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Sample records for atmospheric cherenkov telescopes

  1. Catching GRBs with atmospheric Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Gilmore, R. C.; Primack, J. R.; Bouvier, A.; Otte, A. N.

    2011-08-01

    Fermi has shown GRBs to be a source of >10 GeV photons. We present an estimate of the detection rate of GRBs with a next generation Cherenkov telescope. Our predictions are based on the observed properties of GRBs detected by Fermi, combined with the spectral properties and redshift determinations for the bursts population by instruments operating at lower energies. While detection of VHE emission from GRBs has eluded ground-based instruments thus far, our results suggest that ground-based detection may be within reach of the proposed Cherenkov Telescope Array (CTA), albeit with a low rate, 0.25-0.5/yr. Such a detection would help constrain the emission mechanism of gamma-ray emission from GRBs. Photons at these energies from distant GRBs are affected by the UV-optical background light, and a ground-based detection could also provide a valuable probe of the Extragalactic Background Light (EBL) in place at high redshift.

  2. Large size SiPM matrix for Imaging Atmospheric Cherenkov Telescopes applications

    NASA Astrophysics Data System (ADS)

    Ambrosi, G.; Corti, D.; Ionica, M.; Manea, C.; Mariotti, M.; Rando, R.; Reichardt, I.; Schultz, C.

    2016-07-01

    SiPM photo detectors are nowadays commonly used in many applications. For large size telescopes like MAGIC or the future Large Size Telescope (LST) of the Cherenkov Telescope Array (CTA) project, a pixel size of some square centimeters is needed. An analog amplifier and sum stage was built and characterized. A large and compact SiPM matrix prototype, with the associated focusing optics, was assembled into a monolithic light detector with an active area of 3 cm2. The performance of the electronics is tailored for Imaging Atmospheric Cherenkov Telescopes (IACT) applications, with fast signal and adequate signal-to-noise (S/N) ratio.

  3. Fast pattern recognition trigger for atmospheric cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Vardanyan, A. A.; Chilingarian, S. A.; Eppler, W.; Gemmeke, H.

    2001-08-01

    The ambitions to bridge the energy gap between ground based and satellite borne detectors requires to decrease the threshold of Cherenkov telescopes down to several tens of GeV. The images corresponding to such low energies and registered with high angular resolution will lead to rather complicated disconnected images. The standard second-momentum analysis will not be so effective as for images detected with less angular resolution and/or more compact mirrors and high incident energies above 300 GeV. Since the trigger rate at low thresholds can reach 1 MHz, the main tasks for an "intelligent" trigger are signal pattern recognition and background rejection. We propose to use the hardware neurochip SAND/1 (Simple Applicable Neural Device) as fast "intelligent" Pattern Recognition Trigger (PRT). In addition to decrease the registered event rate down to several kHz, the PRT will reject muon and hadron backgrounds online at present only possible off-line. Using a special board of hardware neural accelerators and evolutionary network training strategies we construct a PRT which meets both timing and pattern recognition requirements.

  4. 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.

  5. PROBING THE PULSAR ORIGIN OF THE ANOMALOUS POSITRON FRACTION WITH AMS-02 AND ATMOSPHERIC CHERENKOV TELESCOPES

    SciTech Connect

    Linden, Tim; Profumo, Stefano

    2013-07-20

    Recent observations by PAMELA, Fermi-LAT, and AMS-02 have conclusively indicated a rise in the cosmic-ray positron fraction above 10 GeV, a feature which is impossible to mimic under the paradigm of secondary positron production with self-consistent Galactic cosmic-ray propagation models. A leading explanation for the positron fraction rise is an additional source of electron-positron pairs, for example one or more mature, energetic, and relatively nearby pulsars. We point out that any one of two well-known nearby pulsars, Geminga and Monogem, can satisfactorily provide enough positrons to reproduce AMS-02 observations. A smoking-gun signature of this scenario is an anisotropy in the arrival direction of the cosmic-ray electrons and positrons, which may be detectable by existing, or future, telescopes. The predicted anisotropy level is, at present, consistent with limits from Fermi-LAT and AMS-02. We argue that the large collecting area of atmospheric Cherenkov telescopes (ACTs) makes them optimal tools for detecting such an anisotropy. Specifically, we show that much of the proton and {gamma}-ray background which affects measurements of the cosmic-ray electron-positron spectrum with ACTs may be controlled in the search for anisotropies. We conclude that observations using archival ACT data could already constrain or substantiate the pulsar origin of the positron anomaly, while upcoming instruments (such as the Cherenkov Telescope Array) will provide strong constraints on the source of the rising positron fraction.

  6. Probing the Pulsar Origin of the Anomalous Positron Fraction with AMS-02 and Atmospheric Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Linden, Tim; Profumo, Stefano

    2013-07-01

    Recent observations by PAMELA, Fermi-LAT, and AMS-02 have conclusively indicated a rise in the cosmic-ray positron fraction above 10 GeV, a feature which is impossible to mimic under the paradigm of secondary positron production with self-consistent Galactic cosmic-ray propagation models. A leading explanation for the positron fraction rise is an additional source of electron-positron pairs, for example one or more mature, energetic, and relatively nearby pulsars. We point out that any one of two well-known nearby pulsars, Geminga and Monogem, can satisfactorily provide enough positrons to reproduce AMS-02 observations. A smoking-gun signature of this scenario is an anisotropy in the arrival direction of the cosmic-ray electrons and positrons, which may be detectable by existing, or future, telescopes. The predicted anisotropy level is, at present, consistent with limits from Fermi-LAT and AMS-02. We argue that the large collecting area of atmospheric Cherenkov telescopes (ACTs) makes them optimal tools for detecting such an anisotropy. Specifically, we show that much of the proton and γ-ray background which affects measurements of the cosmic-ray electron-positron spectrum with ACTs may be controlled in the search for anisotropies. We conclude that observations using archival ACT data could already constrain or substantiate the pulsar origin of the positron anomaly, while upcoming instruments (such as the Cherenkov Telescope Array) will provide strong constraints on the source of the rising positron fraction.

  7. Front-end electronics and data acquisition system for imaging atmospheric Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Chen, Y. T.; de La Taille, C.; Suomijärvi, T.; Cao, Z.; Deligny, O.; Dulucq, F.; Ge, M. M.; Lhenry-Yvon, I.; Martin-Chassard, G.; Nguyen Trung, T.; Wanlin, E.; Xiao, G.; Yin, L. Q.; Yun Ky, B.; Zhang, L.; Zhang, H. Y.; Zhang, S. S.; Zhu, Z.

    2015-09-01

    In this paper, a front-end electronics based on an application-specific integrated circuit (ASIC) is presented for the future imaging atmospheric Cherenkov telescopes (IACTs). To achieve this purpose, a 16-channel ASIC chip, PARISROC 2 (Photomultiplier ARray Integrated in SiGe ReadOut Chip) is used in the analog signal processing and digitization. The digitized results are sent to the server by a user-defined User Datagram Protocol/Internet Protocol (UDP/IP) hardcore engine through Ethernet that is managed by a FPGA. A prototype electronics fulfilling the requirements of the Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO) project has been designed, fabricated and tested to prove the concept of the design. A detailed description of the development with the results of the test measurements are presented. By using a new input structure and a new configuration of the ASIC, the dynamic range of the circuit is extended. A highly precise-time calibrating algorithm is also proposed, verified and optimized for the mass production. The test results suggest that the proposed electronics design fulfills the general specification of the future IACTs.

  8. 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.

  9. 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.

  10. A new analysis strategy for detection of faint γ-ray sources with Imaging Atmospheric Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Becherini, Y.; Djannati-Ataï, A.; Marandon, V.; Punch, M.; Pita, S.

    2011-07-01

    A new background rejection strategy for γ-ray astrophysics with stereoscopic Imaging Atmospheric Cherenkov Telescopes (IACT), based on Monte Carlo (MC) simulations and real background data from the H.E.S.S. [High Energy Stereoscopic System, see [1].] experiment, is described. The analysis is based on a multivariate combination of both previously-known and newly-derived discriminant variables using the physical shower properties, as well as its multiple images, for a total of eight variables. Two of these new variables are defined thanks to a new energy evaluation procedure, which is also presented here. The method allows an enhanced sensitivity with the current generation of ground-based Cherenkov telescopes to be achieved, and at the same time its main features of rapidity and flexibility allow an easy generalization to any type of IACT. The robustness against Night Sky Background (NSB) variations of this approach is tested with MC simulated events. The overall consistency of the analysis chain has been checked by comparison of the real γ-ray signal obtained from H.E.S.S. observations with MC simulations and through reconstruction of known source spectra. Finally, the performance has been evaluated by application to faint H.E.S.S. sources. The gain in sensitivity as compared to the best standard Hillas analysis ranges approximately from 1.2 to 1.8 depending on the source characteristics, which corresponds to an economy in observation time of a factor 1.4 to 3.2.

  11. MACHETE: A transit imaging atmospheric Cherenkov telescope to survey half of the very high energy γ-ray sky

    NASA Astrophysics Data System (ADS)

    Cortina, J.; López-Coto, R.; Moralejo, A.

