed Turbomachinery; Miniature Multi-Axis Mechanism for Hand Controllers; Digitally Enhanced Heterodyne Interferometry; Focusing Light Beams To Improve Atomic-Vapor Optical Buffers; Landmark Detection in Orbital Images Using Salience Histograms; Efficient Bit-to-Symbol Likelihood Mappings; Capacity Maximizing Constellations; Natural-Language Parser for PBEM; Policy Process Editor for P(sup 3)BM Software; A Quality System Database; Trajectory Optimization: OTIS 4; and Computer Software Configuration Item-Specific Flight Software Image Transfer Script Generator.

Probing the diffuse optical-IR background with TeV blazars detected with the MAGIC Telescopes

NASA Astrophysics Data System (ADS)

Prandini, Elisa; Domínguez, Alberto; Fallah Ramazani, Vandad; Hassan, Tarek; Mazin, Daniel; Moralejo, Abelardo; Nievas Rosillo, Mireia; Vanzo, Gaia; Vazquez Acosta, Monica

2017-11-01

Blazars are radio loud quasars whose jet points toward the observer. The observed emission is mostly non-thermal, dominated by the jet emission, and in some cases extends up to the very high energy gamma rays (VHE; E > 100 GeV). To date, more than 60 blazars have been detected at VHE mainly with ground-based imaging atmospheric Cherenkov telescopes (IACTs) such as MAGIC, H.E.S.S. and VERITAS. Energetic photons from a blazar may interact with the diffuse optical and IR background (the extragalactic background light, EBL) leaving an imprint on the blazar energy spectrum. This effect can be used to constrain the EBL, with basic assumptions on the intrinsic energy spectrum. Current generation of IACTs is providing valuable measurements of the EBL density and energy spectrum from optical to infrared frequencies. In this contribution, we present the latest results obtained with the data taken with the MAGIC telescopes: using 32 spectra from 12 blazars, the scale factor of the optical density predicted by the EBL model from Domínguez et al. (2011) is constrained to be 0.95 (+0.11, -0.12)_{stat} (+0.16, -0.07)_{sys}, where a value of 1 means the perfect match with the model.

Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

NASA Astrophysics Data System (ADS)

Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Buson, S.; Carosi, A.; Chatterjee, A.; Clavero, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Oña Wilhelmi, E.; Di Pierro, F.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giammaria, P.; Godinović, N.; González Muñoz, A.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Nogués, L.; Orito, R.; Overkemping, A.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Perri, L.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Saito, T.; Satalecka, K.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Steinbring, T.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Torres, D. F.; Toyama, T.; Treves, A.; Verguilov, V.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.

2016-09-01

Aims: We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year timescales, which can bring additional insight on the processes responsible for its broadband emission. Methods: We observed Mrk 421 in the very high energy (VHE) γ-ray range with the Cherenkov telescope MAGIC-I from March 2007 to June 2009 for a total of 96 h of effective time after quality cuts. The VHE flux variability is quantified using several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes here for the first time. The 2.3 yr long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Metsähovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year timescales. Results: Mrk 421 was found in different γ-ray emission states during the 2.3 yr long observation period: The flux above 400 GeV spans from the minimum nightly value of (1.3 ± 0.4)×10-11 cm-2 s-1 to the maximum flux, that is about 24 times higher, at (3.1 ± 0.1)×10-10 cm-2 s-1. Flares and different levels of variability in the γ-ray light curve could be identified with the Bayesian Block algorithm. The same behaviour of a quiet and active emission was found in the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct correlation in time. The behaviour of the optical light curve of GASP-WEBT and the radio light curves by OVRO and Metsähovi are different as they show no coincident features with the higher energetic light curves and a less variable emission. Overall, the fractional variability increases with energy. The comparable variability in the X-ray and VHE bands and their direct correlation during both high- and low-activity periods spanning many months show that the electron populations radiating the X-ray and γ-ray photons are either the same, as expected in the synchrotron-self-Compton mechanism, or at least strongly correlated, as expected in electromagnetic cascades. The complete data set shown in Fig. 2 and the data points shown in Figs. 3 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A91

Transformation optics beyond the manipulation of light trajectories.

PubMed

Ginis, Vincent; Tassin, Philippe

2015-08-28

Since its inception in 2006, transformation optics has become an established tool to understand and design electromagnetic systems. It provides a geometrical perspective into the properties of light waves without the need for a ray approximation. Most studies have focused on modifying the trajectories of light rays, e.g. beam benders, lenses, invisibility cloaks, etc. In this contribution, we explore transformation optics beyond the manipulation of light trajectories. With a few well-chosen examples, we demonstrate that transformation optics can be used to manipulate electromagnetic fields up to an unprecedented level. In the first example, we introduce an electromagnetic cavity that allows for deep subwavelength confinement of light. The cavity is designed with transformation optics even though the concept of trajectory ceases to have any meaning in a structure as small as this cavity. In the second example, we show that the properties of Cherenkov light emitted in a transformation-optical material can be understood and modified from simple geometric considerations. Finally, we show that optical forces--a quadratic function of the fields--follow the rules of transformation optics too. By applying a folded coordinate transformation to a pair of waveguides, optical forces can be enhanced just as if the waveguides were closer together. With these examples, we open up an entirely new spectrum of devices that can be conceived using transformation optics. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Transformation optics beyond the manipulation of light trajectories

PubMed Central

Ginis, Vincent; Tassin, Philippe

2015-01-01

Since its inception in 2006, transformation optics has become an established tool to understand and design electromagnetic systems. It provides a geometrical perspective into the properties of light waves without the need for a ray approximation. Most studies have focused on modifying the trajectories of light rays, e.g. beam benders, lenses, invisibility cloaks, etc. In this contribution, we explore transformation optics beyond the manipulation of light trajectories. With a few well-chosen examples, we demonstrate that transformation optics can be used to manipulate electromagnetic fields up to an unprecedented level. In the first example, we introduce an electromagnetic cavity that allows for deep subwavelength confinement of light. The cavity is designed with transformation optics even though the concept of trajectory ceases to have any meaning in a structure as small as this cavity. In the second example, we show that the properties of Cherenkov light emitted in a transformation-optical material can be understood and modified from simple geometric considerations. Finally, we show that optical forces—a quadratic function of the fields—follow the rules of transformation optics too. By applying a folded coordinate transformation to a pair of waveguides, optical forces can be enhanced just as if the waveguides were closer together. With these examples, we open up an entirely new spectrum of devices that can be conceived using transformation optics. PMID:26217057

Caracterización y automatización mecánica de los telescopios Cherenkov de CASLEO

NASA Astrophysics Data System (ADS)

Leal, N.; Yelós, L. D.; Mancilla, A.; Maya, J.; Feres, L.; Lazarte, F.; García, B.

2017-10-01

A new automation system for the Cherenkov Telescopes at CASLEO is designed. Two rotation speeds are proposed: a fast speed for positioning and parking and a slow speed for tracking. The wind speed at El Leoncito site is used as a design parameter. In this work we present the first tests with the new setup which shows a correct performance at fast speeds.

Cherenkov detection of cosmic rays in Hanoi: Response to low signals

NASA Astrophysics Data System (ADS)

Thao, N. T.; Anh, P. T.; Darriulat, P.; Diep, P. N.; Dong, P. N.; Hiep, N. V.; Hoai, D. T.; Nhung, P. T. T.

2013-05-01

A replica of one of the 1660 Cherenkov detectors used in the ground array of the Pierre Auger Cosmic Ray Observatory in Argentina has been constructed on the roof of the VATLY astrophysics laboratory in Ha Noi (Viet Nam). We report on measurements of low amplitude signals using the detector to study event pairs occurring within a small time window. The data include time autocorrelation and charge distributions.

Beam and tissue factors affecting Cherenkov image intensity for quantitative entrance and exit dosimetry on human tissue

PubMed Central

Zhang, Rongxiao; Glaser, Adam K.; Andreozzi, Jacqueline; Jiang, Shudong; Jarvis, Lesley A.; Gladstone, David J.; Pogue, Brian W.

2017-01-01

This study’s goal was to determine how Cherenkov radiation emission observed in radiotherapy is affected by predictable factors expected in patient imaging. Factors such as tissue optical properties, radiation beam properties, thickness of tissues, entrance/exit geometry, curved surface effects, curvature and imaging angles were investigated through Monte Carlo simulations. The largest physical cause of variation of the correlation factor between of Cherenkov emission and dose was the entrance/exit geometry (~50%). The largest human tissue effect was from different optical properties (~45%). Beyond these, clinical beam energy varies the correlation factor significantly (~20% for x-ray beams), followed by curved surfaces (~15% for x-ray beams and ~8% for electron beams), and finally, the effect of field size (~5% for x-ray beams). Other investigated factors which caused variations less than 5% were tissue thicknesses and source to surface distance. The effect of non-Lambertian emission was negligible for imaging angles smaller than 60 degrees. The spectrum of Cherenkov emission tends to blue-shift along the curved surface. A simple normalization approach based on the reflectance image was experimentally validated by imaging a range of tissue phantoms, as a first order correction for different tissue optical properties. PMID:27507213

High energy gamma-ray astronomy observations of Geminga with the VERITAS array

NASA Astrophysics Data System (ADS)

Finnegan, Gary Marvin

The closest known supernova remnant and pulsar is Geminga. The Geminga pulsar is the first pulsar to have ever been detected initially by gamma rays and the first pulsar in a class of radio-quiet pulsars. In 2007, the Milagro collaboration detected a large angularly extended (˜ 2.6°) emission of high energy gamma rays (˜ 20 TeV ) that was positionally coincident with Geminga. The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is a ground- based observatory with four imaging Cherenkov telescopes with an energy range between 100 GeV to more than 30 TeV. The imaging Cherenkov telescopes detect the Cherenkov light from charged particles in electromagnetic air showers initiated by high energy particles such as gamma rays and cosmic rays. Most gamma-ray sources detected by VERITAS are point like sources, which have an angular extension smaller than the angular resolution of the telescopes (˜ 0.1°). For a point source, the background noise can be measured in the same field of view (FOV) as the source. For an angularly extended object, such as Geminga, an external FOV from the source region must be used to estimate the background noise, to avoid contamination from the extended source region. In this dissertation, I describe a new analysis procedure that is designed to increase the observation sensitivity of angularly extended objects like Geminga. I apply this procedure to a known extended gamma-ray source, Boomerang, as well as Geminga. The results indicate the detection of very high energy emission from the Geminga region at the level of 4% of the Crab nebula with a weighted average spectral index of -2.8 ± 0.2. A possible extension less than one degree wide is shown. This detection, however, awaits a confirmation by the VERITAS collaboration. The luminosity of the Geminga extended source, the Vela Nebula, and the Crab nebula was calculated for energies greater than 1 TeV. The data suggest that older pulsars, such as Geminga and Vela, convert the spin-down power of the pulsar more efficiently to TeV energies than a younger pulsar such as the Crab pulsar.

The Cherenkov Telescope Array production system for Monte Carlo simulations and analysis

NASA Astrophysics Data System (ADS)

Arrabito, L.; Bernloehr, K.; Bregeon, J.; Cumani, P.; Hassan, T.; Haupt, A.; Maier, G.; Moralejo, A.; Neyroud, N.; pre="for the"> CTA Consortium, DIRAC Consortium,

2017-10-01

The Cherenkov Telescope Array (CTA), an array of many tens of Imaging Atmospheric Cherenkov Telescopes deployed on an unprecedented scale, is the next-generation instrument in the field of very high energy gamma-ray astronomy. An average data stream of about 0.9 GB/s for about 1300 hours of observation per year is expected, therefore resulting in 4 PB of raw data per year and a total of 27 PB/year, including archive and data processing. The start of CTA operation is foreseen in 2018 and it will last about 30 years. The installation of the first telescopes in the two selected locations (Paranal, Chile and La Palma, Spain) will start in 2017. In order to select the best site candidate to host CTA telescopes (in the Northern and in the Southern hemispheres), massive Monte Carlo simulations have been performed since 2012. Once the two sites have been selected, we have started new Monte Carlo simulations to determine the optimal array layout with respect to the obtained sensitivity. Taking into account that CTA may be finally composed of 7 different telescope types coming in 3 different sizes, many different combinations of telescope position and multiplicity as a function of the telescope type have been proposed. This last Monte Carlo campaign represented a huge computational effort, since several hundreds of telescope positions have been simulated, while for future instrument response function simulations, only the operating telescopes will be considered. In particular, during the last 18 months, about 2 PB of Monte Carlo data have been produced and processed with different analysis chains, with a corresponding overall CPU consumption of about 125 M HS06 hours. In these proceedings, we describe the employed computing model, based on the use of grid resources, as well as the production system setup, which relies on the DIRAC interware. Finally, we present the envisaged evolutions of the CTA production system for the off-line data processing during CTA operations and the instrument response function simulations.

Glasses for Detection of Penetrating Radiation via the Cherenkov Effect

DTIC Science & Technology

2015-07-01

neutrons .    Three  peer-­‐reviewed   publications  were  written...case  is  different  in   neutron   interrogation.            This  project  has  educated  7  University  of...Measurements  of  thermal neutron  response  in  Cherenkov  glassed  designed  for  MeV  photon  detection,”  IEEE

Monte Carlo-based Reconstruction in Water Cherenkov Detectors using Chroma

NASA Astrophysics Data System (ADS)

Seibert, Stanley; Latorre, Anthony

2012-03-01

We demonstrate the feasibility of event reconstruction---including position, direction, energy and particle identification---in water Cherenkov detectors with a purely Monte Carlo-based method. Using a fast optical Monte Carlo package we have written, called Chroma, in combination with several variance reduction techniques, we can estimate the value of a likelihood function for an arbitrary event hypothesis. The likelihood can then be maximized over the parameter space of interest using a form of gradient descent designed for stochastic functions. Although slower than more traditional reconstruction algorithms, this completely Monte Carlo-based technique is universal and can be applied to a detector of any size or shape, which is a major advantage during the design phase of an experiment. As a specific example, we focus on reconstruction results from a simulation of the 200 kiloton water Cherenkov far detector option for LBNE.

Interference effects on guided Cherenkov emission in silicon from perpendicular, oblique, and parallel boundaries

NASA Astrophysics Data System (ADS)

Couillard, M.; Yurtsever, A.; Muller, D. A.

2010-05-01

Waveguide electromagnetic modes excited by swift electrons traversing Si slabs at normal and oblique incidence are analyzed using monochromated electron energy-loss spectroscopy and interpreted using a local dielectric theory that includes relativistic effects. At normal incidence, sharp spectral features in the visible/near-infrared optical domain are directly assigned to p -polarized modes. When the specimen is tilted, s -polarized modes, which are completely absent at normal incidence, become visible in the loss spectra. In the tilted configuration, the dispersion of p -polarized modes is also modified. For tilt angles higher than ˜50° , Cherenkov radiation, the phenomenon responsible for the excitation of waveguide modes, is expected to partially escape the silicon slab and the influence of this effect on experimental measurements is discussed. Finally, we find evidence for an interference effect at parallel Si/SiO2 interfaces, as well as a delocalized excitation of guided Cherenkov modes.

An instrument to measure the spectrum of cosmic ray iron and other nuclei to above 100 GeV-nucleon

NASA Technical Reports Server (NTRS)

Arens, J. F.; Balasubrahmanyan, V. K.; Ormes, J. F.; Siohan, F.; Schmidt, W. K. H.; Simon, M.; Spiegelhauer, H.

1978-01-01

A balloon-borne detector system for extending the study of cosmic ray composition to the energy region beyond 100 GeV/nucleon is described. The instrument incorporates an ionization calorimeter and a gas Cherenkov counter filled with freon for the determination of energies, and a charge module, consisting of scintillation and a lucite Cherenkov counter, for determining the charge of the incoming particle. The scintillators were utilized to determine the position of the incoming particle in addition to its charge. The characteristics of these detectors with respect to resolution, and the methods employed in laboratory calibration, cross-checks with flight data and actual performance in the flights are described in detail. Monte Carlo simulation of the ionization calorimeter and comparison of the response of the calorimeter and gas Cherenkov counter for complex nuclei was used to convert the observed calorimeter signal to absolute energy in a consistent manner.

Cherenkov radiation-based three-dimensional position-sensitive PET detector: A Monte Carlo study.

PubMed

Ota, Ryosuke; Yamada, Ryoko; Moriya, Takahiro; Hasegawa, Tomoyuki

2018-05-01

Cherenkov radiation has recently received attention due to its prompt emission phenomenon, which has the potential to improve the timing performance of radiation detectors dedicated to positron emission tomography (PET). In this study, a Cherenkov-based three-dimensional (3D) position-sensitive radiation detector was proposed, which is composed of a monolithic lead fluoride (PbF 2 ) crystal and a photodetector array of which the signals can be readout independently. Monte Carlo simulations were performed to estimate the performance of the proposed detector. The position- and time resolution were evaluated under various practical conditions. The radiator size and various properties of the photodetector, e.g., readout pitch and single photon timing resolution (SPTR), were parameterized. The single photon time response of the photodetector was assumed to be a single Gaussian for the simplification. The photo detection efficiency of the photodetector was ideally 100% for all wavelengths. Compton scattering was included in simulations, but partly analyzed. To estimate the position at which a γ-ray interacted in the Cherenkov radiator, the center-of-gravity (COG) method was employed. In addition, to estimate the depth-of-interaction (DOI) principal component analysis (PCA), which is a multivariate analysis method and has been used to identify the patterns in data, was employed. The time-space distribution of Cherenkov photons was quantified to perform PCA. To evaluate coincidence time resolution (CTR), the time difference of two independent γ-ray events was calculated. The detection time was defined as the first photon time after the SPTR of the photodetector was taken into account. The position resolution on the photodetector plane could be estimated with high accuracy, by using a small number of Cherenkov photons. Moreover, PCA showed an ability to estimate the DOI. The position resolution heavily depends on the pitch of the photodetector array and the radiator thickness. If the readout pitch were ideally 0 and practically 3 mm, a full-width at half-maximum (FWHM) of 0.348 and 1.92 mm was achievable with a 10-mm-thick PbF 2 crystal, respectively. Furthermore, first-order correlation could be observed between the primary principal component and the true DOI. To obtain a coincidence timing resolution better than 100-ps FWHM with a 20-mm-thick PbF 2 crystal, a photodetector with SPTR of better than σ = 30 ps was necessary. From these results, the improvement of SPTR allows us to achieve CTR better than 100-ps FWHM, even in the case where a 20-mm-thick radiator is used. Our proposed detector has the potential to estimate the 3D interaction position of γ-rays in the radiator, using only time and space information of Cherenkov photons. © 2018 American Association of Physicists in Medicine.

Implementation of the next-generation Gas Cherenkov Detector at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Carrera, J. A.; Herrmann, H. W.; Khater, H. Y.; Carpenter, A. C.; Beeman, B. V.; Hernandez, J. E.; Sitaraman, S.; Lopez, F. E.; Zylstra, A. B.; Griego, J. R.; Kim, Y. H.; Gales, S. A.; Horsfield, C. J.; Milnes, J. S.; Hares, J. D.

2017-08-01

The newest Gas Cherenkov Detector (GCD-3) diagnostic has completed its Phase I commissioning/milestone at the National Ignition Facility (NIF). GCD-3 was fielded for several years at the Omega Laser Facility in its initial configuration, before being moved to the NIF. Installation at the NIF involved optimization of GCD-3 for the higher background environment and designing a new insertion carrier assembly. GCD-3 serves as the initial phase towards the implementation of the "Super GCD" (SGCD) at the NIF. During this phase of development GCD-3 took measurements from a re-entrant well, 3.9 meters from target chamber center (TCC). Plans to insert GCD-3 within 20 cm of TCC with a Target and Diagnostic Manipulator (TANDM) will be discussed. Data was collected using a Photomultiplier Tube (PMT) in combination with a Mach-Zehnder based recording system. These measurements were used to aid in shielding analysis, validate MCNP models, and fuel design efforts for the SGCD. Findings from the initial data will be covered extensively, including an in-depth look into sources of background and possible mitigation strategies. Ongoing development of phase two, the addition of an ultra-high bandwidth Pulse Dilatation Photomultiplier Tube (PD-PMT), will also be presented.

Space-atmospheric interactions of energetic cosmic rays

NASA Astrophysics Data System (ADS)

Isar, Paula Gina

2015-02-01

Ultra-high energy cosmic rays are the most energetic particles in the Universe of which origin still remain a mystery since a century from their descovery. They are unique messengers coming from far beyond our Milky Way Galaxy, which provides insights into the fundamental matter, energy, space and time. As subatomic particles flying through space to nearly light speed, the ultra-high energy cosmic rays are so rare that they strike the Earth's atmosphere at a rate of up to only one particle per square kilometer per year or century. While the atmosphere is used as a giant calorimeter where cosmic rays induced air showers are initiated and the medium through which Cherenkov or fluorescence light or radio waves propagate, all cosmic ray measurements (performed either from space or ground) rely on an accurate atmospheric monitoring and understanding of atmospheric effects. The interdisciplinary link between Astroparticle Physics and Atmospheric Environment through the ultra-high energy comic rays space - atmospheric interactions, based on the present ground- and future space-based cosmic ray observatories, will be presented.

Modeling Photodisintegration-induced TeV Photon Emission from Low-luminosity Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Liu, Xue-Wen; Wu, Xue-Feng; Lu, Tan

2012-05-01

Ultra-high-energy cosmic-ray heavy nuclei have recently been considered as originating from nearby low-luminosity gamma-ray bursts that are associated with Type Ibc supernovae. Unlike the power-law decay in long duration gamma-ray bursts, the light curve of these bursts exhibits complex UV/optical behavior: shock breakout dominated thermal radiation peaks at about 1 day, and, after that, nearly constant emission sustained by radioactive materials for tens of days. We show that the highly boosted heavy nuclei at PeV energy interacting with the UV/optical photon field will produce considerable TeV photons via the photodisintegration/photo-de-excitation process. It was later predicted that a thermal-like γ-ray spectrum peaks at about a few TeV, which may serve as evidence of nucleus acceleration. The future observations by the space telescope Fermi and by the ground atmospheric Cherenkov telescopes such as H.E.S.S., VERITAS, and MAGIC will shed light on this prediction.

Recent Local and State Action in Arizona to Maintain Sky Quality

NASA Astrophysics Data System (ADS)

Hall, Jeffrey C.; Shankland, P. D.; Green, R. F.; Jannuzi, B.

2014-01-01

The large number of observatories in Arizona has led to the development of a number of lighting control ordinances around the state, some quite strict. Several factors are now contributing to an increased need for active effort at the local, County, and State levels in maintaining the quality of these codes; these factors include an expansion of competing interests in the state, the increasing use of LED lighting, and the potential for major new investments through projects such as the Cherenkov Telescope Array (CTA) and enhancements to the Navy Precision Optical Interferometer. I will review recent strategies Arizona's observatories have used to effect maintenance of ordinances and preserve sky quality; cases include (1) a statewide effort in 2012 to curb a proliferation of electronic billboards and (2) engagement of a broad group of local, County, and State officials, as well as individuals from the private sector, in support of projects like CTA, including awareness of and support for dark-sky preservation.

Precision analysis of the photomultiplier response to ultra low signals

NASA Astrophysics Data System (ADS)

Degtiarenko, Pavel

2017-11-01

A new computational model for the description of the photon detector response functions measured in conditions of low light is presented, together with examples of the observed photomultiplier signal amplitude distributions, successfully described using the parameterized model equation. In extension to the previously known approximations, the new model describes the underlying discrete statistical behavior of the photoelectron cascade multiplication processes in photon detectors with complex non-uniform gain structure of the first dynode. Important features of the model include the ability to represent the true single-photoelectron spectra from different photomultipliers with a variety of parameterized shapes, reflecting the variability in the design and in the individual parameters of the detectors. The new software tool is available for evaluation of the detectors' performance, response, and efficiency parameters that may be used in various applications including the ultra low background experiments such as the searches for Dark Matter and rare decays, underground neutrino studies, optimizing operations of the Cherenkov light detectors, help in the detector selection procedures, and in the experiment simulations.

UVSiPM: A light detector instrument based on a SiPM sensor working in single photon counting

NASA Astrophysics Data System (ADS)

Sottile, G.; Russo, F.; Agnetta, G.; Belluso, M.; Billotta, S.; Biondo, B.; Bonanno, G.; Catalano, O.; Giarrusso, S.; Grillo, A.; Impiombato, D.; La Rosa, G.; Maccarone, M. C.; Mangano, A.; Marano, D.; Mineo, T.; Segreto, A.; Strazzeri, E.; Timpanaro, M. C.

2013-06-01

UVSiPM is a light detector designed to measure the intensity of electromagnetic radiation in the 320-900 nm wavelength range. It has been developed in the framework of the ASTRI project whose main goal is the design and construction of an end-to-end Small Size class Telescope prototype for the Cherenkov Telescope Array. The UVSiPM instrument is composed by a multipixel Silicon Photo-Multiplier detector unit coupled to an electronic chain working in single photon counting mode with 10 nanosecond double pulse resolution, and by a disk emulator interface card for computer connection. The detector unit of UVSiPM is of the same kind as the ones forming the camera at the focal plane of the ASTRI prototype. Eventually, the UVSiPM instrument can be equipped with a collimator to regulate its angular aperture. UVSiPM, with its peculiar characteristics, will permit to perform several measurements both in lab and on field, allowing the absolute calibration of the ASTRI prototype.