    2016-01-01

    Current imaging atmospheric Cherenkov telescopes for very high energy γ-ray astrophysics are pointing instruments with a field of view up to a few tens of sq deg. We propose to build an array of two non-steerable (drift) telescopes. Each of the telescopes would have a camera with a FOV of 5 × 60 sq deg oriented along the meridian. About half of the sky drifts through this FOV in a year. We have performed a Monte Carlo simulation to estimate the performance of this instrument. We expect it to survey this half of the sky with an integral flux sensitivity of ˜0.77% of the steady flux of the Crab Nebula in 5 years, an analysis energy threshold of ˜150 GeV and an angular resolution of ˜0.1°. For astronomical objects that transit over the telescope for a specific night, we can achieve an integral sensitivity of 12% of the Crab Nebula flux in a night, making it a very powerful tool to trigger further observations of variable sources using steerable IACTs or instruments at other wavelengths.

  12. Muon cherenkov telescope

    NASA Astrophysics Data System (ADS)

    Malamova, E.; Angelov, I.; Kalapov, I.; Davidkov, K.; Stamenov, J.

    2001-08-01

    : The Muon Cerenkov Telescope is a system of water cerenkov detectors, using the coincidence technique to register cosmic ray muons. It is constructed in order to study the variations of cosmic rays and their correlation with solar activity and processes in the Earth magnetosphere. 1 Basic design of the Muon Cerenkov Telescope The telescope has 18 water cerenkov detectors / 0.25 m2 each /, situated in two parallel planes. / Fig. 1/ Each detector /fig. 2/ consists of a container with dimensions 50x50x12.5 cm made of 3mm thick glass with mirror cover of the outer side. The container is filled with distilled water to 10cm level. A photomultiplier is attached to a transparent circle at the floor of the container and the discriminator is placed in its housing. When a charged particle with energy greater than the threshold energy for cerenkov radiation generation passes the radiator, cerenkov photons are initiated and a part of them reach the PMT cathode after multiple reflections from the mirror sides of the container.

  13. 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.

  14. 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.

  15. 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.

  16. Pulsars at the Highest Energies: Questions for AGILE, Fermi (GLAST) and Atmospheric Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Thompson, D. J.

    2008-12-01

    Observational studies of gamma-ray pulsars have languished in recent years, while theoretical studies have made significant strides. Now, with new and improved gamma-ray telescopes coming online, opportunities present themselves for dramatic improvements in our understanding of these objects. The new facilities and better modeling of processes at work in high-energy pulsars will address a number of important open questions.

  17. Pulsars at the Highest Energies: Questions for AGILE, Fermi (GLAST) and Atmospheric Cherenkov Telescopes

    NASA Technical Reports Server (NTRS)

    Thompson, D.J.

    2008-01-01

    Observational studies of gamma-ray pulsars languished in recent years, while theoretical studies made significant strides. Now, with new and improved gamma-ray telescopes coming online, opportunities present themselves for dramatic improvements in our understanding of these objects. The new facilities and better modeling of processes at work in high-energy pulsars should address a number of important open questions, some of which are summarized.

  18. The History of Ground-Based Very High Energy Gamma-Ray Astrophysics with the Atmospheric Air Cherenkov Telescope Technique

    NASA Astrophysics Data System (ADS)

    Mirzoyan, Razmik

    2013-06-01

    In the recent two decades the ground-based technique of imaging atmosphericescopes has established itself as a powerful new discipline in science. As of today some ˜ 150 sources of gamma rays of very different types, of both galactic and extragalactic origin, have been discovered due to this technique. The study of these sources is providing clues to many basic questions in astrophysics, astro-particle physics, physics of cosmic rays and cosmology. The current generation of telescopes, despite the young age of the technique, offers a solid performance. The technique is still maturing, leading to the next generation large instrument known under the name Cherenkov Telescope Array. The latter's sensitivity will be an order of magnitude higher than that of the currently best instruments VERITAS, H.E.S.S. and MAGIC. This article is devoted to outlining the milestones in a long history that step-by-step have given shape to this technique and have brought about today's successful source marathon.

  19. Roughness tolerances for Cherenkov telescope mirrors

    NASA Astrophysics Data System (ADS)

    Tayabaly, K.; Spiga, D.; Canestrari, R.; Bonnoli, G.; Lavagna, M.; Pareschi, G.

    2015-09-01

    The Cherenkov Telescope Array (CTA) is a forthcoming international ground-based observatory for very high-energy gamma rays. Its goal is to reach sensitivity five to ten times better than existing Cherenkov telescopes such as VERITAS, H.E.S.S. or MAGIC and extend the range of observation to energies down to few tens of GeV and beyond 100 TeV. To achieve this goal, an array of about 100 telescopes is required, meaning a total reflective surface of several thousands of square meters. Thence, the optimal technology used for CTA mirrors' manufacture should be both low-cost (~1000 euros/m2) and allow high optical performances over the 300-550 nm wavelength range. More exactly, a reflectivity higher than 85% and a PSF (Point Spread Function) diameter smaller than 1 mrad. Surface roughness can significantly contribute to PSF broadening and limit telescope performances. Fortunately, manufacturing techniques for mirrors are now available to keep the optical scattering well below the geometrically-predictable effect of figure errors. This paper determines first order surface finish tolerances based on a surface microroughness characterization campaign, using Phase Shift Interferometry. That allows us to compute the roughness contribution to Cherenkov telescope PSF. This study is performed for diverse mirror candidates (MAGIC-I and II, ASTRI, MST) varying in manufacture technologies, selected coating materials and taking into account the degradation over time due to environmental hazards.

  20. Acceleration of atmospheric Cherenkov telescope signal processing to real-time speed with the Auto-Pipe design system

    NASA Astrophysics Data System (ADS)

    Tyson, Eric J.; Buckley, James; Franklin, Mark A.; Chamberlain, Roger D.

    2008-10-01

    The imaging atmospheric Cherenkov technique for high-energy gamma-ray astronomy is emerging as an important new technique for studying the high energy universe. Current experiments have data rates of ≈20TB/year and duty cycles of about 10%. In the future, more sensitive experiments may produce up to 1000 TB/year. The data analysis task for these experiments requires keeping up with this data rate in close to real-time. Such data analysis is a classic example of a streaming application with very high performance requirements. This class of application often benefits greatly from the use of non-traditional approaches for computation including using special purpose hardware (FPGAs and ASICs), or sophisticated parallel processing techniques. However, designing, debugging, and deploying to these architectures is difficult and thus they are not widely used by the astrophysics community. This paper presents the Auto-Pipe design toolset that has been developed to address many of the difficulties in taking advantage of complex streaming computer architectures for such applications. Auto-Pipe incorporates a high-level coordination language, functional and performance simulation tools, and the ability to deploy applications to sophisticated architectures. Using the Auto-Pipe toolset, we have implemented the front-end portion of an imaging Cherenkov data analysis application, suitable for real-time or offline analysis. The application operates on data from the VERITAS experiment, and shows how Auto-Pipe can greatly ease performance optimization and application deployment of a wide variety of platforms. We demonstrate a performance improvement over a traditional software approach of 32x using an FPGA solution and 3.6x using a multiprocessor based solution.

  1. Cross calibration of telescope optical throughput efficiencies using reconstructed shower energies for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Mitchell, A. M. W.; Parsons, R. D.; Hofmann, W.; Bernlöhr, K.

    2016-02-01

    For reliable event reconstruction of Imaging Atmospheric Cherenkov Telescopes (IACTs), calibration of the optical throughput efficiency is required. Within current facilities, this is achieved through the use of ring shaped images generated by muons. Here, a complementary approach is explored, achieving cross calibration of elements of IACT arrays through pairwise comparisons between telescopes, focussing on its applicability to the upcoming Cherenkov Telescope Array (CTA). Intercalibration of telescopes of a particular type using eventwise comparisons of shower image amplitudes has previously been demonstrated to recover the relative telescope optical responses. A method utilising the reconstructed energy as an alternative to image amplitude is presented, enabling cross calibration between telescopes of varying types within an IACT array. Monte Carlo studies for two plausible CTA layouts have shown that this calibration procedure recovers the relative telescope response efficiencies at the few per cent level.

  2. On the potential of atmospheric Cherenkov telescope arrays for resolving TeV gamma-ray sources in the Galactic plane

    NASA Astrophysics Data System (ADS)

    Ambrogi, L.; De Oña Wilhelmi, E.; Aharonian, F.

    2016-07-01

    The potential of an array of imaging atmospheric Cherenkov telescopes to detect gamma-ray sources in complex regions has been investigated. The basic characteristics of the gamma-ray instrument have been parameterized using simple analytic representations. In addition to the ideal (Gaussian form) point spread function (PSF), the impact of more realistic non-Gaussian PSFs with tails has been considered. Simulations of isolated point-like and extended sources have been used as a benchmark to test and understand the response of the instrument. The capability of the instrument to resolve multiple sources has been analyzed and the corresponding instrument sensitivities calculated. The results are of particular interest for weak gamma-ray emitters located in crowded regions of the Galactic plane, where the chance of clustering of two or more gamma-ray sources within 1 deg is high.

  3. ctools: Cherenkov Telescope Science Analysis Software

    NASA Astrophysics Data System (ADS)

    Knödlseder, Jürgen; Mayer, Michael; Deil, Christoph; Buehler, Rolf; Bregeon, Johan; Martin, Pierrick

    2016-01-01

    ctools provides tools for the scientific analysis of Cherenkov Telescope Array (CTA) data. Analysis of data from existing Imaging Air Cherenkov Telescopes (such as H.E.S.S., MAGIC or VERITAS) is also supported, provided that the data and response functions are available in the format defined for CTA. ctools comprises a set of ftools-like binary executables with a command-line interface allowing for interactive step-wise data analysis. A Python module allows control of all executables, and the creation of shell or Python scripts and pipelines is supported. ctools provides cscripts, which are Python scripts complementing the binary executables. Extensions of the ctools package by user defined binary executables or Python scripts is supported. ctools are based on GammaLib (ascl:1110.007).

  4. Cherenkov Telescopes Results on Pulsar Wind Nebulae and Pulsars

    NASA Astrophysics Data System (ADS)

    Wilhelmi, Emma De Oña

    The last few years have seen a revolution in very high γ-ray astronomy (VHE; E>100 GeV) driven largely by a new generation of Cherenkov telescopes. These new facilities, namely H.E.S.S. (High Energy Stereoscopic System), MAGIC (Major Atmospheric Gamma Imaging Cherenkov Telescope) and its upgrade MAGIC 2, VERITAS (Very Energetic Radiation Imaging Telescope Array System) and CANGAROO (Collaboration of Australia and Nippon for a Gamma Ray Observatory in the Outback) were designed to increase the flux sensitivity in the energy regime of hundreds of GeV, expanding the observed energy range from 50 to multi-TeV, and fostered as a result a period of rapid growth in our understanding of the Non-ThermalUniverse. As a result of this fast development the number of pulsar wind nebulae (PWNe) detected has increased from a few in the early 90's to more than two dozen of firm candidates nowadays. Also, the low energy threshold achieved allows to investigate the pulsed spectra of the high energy pulsars powering PWNe. A review of the most relevant VHE results concerning pulsars and their relativistic winds is discussed here in the context of Cherenkov telescopes.

  5. Normalized and asynchronous 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 as they are 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 is a challenge. Here we present a computer vision based star tracking alignment method, which also works for limited or changing star light visibility. Our method normalizes the mirror facet reflection intensities to become independent of the reference star's intensity or the cloud coverage. Using two CCD cameras, our method records the mirror facet orientations asynchronously of the telescope drive system, and thus makes the method easy to integrate into existing telescopes. It can be combined with remote facet actuation, but does not require one to work. Furthermore, it can reconstruct all individual mirror facet point spread functions without moving any mirror. We present alignment results on the 4 m First Geiger-mode Avalanche Cherenkov Telescope (FACT).

  6. Very-High-Energy Astrophysics with the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Mukherjee, Reshmi

    2016-04-01

    The Cherenkov Telescope Array (CTA) will be a new gamma-ray observatory in the energy band ~30 GeV to ~100 TeV, designed to achieve an order of magnitude improvement in sensitivity over the currently operating imaging atmospheric Cherenkov telescopes. CTA will probe known sources with unprecedented sensitivity, angular resolution, and spectral coverage, with the potential of detecting hundreds of new sources. The CTA Consortium will also conduct a number of Key Science Projects, including a Galactic Plane survey and a survey of one quarter of the extragalactic sky. Data taken by CTA will be accessible by members of the wider astronomical community, for the first time in this energy band. This presentation will give an overview of CTA, and its proposed key science program.Submitted with the CTA Consortium

  7. 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.

  8. Development of a mid-sized Schwarzschild-Couder Telescope for the Cherenkov Telescope Array

    SciTech Connect

    Cameron, Robert A.

    2012-06-28

    The Cherenkov Telescope Array (CTA) is a ground-based observatory for very high-energy (10 GeV to 100 TeV) gamma rays, planned for operation starting in 2018. It will be an array of dozens of optical telescopes, known as Atmospheric Cherenkov Telescopes (ACTs), of 8 m to 24 m diameter, deployed over an area of more than 1 square km, to detect flashes of Cherenkov light from showers initiated in the Earth's atmosphere by gamma rays. CTA will have improved angular resolution, a wider energy range, larger fields of view and an order of magnitude improvement in sensitivity over current ACT arrays such as H.E.S.S., MAGIC and VERITAS. Several institutions have proposed a research and development program to eventually contribute 36 medium-sized telescopes (9 m to 12 m diameter) to CTA to enhance and optimize its science performance. The program aims to construct a prototype of an innovative, Schwarzschild-Couder telescope (SCT) design that will allow much smaller and less expensive cameras and much larger fields of view than conventional Davies-Cotton designs, and will also include design and testing of camera electronics for the necessary advances in performance, reliability and cost. We report on the progress of the mid-sized SCT development program.

  9. 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.

  10. On the sensitivity of atmospheric Cherenkov telescope arrays for regions with presence of multiple gamma-ray sources

    NASA Astrophysics Data System (ADS)

    Ambrogi, L.; Aharonian, F.; De Oña Wilhelmi, E.

    2016-05-01

    The potential of a next-generation ground based gamma-ray telescope array has been investigated. In addition to the ideal Gaussian shaped PSF, more realistic non-Gaussian PSFs with tails have been considered and their impact on the detector performance has been studied. The capability of the instrument to resolve multiple sources has been analyzed and the corresponding detector sensitivity estimated. These scenarios are particularly interesting in the framework of Galactic objects, where the observation of more than one source in the same field of view (FoV) is very likely to happen.

  11. Energy calibration of Cherenkov Telescopes using GLAST data

    SciTech Connect

    Bastieri, D.; Busetto, G.; Piano, G.; Rando, R.; Saggion, A.; De Angelis, A.; Longo, F.

    2007-07-12

    We discuss the possibility of using the observations by GLAST of steady gamma sources, as the Crab Nebula and some selected AGNs, to calibrate the Imaging Air Cherenkov Telescopes (IACT) and improve their energy resolution, in particular. We show that at around 100 GeV, exploiting the features in the spectrum of the Crab Nebula, the absolute energy calibration uncertainty of Cherenkov telescopes can be reduced to < 10%.

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

    SciTech Connect

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

    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 parameters 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.

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

    DOE PAGESBeta

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

    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

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

    NASA Astrophysics Data System (ADS)

    Wood, M.; Jogler, T.; Dumm, J.; Funk, S.

    2016-01-01

    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 parameters 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. We attribute the increase in point-source sensitivity to the improved optical point-spread function and smaller pixel size of the SC telescope design.

  15. 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.

  16. Test bench for front end electronic of the GCT camera for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    De Franco, A.; Cotter, G.

    2016-02-01

    The Gamma Cherenkov Telescope (GCT) is a design proposed to be part of the Small Sized Telescope (SST) array of the Cherenkov Telescope Array (CTA). The 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 camera thus needs very fast and compact electronics, addressed by the TARGET modules, based on homonymous ASICs which provide digitation at 1 GSample/s and the first level of trigger on the analog output of the photosensors. In this paper we describe a test bench lab set up to evaluate the performance and functionality of the camera' s front end electronics with an added educational value.

  17. On-site mirror facet condensation measurements for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Dipold, J.; Medina, M. C.; García, B.; Rasztocky, E.; Mancilla, A.; Maya, J.; Larrarte, J. J.; de Souza, V.

    2016-09-01

    The Imaging Atmospheric Cherenkov Technique (IACT) has provided very important discoveries in Very High Energy (VHE) γ-ray astronomy for the last two decades, being exploited mainly by experiments such as H.E.S.S., MAGIC and VERITAS. The same technique will be used by the next generation of γ-ray telescopes, Cherenkov Telescope Array - CTA, which is conceived to be an Observatory composed by two arrays strategically placed in both hemispheres, one in the Northern and one in the Southern. Each site will consist of several tens of Cherenkov telescopes of different sizes and will be equipped with about 10000 m2 of reflective surface. Because of its large size, the reflector of a Cherenkov telescope is composed of many individual mirror facets. Cherenkov telescopes operate without any protective system from weather conditions therefore it is important to understand how the reflective surfaces behave under different environmental conditions. This paper describes a study of the behavior of the mirrors in the presence of water vapor condensation. The operational time of a telescope is reduced by the presence of condensation on the mirror surface, therefore, to control and to monitor the formation of condensation is an important issue for IACT observatories. We developed a method based on pictures of the mirrors to identify the areas with water vapor condensation. The method is presented here and we use it to estimate the time and area two mirrors had condensation when exposed to the environmental conditions in the Argentinean site. The study presented here shows important guidelines in the selection procedure of mirror technologies and shows an innovative monitoring tool to be used in future Cherenkov telescopes.

  18. Active optics system of the ASTRI SST-2M prototype for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Gardiol, Daniele; Capobianco, Gerardo; Fantinel, Daniela; Giro, Enrico; Lessio, Luigi; Loreggia, Davide; Rodeghiero, Gabriele; Russo, Federico; Volpicelli, Antonio C.

    2014-07-01

    ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) SST-2M is an end-to-end prototype of Small Size class of Telescope for the Cherenkov Telescope Array. It will apply a dual mirror configuration to Imaging Atmospheric Cherenkov Telescopes. The 18 segments composing the primary mirror (diameter 4.3 m) are equipped with an active optics system enabling optical re-alignment during telescope slew. The secondary mirror (diameter 1.8 m) can be moved along three degrees of freedom to perform focus and tilt corrections. We describe the kinematic model used to predict the system performance as well as the hardware and software design solution that will be implemented for optics control.