Optical instabilities and spontaneous light emission in moving media

NASA Astrophysics Data System (ADS)

Silveirinha, Mario

2015-03-01

We show that when an uncharged plasmonic material is set in relative motion with respect to another uncharged polarizable body the system may be electromagnetically unstable. Particularly, when the relative velocity of the two bodies is enforced to remain constant the system may support natural oscillations that grow exponentially with time, even in presence of realistic material loss and dispersion. It is proven that a friction-type force acts on the moving bodies to oppose their relative motion. Hence, the optical instabilities result from the conversion of kinetic energy into electromagnetic energy. This new purely classical phenomenon is analogous to the Cherenkov and Smith-Purcell effects but for uncharged polarizable matter. We link the optical instabilities to a spontaneous parity-time symmetry breaking of the system, and demonstrate the possibility of optical amplification of a light pulse in the broken parity-time symmetry regime. This work is supported in part by Fundação para a Ciência e a Tecnologia Grant Number PTDC/EEI-TEL/2764/2012.

Recent results from milagro and prospects for HAWC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pretz, John R; Westerhoff, Stefan

2011-01-28

The High Altitude Water Cherenkov (HAWC) observatory is a new experiment for observing 50 GeV to 100 TeV photons from high energy gamma ray sources. The experiment is under construction at Sierra Negra, Mexico and will be comprised of 300 large water tanks instrumenting an area of 150 x 150 meters. HAWC is the next generation of the Milagro experiment which measured multi-TeV emission from the Galactic plane resolving sources and measuring diffuse emission. HAWC will feature approximately 15 times the sensitivity of the Milagro experiment and will be used to measure and constrain particle acceleration in the Galaxy.

Development of a composite large-size SiPM (assembled matrix) based modular detector cluster for MAGIC

NASA Astrophysics Data System (ADS)

Hahn, A.; Mazin, D.; Bangale, P.; Dettlaff, A.; Fink, D.; Grundner, F.; Haberer, W.; Maier, R.; Mirzoyan, R.; Podkladkin, S.; Teshima, M.; Wetteskind, H.

2017-02-01

The MAGIC collaboration operates two 17 m diameter Imaging Atmospheric Cherenkov Telescopes (IACTs) on the Canary Island of La Palma. Each of the two telescopes is currently equipped with a photomultiplier tube (PMT) based imaging camera. Due to the advances in the development of Silicon Photomultipliers (SiPMs), they are becoming a widely used alternative to PMTs in many research fields including gamma-ray astronomy. Within the Otto-Hahn group at the Max Planck Institute for Physics, Munich, we are developing a SiPM based detector module for a possible upgrade of the MAGIC cameras and also for future experiments as, e.g., the Large Size Telescopes (LST) of the Cherenkov Telescope Array (CTA). Because of the small size of individual SiPM sensors (6 mm×6 mm) with respect to the 1-inch diameter PMTs currently used in MAGIC, we use a custom-made matrix of SiPMs to cover the same detection area. We developed an electronic circuit to actively sum up and amplify the SiPM signals. Existing non-imaging hexagonal light concentrators (Winston cones) used in MAGIC have been modified for the angular acceptance of the SiPMs by using C++ based ray tracing simulations. The first prototype based detector module includes seven channels and was installed into the MAGIC camera in May 2015. We present the results of the first prototype and its performance as well as the status of the project and discuss its challenges.

Importance of axion-like particles for very-high-energy astrophysics

NASA Astrophysics Data System (ADS)

Roncadelli, Marco; De Angelis, Alessandro; Galanti, Giorgio

2012-07-01

Several extensions ol the Standard Model predict the existence ol Axion-Like Particles (ALPs), very light spin-zero bosons with a two-photon coupling. ALPs can give rise to observable effects in very-high-energy astrophysics. Above roughly 100 GeV the horizon of the observable Universe progressively shrinks as the energy increases, due to scattering of beam photons off background photons in the optical and infrared bands, which produces e+ e- pairs. In the presence of large-scale magnetic fields photons emitted by a blazar can oscillate into ALPs on the way to us and back into photons before reaching the Earth. Since ALPs do not interact with background photons, the effective mean free path of beam photons increases, enhancing the photon survival probability. While the absorption probability increases with energy, photon-ALP oscillations are energy-independent, and so the survival probability increases with energy compared to standard expectations. We have performed a systematic analysis of this effect, interpreting the present data on very-high-energy photons from blazars. Our predictions can be tested with presently operating Cherenkov Telescopes like H.E.S.S., MAGIC, VERITAS and CANGAROO III as well as with detectors like ARGO-YBJ and MILAGRO and with the planned Cherenkov Telescope Array and the HAWC γ-ray observatory. ALPs with the right properties to produce the above effects can possibly be discovered by the GammeV experiment at FERMILAB and surely by the planned photon regeneration experiment ALPS at DESY.

Calibration strategies for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Gaug, Markus; Berge, David; Daniel, Michael; Doro, Michele; Förster, Andreas; Hofmann, Werner; Maccarone, Maria C.; Parsons, Dan; de los Reyes Lopez, Raquel; van Eldik, Christopher

2014-08-01

The Central Calibration Facilities workpackage of the Cherenkov Telescope Array (CTA) observatory for very high energy gamma ray astronomy defines the overall calibration strategy of the array, develops dedicated hardware and software for the overall array calibration and coordinates the calibration efforts of the different telescopes. The latter include LED-based light pulsers, and various methods and instruments to achieve a calibration of the overall optical throughput. On the array level, methods for the inter-telescope calibration and the absolute calibration of the entire observatory are being developed. Additionally, the atmosphere above the telescopes, used as a calorimeter, will be monitored constantly with state-of-the-art instruments to obtain a full molecular and aerosol profile up to the stratosphere. The aim is to provide a maximal uncertainty of 10% on the reconstructed energy-scale, obtained through various independent methods. Different types of LIDAR in combination with all-sky-cameras will provide the observatory with an online, intelligent scheduling system, which, if the sky is partially covered by clouds, gives preference to sources observable under good atmospheric conditions. Wide-field optical telescopes and Raman Lidars will provide online information about the height-resolved atmospheric extinction, throughout the field-of-view of the cameras, allowing for the correction of the reconstructed energy of each gamma-ray event. The aim is to maximize the duty cycle of the observatory, in terms of usable data, while reducing the dead time introduced by calibration activities to an absolute minimum.

Aplanatic telescopes based on Schwarzschild optical configuration: from grazing incidence Wolter-like x-ray optics to Cherenkov two-mirror normal incidence telescopes

NASA Astrophysics Data System (ADS)

Sironi, Giorgia

2017-09-01

At the beginning of XX century Karl Schwarzschild defined a method to design large-field aplanatic telescopes based on the use of two aspheric mirrors. The approach was then refined by Couder (1926) who, in order to correct for the astigmatic aberration, introduced a curvature of the focal plane. By the way, the realization of normal-incidence telescopes implementing the Schwarzschild aplanatic configuration has been historically limited by the lack of technological solutions to manufacture and test aspheric mirrors. On the other hand, the Schwarzschild solution was recovered for the realization of coma-free X-ray grazing incidence optics. Wolter-like grazing incidence systems are indeed free of spherical aberration, but still suffer from coma and higher order aberrations degrading the imaging capability for off-axis sources. The application of the Schwarzschild's solution to X-ray optics allowed Wolter to define an optical system that exactly obeys the Abbe sine condition, eliminating coma completely. Therefore these systems are named Wolter-Schwarzschild telescopes and have been used to implement wide-field X-ray telescopes like the ROSAT WFC and the SOHO X-ray telescope. Starting from this approach, a new class of X-ray optical system was proposed by Burrows, Burg and Giacconi assuming polynomials numerically optimized to get a flat field of view response and applied by Conconi to the wide field x-ray telescope (WFXT) design. The Schwarzschild-Couder solution has been recently re-discovered for the application to normal-incidence Cherenkov telescopes, thanks to the suggestion by Vassiliev and collaborators. The Italian Institute for Astrophysics (INAF) realized the first Cherenkov telescope based on the polynomial variation of the Schwarzschild configuration (the so-called ASTRI telescope). Its optical qualification was successfully completed in 2016, demonstrating the suitability of the Schwarzschild-like configuration for the Cherenkov astronomy requirements. Moreover, other Cherenkov telescopes based on Schwarzschild-Couder solutions are currently being completed at Fred Lawrence Whipple Observatory in southern Arizona, USA and at the Observatoire de Paris-Meudon. In this paper we will review the Karl Schwarzschild solution and its application to grazing incidence and Cherenkov telescopes, discussing on future applications in the field of high-energy astronomy.

Evaluation of deflectometry for E-ELT optics.

NASA Astrophysics Data System (ADS)

Sironi, G.; Canestrari, R.; Civitani, M. M.

A deflectometrical facility was developed at Italian National Institute for Astrophysics-OAB in the context of the ASTRI project to characterize free-form segments for Cherenkov optics. The test works as an inverse Ronchi test in combination with a ray-tracing code: the under-test surface is illuminated by a known light pattern and the pattern warped by local surface errors is observed. Knowing the geometry of the system it is possible to retrieve the surface normal vectors. This contribution presents the analysis of the upgrades and of the configuration modifications required to allow the use of deflectometry in the realization of optical components suitable for European Extremely Large Telescope and as a specific case to support the manufacturing of the Multi-conjugate Adaptive Optics Relay (MAORY) module.

OSETI with STACEE: a search for nanosecond optical transients from nearby stars.

PubMed

Hanna, D S; Ball, J; Covault, C E; Carson, J E; Driscoll, D D; Fortin, P; Gingrich, D M; Jarvis, A; Kildea, J; Lindner, T; Mueller, C; Mukherjee, R; Ong, R A; Ragan, K; Williams, D A; Zweerink, J

2009-05-01

We have used the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) high-energy gamma-ray detector to look for fast blue-green laser pulses from the vicinity of 187 stars. The STACEE detector offers unprecedented light-collecting capability for the detection of nanosecond pulses from such lasers. We estimate STACEE's sensitivity to be approximately 10 photons/m(2) at a wavelength of 420 nm. The stars have been chosen because their characteristics are such that they may harbor habitable planets, and they are relatively close to Earth. Each star was observed for 10 minutes, and we found no evidence for laser pulses in any of the data sets. Key Words: Search for extraterrestrial intelligence-Optical search for extraterrestrial intelligence-Interstellar communication-Laser.

Observation of pulsed gamma-rays above 25 GeV from the Crab pulsar with MAGIC.

PubMed

Aliu, E; Anderhub, H; Antonelli, L A; Antoranz, P; Backes, M; Baixeras, C; Barrio, J A; Bartko, H; Bastieri, D; Becker, J K; Bednarek, W; Berger, K; Bernardini, E; Bigongiari, C; Biland, A; Bock, R K; Bonnoli, G; Bordas, P; Bosch-Ramon, V; Bretz, T; Britvitch, I; Camara, M; Carmona, E; Chilingarian, A; Commichau, S; Contreras, J L; Cortina, J; Costado, M T; Covino, S; Curtef, V; Dazzi, F; De Angelis, A; De Cea Del Pozo, E; de Los Reyes, R; De Lotto, B; De Maria, M; De Sabata, F; Delgado Mendez, C; Dominguez, A; Dorner, D; Doro, M; Elsässer, D; Errando, M; Fagiolini, M; Ferenc, D; Fernandez, E; Firpo, R; Fonseca, M V; Font, L; Galante, N; Garcia Lopez, R J; Garczarczyk, M; Gaug, M; Goebel, F; Hadasch, D; Hayashida, M; Herrero, A; Höhne, D; Hose, J; Hsu, C C; Huber, S; Jogler, T; Kranich, D; La Barbera, A; Laille, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; Lopez, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martinez, M; Mazin, D; Meucci, M; Meyer, M; Miranda, J M; Mirzoyan, R; Moles, M; Moralejo, A; Nieto, D; Nilsson, K; Ninkovic, J; Otte, N; Oya, I; Paoletti, R; Paredes, J M; Pasanen, M; Pascoli, D; Pauss, F; Pegna, R G; Perez-Torres, M A; Persic, M; Peruzzo, L; Piccioli, A; Prada, F; Prandini, E; Puchades, N; Raymers, A; Rhode, W; Ribó, M; Rico, J; Rissi, M; Robert, A; Rügamer, S; Saggion, A; Saito, T Y; Salvati, M; Sanchez-Conde, M; Sartori, P; Satalecka, K; Scalzotto, V; Scapin, V; Schweizer, T; Shayduk, M; Shinozaki, K; Shore, S N; Sidro, N; Sierpowska-Bartosik, A; Sillanpää, A; Sobczynska, D; Spanier, F; Stamerra, A; Stark, L S; Takalo, L; Tavecchio, F; Temnikov, P; Tescaro, D; Teshima, M; Tluczykont, M; Torres, D F; Turini, N; Vankov, H; Venturini, A; Vitale, V; Wagner, R M; Wittek, W; Zabalza, V; Zandanel, F; Zanin, R; Zapatero, J; de Jager, O C; de Ona Wilhelmi, E

2008-11-21

One fundamental question about pulsars concerns the mechanism of their pulsed electromagnetic emission. Measuring the high-end region of a pulsar's spectrum would shed light on this question. By developing a new electronic trigger, we lowered the threshold of the Major Atmospheric gamma-ray Imaging Cherenkov (MAGIC) telescope to 25 giga-electron volts. In this configuration, we detected pulsed gamma-rays from the Crab pulsar that were greater than 25 giga-electron volts, revealing a relatively high cutoff energy in the phase-averaged spectrum. This indicates that the emission occurs far out in the magnetosphere, hence excluding the polar-cap scenario as a possible explanation of our measurement. The high cutoff energy also challenges the slot-gap scenario.

Development of a 3D-Printed Collimated 90Sr Beta Source

NASA Astrophysics Data System (ADS)

Daniel, Byron; NuDot Collaboration

2017-09-01

Collimated beta particle sources based on 90Sr are common calibration sources for atomic decay detector research and development. Due to the short attenuation length of beta particles in matter, the exact geometry of a collimator can drastically change the rate and energy of beta particles exiting the source. 3D printing allows for the quick and easy prototyping of collimators with custom geometries. I will describe the development of a collimator that interfaces directly to a quartz cuvette for the characterization of liquid scintillator cocktails. Future work will include developing a source for the NuDot detector which aims to reconstruct MeV electrons using the separation of Cherenkov and scintillation light. MIT Summer Research Program.

The GlueX DIRC project

DOE PAGES

Stevens, J.; Barbosa, F.; Bessuille, J.; ...

2016-07-20

Here, the GlueX experiment was designed to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions at a new tagged photon beam facility in Hall D at Jefferson Laboratory. The particle identification capabilities of the GlueX experiment will be enhanced by constructing a DIRC (Detection of Internally Reflected Cherenkov light) detector, utilizing components of the decommissioned BaBar DIRC. The DIRC will allow systematic studies of kaon final states that are essential for inferring the quark flavor content of both hybrid and conventional mesons. In this contribution, the design for the GlueX DIRCmore » will be discussed including new expansion volumes, read out with MaPMTs, that are currently under development.« less

The GlueX DIRC detector

NASA Astrophysics Data System (ADS)

Barbosa, F.; Bessuille, J.; Chudakov, E.; Dzhygadlo, R.; Fanelli, C.; Frye, J.; Hardin, J.; Kelsey, J.; Patsyuk, M.; Schwarz, C.; Schwiening, J.; Stevens, J.; Shepherd, M.; Whitlatch, T.; Williams, M.

2017-12-01

The GlueX DIRC (Detection of Internally Reflected Cherenkov light) detector is being developed to upgrade the particle identification capabilities in the forward region of the GlueX experiment at Jefferson Lab. The GlueX DIRC will utilize four existing decommissioned BaBar DIRC bar boxes, which will be oriented to form a plane roughly 4 m away from the fixed target of the experiment. A new photon camera has been designed that is based on the SuperB FDIRC prototype. The full GlueX DIRC system will consist of two such cameras, with the first planned to be built and installed in 2017. We present the current status of the design and R&D, along with the future plans of the GlueX DIRC detector.

The future of RICH detectors through the light of the LHCb RICH

NASA Astrophysics Data System (ADS)

D'Ambrosio, C.; LHCb RICH Collaboration

2017-12-01

The limitations in performance of the present RICH system in the LHCb experiment are given by the natural chromatic dispersion of the gaseous Cherenkov radiator, the aberrations of the optical system and the pixel size of the photon detectors. Moreover, the overall PID performance can be affected by high detector occupancy as the pattern recognition becomes more difficult with high particle multiplicities. This paper shows a way to improve performance by systematically addressing each of the previously mentioned limitations. These ideas are applied in the present and future upgrade phases of the LHCb experiment. Although applied to specific circumstances, they are used as a paradigm on what is achievable in the development and realisation of high precision RICH detectors.

Evidence for a QPO structure in the TeV and X-ray light curve during the 1997 high state γ emission of Mkn 501

NASA Astrophysics Data System (ADS)

Kranich, D.

1999-08-01

The BL Lac Object Mkn 501 was in a state of high activity in the TeV range in 1997. During this time Mkn 501 was observed by all Cherenkov-Telescopes of the HEGRA-Collaboration. Part of the data were also taken during moonshine thus providing a nearly continuous coverage for this object in the TeV-range. We have carried out a QPO analysis and found evidence for a 23 day periodicity. We applied the same analysis on the 'data by dwell' x-ray lightcurve from the RXTE/ASM database and found also evidence for the 23 day periodicity. The combined probability was -.

Wire Chambers and Cherenkov Detectors at Fermilab Test Beam Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tame Narvaez, Karla

2017-01-01

Fermilab Test Beam Facility (FTBF) is dedicated to helping scientists test their prototypes. For this, FTBF has instrumentation that is very useful for the users. However, before a user can test a detector, it is necessary to ensure the facility has the characteristics they need. During this summer, we studied beam properties by collecting Cherenkov and wire chamber data. Analyzed data will be used for updating the general information that FTBF posts on a web page.

Performance of the High Momentum Particle IDentification detector of ALICE during the LHC run period 2015-2016

NASA Astrophysics Data System (ADS)

de Cataldo, G.; ALICE Collaboration

2017-12-01

In the period June 2015-September 2016 the LHC has delivered pp and Pb-Pb collisions respectively at √s=13 TeV and √sNN=5.02 TeV for a total integrated luminosity in ALICE of 14 pb-1. The High Momentum Particle IDentification detector (HMPID) is part of the ALICE experiment. It is based on seven Ring Imaging Cherenkov (RICH) modules, 1.3×1.3 m2 each, with a proximity focusing geometry. The Cherenkov photon detection is achieved by pad segmented photocathodes, coated with 300 nm thick Caesium Iodide layer, installed in multiwire proportional chambers. Liquid C6F14 (perfluorohexane) with n=1.2989 at λ=175 nm is used as Cherenkov radiator. The HMPID identifies with three sigma separation charged π and K in the momentum range 1-3 GeV/c and protons in the range 1.5-5 GeV/c. The scatter plots of the Cherenkov angle for both pp and Pb-Pb events are presented as preliminary Particle Identification (PID) performance. After the good results shown during 2010-2013, in this paper the HMPID performance in the period 2015-2016, with emphasis on the CsI quantum efficiency stability, are presented. Finally the perspectives of the detector operation in the period HL-LHC 2019-2022, are briefly discussed.

Sedimentation and fouling of optical surfaces at the ANTARES site

NASA Astrophysics Data System (ADS)

ANTARES Collaboration; CAU CEFREM Collaboration; Amram, P.; Anghinolfi, M.; Anvar, S.; Ardellier-Desages, F. E.; Aslanides, E.; Aubert, J.-J.; Azoulay, R.; Bailey, D.; Basa, S.; Battaglieri, M.; Bellotti, R.; Beltramelli, J.; Benhammou, Y.; Berthier, R.; Bertin, V.; Billault, M.; Blaes, R.; Bland, R. W.; Blondeau, F.; de Botton, N.; Boulesteix, J.; Brooks, C. B.; Brunner, J.; Cafagna, F.; Calzas, A.; Capone, A.; Caponetto, L.; Cârloganu, C.; Carmona, E.; Carr, J.; Cartwright, S. L.; Cecchini, S.; Ciacio, F.; Circella, M.; Compère, C.; Cooper, S.; Coyle, P.; Cuneo, S.; Danilov, M.; van Dantzig, R.; de Marzo, C.; Destelle, J.-J.; de Vita, R.; Dispau, G.; Druillole, F.; Engelen, J.; Feinstein, F.; Ferdi, C.; Festy, D.; Fopma, J.; Gallone, J.-M.; Giacomelli, G.; Goret, P.; Gournay, J.-F.; Hallewell, G.; Heijboer, A.; Hernández-Rey, J. J.; Hubbard, J. R.; Jaquet, M.; de Jong, M.; Karolak, M.; Keller, P.; Kooijman, P.; Kouchner, A.; Kudryavtsev, V. A.; Lafoux, H.; Lagier, P.; Lamare, P.; Languillat, J.-C.; Laubier, L.; Laugier, J.-P.; Leilde, B.; Le Provost, H.; Le van Suu, A.; Lo Nigro, L.; Lo Presti, D.; Loucatos, S.; Louis, F.; Lyashuk, V.; Magnier, P.; Marcelin, M.; Margiotta, A.; Masullo, R.; Mazéas, F.; Mazeau, B.; Mazure, A.; McMillan, J. E.; Migneco, E.; Millot, C.; Mols, P.; Montanet, F.; Montaruli, T.; Moscoso, L.; Musumeci, M.; Nezri, E.; Nooren, G. J.; Oberski, J. E. J.; Olivetto, C.; Oppelt-Pohl, A.; Palanque-Delabrouille, N.; Papaleo, R.; Payre, P.; Perrin, P.; Petruccetti, M.; Petta, C.; Piattelli, P.; Poinsignon, J.; Potheau, R.; Queinec, Y.; Racca, C.; Raia, G.; Randazzo, N.; Rethore, F.; Riccobene, G.; Ricol, J.-S.; Ripani, M.; Roca-Blay, V.; Romeyer, A.; Rostovstev, A.; Russo, G. V.; Sacquin, Y.; Salusti, E.; Schuller, J.-P.; Schuster, W.; Soirat, J.-P.; Souvorova, O.; Spooner, N. J. C.; Spurio, M.; Stolarczyk, T.; Stubert, D.; Taiuti, M.; Tao, C.; Thompson, L. F.; Tilav, S.; Triay, R.; Usik, A.; Valdy, P.; Valente, V.; Varlamov, I.; Vaudaine, G.; Vernin, P.; Vladimirsky, E.; Vorobiev, M.; de Witt Huberts, P.; de Wolf, E.; Zakharov, V.; Zavatarelli, S.; Zornoza, Juan de Dios; Zún~Iga, J.; Aloïsi, J.-C.; Kerhervé, Ph.; Monaco, A.

2003-05-01

ANTARES is a project leading towards the construction and deployment of a neutrino telescope in the deep Mediterranean Sea. The telescope will use an array of photomultiplier tubes to detect the Cherenkov light emitted by muons resulting from the interaction with matter of high energy neutrinos. In the vicinity of the deployment site the ANTARES Collaboration has performed a series of in situ measurements to study the change in light transmission through glass surfaces during immersions of several months. The average loss of light transmission is estimated to be only ~2% at the equator of a glass sphere one year after deployment. It decreases with increasing zenith angle, and tends to saturate with time. The transmission loss, therefore, is expected to remain small for the several year lifetime of the ANTARES detector whose optical modules are oriented downwards. The measurements were complemented by the analysis of the 210Pb activity profile in sediment cores and the study of biofouling on glass plates. Despite a significant sedimentation rate at the site, in the 0.02-0.05 cmyr-1 range, the sediments adhere loosely to the glass surfaces and can be washed off by water currents. Further, fouling by deposits of light-absorbing particulates is only significant for surfaces facing upwards.

Bandwidth tunable THz wave generation in large-area periodically poled lithium niobate.

PubMed

Zhang, Caihong; Avetisyan, Yuri; Glosser, Andreas; Kawayama, Iwao; Murakami, Hironaru; Tonouchi, Masayoshi

2012-04-09

A new scheme of optical rectification (OR) of femtosecond laser pulses in a periodically poled lithium niobate (PPLN) crystal, which generates high energy and bandwidth tunable multicycle THz pulses, is proposed and demonstrated. We show that the number of the oscillation cycles of the THz electric field and therefore bandwidth of generated THz spectrum can easily and smoothly be tuned from a few tens of GHz to a few THz by changing the pump optical spot size on PPLN crystal. The minimal bandwidth is 17 GHz that is smallest ever of reported in scheme of THz generation by OR at room temperature. Similar to the case of Cherenkov-type OR in single-domain LiNbO₃, the spectrum of THz generation extends from 0.1 THz to 3 THz when laser beam is focused to a size close to half-period of PPLN structure. The energy spectral density of narrowband THz generation is almost independent of the bandwidth and is typically 220 nJ/THz for ~1 W pump power at 1 kHz repetition rate.

On the theory of polarization radiation in media with sharp boundaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karlovets, D. V., E-mail: d.karlovets@gmail.com

2011-07-15

Polarization radiation generated when a point charge moves uniformly along a straight line in vacuum in the vicinity of media with a finite permittivity {epsilon}({omega}) = {epsilon} Prime + i{epsilon} Double-Prime and sharp boundaries is considered. A method is developed in which polarization radiation is represented as the field of the current induced in the substance by the field of the moving charge. The solution to the problem of radiation induced when a charge moves along the axis of a cylindrical vacuum channel in a thin screen with a finite radius and a finite permittivity is obtained. Depending on themore » parameters of the problem, this solution describes various types of radiation (Cherenkov, transition, and diffraction radiation). In particular, when the channel radius tends to zero and the outer radius of the screen tends to infinity, the expression derived for the emitted energy coincides with the known solution for transition radiation in a plate. In another particular case of ideal conductivity ({epsilon} Double-Prime {yields} {infinity}), the relevant formula coincides with the known results for diffraction radiation from a circular aperture in an infinitely thin screen. The solution is obtained to the problem of radiation generated when the charge flies near a thin rectangular screen with a finite permittivity. This solution describes the diffraction and Cherenkov mechanisms of radiation and takes into account possible multiple re-reflections of radiation in the screen. The solution to the problem of radiation generated when a particles flies near a thin grating consisting of a finite number of strips having a rectangular cross section and a finite permittivity and separated by vacuum gaps (Smith-Purcell radiation) is also obtained. In the special case of ideal conductivity, the expression derived for the emitted energy coincides with the known result in the model of surface currents.« less

Commissioning and first tests of the MAGIC telescope

NASA Astrophysics Data System (ADS)

Baixeras, C.; Bastieri, D.; Bigongiari, C.; Blanch, O.; Blanchot, G.; Bock, R.; Bretz, T.; Chilingarian, A.; Coarasa, J. A.; Colombo, E.; Contreras, J. C.; Corti, D.; Cortina, J.; Domingo, C.; Domingo, E.; Ferenc, D.; Fernández, E.; Flix, J.; Fonseca, V.; Font, L.; Galante, N.; Gaug, M.; Garczarczyk, M.; Gebauer, J.; Giller, M.; Goebel, F.; Hengstebeck, T.; Jacone, P.; de Jager, O. C.; Kalekin, O.; Kestel, M.; Kneiske, T.; Laille, A.; López, M.; López, J.; Lorenz, E.; Mannheim, K.; Mariotti, M.; Martínez, M.; Mase, K.; Merck, M.; Meucci, M.; Miralles, L.; Mirzoyan, R.; Moralejo, A.; Wilhelmi, E. Oña; Orduña, R.; Paneque, D.; Paoletti, R.; Pascoli, D.; Pavel, N.; Pegna, R.; Peruzzo, L.; Piccioli, A.; Roberts, A.; Reyes, R.; Saggion, A.; Sánchez, A.; Sartori, P.; Scalzotto, V.; Schweizer, T.; Sillanpaa, A.; Sobczynska, D.; Stamerra, A.; Stepanian, A.; Stiehler, R.; Takalo, L.; Teshima, M.; Tonello, N.; Torres, A.; Turini, N.; Vitale, V.; Volkov, S.; Wagner, R. M.; Wibig, T.; Wittek, W.

2004-02-01

Major Atmospheric Gamma Imaging Cherenkov telescope is starting its operations with a set of engineering runs to tune the telescope subsystem elements to be ready for the first physics campaign. Many technical improvements have been developed and implemented in several elements of the telescope to reach the lowest energy threshold ever obtained by an Imaging Atmospheric Cherenkov Telescope. A general description of the telescope is presented. The commissioning of the telescope's elements is described and the expected performances are reviewed with the final detector set-up.

Application of imaging to the atmospheric Cherenkov technique

NASA Technical Reports Server (NTRS)

Cawley, M. F.; Fegan, D. J.; Gibbs, K.; Gorham, P. W.; Hillas, A. M.; Lamb, R. C.; Liebing, D. F.; Mackeown, P. K.; Porter, N. A.; Stenger, V. J.

1985-01-01

Turver and Weekes proposed using a system of phototubes in the focal plane of a large reflector to give an air Cherenkov camera for gamma ray astronomy. Preliminary results with a 19 element camera have been reported previously. In 1983 the camera was increased to 37 pixels; it has now been routinely operated for two years. A brief physical description of the camera, its mode of operation, and the data reduction procedures are presented. The Monte Carlo simultations on which these are based on also reviewed.

Kernel analysis in TeV gamma-ray selection

NASA Astrophysics Data System (ADS)

Moriarty, P.; Samuelson, F. W.

2000-06-01

We discuss the use of kernel analysis as a technique for selecting gamma-ray candidates in Atmospheric Cherenkov astronomy. The method is applied to observations of the Crab Nebula and Markarian 501 recorded with the Whipple 10 m Atmospheric Cherenkov imaging system, and the results are compared with the standard Supercuts analysis. Since kernel analysis is computationally intensive, we examine approaches to reducing the computational load. Extension of the technique to estimate the energy of the gamma-ray primary is considered. .

First light on a new fully digital camera based on SiPM for CTA SST-1M telescope

NASA Astrophysics Data System (ADS)

della Volpe, Domenico; Al Samarai, Imen; Alispach, Cyril; Bulik, Tomasz; Borkowski, Jerzy; Cadoux, Franck; Coco, Victor; Favre, Yannick; Grudzińska, Mira; Heller, Matthieu; Jamrozy, Marek; Kasperek, Jerzy; Lyard, Etienne; Mach, Emil; Mandat, Dusan; Michałowski, Jerzy; Moderski, Rafal; Montaruli, Teresa; Neronov, Andrii; Niemiec, Jacek; Njoh Ekoume, T. R. S.; Ostrowski, Michal; Paśko, Paweł; Pech, Miroslav; Rajda, Pawel; Rafalski, Jakub; Schovanek, Petr; Seweryn, Karol; Skowron, Krzysztof; Sliusar, Vitalii; Stawarz, Łukasz; Stodulska, Magdalena; Stodulski, Marek; Travnicek, Petr; Troyano Pujadas, Isaac; Walter, Roland; Zagdański, Adam; Zietara, Krzysztof

2017-08-01

The Cherenkov Telescope Array (CTA) will explore with unprecedented precision the Universe in the gammaray domain covering an energy range from 50 GeV to more the 300 TeV. To cover such a broad range with a sensitivity which will be ten time better than actual instruments, different types of telescopes are needed: the Large Size Telescopes (LSTs), with a ˜24 m diameter mirror, a Medium Size Telescopes (MSTs), with a ˜12 m mirror and the small size telescopes (SSTs), with a ˜4 m diameter mirror. The single mirror small size telescope (SST-1M), one of the proposed solutions to become part of the small-size telescopes of CTA, will be equipped with an innovative camera. The SST-1M has a Davies-Cotton optical design with a mirror dish of 4 m diameter and focal ratio 1.4 focussing the Cherenkov light produced in atmospheric showers onto a 90 cm wide hexagonal camera providing a FoV of 9 degrees. The camera is an innovative design based on silicon photomultipliers (SiPM ) and adopting a fully digital trigger and readout architecture. The camera features 1296 custom designed large area hexagonal SiPM coupled to hollow optical concentrators to achieve a pixel size of almost 2.4 cm. The SiPM is a custom design developed with Hamamatsu and with its active area of almost 1 cm2 is one of the largest monolithic SiPM existing. Also the optical concentrators are innovative being light funnels made of a polycarbonate substrate coated with a custom designed UV-enhancing coating. The analog signals coming from the SiPM are fed into the fully digital readout electronics, where digital data are processed by high-speed FPGAs both for trigger and readout. The trigger logic, implemented into an Virtex 7 FPGA, uses the digital data to elaborate a trigger decision by matching data against predefined patterns. This approach is extremely flexible and allows improvements and continued evolutions of the system. The prototype camera is being tested in laboratory prior to its installation expected in fall 2017 on the telescope prototype in Krakow (Poland). In this contribution, we will describe the design of the camera and show the performance measured in laboratory.

WE-AB-BRB-02: Methods and Applications of 3D Radiochromic Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oldham, M.

Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required. At the heart of radiation therapy dosimetry is the multidimensional dosimeter. However, due to the limited availability ofmore » water-equivalent dosimetry materials, research and development in this important field is challenging. In this session, we will review a few dosimeter developments that are either in the laboratory phase or in the pre-commercialization phase. 1) Radiochromic plastic. Novel formulations exhibit light absorbing optical contrast with very little scatter, enabling faster, broad beam optical CT design. 2) Storage phosphor. After irradiation, the dosimetry panels will be read out using a dedicated 2D scanning apparatus in a non-invasive, electro-optic manner and immediately restored for further use. 3) Liquid scintillator. Scintillators convert the energy from x-rays and proton beams into visible light, which can be recorded with a scientific camera (CCD or CMOS) from multiple angles. The 3D shape of the dose distribution can then be reconstructed. 4) Cherenkov emission imaging. Gated intensified imaging allows video-rate passive detection of Cherenkov emission during radiation therapy with the room lights on. Learning Objectives: To understand the physics of a variety of dosimetry techniques based upon optical imaging To investigate the strategies to overcome respective challenges and limitations To explore novel ideas of dosimeter design Supported in part by NIH Grants R01CA148853, R01CA182450, R01CA109558. Brian Pogue is founder and president of the company DoseOptics LLC, dedicated to developing and commercializing the first dedicated Cerenkov imaging camera and system for radiation dose imaging. Work reported in this talk does not involve the use of DoseOptics technology.; H. Li, this work was supported in part by NIH Grant No. R01CA148853; S. Beddar, NIH funding R01-CA182450.« less

WE-AB-BRB-03: Real-Time Volumetric Scintillation Dosimetry for Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beddar, S.

Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required. At the heart of radiation therapy dosimetry is the multidimensional dosimeter. However, due to the limited availability ofmore » water-equivalent dosimetry materials, research and development in this important field is challenging. In this session, we will review a few dosimeter developments that are either in the laboratory phase or in the pre-commercialization phase. 1) Radiochromic plastic. Novel formulations exhibit light absorbing optical contrast with very little scatter, enabling faster, broad beam optical CT design. 2) Storage phosphor. After irradiation, the dosimetry panels will be read out using a dedicated 2D scanning apparatus in a non-invasive, electro-optic manner and immediately restored for further use. 3) Liquid scintillator. Scintillators convert the energy from x-rays and proton beams into visible light, which can be recorded with a scientific camera (CCD or CMOS) from multiple angles. The 3D shape of the dose distribution can then be reconstructed. 4) Cherenkov emission imaging. Gated intensified imaging allows video-rate passive detection of Cherenkov emission during radiation therapy with the room lights on. Learning Objectives: To understand the physics of a variety of dosimetry techniques based upon optical imaging To investigate the strategies to overcome respective challenges and limitations To explore novel ideas of dosimeter design Supported in part by NIH Grants R01CA148853, R01CA182450, R01CA109558. Brian Pogue is founder and president of the company DoseOptics LLC, dedicated to developing and commercializing the first dedicated Cerenkov imaging camera and system for radiation dose imaging. Work reported in this talk does not involve the use of DoseOptics technology.; H. Li, this work was supported in part by NIH Grant No. R01CA148853; S. Beddar, NIH funding R01-CA182450.« less

WE-AB-BRB-01: Memorial Introduction; Storage Phosphor Panels for Radiation Therapy Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, H.

Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required. At the heart of radiation therapy dosimetry is the multidimensional dosimeter. However, due to the limited availability ofmore » water-equivalent dosimetry materials, research and development in this important field is challenging. In this session, we will review a few dosimeter developments that are either in the laboratory phase or in the pre-commercialization phase. 1) Radiochromic plastic. Novel formulations exhibit light absorbing optical contrast with very little scatter, enabling faster, broad beam optical CT design. 2) Storage phosphor. After irradiation, the dosimetry panels will be read out using a dedicated 2D scanning apparatus in a non-invasive, electro-optic manner and immediately restored for further use. 3) Liquid scintillator. Scintillators convert the energy from x-rays and proton beams into visible light, which can be recorded with a scientific camera (CCD or CMOS) from multiple angles. The 3D shape of the dose distribution can then be reconstructed. 4) Cherenkov emission imaging. Gated intensified imaging allows video-rate passive detection of Cherenkov emission during radiation therapy with the room lights on. Learning Objectives: To understand the physics of a variety of dosimetry techniques based upon optical imaging To investigate the strategies to overcome respective challenges and limitations To explore novel ideas of dosimeter design Supported in part by NIH Grants R01CA148853, R01CA182450, R01CA109558. Brian Pogue is founder and president of the company DoseOptics LLC, dedicated to developing and commercializing the first dedicated Cerenkov imaging camera and system for radiation dose imaging. Work reported in this talk does not involve the use of DoseOptics technology.; H. Li, this work was supported in part by NIH Grant No. R01CA148853; S. Beddar, NIH funding R01-CA182450.« less

WE-AB-BRB-00: Session in Memory of Robert J. Shalek: High Resolution Dosimetry from 2D to 3D to Real-Time 3D

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required. At the heart of radiation therapy dosimetry is the multidimensional dosimeter. However, due to the limited availability ofmore » water-equivalent dosimetry materials, research and development in this important field is challenging. In this session, we will review a few dosimeter developments that are either in the laboratory phase or in the pre-commercialization phase. 1) Radiochromic plastic. Novel formulations exhibit light absorbing optical contrast with very little scatter, enabling faster, broad beam optical CT design. 2) Storage phosphor. After irradiation, the dosimetry panels will be read out using a dedicated 2D scanning apparatus in a non-invasive, electro-optic manner and immediately restored for further use. 3) Liquid scintillator. Scintillators convert the energy from x-rays and proton beams into visible light, which can be recorded with a scientific camera (CCD or CMOS) from multiple angles. The 3D shape of the dose distribution can then be reconstructed. 4) Cherenkov emission imaging. Gated intensified imaging allows video-rate passive detection of Cherenkov emission during radiation therapy with the room lights on. Learning Objectives: To understand the physics of a variety of dosimetry techniques based upon optical imaging To investigate the strategies to overcome respective challenges and limitations To explore novel ideas of dosimeter design Supported in part by NIH Grants R01CA148853, R01CA182450, R01CA109558. Brian Pogue is founder and president of the company DoseOptics LLC, dedicated to developing and commercializing the first dedicated Cerenkov imaging camera and system for radiation dose imaging. Work reported in this talk does not involve the use of DoseOptics technology.; H. Li, this work was supported in part by NIH Grant No. R01CA148853; S. Beddar, NIH funding R01-CA182450.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogue, B.

Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required. At the heart of radiation therapy dosimetry is the multidimensional dosimeter. However, due to the limited availability ofmore » water-equivalent dosimetry materials, research and development in this important field is challenging. In this session, we will review a few dosimeter developments that are either in the laboratory phase or in the pre-commercialization phase. 1) Radiochromic plastic. Novel formulations exhibit light absorbing optical contrast with very little scatter, enabling faster, broad beam optical CT design. 2) Storage phosphor. After irradiation, the dosimetry panels will be read out using a dedicated 2D scanning apparatus in a non-invasive, electro-optic manner and immediately restored for further use. 3) Liquid scintillator. Scintillators convert the energy from x-rays and proton beams into visible light, which can be recorded with a scientific camera (CCD or CMOS) from multiple angles. The 3D shape of the dose distribution can then be reconstructed. 4) Cherenkov emission imaging. Gated intensified imaging allows video-rate passive detection of Cherenkov emission during radiation therapy with the room lights on. Learning Objectives: To understand the physics of a variety of dosimetry techniques based upon optical imaging To investigate the strategies to overcome respective challenges and limitations To explore novel ideas of dosimeter design Supported in part by NIH Grants R01CA148853, R01CA182450, R01CA109558. Brian Pogue is founder and president of the company DoseOptics LLC, dedicated to developing and commercializing the first dedicated Cerenkov imaging camera and system for radiation dose imaging. Work reported in this talk does not involve the use of DoseOptics technology.; H. Li, this work was supported in part by NIH Grant No. R01CA148853; S. Beddar, NIH funding R01-CA182450.« less

Real-time track-less Cherenkov ring fitting trigger system based on Graphics Processing Units

NASA Astrophysics Data System (ADS)

Ammendola, R.; Biagioni, A.; Chiozzi, S.; Cretaro, P.; Cotta Ramusino, A.; Di Lorenzo, S.; Fantechi, R.; Fiorini, M.; Frezza, O.; Gianoli, A.; Lamanna, G.; Lo Cicero, F.; Lonardo, A.; Martinelli, M.; Neri, I.; Paolucci, P. S.; Pastorelli, E.; Piandani, R.; Piccini, M.; Pontisso, L.; Rossetti, D.; Simula, F.; Sozzi, M.; Vicini, P.

2017-12-01

The parallel computing power of commercial Graphics Processing Units (GPUs) is exploited to perform real-time ring fitting at the lowest trigger level using information coming from the Ring Imaging Cherenkov (RICH) detector of the NA62 experiment at CERN. To this purpose, direct GPU communication with a custom FPGA-based board has been used to reduce the data transmission latency. The GPU-based trigger system is currently integrated in the experimental setup of the RICH detector of the NA62 experiment, in order to reconstruct ring-shaped hit patterns. The ring-fitting algorithm running on GPU is fed with raw RICH data only, with no information coming from other detectors, and is able to provide more complex trigger primitives with respect to the simple photodetector hit multiplicity, resulting in a higher selection efficiency. The performance of the system for multi-ring Cherenkov online reconstruction obtained during the NA62 physics run is presented.

Sensitivity of the Cherenkov Telescope Array to the detection of a dark matter signal in comparison to direct detection and collider experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balazs, Csaba; Conrad, Jan; Farmer, Ben

Imaging atmospheric Cherenkov telescopes (IACTs) that are sensitive to potential γ-ray signals from dark matter (DM) annihilation above ~50 GeV will soon be superseded by the Cherenkov Telescope Array (CTA). CTA will have a point source sensitivity an order of magnitude better than currently operating IACTs and will cover a broad energy range between 20 GeV and 300 TeV. Using effective field theory and simplified models to calculate γ-ray spectra resulting from DM annihilation, we compare the prospects to constrain such models with CTA observations of the Galactic center with current and near-future measurements at the Large Hadron Collider (LHC)more » and direct detection experiments. Here, for DM annihilations via vector or pseudoscalar couplings, CTA observations will be able to probe DM models out of reach of the LHC, and, if DM is coupled to standard fermions by a pseudoscalar particle, beyond the limits of current direct detection experiments.« less

Astroparticle Physics: Detectors for Cosmic Rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salazar, Humberto; Villasenor, Luis

2006-09-25

We describe the work that we have done over the last decade to design and construct instruments to measure properties of cosmic rays in Mexico. We describe the measurement of the muon lifetime and the ratio of positive to negative muons in the natural background of cosmic ray muons at 2000 m.a.s.l. Next we describe the detection of decaying and crossing muons in a water Cherenkov detector as well as a technique to separate isolated particles. We also describe the detection of isolated muons and electrons in a liquid scintillator detector and their separation. Next we describe the detection ofmore » extensive air showers (EAS) with a hybrid detector array consisting of water Cherenkov and liquid scintillator detectors, located at the campus of the University of Puebla. Finally we describe work in progress to detect EAS at 4600 m.a.s.l. with a water Cherenkov detector array and a fluorescence telescope at the Sierra Negra mountain.« less

An engineering array for the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory

NASA Astrophysics Data System (ADS)

Longo, Megan; Mostafa, Miguel

2012-03-01

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is currently being deployed at 4100 m in Sierra Negra, Mexico. The HAWC observatory will have 300 Water Cherenkov Detectors (WCDs). Each WCD will be instrumented with 4 upward facing baffled photo multiplier tubes (PMTs) anchored to the bottom of a 5 m deep by 7.3 m diameter steel container with a multilayer hermetic plastic bag containing 200,000 liters of purified water. An engineering array of 6 WCDs was deployed in Summer 2011 at the HAWC site and has been operational since then. This array serves to validate the design and construction methods for the HAWC observatory. It has also been collecting data which allows for the development of data collection and analysis tools. Here we will describe the deployment of the engineering array, the lessons learned from this experience and the implications for HAWC, as well as give an introduction into data collection and initial analysis being done, which will be presented jointly.

Sensitivity of the Cherenkov Telescope Array to the detection of a dark matter signal in comparison to direct detection and collider experiments

DOE PAGES

Balazs, Csaba; Conrad, Jan; Farmer, Ben; ...

2017-10-04

Imaging atmospheric Cherenkov telescopes (IACTs) that are sensitive to potential γ-ray signals from dark matter (DM) annihilation above ~50 GeV will soon be superseded by the Cherenkov Telescope Array (CTA). CTA will have a point source sensitivity an order of magnitude better than currently operating IACTs and will cover a broad energy range between 20 GeV and 300 TeV. Using effective field theory and simplified models to calculate γ-ray spectra resulting from DM annihilation, we compare the prospects to constrain such models with CTA observations of the Galactic center with current and near-future measurements at the Large Hadron Collider (LHC)more » and direct detection experiments. Here, for DM annihilations via vector or pseudoscalar couplings, CTA observations will be able to probe DM models out of reach of the LHC, and, if DM is coupled to standard fermions by a pseudoscalar particle, beyond the limits of current direct detection experiments.« less

Characterization of the ETEL D784UKFLB 11 in. photomultiplier tube

NASA Astrophysics Data System (ADS)

Barros, N.; Kaptanoglu, T.; Kimelman, B.; Klein, J. R.; Moore, E.; Nguyen, J.; Stavreva, K.; Svoboda, R.

2017-04-01

Water Cherenkov and scintillator detectors are a critical tool for neutrino physics. Their large size, low threshold, and low operational cost make them excellent detectors for long baseline neutrino oscillations, proton decay, supernova and solar neutrinos, double beta decay, and ultra-high energy astrophysical neutrinos. Proposals for a new generation of large detectors rely on the availability of large format, fast, cost-effective photomultiplier tubes. The Electron Tubes Enterprises, Ltd (ETEL) D784KFLB 11 in. Photomultiplier Tube has been developed for large neutrino detectors. We have measured the timing characteristics, relative efficiency, and magnetic field sensitivity of the first fifteen prototypes.

Development of Camera Electronics for the Advanced Gamma-ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Tajima, Hiroyasu

2009-05-01

AGIS, a next generation of atmospheric Cherenkov telescope arrays, aims to achieve a sensitivity level of a milliCrab for gamma-ray observations in in the energy band of 40 GeV to 100 TeV. Such improvement requires cost reduction of individual components with high reliability in order to equip the order of 100 telescopes necessary to achieve the sensitivity goal. We are exploring several design concepts to reduce the cost of camera electronics while improving their performance. We have developed test systems for some of these concepts and are testing their performance. Here we present test results of the test systems.

The Advanced Gamma-ray Imaging System (AGIS) - Camera Electronics Development

NASA Astrophysics Data System (ADS)

Tajima, Hiroyasu; Bechtol, K.; Buehler, R.; Buckley, J.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Hanna, D.; Horan, D.; Humensky, B.; Karlsson, N.; Kieda, D.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Mukherjee, R.; Ong, R.; Otte, N.; Quinn, J.; Schroedter, M.; Swordy, S.; Wagner, R.; Wakely, S.; Weinstein, A.; Williams, D.; Camera Working Group; AGIS Collaboration

2010-03-01

AGIS, a next-generation imaging atmospheric Cherenkov telescope (IACT) array, aims to achieve a sensitivity level of about one milliCrab for gamma-ray observations in the energy band of 50 GeV to 100 TeV. Achieving this level of performance will require on the order of 50 telescopes with perhaps as many as 1M total electronics channels. The larger scale of AGIS requires a very different approach from the currently operating IACTs, with lower-cost and lower-power electronics incorporated into camera modules designed for high reliability and easy maintenance. Here we present the concept and development status of the AGIS camera electronics.

The Advanced Gamma-ray Imaging System (AGIS): A Nanosecond Time Scale Stereoscopic Array Trigger System.

NASA Astrophysics Data System (ADS)

Krennrich, Frank; Buckley, J.; Byrum, K.; Dawson, J.; Drake, G.; Horan, D.; Krawzcynski, H.; Schroedter, M.

2008-04-01

Imaging atmospheric Cherenkov telescope arrays (VERITAS, HESS) have shown unprecedented background suppression capabilities for reducing cosmic-ray induced air showers, muons and night sky background fluctuations. Next-generation arrays with on the order of 100 telescopes offer larger collection areas, provide the possibility to see the air shower from more view points on the ground, have the potential to improve the sensitivity and give additional background suppression. Here we discuss the design of a fast array trigger system that has the potential to perform a real time image analysis allowing substantially improved background rate suppression at the trigger level.

Determination of beta emitters ( 90Sr, 14C and 3H) in routine measurements using plastic scintillation beads

NASA Astrophysics Data System (ADS)

Tarancón, A.; García, J. F.; Rauret, G.

2004-01-01

Plastic scintillation has recently been shown to be a powerful alternative to liquid scintillation and Cherenkov techniques in radionuclide determination due to the good values obtained for the measurement parameters and the low amount of wastes generated. The present study evaluated the capability of plastic scintillation beads and polyethylene vials for routine measurements of beta emitters ( 90Sr, 14C, 3H). Results show that high- and medium-energetic beta emitters can be quantified with relative errors less than 5% in low-activity aqueous samples, whereas low-energetic beta emitters can only be quantified in medium-activity samples.

Sensivity studies for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Collado, Tarek Hassan

2015-06-01

Since the creation of the first telescope in the 17th century, every major discovery in astrophysics has been the direct consequence of the development of novel observation techniques, opening new windows in the electromagnetic spectrum. After Karl Jansky discovered serendipitously the first radio source in 1933, Grote Reber built the first parabolic radio telescope in his backyard, planting the seed of a whole new field in astronomy. Similarly, new technologies in the 1950s allowed the establishment of other fields, such as the infrared, ultraviolet or the X-rays. The highest energy end of the electromagnetic spectrum, the γ-ray range, represents the last unexplored window for astronomers and should reveal the most extreme phenomena that take place in the Universe. Given the technical complexity of γ-ray detection and the extremely relative low fluxes, γ-ray astronomy has undergone a slower development compared to other wavelengths. Nowadays, the great success of consecutive space missions together with the development and refinement of new detection techniques from the ground, has allowed outstanding scientific results and has brought gamma-ray astronomy to a worthy level in par with other astronomy fields. This work is devoted to the study and improvement of the future Cherenkov Telescope Array (CTA), the next generation of ground based γ-ray detectors, designed to observe photons with the highest energies ever observed from cosmic sources.