  19. A versatile digital camera trigger for telescopes in the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Schwanke, U.; Shayduk, M.; Sulanke, K.-H.; Vorobiov, S.; Wischnewski, R.

    2015-05-01

    This paper describes the concept of an FPGA-based digital camera trigger for imaging atmospheric Cherenkov telescopes, developed for the future Cherenkov Telescope Array (CTA). The proposed camera trigger is designed to select images initiated by the Cherenkov emission of extended air showers from very-high energy (VHE, E > 20 GeV) photons and charged particles while suppressing signatures from background light. The trigger comprises three stages. A first stage employs programmable discriminators to digitize the signals arriving from the camera channels (pixels). At the second stage, a grid of low-cost FPGAs is used to process the digitized signals for camera regions with 37 pixels. At the third stage, trigger conditions found independently in any of the overlapping 37-pixel regions are combined into a global camera trigger by few central FPGAs. Trigger prototype boards based on Xilinx FPGAs have been designed, built and tested and were shown to function properly. Using these components a full camera trigger with a power consumption and price per channel of about 0.5 W and 19 €, respectively, can be built. With the described design the camera trigger algorithm can take advantage of pixel information in both the space and the time domain allowing, for example, the creation of triggers sensitive to the time-gradient of a shower image; the time information could also be exploited to online adjust the time window of the acquisition system for pixel data. Combining the results of the parallel execution of different trigger algorithms (optimized, for example, for the lowest and highest energies, respectively) on each FPGA can result in a better response over all photons energies (as demonstrated by Monte Carlo simulation in this work).

  20. 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.

  1. Expected performance of the ASTRI mini-array in the framework of the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Di Pierro, F.; Bigongiari, C.; Stamerra, A.; Vallania, P.; ASTRI Collaboration; CTA Consortium, the

    2016-05-01

    The Cherenkov Telescope Array (CTA) Observatory is a world-wide project for the ground-based study of the sources of the highest energy photons. By adopting telescopes of three different size categories it will cover the wide energy range from tens of GeV up to hundreds of TeV, limited only by the source physical properties and the gamma absorption by the extragalactic background light. The full sky coverage will be assured by two arrays, one in each hemisphere. An array of small size telescopes (SSTs), covering the highest energy region (3-100 TeV), the region most flux limited for current imaging atmospheric Cherenkov telescopes, is planned to be deployed at the southern CTA site in the first phase of the CTA project. The ASTRI collaboration has developed a prototype of a dual mirror SST equipped with a SiPM-based focal plane (ASTRI SST-2M) and has proposed to install a mini-array of nine of such telescopes at the CTA southern site (the ASTRI mini-array). In order to study the expected performance and the scientific capabilities of different telescope configurations, full Monte Carlo (MC) simulations of the shower development in the atmosphere for both gammas and hadronic background have been performed, followed by detailed simulations of the telescopes. In this work the expected performance of the ASTRI mini-array in terms of sensitivity, angular and energy resolution are presented and discussed.

  2. Simulation of the ASTRI two-mirrors small-size telescope prototype for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Bigongiari, C.; Cusumano, G.; Di Pierro, F.; La Parola, V.; Stamerra, A.; Vallania, P.; ASTRI Collaboration; CTA Consortium, the

    2016-05-01

    The Cherenkov Telescope Array (CTA) is a world-wide project to build a new generation ground-based gamma-ray instrument operating in the energy range from some tens of GeV to above 100 TeV. To ensure full sky coverage CTA will consist of two arrays of Imaging Atmospheric Cherenkov Telescopes (IACTs), one in the southern hemisphere and another one in the northern hemisphere. CTA has just completed the design phase and it is entering in the pre-production one that includes the development of telescope precursor mini-arrays. ASTRI is an ongoing project, to develop and install at the southern CTA site one of such mini-arrays composed by nine dual-mirror small size telescopes equipped with an innovative camera based on silicon photomultiplier sensors. The end-to-end telescope prototype, named ASTRI SST-2M, has been recently inaugurated at the Serra La Nave observing station, on Mount Etna, Italy. ASTRI SST-2M expected performance has been carefully studied using a full Monte Carlo simulation of the shower development in the atmosphere and detector response. Simulated data have been analyzed using the traditional Hillas moment analysis to obtain the expected angular and energy resolution. Simulation results, together with the comparison with the available experimental measurements, are shown.

  3. Status of the Cherenkov Telescope Array project

    NASA Astrophysics Data System (ADS)

    Barres de Almeida, U.

    2015-11-01

    Gamma-ray astronomy holds a great potential for astrophysics, particle physics, and cosmology. The CTA is an international initiative to build the next generation of ground-based gamma-ray observatories which will represent a factor of 5-10× improvement in the sensitivity of observations in the range 100 GeV-10 TeV, as well as an extension of the observational capabilities down to energies below 100 GeV and beyond 100 TeV. The array will consist of two telescope networks (one in the northern hemisphere and another in the south) so to achieve a full-sky coverage, and will be composed by a hybrid system of 4 different telescope types. It will operate as an observatory, granting open access to the community through calls for submission of proposals competing for observation time. The CTA will give us access to the non-thermal and high-energy universe at an unprecedented level, and will be one of the main instruments for high-energy astrophysics and astroparticle physics of the next 30 years. CTA has now entered its prototyping phase with the first, stand-alone instruments being built. Brazil is an active member of the CTA consortium, and the project is represented in Latin America also by Argentina, Mexico, and Chile. In the next few months the consortium will define the site for installation of CTA South, which might come to be hosted in the Chilean Andes, with important impact for the high-energy community in Latin America. In this talk we will present the basic concepts of the CTA and the detailed project of the observatory. Emphasis will be put on its scientific potential and on the Latin-American involvement in the preparation and construction of the observatory, whose first seed, the ASTRI mini-array, is currently being constructed in Sicily, in a cooperation between Italy, Brazil, and South Africa. ASTRI should be installed on the final CTA site in 2016, whereas the full CTA array is expected to be operational by the end of the decade.

  4. Status of the Cherenkov telescope array project

    NASA Astrophysics Data System (ADS)

    Barres de Almeida, Ulisses

    2015-12-01

    Gamma-ray astronomy holds a great potential for Astrophysics, Particle Physics and Cosmology. The CTA is an international initiative to build the next generation of ground-based gamma-ray observatories, which will represent a factor of 5-10× improvement in the sensitivity of observations in the range 100 GeV - 10 TeV, as well as an extension of the observational capabilities down to energies below 100 GeV and beyond 100 TeV. The array will consist of two telescope networks (one in the Northern Hemisphere and another in the South) so to achieve a full-sky coverage, and will be composed by a hybrid system of 4 different telescope types. It will operate as an observatory, granting open access to the community through calls for submission of proposals competing for observation time. The CTA will give us access to the non-thermal and high-energy universe at an unprecedented level, and will be one of the main instruments for high-energy astrophysics and astroparticle physics of the next 30 years. CTA has now entered its prototyping phase with the first, stand-alone instruments being built. Brazil is an active member of the CTA consortium, and the project is represented in Latin America also by Argentina, Mexico and Chile. In the next few months the consortium will define the site for installation of CTA South, which might come to be hosted in the Chilean Andes, with important impact for the high-energy community in Latin America. In this talk we will present the basic concepts of the CTA and the detailed project of the observatory. Emphasis will be put on its scientific potential and on the Latin-American involvement in the preparation and construction of the observatory, whose first seed, the ASTRI mini-array, is currently being constructed in Sicily, in a cooperation between Italy, Brazil and South Africa. ASTRI should be installed on the final CTA site in 2016, whereas the full CTA array is expected to be operational by the end of the decade.

  5. Detecting new very light bosons by Cherenkov telescopes

    SciTech Connect

    Roncadelli, Marco; De Angelis, Alessandro; Mansutti, Oriana; Persic, Massimo

    2010-03-26

    A generic prediction of several extensions of the Standard Model of elementary-particle interactions is the existence of axion-like particles (ALPs), namely very light spin-zero bosons characterized by a two-photon coupling. While elusive in laboratory experiments, ALPs can give rise to observable astrophysical effects for their relevant parameters in experimentally allowed ranges. We show that the unexpectedly low opacity of the Universe inferred by the Imaging Atmospheric Cherenkov Telescopes since 2006 from blazar observations above 100 GeV can be explained naturally within the De Angelis, Roncadelli and Mansutti--hereafter DARMA--scenario, namely in terms of photon-ALP oscillations occurring in extragalactic magnetic fields. We work out the implications of the DARMA scenario for the VHE gamma-ray spectra of blazars by contemplating all of them at once, so that the emitted GAMMA{sub em} and observed GAMMA{sub obs} spectral indices can be correlated. We demonstrate that by assuming the same nominal value GAMMA{sub em}approx =2.4 for all VHE blazars, the predicted observed spectral index GAMMA{sub obs}{sup DARMA} actually fits all observations. Moreover, GAMMA{sub obs}{sup DARMA} becomes independent of redshift for sufficiently far-away sources. Our prediction can be tested with the satellite-borne Fermi/LAT detector as well as with the ground-based IACTs H.E.S.S., MAGIC, CANGAROO III, VERITAS and the Extensive Air Shower arrays ARGO-YBJ and MILAGRO.