The GlueX DIRC detector

DOE PAGES

Barbosa, F.; Bessuille, J.; Chudakov, E.; ...

2017-02-03

We present the GlueX DIRC (Detection of Internally Reflected Cherenkov light) detector that is being developed to upgrade the particle identification capabilities in the forward region of the GlueX experiment at Jefferson Lab. The GlueX DIRC will utilize four existing decommissioned BaBar DIRC bar boxes, which will be oriented to form a plane roughly 4 m away from the fixed target of the experiment. A new photon camera has been designed that is based on the SuperB FDIRC prototype. The full GlueX DIRC system will consist of two such cameras, with the first planned to be built and installed inmore » 2017. In addition, we present the current status of the design and R&D, along with the future plans of the GlueX DIRC detector.« less

Search for Gamma Ray Bursts at Sierra Negra, Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salazar, H.; Alvarez, C.; Martinez, O.

2006-09-25

We present results from a search for GRBs in the energy range from tens of GeVs to one TeV with an array of 4 water Cherenkov detectors located at 4550 m a.s.l. as part of the high mountain observatory of Sierra Negra (N18 deg. 59.1, W97 deg. 18.76) near Puebla city in Mexico. The detectors consist of light-tight cylindrical containers of 1 m2 and 4 m2 cross section filled with purified water; they are spaced 25 m and have a 5'' photomultiplier (EMI model 9030A) facing down along the cylindrical axis. We report the measured rates of the electromagnetic andmore » mounic components of the background as the photon estimated flux.« less

Novae as Tevatrons: prospects for CTA and IceCube

NASA Astrophysics Data System (ADS)

Metzger, B. D.; Caprioli, D.; Vurm, I.; Beloborodov, A. M.; Bartos, I.; Vlasov, A.

2016-04-01

The discovery of novae as sources of ˜0.1-1 GeV gamma-rays highlights the key role of shocks and relativistic particle acceleration in these transient systems. Although there is evidence for a spectral cut-off above energies ˜1-100 GeV at particular epochs in some novae, the maximum particle energy achieved in these accelerators has remained an open question. The high densities of the nova ejecta (˜10 orders of magnitude larger than in supernova remnants) render the gas far upstream of the shock neutral and shielded from ionizing radiation. The amplification of the magnetic field needed for diffusive shock acceleration requires ionized gas, thus confining the acceleration process to a narrow photoionized layer immediately ahead of the shock. Based on the growth rate of the hybrid non-resonant cosmic ray current-driven instability (considering also ion-neutral damping), we quantify the maximum particle energy, Emax, across the range of shock velocities and upstream densities of interest. We find values of Emax ˜ 10 GeV-10 TeV, which are broadly consistent with the inferred spectral cut-offs, but which could also in principle lead to emission extending to ≳ 100 GeV accessible to atmosphere Cherenkov telescopes, such as the Cherenkov Telescope Array (CTA). Detecting TeV neutrinos with IceCube is more challenging, although the prospects are improved for a nearby event (≲ kpc) or if the shock power during the earliest, densest phases of the outburst is higher than implied by the GeV light curves, due to downscattering of the gamma-rays within the ejecta.

ORCA: measuring the neutrino mass hierarchy with an underwater Cherenkov detector

NASA Astrophysics Data System (ADS)

Hofestädt, Jannik; KM3NeT Collaboration

2016-04-01

It has recently been suggested that the neutrino mass hierarchy can be determined from the oscillation pattern of atmospheric neutrinos passing through the Earth in the energy regime of about 3-20 GeV. In this paper we present the status of a feasibility study for 'Oscillation Research with Cosmics in the Abyss' (ORCA) to evaluate the potential of a megaton-scale underwater Cherenkov detector to determine the mass hierarchy employing the deep-sea neutrino telescope technology developed for the KM3NeT project.

Application of machine learning techniques to lepton energy reconstruction in water Cherenkov detectors

NASA Astrophysics Data System (ADS)

Drakopoulou, E.; Cowan, G. A.; Needham, M. D.; Playfer, S.; Taani, M.

2018-04-01

The application of machine learning techniques to the reconstruction of lepton energies in water Cherenkov detectors is discussed and illustrated for TITUS, a proposed intermediate detector for the Hyper-Kamiokande experiment. It is found that applying these techniques leads to an improvement of more than 50% in the energy resolution for all lepton energies compared to an approach based upon lookup tables. Machine learning techniques can be easily applied to different detector configurations and the results are comparable to likelihood-function based techniques that are currently used.

Inter/intramolecular Cherenkov radiation energy transfer (CRET) from a fluorophore with a built-in radionuclide.

PubMed

Bernhard, Yann; Collin, Bertrand; Decréau, Richard A

2014-06-28

The Cherenkov radiation (CR) from [(18)F]-FDG, [(177)Lu]-LuCl3 and [(90)Y]-YCl3 was detected and CR energy transfer (CRET) to several fluorophores was examined. Subsequent fluorescence emission was found to be a function of the position of absorption bands with respect to the CR peak, energy of emitted particles, radionuclide/fluorophore loading, and fluorophore brightness. A variant of the best fluorophore with a built-in radionuclide was synthesized to achieve inter- and intra-molecular CRET.

TeV radiation from the Crab nebula and other matters

NASA Technical Reports Server (NTRS)

Lamb, R. C.

1990-01-01

The detection of the Crab Nebula via the Cherenkov imaging technique places TeV astronomy on a secure observational footing. The motivation for TeV observations, a discussion of the atmospheric Cherenkov technique, the experimental details of the Crab Nebula detection, and its scientific implications are presented. The present dilemma of VHE/UHE astronomy is that the Crab appears to be the only source whose showers match theoretical expectations. The situation will be clarified as improved ground-based detectors come on-line with sensitivities matching those of the GRO (Gamma Ray Observatory) instruments.

High zenith angle observations of PKS 2155-304 with the MAGIC-I telescope

NASA Astrophysics Data System (ADS)

Aleksić, J.; Alvarez, E. A.; Antonelli, L. A.; Antoranz, P.; Asensio, M.; Backes, M.; Barres de Almeida, U.; Barrio, J. A.; Bastieri, D.; Becerra González, J.; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Borla Tridon, D.; Braun, I.; Bretz, T.; Cañellas, A.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Cea del Pozo, E.; De Lotto, B.; Delgado Mendez, C.; Diago Ortega, A.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Eisenacher, D.; Elsaesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; Fruck, C.; García López, R. J.; Garczarczyk, M.; Garrido, D.; Giavitto, G.; Godinović, N.; Gozzini, S. R.; Hadasch, D.; Häfner, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, D.; Jogler, T.; Kellermann, H.; Klepser, S.; Krähenbühl, T.; Krause, J.; Kushida, J.; La Barbera, A.; Lelas, D.; Leonardo, E.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López, R.; López-Oramas, A.; Lorenz, E.; Makariev, M.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moldón, J.; Moralejo, A.; Munar-Adrover, P.; Niedzwiecki, A.; Nieto, D.; Nilsson, K.; Nowak, N.; Orito, R.; Paiano, S.; Paneque, D.; Paoletti, R.; Pardo, S.; Paredes, J. M.; Partini, S.; Perez-Torres, M. A.; Persic, M.; Peruzzo, L.; Pilia, M.; Pochon, J.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Puerto Gimenez, I.; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shayduk, M.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamatescu, V.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Sun, S.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Tibolla, O.; Torres, D. F.; Treves, A.; Uellenbeck, M.; Vankov, H.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.

2012-08-01

Context. The high frequency peaked BL Lac PKS 2155-304 with a redshift of z = 0.116 was discovered in 1997 in the very high energy (VHE, E > 100 GeV) γ-ray range by the University of Durham Mark VI γ-ray Cherenkov telescope in Australia with a flux corresponding to 20% of the Crab Nebula flux. It was later observed and detected with high significance by the southern Cherenkov observatory H.E.S.S. establishing this source as the best studied southern TeV blazar. Detection from the northern hemisphere is difficult due to challenging observation conditions under large zenith angles. In July 2006, the H.E.S.S. collaboration reported an extraordinary outburst of VHE γ-emission. During the outburst, the VHE γ-ray emission was found to be variable on the time scales of minutes and with a mean flux of ~7 times the flux observed from the Crab Nebula. Follow-up observations with the MAGIC-I standalone Cherenkov telescope were triggered by this extraordinary outburst and PKS 2155-304 was observed between 28 July to 2 August 2006 for 15 h at large zenith angles. Aims: We studied the behavior of the source after its extraordinary flare. Furthermore, we developed an analysis method in order to analyze these data taken under large zenith angles. Methods: Here we present an enhanced analysis method for data taken at high zenith angles. We developed improved methods for event selection that led to a better background suppression. Results: The quality of the results presented here is superior to the results presented previously for this data set: detection of the source on a higher significance level and a lower analysis threshold. The averaged energy spectrum we derived has a spectral index of (-3.5 ± 0.2) above 400 GeV, which is in good agreement with the spectral shape measured by H.E.S.S. during the major flare on MJD 53 944. Furthermore, we present the spectral energy distribution modeling of PKS 2155-304. With our observations we increased the duty cycle of the source extending the light curve derived by H.E.S.S. after the outburst. Finally, we find night-by-night variability with a maximal amplitude of a factor three to four and an intranight variability in one of the nights (MJD 53 945) with a similar amplitude.

Gain Evaluation of Micro-Channel-Plate Photomultipliers in the Upgraded High-B Test Facility at Jefferson Lab

NASA Astrophysics Data System (ADS)

Barber, Corinne; DIRC at EIC Collaboration

2015-10-01

The High-B test facility at Thomas Jefferson National Accelerator Facility allows researchers to evaluate the gain of compact photon sensors, such as Micro-Channel-Plate Photomultipliers (MCP-PMTs), in magnetic fields up to 5 T. These ongoing studies support the development of a Detector of Internally Reflected Cherenkov light (DIRC) to be used in an Electron Ion Collider (EIC). Here, we present our summer 2015 activities to upgrade and improve the facility, and we show results for MCP-PMT gain changes in high B-fields. To monitor the light stability delivered to the MCP-PMTs being tested, we implemented a Silicon Photomultiplier (SiPM) in the setup and calibrated the ADC reading this sensor. A 405-nm Light-Emitting Diode (LED) housed in an optical tube compatible with neutral density filters was also installed. The filters provide an alternative way of reducing the light output of the LED to operate the MCP-PMTs in a single-photon mode. We calibrated a set of filters by means of a photodiode and measured the photon flux at multiple positions relative to the LED. This information helped us to design 3D-printed holders unique to each MCP-PMT so that the photocathode receives the greatest amount of light. The improvements to the setup allow for more precise PMT gain evaluation. This team includes 7 collaborators/co-authors besides myself: Yordanka Ilieva, Kijun Park, Greg Kalicy, Carl Zorn, Pawel Nadel-Turonski, Tongtong Cao, and Lee.

IceCube: An Instrument for Neutrino Astronomy

DOE Office of Scientific and Technical Information (OSTI.GOV)

IceCube Collaboration; Halzen, F.; Klein, S.

Neutrino astronomy beyond the Sun was first imagined in the late 1950s; by the 1970s, it was realized that kilometer-scale neutrino detectors were required. The first such instrument, IceCube, is near completion and taking data. The IceCube project transforms a cubic kilometer of deep and ultra-transparent Antarctic ice into a particle detector. A total of 5,160 optical sensors are embedded into a gigaton of Antarctic ice to detect the Cherenkov light emitted by secondary particles produced when neutrinos interact with nuclei in the ice. Each optical sensor is a complete data acquisition system, including a phototube, digitization electronics, control andmore » trigger systems and LEDs for calibration. The light patterns reveal the type (flavor) of neutrino interaction and the energy and direction of the neutrino, making neutrino astronomy possible. The scientific missions of IceCube include such varied tasks as the search for sources of cosmic rays, the observation of Galactic supernova explosions, the search for dark matter, and the study of the neutrinos themselves. These reach energies well beyond those produced with accelerator beams.« less

Precision analysis of the photomultiplier response to ultra low signals

DOE PAGES

Degtiarenko, Pavel

2017-08-05

Here, a new computational model for the description of the photon detector response functions measured in conditions of low light is presented, together with examples of the observed photomultiplier signal amplitude distributions, successfully described using the parameterized model equation. In extension to the previously known approximations, the new model describes the underlying discrete statistical behavior of the photoelectron cascade multiplication processes in photon detectors with complex non-uniform gain structure of the first dynode. Important features of the model include the ability to represent the true single-photoelectron spectra from different photomultipliers with a variety of parameterized shapes, reflecting the variability inmore » the design and in the individual parameters of the detectors. The new software tool is available for evaluation of the detectors’ performance, response, and efficiency parameters that may be used in various applications including the ultra low background experiments such as the searches for Dark Matter and rare decays, underground neutrino studies, optimizing operations of the Cherenkov light detectors, help in the detector selection procedures, and in the experiment simulations.« less

Factors influencing the temporal growth rate of the high order TM{sub 0n} modes in the Ka-band overmoded Cherenkov oscillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Dapeng, E-mail: vipbenjamin@163.com; Shu, Ting; Ju, Jinchuan

2015-06-15

When the wavelength of overmoded Cherenkov oscillator goes into Ka-band, power handling capacity becomes an essential issue. Using the TM{sub 02} mode or higher order TM{sub 0n} modes as the operating mode is a potential solution. This paper is aimed to find some proper parameters to make the temporal growth rate of the TM{sub 02} mode higher in our previously studied Gigawatt (GW)-class Ka band oscillator. An accurate and fast calculation method of the “hot” dispersion equation is derived for rectangular corrugated SWSs, which are widely used in the high frequency Cherenkov devices. Then, factors that affect the temporal growthmore » rate of the high order TM{sub 0n} modes are analyzed, including the depth of corrugation, the radius of drift tube, and the diode voltage. Results show that, when parameters are chosen properly, the temporal growth rate of the TM{sub 02} mode can be as high as 0.3 ns{sup −1}.« less

Ring Imaging Cherenkov Detector Technologies for Particle Identification in the Electron-Ion Collider Experiments

NASA Astrophysics Data System (ADS)

He, X.

In the proposed Electron-Ion Collider (EIC) experiments, particle identification (PID) of the final state hadrons in the semi-inclusive deep inelastic scattering allows the measurement of flavor-dependent gluon and quark distributions inside nucleons and nuclei. The EIC PID consortium (eRD14 Collaboration) has been formed for identifying and developing PID detectors using Ring Imaging Cherenkov (RICH) techniques for the EIC experiments. A modular Ring Imaging Cherenkov (mRICH) detector has been designed for particle identification in the momentum coverage from 3 GeV/c to 10 GeV/c. The mRICH detector consists of an aerogel radiator block, a Fresnel lens, a mirror-wall and a photosensor plane. The first prototype of this detector was successfully tested at Fermi National Accelerator Laboratory in April 2016 for verifying the detector working principles. This talk will highlight the mRICH beam test results and their comparison with GEANT4-based detector simulations. An implementation of the mRICH detector concept in the Forward Angle sPHENIX spectrometer at BNL will also be mentioned in this talk.

GPU-based low-level trigger system for the standalone reconstruction of the ring-shaped hit patterns in the RICH Cherenkov detector of NA62 experiment

NASA Astrophysics Data System (ADS)

Ammendola, R.; Biagioni, A.; Chiozzi, S.; Cretaro, P.; Cotta Ramusino, A.; Di Lorenzo, S.; Fantechi, R.; Fiorini, M.; Frezza, O.; Gianoli, A.; Lamanna, G.; Lo Cicero, F.; Lonardo, A.; Martinelli, M.; Neri, I.; Paolucci, P. S.; Pastorelli, E.; Piandani, R.; Piccini, M.; Pontisso, L.; Rossetti, D.; Simula, F.; Sozzi, M.; Vicini, P.

2017-03-01

This project aims to exploit the parallel computing power of a commercial Graphics Processing Unit (GPU) to implement fast pattern matching in the Ring Imaging Cherenkov (RICH) detector for the level 0 (L0) trigger of the NA62 experiment. In this approach, the ring-fitting algorithm is seedless, being fed with raw RICH data, with no previous information on the ring position from other detectors. Moreover, since the L0 trigger is provided with a more elaborated information than a simple multiplicity number, it results in a higher selection power. Two methods have been studied in order to reduce the data transfer latency from the readout boards of the detector to the GPU, i.e., the use of a dedicated NIC device driver with very low latency and a direct data transfer protocol from a custom FPGA-based NIC to the GPU. The performance of the system, developed through the FPGA approach, for multi-ring Cherenkov online reconstruction obtained during the NA62 physics runs is presented.

Abundances and energy spectra of high energy heavy cosmic-ray nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barthelmy, S.D.

1985-01-01

We have measured the relative abundances of the cosmic rays in the iron group region at energies from a few GeV/amu to approximately 70 GeV/amu. This is done using a balloon-borne instrument consisting of gas ionization chambers, a plastic scintillator, a plastic Cherenkov counter, and a CO/sub 2/ gas Cherenkov counter. The instrument was flown from Palestine, Texas in the fall of 1982 for a total exposure of 62 m/sup 2/-ster-hr at an average atmospheric depth of 4 g/cm/sup 2/. The elemental charge was determined for a combination of the scintillator and plastic Cherenkov detector. Results are reported on themore » /sub 22/Ti//sub 26/Fe, /sub 24/Cr//sub 26/Fe, /sub 20/Ca//sub 26/Fe, and /sub 28/Ni//sub 28/Fe abundance ratios from 2 to 70 GeV/amu. Within this work results on the previously unused method of relativistic rise in gas ionization chambers is detailed as well as results on the return to nonsaturation of plastic scintillators.« less

Invited review article: IceCube: an instrument for neutrino astronomy.

PubMed

Halzen, Francis; Klein, Spencer R

2010-08-01

Neutrino astronomy beyond the Sun was first imagined in the late 1950s; by the 1970s, it was realized that kilometer-scale neutrino detectors were required. The first such instrument, IceCube, is near completion and taking data. The IceCube project transforms 1 km(3) of deep and ultratransparent Antarctic ice into a particle detector. A total of 5160 optical sensors is embedded into a gigaton of Antarctic ice to detect the Cherenkov light emitted by secondary particles produced when neutrinos interact with nuclei in the ice. Each optical sensor is a complete data acquisition system including a phototube, digitization electronics, control and trigger systems, and light-emitting diodes for calibration. The light patterns reveal the type (flavor) of neutrino interaction and the energy and direction of the neutrino, making neutrino astronomy possible. The scientific missions of IceCube include such varied tasks as the search for sources of cosmic rays, the observation of galactic supernova explosions, the search for dark matter, and the study of the neutrinos themselves. These reach energies well beyond those produced with accelerator beams. The outline of this review is as follows: neutrino astronomy and kilometer-scale detectors, high-energy neutrino telescopes: methodologies of neutrino detection, IceCube hardware, high-energy neutrino telescopes: beyond astronomy, and future projects.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muller, D.; SLD Collaboration

The authors present studies of leading particle production in Z{sup 0} decays into light, c, and b quarks performed with the SLD experiment at SLAC. The SLD precision vertex detector was exploited to tag light-flavor events, to tag charmed meson vertices and separate the prompt and B-decay components, and to reconstruct B-hadrons partially. The relative production of prompt pseudoscalar and vector D-mesons was measured to be P{sub V} = 0.53 {+-} 0.06(stat.) {+-} 0.02(syst.) (preliminary). The shape of the B-hadron energy spectrum was found to be consistent with the predictions of a number of models, and the average energy fractionmore » was measured to be = 0.697 {+-} 0.012(stat.) {+-} 0.028(syst.) (preliminary). Separation of light quark and antiquark jets was achieved using the highly polarized SLC electron beam, and hadrons were identified using the SLD Cherenkov Ring Imaging Detector. Production of particles and antiparticles in quark jets was compared, allowing the first direct observation of leading particles in e{sup +}e{sup {minus}} {r_arrow} u{anti u}, d{anti d}, s{anti s} events. More high momentum baryons and K{sup {minus}}`s than antibaryons and K{sup +}`s were observed, providing evidence for leading baryon and kaon production, as well as for strangeness suppression at high momentum.« less

The Advanced Gamma-ray Imaging System (AGIS): Schwarzschild-Couder (SC) Telescope Mechanical and Optical System Design

NASA Astrophysics Data System (ADS)

Byrum, Karen L.; Vassiliev, V.; AGIS Collaboration

2010-03-01

AGIS is a concept for the next-generation ground-based gamma-ray observatory. It will be an array of 36 imaging atmospheric Cherenkov telescopes (IACTs) sensitive in the energy range from 50 GeV to 200 TeV. The required improvements in sensitivity, angular resolution, and reliability of operation relative to the present generation instruments imposes demanding technological and cost requirements on the design of AGIS telescopes. In this submission, we outline the status of the development of the optical and mechanical systems for a novel Schwarzschild-Couder two-mirror aplanatic telescope. This design can provide a field of view and angular resolution significantly better to those offered by the traditional Davies-Cotton optics utilized in present-day IACTs. Other benefits of the novel design include isochronous focusing and compatibility with cost-effective, high quantum efficiency image sensors such as multi-anode PMTs, silicon PMTs (SiPMs), or image intensifiers.

Simultaneous measurement of the HT and DT fusion burn histories in inertial fusion implosions

DOE PAGES

Zylstra, Alex B.; Herrmann, Hans W.; Kim, Yong Ho; ...

2017-05-23

Measuring the thermonuclear burn history is an important way to diagnose inertial fusion implosions. Here, using the gas Cherenkov detectors at the OMEGA laser facility, we measure the HT fusion burn in a H 2+T 2 gas-fueled implosion for the first time. Then, using multiple detectors with varied Cherenkov thresholds, we demonstrate a technique for simultaneously measuring both the HT and DT burn histories from an implosion where the total reaction yields are comparable. This new technique will be used to study material mixing and kinetic phenomena in implosions.

A program to study antiprotons in the cosmic rays: Arizona collaboration

NASA Technical Reports Server (NTRS)

Bowen, Theodore

1992-01-01

The Cherenkov detector designed and built for the LEAP (Low Energy AntiProton) experiment utilized a novel design to achieve appreciable sensitive area (02. sq m) with a refractive index of 1.25 in a magnetic fringe field region (500-1000 Gauss). The weight was held to only 64 kg by using 16 unshielded Hamamatsu R2490-01 photomultiplier tubes, each aligned with its local magnetic field. A filling and reservoir system for the highly volatile FC-72 liquid Cherenkov radiator also presented many design challenges. Relativistic particles yielded about 72 photoelectrons, total.

Simultaneous measurement of the HT and DT fusion burn histories in inertial fusion implosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zylstra, Alex B.; Herrmann, Hans W.; Kim, Yong Ho

Measuring the thermonuclear burn history is an important way to diagnose inertial fusion implosions. Here, using the gas Cherenkov detectors at the OMEGA laser facility, we measure the HT fusion burn in a H 2+T 2 gas-fueled implosion for the first time. Then, using multiple detectors with varied Cherenkov thresholds, we demonstrate a technique for simultaneously measuring both the HT and DT burn histories from an implosion where the total reaction yields are comparable. This new technique will be used to study material mixing and kinetic phenomena in implosions.

CaloCube: An isotropic spaceborne calorimeter for high-energy cosmic rays. Optimization of the detector performance for protons and nuclei

NASA Astrophysics Data System (ADS)

Adriani, O.; Albergo, S.; Auditore, L.; Basti, A.; Berti, E.; Bigongiari, G.; Bonechi, L.; Bonechi, S.; Bongi, M.; Bonvicini, V.; Bottai, S.; Brogi, P.; Carotenuto, G.; Castellini, G.; Cattaneo, P. W.; Daddi, N.; D'Alessandro, R.; Detti, S.; Finetti, N.; Italiano, A.; Lenzi, P.; Maestro, P.; Marrocchesi, P. S.; Mori, N.; Orzan, G.; Olmi, M.; Pacini, L.; Papini, P.; Pellegriti, M. G.; Rappoldi, A.; Ricciarini, S.; Sciuto, A.; Spillantini, P.; Starodubtsev, O.; Stolzi, F.; Suh, J. E.; Sulaj, A.; Tiberio, A.; Tricomi, A.; Trifiro', A.; Trimarchi, M.; Vannuccini, E.; Zampa, G.; Zampa, N.

2017-11-01

The direct detection of high-energy cosmic rays up to the PeV region is one of the major challenges for the next generation of space-borne cosmic-ray detectors. The physics performance will be primarily determined by their geometrical acceptance and energy resolution. CaloCube is a homogeneous calorimeter whose geometry allows an almost isotropic response, so as to detect particles arriving from every direction in space, thus maximizing the acceptance. A comparative study of different scintillating materials and mechanical structures has been performed by means of Monte Carlo simulation. The scintillation-Cherenkov dual read-out technique has been also considered and its benefit evaluated.

Early Results from TUS, the First Orbital Detector of Extreme Energy Cosmic Rays

NASA Astrophysics Data System (ADS)

Zotov, Mikhail

TUS is the world's first orbital detector of extreme energy cosmic rays (EECRs), which operates as a part of the scientific payload of the Lomonosov satellite since May 19, 2016. TUS employs the nocturnal atmosphere of the Earth to register ultraviolet (UV) fluorescence and Cherenkov radiation from extensive air showers generated by EECRs as well as UV radiation from lightning strikes and transient luminous events, micro-meteors and space debris. The first months of its operation in orbit have demonstrated an unexpectedly rich variety of UV radiation in the atmosphere. We briefly review the design of TUS and present a few examples of events recorded in a mode dedicated to registering EECRs.

The exposure of the hybrid detector of the Pierre Auger Observatory

NASA Astrophysics Data System (ADS)

Abreu, P.; Aglietta, M.; Ahn, E. J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antičić, T.; Anzalone, A.; Aramo, C.; Arganda, E.; Arisaka, K.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Bäcker, T.; Badagnani, D.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Beatty, J. J.; Becker, B. R.; Becker, K. H.; Bellétoile, A.; Bellido, J. A.; Benzvi, S.; Berat, C.; Bergmann, T.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Busca, N. G.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Clay, R. W.; Colombo, E.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Domenico, M.; de Donato, C.; de Jong, S. J.; de La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; de Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; Del Peral, L.; Deligny, O.; Della Selva, A.; Dembinski, H.; Denkiewicz, A.; di Giulio, C.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Dobrigkeit, C.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; Dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Ferrero, A.; Fick, B.; Filevich, A.; Filipčič, A.; Fleck, I.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fröhlich, U.; Fuchs, B.; Fulgione, W.; Gamarra, R. F.; Gambetta, S.; García, B.; García Gámez, D.; Garcia-Pinto, D.; Garrido, X.; Gascon, A.; Gelmini, G.; Gemmeke, H.; Gesterling, K.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gonçalves, P.; Gonzalez, D.; Gonzalez, J. G.; Gookin, B.; Góra, D.; Gorgi, A.; Gouffon, P.; Gozzini, S. R.; Grashorn, E.; Grebe, S.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hague, J. D.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Holmes, V. C.; Homola, P.; Hörandel, J. R.; Horneffer, A.; Hrabovský, M.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jiraskova, S.; Kadija, K.; Kaducak, M.; Kampert, K. H.; Karhan, P.; Karova, T.; Kasper, P.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D.-H.; Kotera, K.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; Lautridou, P.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martínez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; McEwen, M.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Meurer, C.; Mičanović, S.; Micheletti, M. I.; Miller, W.; Miramonti, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Morris, C.; Mostafá, M.; Mueller, S.; Muller, M. A.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nhung, P. T.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Nyklicek, M.; Oehlschläger, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Parrisius, J.; Parsons, R. D.; Pastor, S.; Paul, T.; Pavlidou, V.; Payet, K.; Pech, M.; PeĶala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Phan, N.; Piegaia, R.; Pierog, T.; Pimenta, M.; Pirronello, V.; Platino, M.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rivière, C.; Rizi, V.; Robledo, C.; Rodriguez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Cabo, I.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-D'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Salamida, F.; Salazar, H.; Salina, G.; Sánchez, F.; Santander, M.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Schmidt, F.; Schmidt, T.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovánek, P.; Schroeder, F.; Schulte, S.; Schüssler, F.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Semikoz, D.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Stapleton, J.; Stasielak, J.; Stephan, M.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Tamashiro, A.; Tapia, A.; Tarutina, T.; Taşcău, O.; Tcaciuc, R.; Tcherniakhovski, D.; Tegolo, D.; Thao, N. T.; Thomas, D.; Tiffenberg, J.; Timmermans, C.; Tiwari, D. K.; Tkaczyk, W.; Todero Peixoto, C. J.; Tomé, B.; Tonachini, A.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.; Vargas Cárdenas, B.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Venters, T.; Verzi, V.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Warner, D.; Watson, A. A.; Weidenhaupt, K.; Weindl, A.; Westerhoff, S.; Whelan, B. J.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Winders, L.; Winnick, M. G.; Wommer, M.; Wundheiler, B.; Yamamoto, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Ziolkowski, M.; Pierre Auger Collaboration

2011-01-01

The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a surface array to measure secondary particles at ground level and a fluorescence detector to measure the development of air showers in the atmosphere above the array. The "hybrid" detection mode combines the information from the two subsystems. We describe the determination of the hybrid exposure for events observed by the fluorescence telescopes in coincidence with at least one water-Cherenkov detector of the surface array. A detailed knowledge of the time dependence of the detection operations is crucial for an accurate evaluation of the exposure. We discuss the relevance of monitoring data collected during operations, such as the status of the fluorescence detector, background light and atmospheric conditions, that are used in both simulation and reconstruction.

Enhancing the Spectral Hardening of Cosmic TeV Photons by Mixing with Axionlike Particles in the Magnetized Cosmic Web.

PubMed

Montanino, Daniele; Vazza, Franco; Mirizzi, Alessandro; Viel, Matteo

2017-09-08

Large-scale extragalactic magnetic fields may induce conversions between very-high-energy photons and axionlike particles (ALPs), thereby shielding the photons from absorption on the extragalactic background light. However, in simplified "cell" models, used so far to represent extragalactic magnetic fields, this mechanism would be strongly suppressed by current astrophysical bounds. Here we consider a recent model of extragalactic magnetic fields obtained from large-scale cosmological simulations. Such simulated magnetic fields would have large enhancement in the filaments of matter. As a result, photon-ALP conversions would produce a significant spectral hardening for cosmic TeV photons. This effect would be probed with the upcoming Cherenkov Telescope Array detector. This possible detection would give a unique chance to perform a tomography of the magnetized cosmic web with ALPs.

The exposure of the hybrid detector of the Pierre Auger Observatory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2010-06-01

The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a surface array to measure secondary particles at ground level and a fluorescence detector to measure the development of air showers in the atmosphere above the array. The 'hybrid' detection mode combines the information from the two subsystems. We describe the determination of the hybrid exposure for events observed by the fluorescence telescopes in coincidence with at least one water-Cherenkov detector of the surface array. A detailed knowledge of the time dependence of the detection operations is crucial for an accurate evaluation of the exposure.more » We discuss the relevance of monitoring data collected during operations, such as the status of the fluorescence detector, background light and atmospheric conditions, that are used in both simulation and reconstruction.« less

Improving treatment geometries in total skin electron therapy: Experimental investigation of linac angles and floor scatter dose contributions using Cherenkov imaging.

PubMed

Andreozzi, Jacqueline M; Brůža, Petr; Tendler, Irwin I; Mooney, Karen E; Jarvis, Lesley A; Cammin, Jochen; Li, Harold; Pogue, Brian W; Gladstone, David J

2018-06-01

The purpose of this study was to identify the optimal treatment geometry for total skin electron therapy (TSET) using a new optimization metric from Cherenkov image analysis, and to investigate the sensitivity of the Cherenkov imaging method to floor scatter effects in this unique treatment setup. Cherenkov imaging using an intensified charge coupled device (ICCD) was employed to measure the relative surface dose distribution as a 2D image in the total skin electron treatment plane. A 1.2 m × 2.2 m × 1 cm white polyethylene sheet was placed vertically at a source to surface distance (SSD) of 300 cm, and irradiated with 6 MeV high dose rate TSET beams. The linear accelerator coordinate system used stipulates 0° is the bottom of the gantry arc, and progresses counterclockwise so that gantry angle 270° produces a horizontal beam orthogonal to the treatment plane. First, all unique pairs of treatment beams were analyzed to determine the performance of the currently recommended symmetric treatment angles (±20° from the horizontal), compared to treatment geometries unconstrained to upholding gantry angle symmetry. This was performed on two medical linear accelerators (linacs). Second, the extent of the floor scatter contributions to measured surface dose at the extended SSD required for TSET were imaged using three gantry angles of incidence: 270° (horizontal), 253° (-17°), and 240° (-30°). Images of the surface dose profile at each angle were compared to the standard concrete floor when steel plates, polyvinyl chloride (PVC), and solid water were placed on the ground at the base of the treatment plane. Postprocessing of these images allowed for comparison of floor material-based scatter profiles with previously published simulation results. Analysis of the symmetric treatment geometry (270 ± 20°) and the identified optimal treatment geometry (270 + 23° and 270 - 17°) showed a 16% increase in the 90% isodose area for the latter field pair on the first linac. The optimal asymmetric pair for the second linac (270 + 25° and 270 - 17°) provided a 52% increase in the 90% isodose area when compared to the symmetric geometry. Difference images between Cherenkov images captured with test materials (steel, PVC, and solid water) and the control (concrete floor) demonstrated relative changes in the two-dimensional (2D) dose profile over a 1 × 1.9 m region of interest (ROI) that were consistent with published simulation data. Qualitative observation of the residual images demonstrates localized increases and decreases with respect to the change in floor material and gantry angle. The most significant changes occurred when the beam was most directly impinging the floor (gantry angle 240°, horizontal -30°), where the PVC floor material decreased scatter dose by 1-3% in 7.2% of the total ROI area, and the steel plate increased scatter dose by 1-3% in 7.0% of the total ROI area. An updated Cherenkov imaging method identified asymmetric, machine-dependent TSET field angle pairs that provided much larger 90% isodose areas than the commonly adopted symmetric geometry suggested by Task Group 30 Report 23. A novel demonstration of scatter dose Cherenkov imaging in the TSET field was established. © 2018 American Association of Physicists in Medicine.

First beam test of a liquid Cherenkov detector prototype for a future TOF measurements at the Super-FRS

NASA Astrophysics Data System (ADS)

Kuzminchuk-Feuerstein, Natalia; Ferber, Nadine; Rozhkova, Elena; Kaufeld, Ingo; Voss, Bernd

2017-09-01

In order to separate and identify fragmentation products with the Super-Fragment Separator (SuperFRS) at FAIR a high resolving power detector system is required for position and Time-Of-Flight (TOF) measurements. The TOF detector is used to measure the velocity of the particles and hence, in conjunction with their momentum or energy, to determine their mass and hence their identity. Aiming to develop a system with a precision down to about 50 ps in time and resistant to a high radiation rate of relativistic heavy ions of up to 107 per spill (at the second focal plane), we have shown a conceptual design for a Cherenkov detector envisioned for the future TOF measurements employing Iodine Naphthalene (C10H7I) as a fluid radiator. The application of a liquid radiator allows the circulation of the active material and therefore to greatly reduce the effects of the degradation of the optical performance expected after exposure to the high ion rates at the Super-FRS. The prototype of a TOF-Cherenkov detector was designed, constructed and its key-properties have been investigated in measurements with heavy ions at CaveC at GSI. These measurements were performed with nickel ions at 300-1500 MeV/u and ion-beam intensities of up to 4 × 106 ions/spill of 8 s. As a first result a maximum detection efficiency of 70% and a timing resolution of 267 ps (σ) was achieved. We report the first attempt of time measurements with a Cherenkov detector based on a liquid radiator. Further optimization is required.

Open high-level data formats and software for gamma-ray astronomy

NASA Astrophysics Data System (ADS)

Deil, Christoph; Boisson, Catherine; Kosack, Karl; Perkins, Jeremy; King, Johannes; Eger, Peter; Mayer, Michael; Wood, Matthew; Zabalza, Victor; Knödlseder, Jürgen; Hassan, Tarek; Mohrmann, Lars; Ziegler, Alexander; Khelifi, Bruno; Dorner, Daniela; Maier, Gernot; Pedaletti, Giovanna; Rosado, Jaime; Contreras, José Luis; Lefaucheur, Julien; Brügge, Kai; Servillat, Mathieu; Terrier, Régis; Walter, Roland; Lombardi, Saverio

2017-01-01

In gamma-ray astronomy, a variety of data formats and proprietary software have been traditionally used, often developed for one specific mission or experiment. Especially for ground-based imaging atmospheric Cherenkov telescopes (IACTs), data and software are mostly private to the collaborations operating the telescopes. However, there is a general movement in science towards the use of open data and software. In addition, the next-generation IACT instrument, the Cherenkov Telescope Array (CTA), will be operated as an open observatory. We have created a Github organisation at https://github.com/open-gamma-ray-astro where we are developing high-level data format specifications. A public mailing list was set up at https://lists.nasa.gov/mailman/listinfo/open-gamma-ray-astro and a first face-to-face meeting on the IACT high-level data model and formats took place in April 2016 in Meudon (France). This open multi-mission effort will help to accelerate the development of open data formats and open-source software for gamma-ray astronomy, leading to synergies in the development of analysis codes and eventually better scientific results (reproducible, multi-mission). This write-up presents this effort for the first time, explaining the motivation and context, the available resources and process we use, as well as the status and planned next steps for the data format specifications. We hope that it will stimulate feedback and future contributions from the gamma-ray astronomy community.

120th anniversary of the birth of Sergei Ivanovich Vavilov (Scientific session of the Physical Sciences Division of the Russian Academy of Sciences, 30 March 2011)

NASA Astrophysics Data System (ADS)

2011-12-01

A scientific session of the Physical Sciences Division of the Russian Academy of Sciences (RAS) dedicated to the 120th anniversary of the birth of Sergei Ivanovich Vavilov was held in the Conference Hall of the P N Lebedev Physical Institute, RAS, on 30 March 2011. The following reports were put on the session's agenda posted on the web site www.gpad.ac.ru of the Physical Sciences Division, RAS: (1) Masalov A V (P N Lebedev Physical Institute, RAS, Moscow) "S I Vavilov and nonlinear optics"; (2) Basiev T T (Laser Materials and Technology Research Center, A M Prokhorov General Physics Institute, RAS, Moscow) "Luminescent nanophotonics and high-power lasers"; (3) Vitukhnovsky A G (P N Lebedev Physical Institute, RAS, Moscow) "Advances in luminescent light sources and displays"; (4) Aleksandrov E B (Ioffe Physical Technical Institute, RAS, St. Petersburg) "Sergei Ivanovich Vavilov and the special theory of relativity"; (5) Bolotovsky B M (P N Lebedev Physical Institute, RAS, Moscow) "Vavilov-Cherenkov effect"; (6) Vizgin V P (S I Vavilov Institute of the History of Natural Scienses and Technology, RAS, Moscow) "Sergei Ivanovich Vavilov as a historian of science"; (7) Ginzburg A S (Knowledge Society) "Academician S I Vavilov — a devotee of the enlightenment and the first president of the Knowledge Society of the USSR". The papers written on the basis of reports 1-4 and 6 are given below. The main contents of report 5 is reflected in the paper "Vavilov-Cherenkov radiation: its discovery and application" [Usp. Fiz. Nauk 179 1161 (2009); Phys. Usp. 52 1099 (2009)] published earlier by B M Bolotovsky. • S I Vavilov and nonlinear optics, A V Masalov, Z A Chizhikova Physics-Uspekhi, 2011, Volume 54, Number 12, Pages 1257-1262 • Luminescent nanophotonics, fluoride laser ceramics, and crystals, T T Basiev, I T Basieva, M E Doroshenko Physics-Uspekhi, 2011, Volume 54, Number 12, Pages 1262-1268 • Advances in light sources and displays, A G Vitukhnovsky Physics-Uspekhi, 2011, Volume 54, Number 12, Pages 1268-1272 • Direct experimental demonstration of the second special relativity postulate: the speed of light is independent of the speed of the source, E B Aleksandrov, P A Aleksandrov, V S Zapasskii, V N Korchuganov, A I Stirin Physics-Uspekhi, 2011, Volume 54, Number 12, Pages 1272-1278 • Sergei Ivanovich Vavilov as a historian of science, V P Vizgin, A V Kessenikh, K A Tomilin Physics-Uspekhi, 2011, Volume 54, Number 12, Pages 1278-1283

Test of the HAPD light sensor for the Belle II Aerogel RICH

NASA Astrophysics Data System (ADS)

Yusa, Y.; Adachi, I.; Dolenec, R.; Hayata, K.; Iori, S.; Iwata, S.; Kakuno, H.; Kataura, R.; Kawai, H.; Kindo, H.; Kobayashi, T.; Korpar, S.; Krizan, P.; Kumita, T.; Mrvar, M.; Nishida, S.; Ogawa, K.; Pestotnik, R.; Santelj, L.; Sumiyoshi, T.; Tabata, M.; Yonenaga, M.

2017-12-01

The Aerogel Ring-Imaging Cherenkov detector (ARICH) is being installed in the endcap region of Belle II spectrometer to identify particles from B meson decays by detecting the Cherenkov ring image from aerogel radiators. To detect single photons, high-sensitive photon detector which has wide effective area (∼70 mm × 70 mm), a Hybrid Avalanche Photo Detector (HAPD), has been developed in a collaboration with Hamamatsu K.K. The HAPD consists of hybrid structure of a vacuum tube and an avalanche photodiode (APD). It can be operated in 1.5 T magnetic field of the spectrometer and withstands the radiation levels expected in the Belle II experiment. There are two steps of electric pulse amplification: acceleration of photo-electron in electric field in the vacuum tube part and electron avalanche in the APD part resulting in total gain of order 105. For the ARICH, we use 420 HAPDs in total. Before installing them, we performed quality assessment studies such as measurements of dark current, noise level, signal-to-noise ratio and two-dimensional scan with laser illumination. We also measured quantum efficiency of the photocathode. During the HAPD performance tests in the magnetic field, we observed very large signal pulses which cause long dead time of the readout electronics in some of the HAPDs. We have carried out a number of studies to understand this phenomenon, and have found a way to mitigate it and suppress the degradation of the ARICH performance. In this report, we will show a summary of the HAPD performance and quality assessment measurements including validation in the magnetic field for all of the HAPDs manufactured for the ARICH in the Belle II.

Trigger and Readout System for the Ashra-1 Detector

NASA Astrophysics Data System (ADS)

Aita, Y.; Aoki, T.; Asaoka, Y.; Morimoto, Y.; Motz, H. M.; Sasaki, M.; Abiko, C.; Kanokohata, C.; Ogawa, S.; Shibuya, H.; Takada, T.; Kimura, T.; Learned, J. G.; Matsuno, S.; Kuze, S.; Binder, P. M.; Goldman, J.; Sugiyama, N.; Watanabe, Y.

Highly sophisticated trigger and readout system has been developed for All-sky Survey High Resolution Air-shower (Ashra) detector. Ashra-1 detector has 42 degree diameter field of view. Detection of Cherenkov and fluorescence light from large background in the large field of view requires finely segmented and high speed trigger and readout system. The system is composed of optical fiber image transmission system, 64 × 64 channel trigger sensor and FPGA based trigger logic processor. The system typically processes the image within 10 to 30 ns and opens the shutter on the fine CMOS sensor. 64 × 64 coarse split image is transferred via 64 × 64 precisely aligned optical fiber bundle to a photon sensor. Current signals from the photon sensor are discriminated by custom made trigger amplifiers. FPGA based processor processes 64 × 64 hit pattern and correspondent partial area of the fine image is acquired. Commissioning earth skimming tau neutrino observational search was carried out with this trigger system. In addition to the geometrical advantage of the Ashra observational site, the excellent tau shower axis measurement based on the fine imaging and the night sky background rejection based on the fine and fast imaging allow zero background tau shower search. Adoption of the optical fiber bundle and trigger LSI realized 4k channel trigger system cheaply. Detectability of tau shower is also confirmed by simultaneously observed Cherenkov air shower. Reduction of the trigger threshold appears to enhance the effective area especially in PeV tau neutrino energy region. New two dimensional trigger LSI was introduced and the trigger threshold was lowered. New calibration system of the trigger system was recently developed and introduced to the Ashra detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Wenkai; Ghosh, Priyarshini; Harrison, Mark

The performance of traditional Hornyak buttons and two proposed variants for fast-neutron hodoscope applications was evaluated using Geant4. The Hornyak button is a ZnS(Ag)-based device previously deployed at the Idaho National Laboratory's TRansient REActor Test Facility (better known as TREAT) for monitoring fast neutrons emitted during pulsing of fissile fuel samples. Past use of these devices relied on pulse-shape discrimination to reduce the significant levels of background Cherenkov radiation. Proposed are two simple designs that reduce the overall light guide mass (here, polymethyl methacrylate or PMMA), employ silicon photomultipliers (SiPMs), and can be operated using pulse-height discrimination alone to eliminatemore » background noise to acceptable levels. Geant4 was first used to model a traditional Hornyak button, and for assumed, hodoscope-like conditions, an intrinsic efficiency of 0.35% for mono-directional fission neutrons was predicted. The predicted efficiency is in reasonably good agreement with experimental data from the literature and, hence, served to validate the physics models and approximations employed. Geant4 models were then developed to optimize the materials and geometries of two alternatives to the Hornyak button, one based on a homogeneous mixture of ZnS(Ag) and PMMA, and one based on alternating layers of ZnS(Ag) and PMMA oriented perpendicular to the incident neutron beam. For the same radiation environment, optimized, 5-cm long (along the beam path) devices of the homogeneous and layered designs were predicted to have efficiencies of approximately 1.3% and 3.3%, respectively. For longer devices, i.e., lengths larger than 25 cm, these efficiencies were shown to peak at approximately 2.2% and 5.9%, respectively. Furthermore, both designs were shown to discriminate Cherenkov noise intrinsically by using an appropriate pulse-height discriminator level, i.e., pulse-shape discrimination is not needed for these devices.« less

[Results of the EGRET Detector Program

NASA Technical Reports Server (NTRS)

Carter-Lewis, D. A.

1998-01-01

This NASA grant has funded studies of cosmic objects observed by both the EGRET detector aboard the Compton Gamma-ray Observatory and Whipple Gamma-ray imaging telescope. The former has sensitivity up to a few GeV and latter has sensitivity starting at about 200 GeV extending up to beyond 10 TeV. Thus these instruments probe some of the most energetic phenomena in the universe. This program has been in place for several years and led to important results referred to below. The Whipple Observatory Imaging Cherenkov Telescope consists of a 10-meter reflector with a nanosecond photomultiplier-tube camera at the focal plane. During the time period covered by this grant, it had either 109 pixels or 151 pixels on a 1/4 degree hexagonal pattern. As a TeV gamma ray enters the atmosphere, it produces an electron/positron pair initiating an extensive air shower. Cherenkov light from the electrons and positrons in the shower form an image of the shower at the phototube camera. The shape and intensity of this image is used to distinguish gamma-ray initiated showers from cosmic-ray (largely proton and alpha-particle) background showers and to derive an energy estimate for the primary gamma-ray. The Whipple Observatory gamma-ray collaboration pioneered this imaging technique which normally rejects over 99 percent of the cosmic-ray background while keeping over 70 percent of the gamma-ray signal. One of its key features is 2 large collection area which can exceed 50,000 meters. This grant covered primarily correlated observations of Markarian 421 and observations of the Cygnus region. The former resulted in a multiwavelength campaign showing correlations in several wavebands. The TeV data showed dramatic variability with the emission characterized by day-scale flickering and with now well defined steady component.

Redshift measurement of Fermi blazars for the Cherenkov telescope array

NASA Astrophysics Data System (ADS)

Pita, S.; Goldoni, P.; Boisson, C.; Cotter, G.; Lefaucheur, J.; Lenain, J.-P.; Lindfors, E.; Williams, D. A.

2017-01-01

Blazars are active galactic nuclei, and the most numerous High Energy (HE) and Very High Energy (VHE) γ-ray emitters. Their optical emission is often dominated by non-thermal, and, in the case of BL Lacs, featureless continuum radiation. This makes the determination of their redshift extremely difficult. Indeed, as of today only about 50% of γ-ray blazars have a measured spectroscopic redshift. The knowledge of redshift is fundamental because it allows the precise modeling of the VHE emission and also of its interaction with the extragalactic background light (EBL). The beginning of the Cherenkov Telescope Array (CTA) operations in the near future will allow the detection of several hundreds of new blazars. Using the Fermi catalogue of sources above 50 GeV (2FHL), we performed simulations which indicate that a significant fraction of the 2FHL blazars detectable by CTA will not have a measured redshift. As a matter of fact, the organization of observing campaigns to measure the redshift of these blazars has been recognized as a necessary support for the AGN Key Science Project of CTA. We are planning such an observing campaign. In order to optimize our chances of success, we will perform preliminary deep imaging observations aimed at detecting or setting upper limits to the host galaxy. We will then take spectra of the candidates with the brightest host galaxies. Taking advantage of the recent success of an X-shooter GTO observing campaign, these observations will be different with respect to previous ones due to the use of higher resolution spectrographs and of 8 meter class telescopes. We are starting to submit proposals for these observations. In this paper we briefly describe how candidates are selected and the corresponding observation program.

Fermi Large Area Telescope observations of the active galaxy 4C +55.17: Steady, hard gamma-ray emission and its implications

DOE PAGES

McConville, W.; Ostorero, L.; Moderski, R.; ...

2011-08-19

Here, we report Fermi Large Area Telescope (LAT) observations and broadband spectral modeling of the radio-loud active galaxy 4C +55.17 (z = 0.896), formally classified as a flat-spectrum radio quasar. Using 19 months of all-sky survey Fermi-LAT data, we detect a γ-ray continuum extending up to an observed energy of 145 GeV, and furthermore we find no evidence of γ-ray variability in the source over its observed history. We illustrate the implications of these results in two different domains. First, we investigate the origin of the steady γ-ray emission, where we re-examine the common classification of 4C +55.17 as amore » quasar-hosted blazar and consider instead its possible nature as a young radio source. We analyze and compare constraints on the source physical parameters in both blazar and young radio source scenarios by means of a detailed multiwavelength analysis and theoretical modeling of its broadband spectrum. Second, we show that the γ-ray spectrum may be formally extrapolated into the very high energy (VHE, ≥100 GeV) range at a flux level detectable by the current generation of ground-based Cherenkov telescopes. This enables us to place constraints on models of extragalactic background light within LAT energies and features the source as a promising candidate for VHE studies of the universe at an unprecedented redshift of z = 0.896.« less

Design and performance of the readout electronics chain of the Delphi Forward Ring Imaging Cherenkov Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dam, P.; Nielsen, B.S.; Formenti, F.