  6. The ASTRI SST-2M prototype for the Cherenkov Telescope Array: opto-mechanical test results

    NASA Astrophysics Data System (ADS)

    Canestrari, Rodolfo; Giro, Enrico; Antolini, Elisa; Bonnoli, Giacomo; Cascone, Enrico; La Palombara, Nicola; Leto, Giuseppe; Pareschi, Giovanni; Scuderi, Salvo; Stringhetti, Luca; Tanci, Claudio; Tosti, Gino

    2015-09-01

    The Cherenkov Telescope Array (CTA) observatory, with a combination of large-, medium-, and small-size telescopes (LST, MST and SST, respectively), will represent the next generation of imaging atmospheric Cherenkov telescopes. It will explore the very high-energy domain from a few tens of GeV up to few hundreds of TeV with unprecedented sensitivity, angular resolution and imaging resolution. In this framework, the Italian ASTRI program, led by the Italian National Institute of Astrophysics (INAF), is currently developing a scientific and technological SST dual-mirror end-to-end prototype named ASTRI SST-2M. It is a 4-meter class telescope; it adopts an aplanatic, wide-field, double-reflection optical layout in a Schwarzschild-Couder configuration. The ASTRI SST-2M telescope structure and mirrors have been already installed at the INAF observing station at Serra La Nave, on Mt. Etna (Sicily, Italy). In this contribution we report about the on-site deployment and the latest results on the opto-mechanical performance test conducted soon after the telescope installation

  7. Seismic analysis of the 4-meter telescope SST-GATE for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Dournaux, Jean-Laurent; Huet, Jean-Michel; Amans, Jean-Philippe; Dumas, Delphine; Blake, Simon; Sol, Hélène

    2014-07-01

    The Cherenkov Telescope Array (CTA) project aims to create a next generation Very High Energy (VHE)γ-ray telescope array, devoted to the observation in a wide band of energy, from a few tens of GeV to more than 100 TeV. Two sites are foreseen to view the whole sky, with the main one in the Southern Hemisphere where about 100 telescopes of three different classes, related to the specific energy region to be investigated, will be installed. Among these, the Small Size class of Telescopes, SSTs, are 4-meter telescopes and are devoted to the highest energy region, from 1 TeV to beyond 100 TeV. Some of these sites considered for CTA exhibit strong seismic constraints. At the Observatoire de Paris, we have designed a prototype of a Small Size Telescope named SST-GATE, based on the dual-mirror Schwarzschild-Couder optical formula, which was never before implemented in the design of a Cherenkov telescope. The integration of this telescope on the site of the Observatoire de Paris is currently in progress. Technical solutions exist in the literature to protect structures from dynamic loads caused by earthquakes without increasing the mass and cost of the structure. This paper presents a state of the art of these techniques by keeping in mind that the operational performance of the telescope should not be compromised. The preliminary seismic analysis of SSTGATE performed by the finite element method is described before.

  8. Probing the inert doublet dark matter model with Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Garcia-Cely, Camilo; Gustafsson, Michael; Ibarra, Alejandro

    2016-02-01

    We present a detailed study of the annihilation signals of the inert dark matter doublet model in its high mass regime. Concretely, we study the prospects to observe gamma-ray signals of the model in current and projected Cherenkov telescopes taking into account the Sommerfeld effect and including the contribution to the spectrum from gamma-ray lines as well as from internal bremsstrahlung. We show that present observations of the galactic center by the H.E.S.S. instrument are able to exclude regions of the parameter space that give the correct dark matter relic abundance. In particular, models with the charged and the neutral components of the inert doublet nearly degenerate in mass have strong gamma-ray signals. Furthermore, for dark matter particle masses above 1 TeV, we find that the non-observation of the continuum of photons generated by the hadronization of the annihilation products typically give stronger constraints on the model parameters than the sharp spectral features associated to annihilation into monochromatic photons and the internal bremsstrahlung process. Lastly, we also analyze the interplay between indirect and direct detection searches for this model, concluding that the prospects for the former are more promising. In particular, we find that the upcoming Cherenkov Telescope Array will be able to probe a significant part of the high mass regime of the model.

  9. On the use of Cherenkov Telescopes for outer Solar system body occultations

    NASA Astrophysics Data System (ADS)

    Lacki, Brian C.

    2014-12-01

    Imaging Atmospheric Cherenkov Telescopes (IACTs) are arrays of very large optical telescopes that are well-suited for rapid photometry of bright sources. I investigate their potential in observing stellar occultations by small objects in the outer Solar system, Transjovian Objects (TJOs). These occultations cast diffraction patterns on the Earth. Current IACT arrays are capable of detecting objects smaller than 100 m in radius in the Kuiper Belt and 1 km radius out to 5000 au. The future Cherenkov Telescope Array (CTA) will have even greater capabilities. Because the arrays include several telescopes, they can potentially measure the speeds of TJOs without degeneracies, and the sizes of the TJOs and background stars. I estimate the achievable precision using a Fisher matrix analysis. With CTA, the precisions of these parameter estimations will be as good as a few per cent. I consider how often detectable occultations occur by members of different TJO populations, including Centaurs, Kuiper Belt Objects (KBOs), Oort Cloud objects, and satellites and Trojans of Uranus and Neptune. The great sensitivity of IACT arrays means that they likely detect KBO occultations once every O(10) hours when looking near the ecliptic. IACTs can also set useful limits on many other TJO populations.

  10. Construction of prototype two-mirror Schwartzchild-Couder Imaging Air Cherenkov Telescope (IACT) for VHE gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Kieda, David; CTA-US Collaboration Collaboration

    2016-03-01

    Next generation ground-based VHE gamma-ray observatories such as the Cherenkov Telescope Array (CTA) will employ an array of different sized IACTs distributed across square kilometer areas. During 2015-2016, the CTA-US collaboration is constructing a prototype 9.6 m primary diameter Schwartzchild-Couder IACT (SCT) at the FL Whipple Observatory, Amado, AZ USA. The two-mirror SCT design provides 8 degree field of view with 0.067 degree pixel size. The SCT uses a high resolution (11,328 pixel) Silicon PhotoMultiplier (SiPM) camera to record atmospheric Cherenkov light images generated by gamma-ray and cosmic ray primaries. Incorporation of SCT telescopes into a CTA-type observatory can provide superior angular resolution (30 % improvement) and point source sensitivity (30-50 %). In this talk, I will describe the capabilities of the SCT telescope, and the construction and commissioning of the prototype SCT telescope during 2016.

  11. The Alignment System for a Medium-Sized Schwarzschild-Couder Telescope Prototype for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Ribeiro, Deivid; Humensky, Brian; Nieto, Daniel; V Vassiliev Group in UCLA division of Astronomy and Astrophysics, P Kaaret Group at Iowa University Department of Physics and Astronomy, CTA Consortium

    2016-01-01

    The Cherenkov Telescope Array (CTA) is an international project for a next-generation ground-based gamma-ray observatory. CTA, conceived as an array of tens of imaging atmospheric Cherenkov telescopes, comprising small, medium and large-size telescopes, is aiming to improve on the sensitivity of current-generation experiments by an order of magnitude and provide energy coverage from 20 GeV to more than 300 TeV. The Schwarzschild-Couder design is a candidate 9-m diameter medium-sized telescope featuring a novel aplanatic two-mirror optical design capable of a wide field of view with significantly improved imaging resolution as compared to the traditional Davies-Cotton optical design. Achieving this imaging resolution imposes strict mirror alignment requirements that necessitate a sophisticated alignment system. This system uses a collection of position sensors between panels to determine the relative position of adjacent panels; each panel is mounted on a Stewart platform to allow motion control with six degrees of freedom, facilitating the alignment of the optical surface for the segmented primary and secondary mirrors. Alignments of the primary and secondary mirrors and the camera focal plane with respect to each other are performed utilizing a set of CCD cameras which image LEDs placed on the mirror panels to measure relative translation, and custom-built auto-collimators to measure relative tilt between the primary and secondary mirrors along the optical axis of the telescope. In this contribution we present the status of the development of the SC optical alignment system, soon to be materialized in a full-scale prototype SC medium-size telescope (pSCT) at the Fred Lawrence Whipple Observatory in southern Arizona.

  12. 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.

  13. 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

  14. The glass cold-shaping technology for the mirrors of the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Canestrari, Rodolfo; Bonnoli, Giacomo; Crimi, Giuseppe; Fiorini, Mauro; Giro, Enrico; La Palombara, Nicola; Pareschi, Giovanni; Perri, Luca; Rodeghiero, Gabriele; Sironi, Giorgia; Stringhetti, Luca; Toso, Giorgio; Pelliciari, Carlo

    2014-07-01

    The next generation of imaging atmospheric Cherenkov telescopes will require the production of thousands of mirror segments; an unprecedented amount of optical surface. To accomplish this, the Italian Istituto Nazionale di AstroFisica (INAF) has recently developed a successful technique. This method, called glass cold-shaping, is mainly intended for the manufacturing of mirrors for optical systems with an angular resolution of a few arcminutes, intended to operate in extreme environments. Its principal mechanical features are very low weight and high rigidity of the resulting segments, and its cost and production time turn out to be very competitive as well. The process is based on the shaping of thin glass foils by means of forced bending at room temperature; a sandwich structure is then assembled for retaining the imposed shape. These mirrors are composted of commercial, off-the-shelf materials. In this contribution we give an overview of the latest results achieved in the manufacturing of the pre-production series of mirrors for the Medium Size and Small Size Telescopes of the Cherenkov Telescope Array observatory.