1992-10-01

In this paper the Front End Readout electronics chain of the Forward Ring Imaging CHerenkov (FRICH) Detector used at the Delphi experiment of the Large Electron Positron (LEP) collider is presented. The system incorporates a wide band low noise preamplifier, mounted in the proximity of the MultiWire Proportional Chamber, an Amplifying-Discriminating-Multiple-xing FASTBUS unit for further signal amplification, discrimination and channel reduction and a LEP Time Digitizer FASTBUS unit for time digitization. The paper gives a general view of the detector and its electronics with particular emphasis on the novel characteristics and capabilities of the system.

Monitoring system for testing the radiation hardness of a KINTEX-7 FPGA

NASA Astrophysics Data System (ADS)

Cojocariu, L. N.; Placinta, V. M.; Dumitru, L.

2016-03-01

A much more efficient Ring Imaging Cherenkov sub-detector system will be rebuilt in the second long shutdown of Large Hadron Collider for the LHCb experiment. Radiation-hard electronic components together with Commercial Off-The-Shelf ones will be used in the new Cherenkov photon detection system architecture. An irradiation program was foreseen to determine the radiation tolerance for the new electronic devices, including a Field Programmable Gate Array from KINTEX-7 family of XILINX. An automated test bench for online monitoring of the XC7K70T KINTEX-7 device operation in radiation conditions was designed and implemented by the LHCb Romanian group.

Status of the Tunka Advanced Instrument for Cosmic Ray Physics and Gamma Astronomy (TAIGA)

NASA Astrophysics Data System (ADS)

Tkachev, L.; Astapov, I.; Bezyazeekov, P.; Borodin, A.; Brueckner, M.; Budnev, N.; Chiavassa, A.; Gress, O.; Gress, T.; Grishin, O.; Dyachok, A.; Fedorov, O.; Gafarov, A.; Grebenyuk, V.; Grinyuk, A.; Ivanova, A.; Kalmykov, N.; Kazarina, Y.; Kindin, V.; Kiryuhin, S.; Kokoulin, R.; Kompaniets, K.; Korosteleva, E.; Kozhin, V.; Kravchenko, E.; Kunnas, M.; Kuzmichev, L.; Lemeshev, Yu.; Lenok, V.; Lubsandorzhiev, B.; Lubsandorzhiev, N.; Mirgazov, R.; Mirzoya, R.; Monkhoev, R.; Nachtigall, R.; Osipova, E.; Pakhorukov, A.; Panasyuk, M.; Pankov, L.; Petrukhin, A.; Poleschuk, V.; Popesku, M.; Popova, E.; Porelli, A.; Postnikov, E.; Prosin, V.; Ptuskin, V.; Rjabov, E.; Rubtsov, G.; Pushnin, A.; Sabirov, B.; Sagan, Y.; Samoliga, V.; Semeney, Yu.; Silaev, A.; Silaev, A.; Sidorenkov, A.; Skurikhin, A.; Slunecka, V.; Sokolov, A.; Spiering, C.; Sveshnikova, L.; Tabolenko, V.; Tarashansky, B.; Tkachenko, A.; Tluczykont, M.; Wischnewski, R.; Zagorodnikov, A.; Zurbanov, V.; Yashin, I.; Zhurov, D.

The new TAIGA project is proposed to solve a number of fundamental problems of high- energy gamma astronomy, cosmic-ray and particle physics. The array will be located in the Tunka valley at the site of the Tunka-133 array. TAIGA will consist of wide-angle (FOV 0.6 sr) non-imaging Cherenkov optical detectors (TAIGA-HiSCORE) covering an area of up to 5 km2, and up to 16 IACTs (Imaging Atmospheric Cherenkov Telescopes) (FOV 10 × 10°) based on 9 m2 mirrors and muon detectors with a total sensitive area of 2000 m2. The current TAIGA status is presented.

Cherenkov emission of terahertz surface plasmon polaritons from a superluminal optical spot on a structured metal surface.

PubMed

Bakunov, M I; Tsarev, M V; Hangyo, M

2009-05-25

We propose to launch terahertz surface plasmon polaritons on a structured metal surface by using a femtosecond laser pulse obliquely incident on a strip of an electro-optic material deposited on the surface. The laser pulse creates a nonlinear polarization that moves along the strip with a superluminal velocity and emits surface terahertz waves via the Cherenkov radiation mechanism. We calculate the radiated fields and frequency distribution of the radiated energy for a grooved perfect-conductor surface with a GaAs strip illuminated by Ti:sapphire laser. This technique can be used to perform surface terahertz spectroscopy.

Cherenkov-like emission of Z bosons

NASA Astrophysics Data System (ADS)

Colladay, D.; Noordmans, J. P.; Potting, R.

2017-07-01

We study CPT and Lorentz violation in the electroweak gauge sector of the Standard Model in the context of the Standard-Model Extension (SME). In particular, we show that any non-zero value of a certain relevant Lorentz violation parameter that is thus far unbounded by experiment would imply that for sufficiently large energies one of the helicity modes of the Z boson should propagate with spacelike four-momentum and become stable against decay in vacuum. In this scenario, Cherenkov-like radiation of Z bosons by ultra-high-energy cosmic-ray protons becomes possible. We deduce a bound on the Lorentz violation parameter from the observational data on ultra-high energy cosmic rays.

Metal-Coated <100>-Cut GaAs Coupled to Tapered Parallel-Plate Waveguide for Cherenkov-Phase-Matched Terahertz Detection: Influence of Crystal Thickness

NASA Astrophysics Data System (ADS)

delos Santos, Ramon; Mag-usara, Valynn; Tuico, Anthony; Copa, Vernalyn; Salvador, Arnel; Yamamoto, Kohji; Somintac, Armando; Kurihara, Kazuyoshi; Kitahara, Hideaki; Tani, Masahiko; Estacio, Elmer

2018-04-01

The influence of crystal thickness of metal-coated <100>-cut GaAs (M-G-M) on Cherenkov-phase-matched terahertz (THz) pulse detection was studied. The M-G-M detectors were utilized in conjunction with a metallic tapered parallel-plate waveguide (TPPWG). Polarization-sensitive measurements were carried out to exemplify the efficacy of GaAs in detecting transverse magnetic (TM)- and transverse electric (TE)-polarized THz waves. The reduction of GaAs' thickness increased the THz amplitude spectra of the detected TM-polarized THz electro-optic (EO) signal due to enhanced electric field associated with a more tightly-focused and well-concentrated THz radiation on the thinner M-G-M. The higher-fluence THz beam coupled to the thinner M-G-M improved the integrated intensity of the detected THz amplitude spectrum. This trend was not observed for TE-polarized THz waves, wherein the integrated intensities were almost comparable. Nevertheless, good agreement of spectral line shapes of the superposed TM- and TE-polarized THz-EO signals with that of elliptically polarized THz-EO signal demonstrates excellent polarization-resolved detection capabilities of M-G-M via Cherenkov-phase-matched EO sampling technique.

Impact of aerosols and adverse atmospheric conditions on the data quality for spectral analysis of the H.E.S.S. telescopes

NASA Astrophysics Data System (ADS)

Hahn, J.; de los Reyes, R.; Bernlöhr, K.; Krüger, P.; Lo, Y. T. E.; Chadwick, P. M.; Daniel, M. K.; Deil, C.; Gast, H.; Kosack, K.; Marandon, V.

2014-02-01

The Earth's atmosphere is an integral part of the detector in ground-based imaging atmospheric Cherenkov telescope (IACT) experiments and has to be taken into account in the calibration. Atmospheric and hardware-related deviations from simulated conditions can result in the mis-reconstruction of primary particle energies and therefore of source spectra. During the eight years of observations with the High Energy Stereoscopic System (H.E.S.S.) in Namibia, the overall yield in Cherenkov photons has varied strongly with time due to gradual hardware aging, together with adjustments of the hardware components, and natural, as well as anthropogenic, variations of the atmospheric transparency. Here we present robust data selection criteria that minimize these effects over the full data set of the H.E.S.S. experiment and introduce the Cherenkov transparency coefficient as a new atmospheric monitoring quantity. The influence of atmospheric transparency, as quantified by this coefficient, on energy reconstruction and spectral parameters is examined and its correlation with the aerosol optical depth (AOD) of independent MISR satellite measurements and local measurements of atmospheric clarity is investigated.

The aerogel Ring Imaging Cherenkov system at the Belle II spectrometer

NASA Astrophysics Data System (ADS)

Pestotnik, R.; Adachi, I.; Dolenec, R.; Hataya, K.; Iori, S.; Iwata, S.; Kakuno, H.; Kataura, R.; Kawai, H.; Kindo, H.; Kobayashi, T.; Korpar, S.; Križan, P.; Kumita, T.; Mrvar, M.; Nishida, S.; Ogawa, K.; Ogawa, S.; Šantelj, L.; Sumiyoshi, T.; Tabata, M.; Yonenaga, M.; Yusa, Y.

2017-12-01

In the forward end-cap of the Belle II spectrometer, a proximity focusing Ring Imaging Cherenkov counter with an aerogel radiator will be installed. The detector will occupy a limited space inside solenoid magnet with longitudinal field of 1.5 T. It will consist of a double layer aerogel radiator, an expansion volume and a photon detector. 420 Hamamatsu hybrid avalanche photo sensors with 144 channels each will be used to read out single Cherenkov photons with high efficiency. More than 60,000 analog signals will be digitized and processed in the front end electronics and send to the unified experiment data acquisition system. The detector components have been successfully produced and are now being installed in the spectrometer. Tested before on the bench, they are currently being installed in the mechanical frame. Part of the detector have been commissioned and connected to the acquisition system to register the cosmic ray particles. The first preliminary results are in accordance with previous expectations. We expect an excellent performance of the device which will allow at least a 4σ separation of pions from kaons in the experiment kinematic region from 0.5 GeV/c to 4 GeV/c.

Metal-Coated <100>-Cut GaAs Coupled to Tapered Parallel-Plate Waveguide for Cherenkov-Phase-Matched Terahertz Detection: Influence of Crystal Thickness

NASA Astrophysics Data System (ADS)

delos Santos, Ramon; Mag-usara, Valynn; Tuico, Anthony; Copa, Vernalyn; Salvador, Arnel; Yamamoto, Kohji; Somintac, Armando; Kurihara, Kazuyoshi; Kitahara, Hideaki; Tani, Masahiko; Estacio, Elmer

2018-06-01

The influence of crystal thickness of metal-coated <100>-cut GaAs (M-G-M) on Cherenkov-phase-matched terahertz (THz) pulse detection was studied. The M-G-M detectors were utilized in conjunction with a metallic tapered parallel-plate waveguide (TPPWG). Polarization-sensitive measurements were carried out to exemplify the efficacy of GaAs in detecting transverse magnetic (TM)- and transverse electric (TE)-polarized THz waves. The reduction of GaAs' thickness increased the THz amplitude spectra of the detected TM-polarized THz electro-optic (EO) signal due to enhanced electric field associated with a more tightly-focused and well-concentrated THz radiation on the thinner M-G-M. The higher-fluence THz beam coupled to the thinner M-G-M improved the integrated intensity of the detected THz amplitude spectrum. This trend was not observed for TE-polarized THz waves, wherein the integrated intensities were almost comparable. Nevertheless, good agreement of spectral line shapes of the superposed TM- and TE-polarized THz-EO signals with that of elliptically polarized THz-EO signal demonstrates excellent polarization-resolved detection capabilities of M-G-M via Cherenkov-phase-matched EO sampling technique.

Upgrade of the Cherenkov Detector of the JLab Hall A BigBite Spectrometer

NASA Astrophysics Data System (ADS)

Nycz, Michael

2015-04-01

The BigBite Spectrometer of the Hall A Facility of Jefferson Lab will be used in the upcoming MARATHON experiment at Jefferson Lab to measure the ratio of neutron to proton F2 inelastic structure functions and the ratio of up to down, d/u, quark nucleon distributions at medium and large values of Bjorken x. In preparation for this experiment, the BigBite Cherenkov detector is being modified to increase its overall efficiency for detecting electrons. This large volume counter is based on a dual system of segmented mirrors reflecting Cherenkov radiation to twenty photomultipliers. In this talk, a description of the detector and its past performance will be presented, along with the motivations for improvements and their implementation. An update on the status of the rest of the BigBite detector package, will be also presented. Additionally, current issues related to obtaining C4 F8 O, the commonly used radiator gas, which has been phased out of production by U.S. gas producers, will be discussed. This work is supported by Kent State University, NSF Grant PHY-1405814, and DOE Contract DE-AC05-06OR23177.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cardani, L.; Bellini, F.; Casali, N.

The development of background-free detectors is essential for experiments searching for rare events. Bolometers, that are among the most competitive devices for the study of neutrino-less double beta decay (0νDBD) and Dark Matter interactions, suffer from the absence of techniques that allow to identify the nature of the interacting particles. This limit can be overcome by coupling the bolometer to an independent device for the measurement of the light emitted by interactions, as the combined read-out of the bolometric and light signals allows to identify and reject particles different from those of interest. CUORE, the most advanced bolometric experiment formore » 0νDBD searches, could disentangle the electrons produced by 0νDBD from the dangerous background due to α particles, by measuring the (tiny) Cherenkov light emitted by electrons and not by α’s. LUCIFER, a project based on ZnSe scintillating bolometers for the study of {sup 82}Se 0νDBD, would be competitive also in the search of Dark Matter interactions if equipped with light detectors that allow to distinguish and reject the background due to electrons and γ’s. These advances require cryogenic detectors characterized by noise lower than 20 eV, large active area, wide temperature range of operation, high radio-purity and ease in fabricating hundreds of channels. The CALDER collaboration aims to develop such detectors by exploiting the superb energy resolution and natural multiplexed read-out provided by Kinetic Inductance Detectors.« less

Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET.

PubMed

Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

2016-04-07

The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time (τd) and the number of photons detected (n'), i.e. CTR proportional variant √τd/n'. However, it is still an open question to what extent the scintillation rise time (τr) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the single photon time resolution (SPTR) of the photodetector and the photon travel spread (PTS) in the crystal. The timing benefits of prompt photons at the beginning of the scintillation process (Cherenkov etc) are further studied, which leads to the conclusion that the scintillation rise time, SPTR and PTS have to be lowered simultaneously to fully profit from these fast photons in order to improve the CTR significantly.

Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET

NASA Astrophysics Data System (ADS)

Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

2016-04-01

The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time ({τd} ) and the number of photons detected ({{n}\\prime} ), i.e. CTR\\propto \\sqrt{{τd}/{{n}\\prime}} . However, it is still an open question to what extent the scintillation rise time ({τr} ) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the single photon time resolution (SPTR) of the photodetector and the photon travel spread (PTS) in the crystal. The timing benefits of prompt photons at the beginning of the scintillation process (Cherenkov etc) are further studied, which leads to the conclusion that the scintillation rise time, SPTR and PTS have to be lowered simultaneously to fully profit from these fast photons in order to improve the CTR significantly.

Tau Now

NASA Astrophysics Data System (ADS)

Fargion, D.; Oliva, P.

2016-10-01

Ultra High Energy Cosmic Rays and UHE neutrinos may lead to a new deep astronomy. However the most recent results on their correlations and clustering seem to most authors inconclusive. We briefly remind some UHECR models and past and recent results. Our reading and overlapping of IR-gamma-UHECR maps and their correlations seem to answer to several key puzzles, offering a first hope of the UHECR astronomy, mostly ruled by lightest nuclei from nearby Universe. Regarding the UHE neutrino we recently noted that the flavor ratio and the absence of double bang in IceCube within highest energetic ten events may suggest still a dominant noisy prompt component. However a first correlated UHE crossing muon with expected location (through going upward muon neutrino or horizontally) in IceCube is in our view a milestone in neutrino astronomy road map, possibly partially related, to galactic UHECR narrow clustering. The disturbing and persistent atmospheric neutrino noises, both conventional and prompt, call for a better filtered neutrino astronomy: the tau neutrino ones. There are no yet (at present, detectable) TeV-PeVs or more energetic tau neutrino of atmospheric, conventional or prompt nature; only astrophysical ones might soon shine. Double bangs in IceCube and in particular the tau air-showers in large array are the unique definitive expected signatures of astrophysical signals. In particular tau air-shower amplify in a huge way the otherwise single lepton track, once in decay in flight, into a richest three of secondaries (up to a million of billion Cherenkov photons for PeV tau energy) whose wide areas may extend up to nearly kilometer size. Such airshowers are very directional. PeVs energetic tau lepton penetrate hundreds meters inside the rock before its decay. Therefore horizontal tau air-shower in front of deep, wide valleys or mountain cliff [D. Fargion, A. Aiello, R. Conversano; 26th ICRC, He 6.1.09, 6 p. 396-398. (1999). Ed. D. Kieda, et al. arxiv:arXiv:astro-ph/9906450], as well as up-going tau air showers escaping our Earth, observable in air by their fluorescence lights as in AUGER and TA, might be a signal at EeVs energies. At lower energies blazing few PeVs tau airshower flashes are better observable from the top of the mountains, by an array located in a crown edge (as water Cherenkov, telescope Cherenkov or radio array), as it has been done in ASHRA or it might be done on ideal modified GRAND experiments constructed within aeolian towers by radio array possibly in mountains, facing the wide peculiar τ neutrino sky: our own Earth.

The positioning system of the ANTARES Neutrino Telescope

NASA Astrophysics Data System (ADS)

Adrián-Martínez, S.; Ageron, M.; Aguilar, J. A.; Samarai, I. Al; Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Assis Jesus, A. C.; Astraatmadja, T.; Aubert, J.-J.; Baret, B.; Basa, S.; Bertin, V.; Biagi, S.; Bigi, A.; Bigongiari, C.; Bogazzi, C.; Bou-Cabo, M.; Bouhou, B.; Bouwhuis, M. C.; Brunner, J.; Busto, J.; Camarena, F.; Capone, A.; Cârloganu, C.; Carminati, G.; Carr, J.; Cecchini, S.; Charif, Z.; Charvis, Ph; Chiarusi, T.; Circella, M.; Coniglione, R.; Costantini, H.; Coyle, P.; Curtil, C.; De Bonis, G.; Decowski, M. P.; Dekeyser, I.; Deschamps, A.; Distefano, C.; Donzaud, C.; Dornic, D.; Dorosti, Q.; Drouhin, D.; Eberl, T.; Emanuele, U.; Enzenhöfer, A.; Ernenwein, J.-P.; Escoffier, S.; Fermani, P.; Ferri, M.; Flaminio, V.; Folger, F.; Fritsch, U.; Fuda, J.-L.; Galatà, S.; Gay, P.; Giacomelli, G.; Giordano, V.; Gómez-González, J. P.; Graf, K.; Guillard, G.; Halladjian, G.; Hallewell, G.; van Haren, H.; Hartman, J.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Herold, B.; Hößl, J.; Hsu, C. C.; de Jong, M.; Kadler, M.; Kalekin, O.; Kappes, A.; Katz, U.; Kavatsyuk, O.; Keller, P.; Kooijman, P.; Kopper, C.; Kouchner, A.; Kreykenbohm, I.; Kulikovskiy, V.; Lahmann, R.; Lamare, P.; Larosa, G.; Lattuada, D.; Lefèvre, D.; Le Van Suu, A.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martínez-Mora, J. A.; Meli, A.; Montaruli, T.; Moscoso, L.; Motz, H.; Neff, M.; Nezri, E.; Niess, V.; Palioselitis, D.; Păvălaş, G. E.; Payet, K.; Payre, P.; Petrovic, J.; Piattelli, P.; Picot-Clemente, N.; Popa, V.; Pradier, T.; Presani, E.; Racca, C.; Real, D.; Reed, C.; Riccobene, G.; Richardt, C.; Richter, R.; Rivière, C.; Robert, A.; Roensch, K.; Rostovtsev, A.; Ruiz-Rivas, J.; Rujoiu, M.; Russo, G. V.; Salesa, F.; Samtleben, D. F. E.; Schöck, F.; Schuller, J.-P.; Schüssler, F.; Seitz, T.; Shanidze, R.; Simeone, F.; Spies, A.; Spurio, M.; Steijger, J. J. M.; Stolarczyk, Th; Sánchez-Losa, A.; Taiuti, M.; Tamburini, C.; Toscano, S.; Vallage, B.; Van Elewyck, V.; Vannoni, G.; Vecchi, M.; Vernin, P.; Wagner, S.; Wijnker, G.; Wilms, J.; de Wolf, E.; Yepes, H.; Zaborov, D.; Zornoza, J. D.; Zúñiga, J.

2012-08-01

The ANTARES neutrino telescope, located 40 km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475 m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10 cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning system is described. It consists of an acoustic positioning system, for distance triangulation, and a compass-tiltmeter system, for the measurement of the orientation and inclination of the storeys. Necessary corrections are discussed and the results of the detector alignment procedure are described.

Aspects of the optical system relevant for the KM3NeT timing calibration

NASA Astrophysics Data System (ADS)

Kieft, Gerard

2016-04-01

KM3NeT is a future research infrastructure in the Mediterranean Sea housing the large Cherenkov telescope arrays of optical modules for neutrino detection. The detector control and data transmission system is based on fibre optical technology. For timing calibration of the detector signals the optical system is used to send and fan-out an onshore clock signal, derived from a GPS receiver, to all optical modules in the deep sea. The optical modules use this clock signal to time stamp the light pulses detected by the photomultipliers inside the modules. The delay time between the GPS clock on shore and the clock in each optical module is measured with sub-nanosecond precision using a White Rabbit based timing calibration system. The aspects of the optical system relevant for the timing calibration and the quantification of their effect will be presented.

The PANDA DIRC detectors at FAIR

NASA Astrophysics Data System (ADS)

Schwarz, C.; Ali, A.; Belias, A.; Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Kalicy, G.; Krebs, M.; Lehmann, D.; Nerling, F.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwiening, J.; Traxler, M.; Zühlsdorf, M.; Böhm, M.; Britting, A.; Eyrich, W.; Lehmann, A.; Pfaffinger, M.; Uhlig, F.; Düren, M.; Etzelmüller, E.; Föhl, K.; Hayrapetyan, A.; Kreutzfeld, K.; Kröck, B.; Merle, O.; Rieke, J.; Schmidt, M.; Wasem, T.; Achenbach, P.; Cardinali, M.; Hoek, M.; Lauth, W.; Schlimme, S.; Sfienti, C.; Thiel, M.; Allison, L.; Hyde, C.

2017-07-01

The PANDA detector at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR) addresses fundamental questions of hadron physics. An excellent hadronic particle identification (PID) will be accomplished by two DIRC (Detection of Internally Reflected Cherenkov light) counters in the target spectrometer. The design for the barrel region covering polar angles between 22o to 140o is based on the successful BABAR DIRC with several key improvements, such as fast photon timing and a compact imaging region. The novel Endcap Disc DIRC will cover the smaller forward angles between 5o (10o) to 22o in the vertical (horizontal) direction. Both DIRC counters will use lifetime-enhanced microchannel plate PMTs for photon detection in combination with fast readout electronics. Geant4 simulations and tests with several prototypes at various beam facilities have been used to evaluate the designs and validate the expected PID performance of both PANDA DIRC counters.

Intensity Interferometry: Imaging Stars with Kilometer Baselines

NASA Astrophysics Data System (ADS)

Dravins, Dainis

2018-04-01

Microarcsecond imaging will reveal stellar surfaces but requires kilometer-scale interferometers. Intensity interferometry circumvents atmospheric turbulence by correlating intensity fluctuations between independent telescopes. Telescopes connect only electronically, and the error budget relates to electronic timescales of nanoseconds (light-travel distances on the order of a meter), enabling the use of imperfect optics in a turbulent atmosphere. Once pioneered by Hanbury Brown and Twiss, digital versions have now been demonstrated in the laboratory, reconstructing diffraction-limited images from hundreds of optical baselines. Arrays of Cherenkov telescopes (primarily erected for gamma-ray studies) will extend over a few km, enabling an optical equivalent of radio interferometers. Resolutions in the tens of microarcseconds will resolve rotationally flattened stars with their circumstellar disks and winds, or possibly even the silhouettes of transiting exoplanets. Applying the method to mirror segments in extremely large telescopes (even with an incompletely filled main mirror, poor seeing, no adaptive optics), the diffraction limit in the blue may be reached.

Application of atomic layer deposited microchannel plates to imaging photodetectors with high time resolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siegmund, O. H. W.; McPhate, J. B.; Tremsin, A. S.

Novel microchannel plates have been constructed using borosilicate glass micro-capillary array substrates with 20 mu m and 10 mu m pores and coated with resistive, and secondary electron emissive, layers by atomic layer deposition. Microchannel plates in 33 mm, 50 mm and 20 cm square formats have been made and tested. Although their amplification, imaging, and timing properties are comparable to standard glass microchannel plates, the background rates and lifetime characteristics are considerably improved. Sealed tube detectors based on the Planacon tube, and a 25 mm cross delay line readout tube with a GaN(Mg) opaque photocathode deposited on borosilicate microchannelmore » plates have been fabricated. Considerable progress has also been made with 20 cm microchannel plates for a 20 cm format sealed tube sensor with strip-line readout that is being developed for Cherenkov light detection.« less

Optical aperture synthesis with electronically connected telescopes

PubMed Central

Dravins, Dainis; Lagadec, Tiphaine; Nuñez, Paul D.

2015-01-01

Highest resolution imaging in astronomy is achieved by interferometry, connecting telescopes over increasingly longer distances and at successively shorter wavelengths. Here, we present the first diffraction-limited images in visual light, produced by an array of independent optical telescopes, connected electronically only, with no optical links between them. With an array of small telescopes, second-order optical coherence of the sources is measured through intensity interferometry over 180 baselines between pairs of telescopes, and two-dimensional images reconstructed. The technique aims at diffraction-limited optical aperture synthesis over kilometre-long baselines to reach resolutions showing details on stellar surfaces and perhaps even the silhouettes of transiting exoplanets. Intensity interferometry circumvents problems of atmospheric turbulence that constrain ordinary interferometry. Since the electronic signal can be copied, many baselines can be built up between dispersed telescopes, and over long distances. Using arrays of air Cherenkov telescopes, this should enable the optical equivalent of interferometric arrays currently operating at radio wavelengths. PMID:25880705

VizieR Online Data Catalog: Swift and NuSTAR obs. of the BL Lac Mrk 421 (Kapanadze+, 2016)

NASA Astrophysics Data System (ADS)

Kapanadze, B.; Dorner, D.; Vercellone, S.; Romano, P.; Aller, H.; Aller, M.; Hughes, P.; Reynolds, M.; Kapanadze, S.; Tabagari, L.

2017-01-01

We retrieved the Swift-XRT data from the publicly available archive, maintained by HEASARC. We present the results of X-ray observations of the high-energy peaked BL Lac (HBL) source Mrk421 performed by Swift-XRT and NuSTAR during 2013 January-June. Along with the 0.3-10keV and 3-79keV data obtained with the Swift-XRT and NuSTAR instruments, we have processed and analyzed those obtained with the Ultraviolet-Optical Telescope (UVOT) and Large Area Telescope (LAT) onboard Fermi. We have also used the publicly available light curves from the observations performed with the Burst Alert Telescope (BAT) onboard Swift, Monitor of All Sky X-ray Image (MAXI), MAGIC, First G-APD Cherenkov Telescope (FACT), and the OVRO 40m telescope during the 2013 January-June period to draw conclusions about the interband correlations. (8 data files).

The Advanced Gamma-ray Imaging System (AGIS): Extragalactic Science

NASA Astrophysics Data System (ADS)

Coppi, Paolo S.; Extragalactic Science Working Group; AGIS Collaboration

2010-03-01

The Advanced Gamma-ray Imaging System (AGIS), a proposed next-generation array of Cherenkov telescopes, will provide an unprecedented view of the high energy universe. We discuss how AGIS, with its larger effective area, improved angular resolution, lower threshold, and an order of magnitude increase in sensitivity, impacts the extragalactic science possible in the very high energy domain. Likely source classes detectable by AGIS include AGN, GRBs, clusters, star-forming galaxies, and possibly the cascade radiation surrounding powerful cosmic accelerators. AGIS should see many of the sources discovered by Fermi. With its better sensitivity and angular resolution, AGIS then becomes a key instrument for identifying and characterizing Fermi survey sources, the majority of which will have limited Fermi photon statistics and localizations.

A Topological Array Trigger for AGIS, the Advanced Gamma ray Imaging System

NASA Astrophysics Data System (ADS)

Krennrich, F.; Anderson, J.; Buckley, J.; Byrum, K.; Dawson, J.; Drake, G.; Haberichter, W.; Imran, A.; Krawczynski, H.; Kreps, A.; Schroedter, M.; Smith, A.

2008-12-01

Next generation ground based γ-ray observatories such as AGIS1 and CTA2 are expected to cover a 1 km2 area with 50-100 imaging atmospheric Cherenkov telescopes. The stereoscopic view ol air showers using multiple view points raises the possibility to use a topological array trigger that adds substantial flexibility, new background suppression capabilities and a reduced energy threshold. In this paper we report on the concept and technical implementation of a fast topological trigger system, that makes use of real time image processing of individual camera patterns and their combination in a stereoscopic array analysis. A prototype system is currently under construction and we discuss the design and hardware of this topological array trigger system.

Focal Plane Detectors for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Wagner, R. G.; Byrum, K.; Drake, G.; Funk, S.; Otte, N.; Smith, A.; Tajima, H.; Williams, D.

2009-05-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. It is being designed to achieve a significant improvement in sensitivity compared to current Imaging Air Cherenkov Telescope (IACT) Arrays. One of the main requirements in order that AGIS fulfills this goal will be to achieve higher angular resolution than current IACTs. Simulations show that a substantial improvement in angular resolution may be achieved if the pixel size is reduced to 0.05 deg, i.e. two to three times smaller than for current IACT cameras. Here we present results from testing of alternatives being considered for AGIS, including both silicon photomultipliers (SiPMs) and multi-anode photomultipliers (MAPMTs).

Fermi-LAT high-z active galactic nuclei and the extragalactic background light

NASA Astrophysics Data System (ADS)

Armstrong, Thomas; Brown, Anthony M.; Chadwick, Paula M.

2017-10-01

Observations of distant gamma-ray sources are hindered by the presence of the extragalactic background light (EBL). In order to understand the physical processes that result in the observed spectrum of sources, it is imperative that a good understanding of the EBL is included. In this work, an investigation into the imprint of the EBL on the observed spectra of high-redshift Fermi-LAT active galactic nuclei is presented. By fitting the spectrum below ˜10 GeV, an estimation of the unabsorbed intrinsic source spectrum is obtained; by applying this spectrum to data up to 300 GeV, it is then possible to derive a scaling factor for different EBL models. A second approach uses five sources (PKS 0426-380, 4C +55.17, Ton 116, PG 1246+586 and RBS 1432) that were found to exhibit very high energy (VHE) emission (Eγ > 100 GeV). Through Monte Carlo simulations, it is shown that the observation of VHE photons, despite the large distances of these objects, is consistent with current EBL models. Many of these sources would be observable with the upcoming ground-based observatory, the Cherenkov Telescope Array, leading to a better understanding of the EBL.

Runaway electron generation and control

NASA Astrophysics Data System (ADS)

Esposito, B.; Boncagni, L.; Buratti, P.; Carnevale, D.; Causa, F.; Gospodarczyk Martin-Solis, M., Jr.; Popovic, Z.; Agostini, M.; Apruzzese, G.; Bin, W.; Cianfarani, C.; De Angelis, R.; Granucci, G.; Grosso, A.; Maddaluno, G.; Marocco, D.; Piergotti, V.; Pensa, A.; Podda, S.; Pucella, G.; Ramogida, G.; Rocchi, G.; Riva, M.; Sibio, A.; Sozzi, C.; Tilia, B.; Tudisco, O.; Valisa, M.; FTU Team

2017-01-01

We present an overview of FTU experiments on runaway electron (RE) generation and control carried out through a comprehensive set of real-time (RT) diagnostics/control systems and newly installed RE diagnostics. An RE imaging spectrometer system detects visible and infrared synchrotron radiation. A Cherenkov probe measures RE escaping the plasma. A gamma camera provides hard x-ray radial profiles from RE bremsstrahlung interactions in the plasma. Experiments on the onset and suppression of RE show that the threshold electric field for RE generation is larger than that expected according to a purely collisional theory, but consistent with an increase due to synchrotron radiation losses. This might imply a lower density to be targeted with massive gas injection for RE suppression in ITER. Experiments on active control of disruption-generated RE have been performed through feedback on poloidal coils by implementing an RT boundary-reconstruction algorithm evaluated on magnetic moments. The results indicate that the slow plasma current ramp-down and the simultaneous reduction of the reference plasma external radius are beneficial in dissipating the RE beam energy and population, leading to reduced RE interactions with plasma facing components. RE active control is therefore suggested as a possible alternative or complementary technique to massive gas injection.

Evaluation of Light Collection System for Pion and Kaon Experiments in Hall C at Jefferson Lab

NASA Astrophysics Data System (ADS)

Roustom, Salim

2017-09-01

The neutral pion and the kaon are opportune to study the hadron structure through General Parton Distributions, which can be viewed as spatial densities at different momenta of the quarks inside the proton. To study hadron structure with pion or kaon experiments in Hall C at 12 GeV Jefferson Lab, one must analyze the final state neutral pions and kaons and their decay products. For the analysis of these particles, dedicated detectors based on the Cherenkov or scintillation mechanism are used, e.g. the HMS and SHMS aerogel detectors and the PbWO4-based Neutral Particle Spectrometer. A critical part of these detectors is the light collection system. Photomultiplier Tubes (PMTs) have many advantages, however, they are sensitive to magnetic fields and can get damaged by elevated helium levels in the atmosphere. An alternative to PMTs are Avalanche Photodiodes (APDs). APDs are sensitive to background noise, temperature, and radiation. It is thus important to evaluate the benefits of each light collection system and optimize operating conditions to ensure performance over a reasonably long time. I will present a performance study of PMTs exposed to elevated levels of helium and a comparison of APDs as alternatives, as well as new, compact readout methods. Supported in part by NSF Grants PHY-1714133, PHY-1530874, PHY-1306227 and PHY-1306418.

Fast determination of ⁹⁰Sr/⁹⁰Y activity in milk by Cherenkov counting.

PubMed

Tsroya, S; Dolgin, B; German, U; Pelled, O; Alfassi, Z B

2013-12-01

Cherenkov counting of the ⁹⁰Sr/⁹⁰Y pure beta emitters is an attractive method for ⁹⁰Sr activity determination, but the color quenching effect may be significant, especially for strongly colored or semi-opaque media. A quench correction method based on the external source of some liquid scintillation systems (named ESAR - external source area ratio) was proposed and checked for aqueous solutions and was proved to be effective also for urine samples. In the present work, the application of the ESAR method for fast determination of ⁹⁰Sr/⁹⁰Y activity in milk samples is described. © 2013 Elsevier Ltd. All rights reserved.

Layered water Cherenkov detector for the study of ultra high energy cosmic rays

NASA Astrophysics Data System (ADS)

Letessier-Selvon, Antoine; Billoir, Pierre; Blanco, Miguel; Mariş, Ioana C.; Settimo, Mariangela

2014-12-01

We present a new design for the water Cherenkov detectors that are in use in various cosmic ray observatories. This novel design can provide a significant improvement in the independent measurement of the muonic and electromagnetic component of extensive air showers. From such multi-component data an event by event classification of the primary cosmic ray mass becomes possible. According to popular hadronic interaction models, such as EPOS-LHC or QGSJetII-04, the discriminating power between iron and hydrogen primaries reaches Fisher values of 2 or above for energies in excess of 1019 eV with a detector array layout similar to that of the Pierre Auger Observatory.

CHERENCUBE: concept definition and implementation challenges of a Cherenkov-based detector block for PET.

PubMed

Somlai-Schweiger, I; Ziegler, S I

2015-04-01

A new concept for a depth-of-interaction (DOI) capable time-of-flight (TOF) PET detector is defined, based only on the detection of Cherenkov photons. The proposed "CHERENCUBE" consists of a cubic Cherenkov radiator with position-sensitive photodetectors covering each crystal face. By means of the spatial distribution of the detected photons and their time of arrival, the point of interaction of the gamma-ray in the crystal can be determined. This study analyzes through theoretical calculations and Monte Carlo simulations the potential advantages of the concept toward reaching a Cherenkov-only detector for TOF-PET with DOI capability. Furthermore, an algorithm for the DOI estimation is presented and the requirements for a practical implementation of the proposed concept are defined. The Monte Carlo simulations consisted of a cubic crystal with one photodetector coupled to each one of the faces of the cube. The sensitive area of the detector matched exactly the crystal size, which was varied in 1 mm steps between 1 × 1 × 1 mm(3) and 10 × 10 × 10 mm(3). For each size, five independent simulations of ten thousand 511 keV gamma-rays were triggered at a fixed distance of 10 mm. The crystal chosen was PbWO4. Its scintillation properties were simulated, but only Cherenkov photons were analyzed. Photodetectors were simulated having perfect photodetection efficiency and infinite time resolution. For every generated particle, the analysis considered its creation process, parent and daughter particles, energy, origin coordinates, trajectory, and time and position of detection. The DOI determination is based on the distribution of the emission time of all photons per event. These values are calculated as a function of the coordinates of detection and origin for every photon. The common origin is estimated by finding the distribution with the most similar emission time-points. Detection efficiency increases with crystal size from 8.2% (1 × 1 × 1 mm(3)) to 58.6% (10 × 10 × 10 mm(3)) and decreases applying a photon detection threshold of 5/10/20 photons to 6.3%/4.3%/0.7% and 49.3%/30.4%/2.8%, respectively. The detection rate in the six photodetectors is uniform due to the nearly isotropic cone emission. Most cones originated after a photoelectric effect interaction, with two dominating peaks for the kinetic energy of the electron at 422.99 and 441.47 keV. The detection distance between same-event photons defines the spatial resolution of the detector required for individual photon recognition, with 20% of the detected photons having their closest neighbor within a distance of 5% of the length of the cube. Same-event photons are detected within a time window whose width is determined by the crystal size, with values of 30 and 150 ps for a 1 × 1 × 1 mm(3) and a 10 × 10 × 10 mm(3) cube, respectively. The DOI reconstruction has an accuracy of approximately 23% of the length of the cube, with an average value of 2.2 mm for a 10 × 10 × 10 mm(3) CHERENCUBE. The proposed concept requires a detector with high photodetection efficiency. The structure of the sensitive surface of the detector should be a two dimensional array of microcells, able to provide individual detection coordinates and time stamps. The microcell size determines the ability to recognize individual photons, influencing detection efficiency. The 3D DOI recognition relies on the accuracy of the time stamps and detection coordinates, without the need for a recognition of the projected patterns of photons. The refractive index of the material defines a detector intrinsic energy-based rejection of scattered PET events at the cost of reduced sensitivity.

CHERENCUBE: Concept definition and implementation challenges of a Cherenkov-based detector block for PET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Somlai-Schweiger, I., E-mail: ian.somlai@tum.de; Ziegler, S. I.

Purpose: A new concept for a depth-of-interaction (DOI) capable time-of-flight (TOF) PET detector is defined, based only on the detection of Cherenkov photons. The proposed “CHERENCUBE” consists of a cubic Cherenkov radiator with position-sensitive photodetectors covering each crystal face. By means of the spatial distribution of the detected photons and their time of arrival, the point of interaction of the gamma-ray in the crystal can be determined. This study analyzes through theoretical calculations and Monte Carlo simulations the potential advantages of the concept toward reaching a Cherenkov-only detector for TOF-PET with DOI capability. Furthermore, an algorithm for the DOI estimationmore » is presented and the requirements for a practical implementation of the proposed concept are defined. Methods: The Monte Carlo simulations consisted of a cubic crystal with one photodetector coupled to each one of the faces of the cube. The sensitive area of the detector matched exactly the crystal size, which was varied in 1 mm steps between 1 × 1 × 1 mm{sup 3} and 10 × 10 × 10 mm{sup 3}. For each size, five independent simulations of ten thousand 511 keV gamma-rays were triggered at a fixed distance of 10 mm. The crystal chosen was PbWO{sub 4}. Its scintillation properties were simulated, but only Cherenkov photons were analyzed. Photodetectors were simulated having perfect photodetection efficiency and infinite time resolution. For every generated particle, the analysis considered its creation process, parent and daughter particles, energy, origin coordinates, trajectory, and time and position of detection. The DOI determination is based on the distribution of the emission time of all photons per event. These values are calculated as a function of the coordinates of detection and origin for every photon. The common origin is estimated by finding the distribution with the most similar emission time-points. Results: Detection efficiency increases with crystal size from 8.2% (1 × 1 × 1 mm{sup 3}) to 58.6% (10 × 10 × 10 mm{sup 3}) and decreases applying a photon detection threshold of 5/10/20 photons to 6.3%/4.3%/0.7% and 49.3%/30.4%/2.8%, respectively. The detection rate in the six photodetectors is uniform due to the nearly isotropic cone emission. Most cones originated after a photoelectric effect interaction, with two dominating peaks for the kinetic energy of the electron at 422.99 and 441.47 keV. The detection distance between same-event photons defines the spatial resolution of the detector required for individual photon recognition, with 20% of the detected photons having their closest neighbor within a distance of 5% of the length of the cube. Same-event photons are detected within a time window whose width is determined by the crystal size, with values of 30 and 150 ps for a 1 × 1 × 1 mm{sup 3} and a 10 × 10 × 10 mm{sup 3} cube, respectively. The DOI reconstruction has an accuracy of approximately 23% of the length of the cube, with an average value of 2.2 mm for a 10 × 10 × 10 mm{sup 3} CHERENCUBE. Conclusions: The proposed concept requires a detector with high photodetection efficiency. The structure of the sensitive surface of the detector should be a two dimensional array of microcells, able to provide individual detection coordinates and time stamps. The microcell size determines the ability to recognize individual photons, influencing detection efficiency. The 3D DOI recognition relies on the accuracy of the time stamps and detection coordinates, without the need for a recognition of the projected patterns of photons. The refractive index of the material defines a detector intrinsic energy-based rejection of scattered PET events at the cost of reduced sensitivity.« less

The ICT monitoring system of the ASTRI SST-2M prototype proposed for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Gianotti, F.; Bruno, P.; Tacchini, A.; Conforti, V.; Fioretti, V.; Tanci, C.; Grillo, A.; Leto, G.; Malaguti, G.; Trifoglio, M.

2016-08-01

In the framework of the international Cherenkov Telescope Array (CTA) observatory, the Italian National Institute for Astrophysics (INAF) has developed a dual mirror, small sized, telescope prototype (ASTRI SST-2M), installed in Italy at the INAF observing station located at Serra La Nave, Mt. Etna. The ASTRI SST-2M prototype is the basis of the ASTRI telescopes that will form the mini-array proposed to be installed at the CTA southern site during its preproduction phase. This contribution presents the solutions implemented to realize the monitoring system for the Information and Communication Technology (ICT) infrastructure of the ASTRI SST-2M prototype. The ASTRI ICT monitoring system has been implemented by integrating traditional tools used in computer centers, with specific custom tools which interface via Open Platform Communication Unified Architecture (OPC UA) to the Alma Common Software (ACS) that is used to operate the ASTRI SST-2M prototype. The traditional monitoring tools are based on Simple Network Management Protocol (SNMP) and commercial solutions and features embedded in the devices themselves. They generate alerts by email and SMS. The specific custom tools convert the SNMP protocol into the OPC UA protocol and implement an OPC UA server. The server interacts with an OPC UA client implemented in an ACS component that, through the ACS Notification Channel, sends monitor data and alerts to the central console of the ASTRI SST-2M prototype. The same approach has been proposed also for the monitoring of the CTA onsite ICT infrastructures.

Fast fission neutron detection using the Cherenkov effect

NASA Astrophysics Data System (ADS)

Millard, Matthew James

The Cherenkov effect in optically clear media of varying indices of refraction and composition was investigated for quantification of fast neutrons. The ultimate application of the proposed detection system is criticality monitoring. The optically clear medium, composed of select target nuclei, was coupled to a photomultiplier tube. Neutron reaction products of the target nuclei contained within the optical medium emit beta particles and gamma rays that produce Cherenkov photons within the medium which can be detected. Assessed media include quartz (SiO2), sapphire (Al2O3), spinel (MgAl2O4), and zinc sulfide (ZnS), which were irradiated with un-moderated 252Cf. Monte Carlo N-Particle (MCNP) code simulations were conducted to quantify the neutron flux incident on the media. High resolution gamma-ray spectroscopic measurements of the samples were conducted to verify the MCNP estimate. The threshold reactions of interest were 28Si (n, p) 28Al, 27 Al (n, p) 27Mg, 24Mg(n, p)24 Na, and 64Zn(n, p)64Cu which have neutron reaction cross sections in the 1 to 10 MeV range on the order of 0.1 barn. The detection system offers a unique way to measure a criticality event; it can count in place, making retrieval by emergency personnel unnecessary.

The software architecture of the camera for the ASTRI SST-2M prototype for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Sangiorgi, Pierluca; Capalbi, Milvia; Gimenes, Renato; La Rosa, Giovanni; Russo, Francesco; Segreto, Alberto; Sottile, Giuseppe; Catalano, Osvaldo

2016-07-01

The purpose of this contribution is to present the current status of the software architecture of the ASTRI SST-2M Cherenkov Camera. The ASTRI SST-2M telescope is an end-to-end prototype for the Small Size Telescope of the Cherenkov Telescope Array. The ASTRI camera is an innovative instrument based on SiPM detectors and has several internal hardware components. In this contribution we will give a brief description of the hardware components of the camera of the ASTRI SST-2M prototype and of their interconnections. Then we will present the outcome of the software architectural design process that we carried out in order to identify the main structural components of the camera software system and the relationships among them. We will analyze the architectural model that describes how the camera software is organized as a set of communicating blocks. Finally, we will show where these blocks are deployed in the hardware components and how they interact. We will describe in some detail, the physical communication ports and external ancillary devices management, the high precision time-tag management, the fast data collection and the fast data exchange between different camera subsystems, and the interfacing with the external systems.

Muon data from a water Cherenkov detector prototype at Colorado State University

NASA Astrophysics Data System (ADS)

Longo, Megan; Mostafa, Miguel

2013-04-01

The High Altitude Water Cherenkov (HAWC) Observatory is a very high energy gamma-ray experiment currently under construction in Sierra Negra in the state of Puebla, Mexico, at an altitude of 4,100 m a.s.l. The HAWC Observatory will consist of 300 water Cherenkov detectors (WCDs), each instrumented with three 8'' photomultiplier tubes (PMTs) and one 10'' high efficiency (HE) PMT. The PMTs are upward facing, anchored to the bottom of a 5 m deep by 7.3 m diameter steel tank, containing a multilayer hermetic plastic bag holding 200,000 L of purified water. The only full size WCD prototype outside of the HAWC site is located at Colorado State University (CSU) in Fort Collins, CO at an altitude of 1,525 m a.s.l. This prototype is instrumented with six 8'' PMTs, one 10'' HE PMT, and the same laser calibration system, electronics, and data acquisition system as the WCDs at the HAWC site. The CSU prototype is additionally equipped with scintillator paddles both under and above the volume of water, temperature probes (in the water, outside, and in the DAQ room), and one covered PMT. Preliminary results for muon rates and their temperature dependance using data collected with the CSU prototype will be presented.

A detailed study of FDIRC prototype with waveform digitizing electronics in cosmic ray telescope using 3D tracks

NASA Astrophysics Data System (ADS)

Nishimura, K.; Dey, B.; Aston, D.; Leith, D. W. G. S.; Ratcliff, B.; Roberts, D.; Ruckman, L.; Shtol, D.; Varner, G. S.; Va'vra, J.

2013-02-01

We present a detailed study of a novel Cherenkov imaging detector called the Focusing DIRC (FDIRC) with waveform digitizing electronics. In this study, the FDIRC prototype has been instrumented with seven Hamamatsu H-8500 MaPMTs. Waveforms from 384 pixels are digitized with waveform sampling electronics based on the BLAB2 ASIC, operating at a sampling speed of ∼2.5 GSa/s. The FDIRC prototype was tested in a large cosmic ray telescope (CRT) providing 3D muon tracks with ∼1.5 mrad angular resolution and muon energy of Emuon> 1.6 GeV. In this study we provide a detailed analysis of the tails in the Cherenkov angle distribution as a function of various variables, compare experimental results with simulation, and identify the major contributions to the tails. We demonstrate that to see the full impact of these tails on the Cherenkov angle resolution, it is crucial to use 3D tracks, and have a full understanding of the role of reconstruction ambiguities. These issues could not be fully explored in previous FDIRC studies where the beam was perpendicular to the quartz radiator bars. This work is relevant for the final FDIRC prototype of the PID detector at SuperB, which will be tested this year in the CRT setup.

AGIS: A Next-generation TeV Gamma-ray Observatory

NASA Astrophysics Data System (ADS)

Vandenbroucke, Justin

2010-05-01

The Advanced Gamma-ray Imaging System (AGIS) is a next-generation array of imaging atmospheric Cherenkov telescopes for gamma-ray astronomy in the 100 GeV to 100 TeV band. TeV astronomy has flourished in the last few years. Together with the extremely successful first year of the Fermi LAT telescope for GeV gamma-ray astronomy, we are now in a golden age of gamma-ray astronomy. AGIS seeks to continue the success of gamma-ray astronomy by discovering hundreds of new TeV sources and improving our understanding of known sources, as well as searching for signals from dark matter annihilation. AGIS will feature 36 Schwarzschild-Couder (SC) telescopes spanning 1 km2. The two-mirror SC design allows a wide field of view (8 deg diameter) and high-resolution (0.05 deg diameter) pixellation. I will present the science capabilities of the AGIS observatory as well as the technical design and current status of the project.