  15. 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.

  16. 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.

  17. Stellar intensity interferometry over kilometer baselines: laboratory simulation of observations with the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Dravins, Dainis; Lagadec, Tiphaine

    2014-07-01

    A long-held astronomical vision is to realize diffraction-limited optical aperture synthesis over kilometer baselines. This will enable imaging of stellar surfaces and their environments, show their evolution over time, and reveal interactions of stellar winds and gas flows in binary star systems. An opportunity is now opening up with the large telescope arrays primarily erected for measuring Cherenkov light in air induced by gamma rays. With suitable software, such telescopes could be electronically connected and used also for intensity interferometry. With no optical connection between the telescopes, the error budget is set by the electronic time resolution of a few nanoseconds. Corresponding light-travel distances are on the order of one meter, making the method practically insensitive to atmospheric turbulence or optical imperfections, permitting both very long baselines and observing at short optical wavelengths. Theoretical modeling has shown how stellar surface images can be retrieved from such observations and here we report on experimental simulations. In an optical laboratory, artificial stars (single and double, round and elliptic) are observed by an array of telescopes. Using high-speed photon-counting solid-state detectors and real-time electronics, intensity fluctuations are cross correlated between up to a hundred baselines between pairs of telescopes, producing maps of the second-order spatial coherence across the interferometric Fourier-transform plane. These experiments serve to verify the concepts and to optimize the instrumentation and observing procedures for future observations with (in particular) CTA, the Cherenkov Telescope Array, aiming at order-of-magnitude improvements of the angular resolution in optical astronomy.

  18. Intensity Interferometry with Cherenkov Telescope Arrays: Prospects for submilliarcsecond optical imaging

    NASA Astrophysics Data System (ADS)

    Dravins, D.

    2014-04-01

    Intensity interferometry measures the second-order coherence of light. Very rapid (nanosecond) fluctuations are correlated between separate telescopes, without any optical connection. This makes the method insensitive to atmospheric turbulence and optical imperfections, permitting observations over long baselines, and at short wavelengths. The required large telescopes are becoming available as those primarily erected to study gamma rays: the planned Cherenkov Telescope Array (https://www.cta-observatory.org/) envisions many tens of telescopes distributed over a few square km. Digital signal handling enables very many baselines to be simultaneously synthesized between many pairs of telescopes, while stars may be tracked across the sky with electronic time delays, synthesizing an optical interferometer in software. Simulations indicate limiting magnitudes around m(v)=8, reaching a resolution of 30 microarcseconds in the violet. Since intensity interferometry provides only the modulus (not phase) of any spatial frequency component of the source image, image reconstruction requires phase retrieval techniques. As shown in simulations, full two-dimensional images can be retrieved, provided there is an extensive coverage of the (u,v)-plane, such as will be available once the number of telescopes reaches numbers on the order of ten.

  19. SST-GATE telescope: an innovative dual-mirror prototype for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Dumas, Delphine; Huet, Jean-Michel; Dournaux, Jean-Laurent; Laporte, Philippe; Amans, Jean-Philippe; Fasola, Gilles; Zech, Andreas; Rulten, Cameron; Sol, Hélène; Blake, Simon; Schmoll, Jurgen

    2014-07-01

    The Observatoire de Paris is involved in the Cherenkov Telescope Array (CTA) project by designing and constructing on the site of Meudon a Small Size Telescope prototype, named SST-GATE, in collaboration with the CHEC team (Compact High Energy Camera) which is providing the camera. The telescope structure is based on the Schwarzschild- Couder optical design which has never been adopted before in the design of a ground-based telescope. This concept allows a larger field of view and cheaper and smaller telescope and camera design with improved performance compared to the Davies-Cotton design traditionally used in very high energy gamma-ray telescopes. The SST-GATE telescope has been designed with the prime objectives of being light, versatile and simple to assemble with a minimal maintenance cost. This papers aims at reviewing the SST-GATE telescope structure from mechanics to optics along with the control command architecture; several innovative developments implemented within the design are discussed. Updates of the project status and perspectives are made.

  20. 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

    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.

  1. Microsecond Time Resolution Optical Photometry using a H.E.S.S. Cherenkov Telescope

    SciTech Connect

    Deil, Christoph; Domainko, Wilfried; Hermann, German

    2008-02-22

    We have constructed an optical photometer with microsecond time resolution, which is currently being operated on one of the H.E.S.S. telescopes. H.E.S.S. is an array of four Cherenkov telescopes, each with a 107 m{sup 2} mirror, located in the Khomas highland in Namibia. In its normal mode of operation H.E.S.S. observes Cherenkov light from air showers generated by very high energy gamma-rays in the upper atmosphere. Our detector consists of seven photomultipliers, one in the center to record the lightcurve from the target and six concentric photomultipliers as a veto system to reject disturbing signals e.g. from meteorites or lightning at the horizon. The data acquisition system has been designed to continuously record the signals with zero deadtime. The Crab pulsar has been observed to verify the performance of the instrument and the GPS timing system. Compact galactic targets were observed to search for flares on timescales of a few microseconds to {approx}100 ms. The design and sensitivity of the instrument as well as the data analysis method are presented.

  2. Mechanical design of SST-GATE, a dual-mirror telescope for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Dournaux, Jean-Laurent; Huet, Jean-Michel; Amans, Jean-Philippe; Dumas, Delphine; Laporte, Philippe; Sol, Hélène; Blake, Simon

    2014-07-01

    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 over a wide band of energy, from a few tens of GeV to more than 100 TeV. Two sites are foreseen to view the whole sky where about 100 telescopes, composed of three different classes, related to the specific energy region to be investigated, will be installed. Among these, the Small Size class of Telescopes, SSTs, are devoted to the highest energy region, to beyond 100 TeV. Due to the large number of SSTs, their unit cost is an important parameter. At the Observatoire de Paris, we have designed a prototype of a Small Size Telescope named SST-GATE, based on the dual-mirror Schwarzschild-Couder optical formula, which has never before been implemented in the design of a telescope. Over the last two years, we developed a mechanical design for SST-GATE from the optical and preliminary mechanical designs made by the University of Durham. The integration of this telescope is currently in progress. Since the early stages of mechanical design of SST-GATE, finite element method has been used employing shape and topology optimization techniques to help design several elements of the telescope. This allowed optimization of the mechanical stiffness/mass ratio, leading to a lightweight and less expensive mechanical structure. These techniques and the resulting mechanical design are detailed in this paper. We will also describe the finite element analyses carried out to calculate the mechanical deformations and the stresses in the structure under observing and survival conditions.

  3. The Cherenkov Telescope Array: An observatory for Ground-based High Energy Gamma Ray Astronomy.

    NASA Astrophysics Data System (ADS)

    Medina, M. C.; CTA Consortium

    Over the past 15 years; Very High Energy (VHE) -ray experiments as H.E.S.S.; MAGIC and VERITAS have been very successful unveiling the mysteries of the non-thermal Universe using Cherenkov telescopes based on Earth. The next step in the evolution of the -ray Astronomy is to gather their efforts to build a global and innovative ground based facility: the Cherenkov Telescope Array (CTA). This is being conceived as an array of Cherenkov telescopes working as an open observatory; covering a wide energy range; with an enhanced sensitivity and improved spatial; temporal and energy resolution. The project is at the end of its Preparatory Phase. The decision on its location is about to be taken and the construction is expected to begin in 2015. In this article; we briefly describe the general status of the project and the Argentinian participation.

  4. The ASTRI prototype and mini-array: precursor telescopes for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Pareschi, Giovanni

    2016-07-01

    In the framework of the Cherenkov Telescope Array (CTA) Observatory, the Italian National Institute of Astrophysics (INAF) has recently inaugurated in Sicily (Italy), at the Serra La Nave astronomical site on the slopes of Mount Etna, a large field of view (9.6 degrees) dual-mirror prototype (ASTRI SST-2M) of the CTA small size class of telescopes. CTA plans to install about 70 small size telescopes in the southern site to allow the study of the gamma rays from a few TeV up to hundreds of TeV. The ASTRI SST-2M telescope prototype has been developed following an end-to-end approach, since it includes the entire system of structure, mirror's optics (primary and secondary mirrors), camera, and control/acquisition software. Although it is a technological prototype, the ASTRI SST-2M prototype will be able to perform systematic monitoring of bright TeV sources. A remarkable improvement in terms of performance could come from the operation of the ASTRI mini-array, led by INAF in synergy with the Universidade de Sao Paulo (Brazil) and the North-West University (South Africa) and with also a contribution by INFN. The ASTRI mini-array will be composed of at least nine ASTRI SST-2M units. It is proposed as one of the CTA mini-array of telescope precursors and initial seeds of CTA, to be installed at the final CTA southern site. Apart from the assessment of a number of technological aspects related to CTA, the ASTRI mini-array will extend and improve the sensitivity, similar to the H.E.S.S. one in the 1-10 TeV energy range, up to about 100 TeV.

  5. The mini-array of ASTRI SST-2M telescopes, precursors for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Pareschi, Giovanni; Bonnoli, Giacomo; Vercellone, Stefano; ASTRI Collaboration; CTA Consortium

    2016-05-01

    In the framework of the Cherenkov Telescope Array (CTA) Observatory, the Italian National Institute of Astrophysics (INAF) has recently inaugurated in Sicily (Italy), at the Serra La Nave astronomical site on the slopes of Mount Etna, a large field of view (FoV, ~ 9.6°) dual-mirror prototype (ASTRI SST-2M) of the CTA small size class of telescopes (SST). The CTA plans to install about 70 SST in the southern site to allow the study of the gamma rays from a few TeV up to hundreds of TeV. The ASTRI SST-2M telescope prototype has been developed following an end-to-end approach, since it includes the entire system of structure, mirrors optics (primary and secondary mirrors), camera, and control/acquisition software. A remarkable performance improvement could come from the operation of the ASTRI mini-array, led by INAF in synergy with the Universidade de Sao Paulo (Brazil) and the North-West University (South Africa). The ASTRI mini-array will be composed of nine ASTRI SST-2M units and it is proposed as a precursor and initial seed of the CTA to be installed at the final CTA southern site. Apart from the assessment of a number of technological aspects related to the CTA, the ASTRI mini-array will, if compared for instance to H.E.S.S., extend the point source sensitivity up to ~ 100 TeV, also improving it above 5-10 TeV. Moreover, the unprecedented width of the FoV, with its homogeneous acceptance and angular resolution, will significantly contribute to the achievement of original results during the early CTA science phase.

  6. NICHE: Using Cherenkov radiation to extend Telescope Array to sub-PeV energies

    NASA Astrophysics Data System (ADS)

    Bergman, Douglas; Krizmanic, John; Tsunesada, Yoshiki; Abu-Zayyad, Tareq; Belz, John; Thomson, Gordon

    2016-03-01

    The Non-Imaging CHErenkov (NICHE) Array will measure the flux and nuclear composition evolution of cosmic rays (CRs) from below 1 PeV to 1 EeV. NICHE will be co-sited with the Telescope Array (TA) Low Energy (TALE) extension, and will observe events simultaneously with the TALE telescopes acting in imaging-Cherenkov mode. This will be the first hybrid-Cherenkov (simultaneous imaging and non-imaging Cherenkov) measurements of CRs in the Knee region of the CR energy spectrum. NICHE uses easily deployable detectors to measure the amplitude and time-spread of the air-shower Cherenkov signal to achieve an event-by-event measurement of Xmax and energy, each with excellent resolution. First generation detectors are under construction and will form an initial prototype array (j-NICHE) that will be deployed in Summer 2016. In this talk, the NICHE design, array performance, prototype development, and status will be discussed as well as NICHE's ability to measure the cosmic ray nuclear composition as a function of energy.

  7. Feasibility of utilizing Cherenkov Telescope Array gamma-ray telescopes as free-space optical communication ground stations.

    PubMed

    Carrasco-Casado, Alberto; Vilera, Mariafernanda; Vergaz, Ricardo; Cabrero, Juan Francisco

    2013-04-10

    The signals that will be received on Earth from deep-space probes in future implementations of free-space optical communication will be extremely weak, and new ground stations will have to be developed in order to support these links. This paper addresses the feasibility of using the technology developed in the gamma-ray telescopes that will make up the Cherenkov Telescope Array (CTA) observatory in the implementation of a new kind of ground station. Among the main advantages that these telescopes provide are the much larger apertures needed to overcome the power limitation that ground-based gamma-ray astronomy and optical communication both have. Also, the large number of big telescopes that will be built for CTA will make it possible to reduce costs by economy-scale production, enabling optical communications in the large telescopes that will be needed for future deep-space links. PMID:23670767

  8. Results and developments from the 12m Davies-Cotton medium-sized telescope prototype for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Oakes, Louise; Garczarcyk, Markus; Schlenstedt, Stefan; Sternberger, Ronny; Schwanke, Ullrich

    2015-09-01

    The Cherenkov Telescope Array (CTA) will be the next generation ground-based observatory for gamma-ray astronomy, covering an energy range from a few tens of GeV to a few hundred TeV. The CTA project is currently in the design and prototyping phase, the start of construction is planned for 2016. The planned sensitivity of CTA improves on current ground based Cherenkov telescope experiments by about an order of magnitude. In the core energy range this sensitivity will be dominated by up to 40 Medium-Sized Telescopes (MSTs). These telescopes, of a modified Davies-Cotton mount type with a reflector diameter of 12 m, are currently being prototyped. A full-size mechanical prototype has been operating in Berlin since 2012. Several types of prototype mirrors have been developed and tested, and are mounted on the telescope. CCD cameras with various lenses are mounted on the prototype for studying deformation of the structure, testing alignment techniques, and telescope pointing using astrometry methods. The report will focus on results of optical and structural measurements, commissioning and testing of the MST prototype in Berlin, as well as the final design.

  9. Prototype of a production system for Cherenkov Telescope Array with DIRAC

    NASA Astrophysics Data System (ADS)

    Arrabito, L.; Bregeon, J.; Haupt, A.; Graciani Diaz, R.; Stagni, F.; Tsaregorodtsev, A.

    2015-12-01

    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. CTA will operate as an open observatory providing data products to the scientific community. An average data stream of about 10 GB/s for about 1000 hours of observation per year, thus producing several PB/year, is expected. Large CPU time is required for data-processing as well for massive Monte Carlo simulations needed for detector calibration purposes. The current CTA computing model is based on a distributed infrastructure for the archive and the data off-line processing. In order to manage the off-line data-processing in a distributed environment, CTA has evaluated the DIRAC (Distributed Infrastructure with Remote Agent Control) system, which is a general framework for the management of tasks over distributed heterogeneous computing environments. In particular, a production system prototype has been developed, based on the two main DIRAC components, i.e. the Workload Management and Data Management Systems. After three years of successful exploitation of this prototype, for simulations and analysis, we proved that DIRAC provides suitable functionalities needed for the CTA data processing. Based on these results, the CTA development plan aims to achieve an operational production system, based on the DIRAC Workload Management System, to be ready for the start of CTA operation phase in 2017-2018. One more important challenge consists of the development of a fully automatized execution of the CTA workflows. For this purpose, we have identified a third DIRAC component, the so-called Transformation System, which offers very interesting functionalities to achieve this automatisation. The Transformation System is a ’data-driven’ system, allowing to automatically trigger data-processing and data management operations according to pre

  10. A Trigger And Readout Scheme For Future Cherenkov Telescope Arrays

    NASA Astrophysics Data System (ADS)

    Hermann, G.; Bauer, C.; Föhr, C.; Hofmann, W.; Kihm, T.

    2008-12-01

    The next generation of ground-based gamma-ray observatories, such as e.g. CTA will consists of about 50-100 Telescopes, and cameras with in total ~100000 to ~200000 channels. The telescopes of the core array will cover and effective area of ~1 km2 and will be possibly accompanied by a large ``halo'' of smaller telescopes spread over about 10 km2. In order to make maximum use of the stereoscopic approach, a very flexible inter-telescope trigger scheme is needed which will allow to couple telescopes that located up to ~1 km apart. At the same time, the development of a cost effective readout scheme for the camera signals exhibits a major technological challenge. Here we present ideas on a new asynchronous inter-telescope trigger scheme, and a very cost-effective, high-bandwidth frontend to backend data transfer system, both based on standard Ethernet components and an Ethernet front-end interface based on mass production standard FPGAs.

  11. A Trigger And Readout Scheme For Future Cherenkov Telescope Arrays

    SciTech Connect

    Hermann, G.; Bauer, C.; Foehr, C.; Hofmann, W.; Kihm, T.

    2008-12-24

    The next generation of ground-based gamma-ray observatories, such as e.g. CTA will consists of about 50-100 Telescopes, and cameras with in total {approx}100000 to {approx}200000 channels. The telescopes of the core array will cover and effective area of {approx}1 km{sup 2} and will be possibly accompanied by a large 'halo' of smaller telescopes spread over about 10 km{sup 2}. In order to make maximum use of the stereoscopic approach, a very flexible inter-telescope trigger scheme is needed which will allow to couple telescopes that located up to {approx}1 km apart. At the same time, the development of a cost effective readout scheme for the camera signals exhibits a major technological challenge. Here we present ideas on a new asynchronous inter-telescope trigger scheme, and a very cost-effective, high-bandwidth frontend to backend data transfer system, both based on standard Ethernet components and an Ethernet front-end interface based on mass production standard FPGAs.

  12. An overview on mirrors for Cherenkov telescopes manufactured by glass cold-shaping technology

    NASA Astrophysics Data System (ADS)

    Canestrari, Rodolfo; Sironi, Giorgia

    2015-09-01

    The cold glass-slumping technique is a low cost processing developed at INAF-Osservatorio Astronomico di Brera for the manufacturing of mirrors for Cherenkov telescopes. This technology is based on the shaping of thin glass foils by means of bending at room temperature. The glass foils are thus assembled into a sandwich structure for retaining the imposed shape by the use of a honeycomb core. The mirrors so manufactured employ commercial off-the-shelf materials thus allowing a competitive cost and production time. They show very low weight, rigidity and environmental robustness. In this contribution we give an overview on the most recent results achieved from the adoption of the cold-shaping technology to different projects of Cherenkov telescopes. We show the variety of optical shapes implemented ranging from those spherical with long radius of curvature up to the most curved free form ones.