The Cherenkov Telescope Array For Very High-Energy Astrophysics

NASA Astrophysics Data System (ADS)

Kaaret, Philip

2015-08-01

The field of very high energy (VHE) astrophysics had been revolutionized by the results from ground-based gamma-ray telescopes, including the current imaging atmospheric Cherenkov telescope (IACT) arrays: HESS, MAGIC and VERITAS. A worldwide consortium of scientists from 29 countries has formed to propose the Cherenkov Telescope Array (CTA) that will capitalize on the power of this technique to greatly expand the scientific reach of ground-based gamma-ray telescopes. CTA science will include key topics such as the origin of cosmic rays and cosmic particle acceleration, understanding extreme environments in regions close to neutron stars and black holes, and exploring physics frontiers through, e.g., the search for WIMP dark matter, axion-like particles and Lorentz invariance violation. CTA is envisioned to consist of two large arrays of Cherenkov telescopes, one in the southern hemisphere and one in the north. Each array will contain telescopes of different sizes to provide a balance between cost and array performance over an energy range from below 100 GeV to above 100 TeV. Compared to the existing IACT arrays, CTA will have substantially better angular resolution and energy resolution, will cover a much wider energy range, and will have up to an order of magnitude better sensitivity. CTA will also be operated as an open observatory and high-level CTA data will be placed into the public domain; these aspects will enable broad participation in CTA science from the worldwide scientific community to fully capitalize on CTA's potential. This talk will: 1) review the scientific motivation and capabilities of CTA, 2) provide an overview of the technical design and the status of prototype development, and 3) summarize the current status of the project in terms of its proposed organization and timeline. The plans for access to CTA data and opportunities to propose for CTA observing time will be highlighed.Presented on behalf of the CTA Consortium.

Optical transmission radiation damage and recovery stimulation of DSB: Ce3+ inorganic scintillation material

NASA Astrophysics Data System (ADS)

Borisevich, A.; Dormenev, V.; Korjik, M.; Kozlov, D.; Mechinsky, V.; Novotny, R. W.

2015-02-01

Recently, a new scintillation material DSB: Ce3+ was announced. It can be produced in a form of glass or nano-structured glass ceramics with application of standard glass production technology with successive thermal annealing. When doped with Ce3+, material can be applied as scintillator. Light yield of scintillation is near 100 phe/MeV. Un-doped material has a wide optical window from 4.5eV and can be applied to detect Cherenkov light. Temperature dependence of the light yield LY(T) is 0.05% which is 40 times less than in case of PWO. It can be used for detectors tolerant to a temperature variation between -20° to +20°C. Several samples with dimensions of 15x15x7 mm3 have been tested for damage effects on the optical transmission under irradiation with γ-quanta. It was found that the induced absorption in the scintillation range depends on the doping concentration and varies in range of 0.5-7 m-1. Spontaneous recovery of induced absorption has fast initial component. Up to 25% of the damaged transmission is recuperated in 6 hours. Afterwards it remains practically constant if the samples are kept in the dark. However, induced absorption is reduced by a factor of 2 by annealing at 50°C and completely removed in a short time when annealing at 100°C. A significant acceleration of the induced absorption recovery is observed by illumination with visible and IR light. This effect is observed for the first time in a Ce-doped scintillation material. It indicates, that radiation induced absorption in DSB: Ce scintillation material can be retained at the acceptable level by stimulation with light in a strong irradiation environment of collider experiments.

Modular focusing ring imaging Cherenkov detector for electron-ion collider experiments

NASA Astrophysics Data System (ADS)

Wong, C. P.; Alfred, M.; Allison, L.; Awadi, M.; Azmoun, B.; Barbosa, F.; Barion, L.; Bennett, J.; Brooks, W.; Butler, C.; Cao, T.; Chiu, M.; Cisbani, E.; Contalbrigo, M.; Datta, A.; Del Dotto, A.; Demarteau, M.; Durham, J. M.; Dzhygadlo, R.; Elder, T.; Fields, D.; Furletova, Y.; Gleason, C.; Grosse-Perdekamp, M.; Harris, J.; Haseler, T. O. S.; He, X.; van Hecke, H.; Horn, T.; Hruschka, A.; Huang, J.; Hyde, C.; Ilieva, Y.; Kalicy, G.; Kimball, M.; Kistenev, E.; Kulinich, Y.; Liu, M.; Majka, R.; McKisson, J.; Mendez, R.; Nadel-Turonski, P.; Park, K.; Peters, K.; Rao, T.; Pisani, R.; Qiang, Y.; Rescia, S.; Rossi, P.; Sarajlic, O.; Sarsour, M.; Schwarz, C.; Schwiening, J.; da Silva, C. L.; Smirnov, N.; Stien, H. D.; Stevens, J.; Sukhanov, A.; Syed, S.; Tate, A. C.; Toh, J.; Towell, C. L.; Towell, R. S.; Tsang, T.; Turisini, M.; Wagner, R.; Wang, J.; Woody, C.; Xi, W.; Xie, J.; Zhao, Z. W.; Zihlmann, B.; Zorn, C.

2017-11-01

A powerful new electron-ioncollider (EIC) has been recommended in the 2015 Long Range Plan for Nuclear Science for probing the partonic structure inside nucleons and nuclei with unprecedented precision and versatility [1]. EIC detectors are currently under development [2], all of which require hadron identification over a broad kinematic range. A prototype ring imaging Cherenkov detector has been developed for hadron identification in the momentum range from 3 GeV/c to 10 GeV/c. The key feature of this new detector is a compact and modular design, achieved by using aerogel as radiator and a Fresnel lens for ring focusing. In this paper, the results from a beam test of a prototype device at Fermilab are reported.

KM3NeT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jong, M. de; Leiden Institute of Physics, Leiden University, Leiden; Collaboration: KM3NeT Collaboration

2015-07-15

KM3NeT is a large research infrastructure, that will consist of a network of deep-sea neutrino telescopes in the Mediterranean Sea. The main objective of KM3NeT is the discovery and subsequent observation of high-energy neutrino sources in the Universe. A further physics perspective is the measurement of the mass hierarchy of neutrinos. A corresponding study, ORCA, is ongoing within KM3NeT. A cost effective technology for (very) large water Cherenkov detectors has been developed based on a new generation of low price 3-inch photo-multiplier tubes. Following the successful deployment and operation of two prototypes, the construction of the KM3NeT research infrastructure hasmore » started. The prospects of the different phases of the implementation of KM3NeT are summarised.« less

KM3NeT

NASA Astrophysics Data System (ADS)

de Jong, M.

2015-07-01

KM3NeT is a large research infrastructure, that will consist of a network of deep-sea neutrino telescopes in the Mediterranean Sea. The main objective of KM3NeT is the discovery and subsequent observation of high-energy neutrino sources in the Universe. A further physics perspective is the measurement of the mass hierarchy of neutrinos. A corresponding study, ORCA, is ongoing within KM3NeT. A cost effective technology for (very) large water Cherenkov detectors has been developed based on a new generation of low price 3-inch photo-multiplier tubes. Following the successful deployment and operation of two prototypes, the construction of the KM3NeT research infrastructure has started. The prospects of the different phases of the implementation of KM3NeT are summarised.

Superradiant Ka-band Cherenkov oscillator with 2-GW peak power

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rostov, V. V.; Romanchenko, I. V.; Pedos, M. S.

The generation of a 2-GW microwave superradiance (SR) pulses has been demonstrated at 29-GHz using a single-mode relativistic backward-wave oscillator possessing the beam-to-wave power conversion factor no worse than 100%. A record-breaking radiation power density in the slow-wave structure (SWS) of ∼1.5 GW/cm{sup 2} required the use of high guiding magnetic field (7 T) decreasing the beam losses to the SWS in strong rf fields. Despite the field strength at the SWS wall of 2 MV/cm, a single-pass transmission mode of a short SR pulse in the SWS allows one to obtain extremely high power density in subnanosecond time scale due tomore » time delay in the development of the breakdown phenomena.« less

Enhanced photon traps for Hyper-Kamiokande

NASA Astrophysics Data System (ADS)

Rott, Carsten; In, Seongjin; Retière, Fabrice; Gumplinger, Peter

2017-11-01

Hyper-Kamiokande, the next generation large water Cherenkov detector in Japan, is planning to use approximately 80,000 20-inch photomultiplier tubes (PMTs). They are one of the major cost factors of the experiment. We propose a novel enhanced photon trap design based on a smaller and more economical PMT in combination with wavelength shifters, dichroic mirrors, and broadband mirrors. GEANT4 is utilized to obtain photon collection efficiencies and timing resolution of the photon traps. We compare the performance of different trap configurations and sizes. Our simulations indicate an enhanced photon trap with a 12-inch PMT can match a 20-inch PMT's collection efficiency, however at a cost of reduced timing resolution. The photon trap might be suitable as detection module for the outer detector with large photo coverage area.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratcliff, Blair N

Some conceptual design features of the total internally reflecting,imaging Cherenkov counter (DIRC) are described. Limits of the DIRC approach to particle identification, and a few features of alternative DIRC designs, are briefly explored.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratcliff, Blair N

Some general conceptual design features of total internally reflecting, imaging Cherenkov counters (DIRCs) are described. Limits of the DIRC approach to particle identification and a few features of alternative DIRC designs are briefly explored.

FACT - Status and experience from five years of operation of the first G-APD Cherenkov Telescope

NASA Astrophysics Data System (ADS)

Neise, D.; Adam, J.; Ahnen, M. L.; Baack, D.; Balbo, M.; Bergmann, M.; Biland, A.; Blank, M.; Bretz, T.; Brügge, K. A.; Buss, J.; Dmytriiev, A.; Dorner, D.; Einecke, S.; Hempfling, C.; Hildebrand, D.; Hughes, G.; Linhoff, L.; Mannheim, K.; Müller, S.; Neronov, A.; Nöthe, M.; Paravac, A.; Pauss, F.; Rhode, W.; Shukla, A.; Temme, F.; Thaele, J.; Walter, R.

2017-12-01

The First G-APD Cherenkov Telescope (FACT) demonstrates the usability of novel Geiger-mode operated Avalanche Photo Diodes (G-APD, often called SiPM) for Imaging Atmospheric Cherenkov Telescopes (IACT). The camera consists of 1440 pixels with dedicated electronics operating at 2 Giga samples per second. It is installed on the refurbished HEGRA telescope with a mirror area of ≈ 9.5m2 on the Canary Island La Palma. FACT is taking data almost every night since the camera was installed in October 2011. It was possible to improve the data taking efficiency to very high values due to the very stable and reliable operation. This also allows to operate FACT remotely without any need for operators on site. Even remote human intervention became less and less frequent over the years, allowing operation to become mostly automatic. FACT is monitoring the long-term behavior of some very-high energy variable extra-galactic sources with unparalleled sampling density as well as testing the behavior of the sensors under severe weather conditions. Due to the long exposure of FACT's G-APDs under strong moonlight conditions it was possible to evaluate the aging effects of G-APDs due to collected charge. No indication of aging was found. No external calibration device is needed to operate FACT since the properties of the sensors themselves allow for a high precision self-calibration of the camera.

Investigation Of Aeroacoustic Mechanisms By Remote Thermal Imaging

NASA Astrophysics Data System (ADS)

Witten, Alan J.; Courville, George E.

1988-01-01

A hush house is a hangar-like structure designed to isolate, from the surrounding environment, the noise produced by extended aircraft engine operations during diagnostic testing. While hush houses meet this intended need by suppressing audible noise, they do emit significant subaudible acoustic energy which has caused structural vibrations in nearby facilities. As a first step in mitigating the problems associated with hush house induced vibrations, it is necessary to identify the mechanism responsible for the low frequency acoustic emissions. It was hypothesized that the low frequency acoustic waves are a result of acoustic Cherenkov radiation. This radiation is in the form of a coherent wave produced by the engine exhaust gas flow. The speed of sound in the exhaust gas is quite high as a result of its elevated temperature. Therefore, the gas flow is sonic or subsonic relative to its own sound speed, but is supersonic relative to sound speed in the surrounding cooler air and, as a result, produces acoustic Cherenkov radiation. To confirm this hypothesis, thermographic surveys were conducted to image the thermal structure of the engine exhaust gas within the hush house. In the near-field, these images revealed that the exhaust gases did not behave like a high Reynolds number turbulent jet, but rather, the transition to turbulence is delayed by a suppression in growth of the self-excited instability wave as a result of acoustic Cherenkov radiation.

The water Cherenkov detectors of the HAWC Observatory

NASA Astrophysics Data System (ADS)

Longo, Megan; Mostafa, Miguel

2012-10-01

The High Altitude Water Cherenkov (HAWC) observatory is a very high-energy gamma-ray detector which is currently under construction at 4100 m in Sierra Negra, Mexico. The observatory will be composed of an array of 300 Water Cherenkov Detectors (WCDs). Each WCD consists of a 5 m tall by 7.3 m wide steel tank containing a hermetically sealed plastic bag, called a bladder, which is filled with 200,000 liters of purified water. The detectors are each equipped with four upward-facing photomultiplier tubes (PMTs), anchored to the bottom of the bladder. At Colorado State University (CSU) we have the only full-size prototype outside of the HAWC site. It serves as a testbed for installation and operation procedures for the HAWC observatory. The WCD at CSU has been fully operational since March 2011, and has several components not yet present at the HAWC site. In addition to the four HAWC position PMTs, our prototype has three additional PMTs, including one shrouded (dark) PMT. We also have five scintillator paddles, four buried underneath the HAWC position PMTs, and one freely moving paddle above the volume of water. These extra additions will allow us to work on muon reconstruction with a single WCD. We will describe the analysis being done with the data taken with the CSU prototype, its impact on the HAWC detector, and future plans for the prototype.

Emission spectra of electron irradiated metal foils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emerson, L. C.; Arakawa, E. T.; Ritchie, R. H.

1963-08-09

Thesis submitted to Univ. of Tennessee by L. C. Emerson. An experimental investigation of the visible and ultraviolet light emitted when a charged particle moves across a boundary between two media with different dielectric properties was carried out. The spectral distributions of the light from evaporated foils of copper, germanium, silver, tin, and antimony bombarded by a 1.5-microamp beam of electrons were measured as a function of electron energy between 25 and 100 kev. The analysis was carried out with a Seya-Namioka vacuum ultraviolet spectrometer, Glan-Foucault prism polarizer, and a quartz- window photomultiplier. Calibration of the optical system with amore » NBS tungsten filament lamp enabled the intensity measurements to be carried out on an absolute basis. The experimental results for light polarized parallel to the plane containing the photon and the electron were compared with the calculated intensity of transftion radiation, and in general the agreement was found to be excellent. The component of the photon intensity polarized perpendicular to this plane was compared with the calculated intensity of the optical portion of the bremsstrahlung spectrum. The predicted dependence on electron energy, photon wavelength, and foil thickness was observed although the measured yield was higher than that predicted by theory. The possibility of contributions from Cherenkov radiation and plasma radiation is also considered, but it is shown that it would be unlikely for these radiations to be observed under the experimental conditions of this study.« less

Preparatory Study of Photomultiplier Tubes of 10-inch and 3-inch Diameter for KM3NeT Underwater Neutrino Telescope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aiello, S.; Giordano, V.; Leonora, E.

Large area photomultipliers are widely used in neutrino and astro-particle detectors to measure Cherenkov light in media like water or ice. The key element of these detectors are the so-called 'optical module', which consists of a photodetector enclosed in a transparent pressure-resistant container to protect it and ensure good light transmission. KM3NeT collaboration aims to construct an underwater 'hybrid' neutrino telescope by using two models detection unit. The 'tower' detection unit will be composed of large area 10-inch photomultipliers tube enclosed into 13-inch glass vessel sphere. In the 'string' detection unit instead, the light detector will be the 'digital opticalmore » module' (DOM) a glass vessel of 17-inch with 31 photomultipliers of 3- inch diameter looking upwards and downwards. The choice of two different kinds of photomultipliers, obliges us to investigate their main characteristics. Noise pulses at the anode of each photomultiplier strongly affect the performance of the detector. A large study was conducted on noise pulses of large area photomultipliers, considering time and charge distributions of dark pulses, pre-pulses, delayed pulses, and after-pulses. The contribution to noise pulses due to the presence of the external glass vessels was also studied. Moreover the presence of the Earth's magnetic field should modify quantities like gain and transit time spread in photomultipliers and we will deeply investigate on this. (authors)« less

The Advanced Gamma-ray Imaging System (AGIS): Next-generation Cherenkov telescopes array.

NASA Astrophysics Data System (ADS)

Vassiliev, Vladimir; AGIS Collaboration

2010-03-01

AGIS is a concept for a next-generation ground-based gamma-ray observatory in the energy range from 50 GeV to 200 TeV. AGIS is being designed to have significantly improved sensitivity, angular resolution, and reliability of operation relative to the present generation instruments such as VERITAS and H.E.S.S. The novel technologies of AGIS are expected to enable great advances in the understanding of the populations and physics of sources of high-energy gamma rays in the Milky Way (e.g. SNR, X-ray binaries, dense molecular clouds) and outside the Galaxy (e.g. AGN, GRBs, galaxy clusters, and star-forming galaxies). AGIS will complement and extend the results now being obtained in the GeV range with the Fermi mission providing wide energy coverage, superior angular resolution, and sensitivity to variability on short time scales. AGIS will be a key instrument for identifying and characterizing Fermi LAT sources. In this submission we outline the status of the development of AGIS project, design concept, and principal technologies. As illustrations of the scientific capabilities of AGIS, we review its potential to indirectly search for dark matter and measure cosmological magnetic fields.

Status of air-shower measurements with sparse radio arrays

NASA Astrophysics Data System (ADS)

Schröder, Frank G.

2017-03-01

This proceeding gives a summary of the current status and open questions of the radio technique for cosmic-ray air showers, assuming that the reader is already familiar with the principles. It includes recent results of selected experiments not present at this conference, e.g., LOPES and TREND. Current radio arrays like AERA or Tunka-Rex have demonstrated that areas of several km2 can be instrumented for reasonable costs with antenna spacings of the order of 200m. For the energy of the primary particle such sparse antenna arrays can already compete in absolute accuracy with other precise techniques, like the detection of air-fluorescence or air-Cherenkov light. With further improvements in the antenna calibration, the radio detection might become even more accurate. For the atmospheric depth of the shower maximum, Xmax, currently only the dense array LOFAR features a precision similar to the fluorescence technique, but analysis methods for the radio measurement of Xmax are still under development. Moreover, the combination of radio and muon measurements is expected to increase the accuracy of the mass composition, and this around-the-clock recording is not limited to clear nights as are the light-detection methods. Consequently, radio antennas will be a valuable add-on for any air shower array targeting the energy range above 100 PeV.

Editorial

NASA Astrophysics Data System (ADS)

Buitink, S.; Hörandel, J. R.; de Jong, S.; Lahmann, R.; Nahnhauer, R.; Scholten, O.

2017-03-01

This proceeding gives a summary of the current status and open questions of the radio technique for cosmic-ray air showers, assuming that the reader is already familiar with the principles. It includes recent results of selected experiments not present at this conference, e.g., LOPES and TREND. Current radio arrays like AERA or Tunka-Rex have demonstrated that areas of several km2 can be instrumented for reasonable costs with antenna spacings of the order of 200m. For the energy of the primary particle such sparse antenna arrays can already compete in absolute accuracy with other precise techniques, like the detection of air-fluorescence or air-Cherenkov light. With further improvements in the antenna calibration, the radio detection might become even more accurate. For the atmospheric depth of the shower maximum, Xmax, currently only the dense array LOFAR features a precision similar to the fluorescence technique, but analysis methods for the radio measurement of Xmax are still under development. Moreover, the combination of radio and muon measurements is expected to increase the accuracy of the mass composition, and this around-the-clock recording is not limited to clear nights as are the light-detection methods. Consequently, radio antennas will be a valuable add-on for any air shower array targeting the energy range above 100 PeV.

Cherenkov radiation due to the passage of an oscillatory dipole moving parallel to a conducting barrier

DOE Office of Scientific and Technical Information (OSTI.GOV)

De, P.K.

1973-08-01

The Cherenkov radiation emitted by an oscillating dipole moving in a semi-infinite dielectric with a constant velocity along a straight line parallel to the conducting boundary is calculated by using Maxwell's equations. The wave nature of electromagnetic intensities reveals that waves propagate in two modes, and the radiation takes place in the form of two cones which are semicircular in section, the axes of the cones coinciding wiih the path of the dipole. Conditions for the existence of only one cone are given. The intensity of radiation fluctuates spatially. The conducting boundary acts as a promoter and plays an importantmore » role in the graduation of energy loss which is technically important for concentration of radiation. (RWR)« less

Modular focusing ring imaging Cherenkov detector for electron–ion collider experiments

DOE PAGES

Wong, C. P.; Alfred, M.; Allison, L.; ...

2017-07-16

Here, a powerful new electron–ioncollider (EIC) has been recommended in the 2015 Long Range Plan for Nuclear Science for probing the partonic structure inside nucleons and nuclei with unprecedented precision and versatility. EIC detectors are currently under development, all of which require hadron identification over a broad kinematic range. A prototype ring imaging Cherenkov detector has been developed for hadron identification in the momentum range from 3 GeV/c to 10 GeV/c. The key feature of this new detector is a compact and modular design, achieved by using aerogel as radiator and a Fresnel lens for ring focusing. In this paper,more » the results from a beam test of a prototype device at Fermilab are reported.« less

The DarkSide-50 outer detectors

NASA Astrophysics Data System (ADS)

Westerdale, S.; Agnes, P.; Agostino, L.; Albuquerque, I. F. M.; Alexander, T.; Alton, A. K.; Arisaka, K.; Back, H. O.; Baldin, B.; Biery, K.; Bonfini, G.; Bossa, M.; Bottino, B.; Brigatti, A.; Brodsky, J.; Budano, F.; Bussino, S.; Cadeddu, M.; Cadonati, L.; Cadoni, M.; Calaprice, F.; Canci, N.; Candela, A.; Cao, H.; Cariello, M.; Carlini, M.; Catalanotti, S.; Cavalcante, P.; Chepurnov, A.; Cocco, A. G.; Covone, G.; D'Angelo, D.; D'Incecco, M.; Davini, S.; De Cecco, S.; De Deo, M.; De Vincenzi, M.; Derbin, A.; Devoto, A.; Di Eusanio, F.; Di Pietro, G.; Edkins, E.; Empl, A.; Fan, A.; Fiorillo, G.; Fomenko, K.; Foster, G.; Franco, D.; Gabriele, F.; Galbiati, C.; Giganti, C.; Goretti, A. M.; Granato, F.; Grandi, L.; Gromov, M.; Guan, M.; Guardincerri, Y.; Hackett, B. R.; Herner, K. R.; Hungerford, E. V.; Aldo, Ianni; Andrea, Ianni; James, I.; Jollet, C.; Keeter, K.; Kendziora, C. L.; Kobychev, V.; Koh, G.; Korablev, D.; Korga, G.; Kubankin, A.; Li, X.; Lissia, M.; Lombardi, P.; Luitz, S.; Ma, Y.; Machulin, I. N.; Mandarano, A.; Mari, S. M.; Maricic, J.; Marini, L.; Martoff, C. J.; Meregaglia, A.; Meyers, P. D.; Miletic, T.; Milincic, R.; Montanari, D.; Monte, A.; Montuschi, M.; Monzani, M. E.; Mosteiro, P.; Mount, B. J.; Muratova, V. N.; Musico, P.; Napolitano, J.; Orsini, M.; Ortica, F.; Pagani, L.; Pallavicini, M.; Pantic, E.; Parmeggiano, S.; Pelczar, K.; Pelliccia, N.; Perasso, S.; Pocar, A.; Pordes, S.; Pugachev, D. A.; Qian, H.; Randle, K.; Ranucci, G.; Razeto, A.; Reinhold, B.; Renshaw, A. L.; Romani, A.; Rossi, B.; Rossi, N.; Rountree, S. D.; Sablone, D.; Saggese, P.; Saldanha, R.; Sands, W.; Sangiorgio, S.; Savarese, C.; Segreto, E.; Semenov, D. A.; Shields, E.; Singh, P. N.; DSkorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Stanford, C.; Suvorov, Y.; Tartaglia, R.; Tatarowicz, J.; Testera, G.; Tonazzo, A.; Trinchese, P.; Unzhakov, E. V.; Vishneva, A.; Vogelaar, B.; Wada, M.; Walker, S.; Wang, H.; Wang, Y.; Watson, A. W.; Wilhelmi, J.; Wojcik, M. M.; Xiang, X.; Xu, J.; Yang, C.; Yoo, J.; Zavatarelli, S.; Zec, A.; Zhong, W.; Zhu, C.; Zuzel, G.; DarkSide Collaboration

2016-05-01

DarkSide-50 is a dark matter detection experiment searching for Weakly Interacting Massive Particles (WIMPs), in Gran Sasso National Laboratory. For experiments like DarkSide-50, neutrons are one of the primary backgrounds that can mimic WIMP signals. The experiment consists of three nested detectors: a liquid argon time projection chamber surrounded by two outer detectors. The outermost detector is a 10 m by 11 m cylindrical water Cherenkov detector with 80 PMTs, designed to provide shielding and muon vetoing. Inside the water Cherenkov detector is the 4 m diameter spherical boron-loaded liquid scintillator veto, with a cocktail of pseudocumene, trimethyl borate, and PPO wavelength shifter, designed to provide shielding, neutron vetoing, and in situ measurements of the TPC backgrounds. We present design and performance details of the DarkSide-50 outer detectors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adamson, P.; Austin, J.; Cao, S. V.

This Letter of Intent outlines a proposal to build a large, yet cost-effective, 100 kton fiducial mass water Cherenkov detector that will initially run in the NuMI beam line. The CHIPS detector (CHerenkov detector In Mine PitS) will be deployed in a flooded mine pit, removing the necessity and expense of a substantial external structure capable of supporting a large detector mass. There are a number of mine pits in northern Minnesota along the NuMI beam that could be used to deploy such a detector. In particular, the Wentworth Pit 2W is at the ideal off-axis angle to contribute tomore » the measurement of the CP violating phase. The detector is designed so that it can be moved to a mine pit in the LBNE beam line once that becomes operational.« less