  13. Auxiliary instruments for the absolute calibration of the ASTRI SST-2M prototype for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Maccarone, Maria C.; Segreto, Alberto; Catalano, Osvaldo; La Rosa, Giovanni; Russo, Francesco; Sottile, Giuseppe; Gargano, Carmelo; Biondo, Benedetto; Fiorini, Mauro; Incorvaia, Salvatore; Toso, Giorgio

    2014-08-01

    ASTRI SST-2M is the end-to-end prototype telescope under development by the Italian National Institute of Astrophysics, INAF, proposed for the investigation of the highest-energy gamma-ray band in the framework of the Cherenkov Telescope Array, CTA. The ASTRI SST-2M prototype will be installed in Italy at the INAF station located at Serra La Nave on Mount Etna during Fall 2014. The calibration and scientific validation phase will start soon after. The calibration of a Cherenkov telescope includes several items and tools. The ASTRI SST- 2M camera is equipped with an internal fiber illumination system that allows to perform the relative calibration through monitoring of gain and efficiency variations of each pixel. The absolute calibration of the overall system, including optics, will take advantage from auxiliary instrumentation, namely UVscope and UVSiPM, two small-aperture multi-pixels photon detectors NIST calibrated in lab. During commissioning phase, to measure the main features of ASTRI SST-2M, as its overall spectral response, the main telescope and the auxiliary UVscope-UVSiPM will be illuminated simultaneously by a spatially uniform flux generated by a ground-based light source, named Illuminator, placed at a distance of few hundreds meters. Periodically, during clear nights, the flux profiles of a reference star tracked simultaneously by ASTRI SST-2M and UVscope-UVSiPM will allow to evaluate the total atmospheric attenuation and the absolute calibration constant of the ASTRI SST-2M prototype. In this contribution we describe the auxiliary UVscope-UVSiPM and Illuminator sub-system together with an overview of the end-to-end calibration procedure foreseen for the ASTRI SST-2M telescope prototype.

  14. Searches for dark matter subhaloes with wide-field Cherenkov telescope surveys

    SciTech Connect

    Brun, Pierre; Moulin, Emmanuel; Glicenstein, Jean-Francois; Diemand, Juerg

    2011-01-01

    The presence of substructures in dark matter haloes is an unavoidable consequence of the cold dark matter paradigm. Indirect signals from these objects have been extensively searched for with cosmic rays and {gamma} rays. At first sight, Cherenkov telescopes seem not very well suited for such searches, due to their small fields of view and the random nature of the possible dark matter substructure positions in the sky. However, with long enough exposure and an adequate observation strategy, the very good sensitivity of this experimental technique allows us to constrain particle dark matter models. We confront here the sensitivity map of the HESS experiment built out of their Galactic scan survey to the state-of-the-art cosmological N-body simulation Via Lactea II. We obtain competitive constraints on the annihilation cross section, at the level of 10{sup -24}-10{sup -23} cm{sup 3} s{sup -1}. The results are extrapolated to the future Cherenkov Telescope Array, in the cases of a Galactic plane survey and of an even wider extragalactic survey. In the latter case, it is shown that the sensitivity of the Cherenkov Telescope Array will be sufficient to reach the most natural particle dark matter models.

  15. 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

  16. 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

  17. The ASTRI SST-2M prototype for the Cherenkov Telescope Array: primary mirror characterization by deflectometry

    NASA Astrophysics Data System (ADS)

    Sironi, Giorgia; Canestrari, Rodolfo

    2015-09-01

    In 2014 the ASTRI Collaboration, led by the Italian National Institute for Astrophysics, has constructed an end-to-end prototype of a dual-mirror imaging air Cherenkov telescope, proposed for the small size class of telescopes for the Cherenkov Telescope Array. The prototype, named ASTRI SST-2M, has been installed at the observing station located at Serra La Nave (Italy). In this project the Brera Astronomical Observatory was responsible for the production and the testing of the primary mirror. The ASTRI SST-2M telescope's primary mirror has an aperture of ~ 4 m, a polynomial design, and consists of 18 individual hexagonal facets. These characteristics require the production and testing of panels with a typical size of ~1 m vertex-to-vertex and with an aspheric component of up to several millimetres. The mirror segments were produced assembling a sandwich of thin glass foils bent at room temperature to reach the desired shape. For the characterization of the mirrors we developed an ad-hoc deflectometry facility that works as an inverse Ronchi test in combination with a ray-tracing code. In this contribution we report the results of the deflectometric measurements performed on the primary mirror segments of the ASTRI SST-2M dual mirror telescope. The expected point spread function and the contributions to the degradation of the image quality are studied.

  18. Searching for Dark Matter signatures in dwarf spheroidal galaxies with the ASTRI mini-array in the framework of Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Giammaria, P.; Lombardi, S.; Antonelli, L. A.; Brocato, E.; Bigongiari, C.; Di Pierro, F.; Stamerra, A.; ASTRI Collaboration; CTA Consortium, the

    2016-07-01

    The nature of Dark Matter (DM) is an open issue of modern physics. Cosmological considerations and observational evidences indicate a behaviour beyond the Standard Model for feasible DM particle candidates. Non-baryonic DM is compatible with cold and weakly interacting massive particles (WIMPs) expected to have a mass in the range between ∼10 GeV and ∼100 TeV. Indirect DM searches with imaging atmospheric Cherenkov telescopes may play a crucial role in constraining the nature of the DM particle(s) through the study of their annihilation in very high energy (VHE) gamma rays from promising targets, such as the dwarf spheroidal satellite galaxies (dSphs) of the Milky Way. Here, we focus on indirect DM searches in dSphs, presenting the preliminary prospects of this research beyond the TeV mass region achievable with the ASTRI mini-array, proposed to be installed at the Cherenkov Telescope Array southern site.

  19. An optical design of the telescope in the Wide Field of View Cherenkov/Fluorescence Telescope Array

    NASA Astrophysics Data System (ADS)

    Liu, Jiali; Yang, Rui; Xiao, Gang; Cao, Zhen; Ma, Lingling; Zha, Min; Zhang, Bingkai; Zhang, Shoushan; Zhang, Yong

    2015-07-01

    Spherical design and Davies-cotton design, which can supply a wide Field of View (FOV) and have a single optical element structure, are the two candidate optics for Wide FOV Cherenkov/Fluorescence Telescope Array (WFCTA). To obtain a good imaging quality, we have done a detailed study to acquire optimal configurations for these two optics. In this paper, first, a proper curvature radius for the reflector, an optimized location for the camera, as well as a tolerance for the distortion of images for two designs have been presented. Furthermore, using such optimal configurations, the features of Cherenkov images initiated by proton and iron showers both with two optics have been investigated. Based on these results, it can be concluded that spherical design has the prior optical properties, such as a wider FOV of 16°, a higher and more homogeneous resolution for all incident directions within the 16° FOV and a lower light loss in the spots, as well as more signals collected in an Cherenkov image, relatively shorter arrival time difference for lights in a shower and brighter PMTs in the central part of a shower track. Thus it will be chosen as WFCTA optics. Finally, the optical properties of the two designs with 10° FOV have also been investigated. It should be mentioned that with such a smaller FOV, Davies-cotton optics is an effective design for it has a great imaging quality comparing with the setup of 16° FOV.

  20. An autocollimator alignment system for a Schwarzschild-Couder Cherenkov telescope

    NASA Astrophysics Data System (ADS)

    Griffiths, S. T.; Kaaret, P.; Smith, E.

    2016-08-01

    We present a digital autocollimator which will be used in the alignment system of a prototype medium-sized telescope, which is part of the U.S. contribution to the Cherenkov Telescope Array (CTA). The Schwarzschild-Couder optics in the prototype telescope (which is currently under construction) requires the precise alignment of three components: the primary and secondary segmented mirrors, and the gamma-ray camera. The approximately 9 meter separation between the mirrors necessitates remote optical measurement. Our autocollimator will measure the angle of a segment in one mirror relative to the center of the other mirror with a precision better than 5 arcsec over a range of ±0.126 °. We present a detailed description of the instrument and describe its performance in the laboratory.

  1. An autocollimator alignment system for a Schwarzschild-Couder Cherenkov telescope

    NASA Astrophysics Data System (ADS)

    Griffiths, S. T.; Kaaret, P.; Smith, E.

    2016-04-01

    We present a digital autocollimator which will be used in the alignment system of a prototype medium-sized telescope, which is part of the U.S. contribution to the Cherenkov Telescope Array (CTA). The Schwarzschild-Couder optics in the prototype telescope (which is currently under construction) requires the precise alignment of three components: the primary and secondary segmented mirrors, and the gamma-ray camera. The approximately 9 meter separation between the mirrors necessitates remote optical measurement. Our autocollimator will measure the angle of a segment in one mirror relative to the center of the other mirror with a precision better than 5 arcsec over a range of ±0.126°. We present a detailed description of the instrument and describe its performance in the laboratory.

  2. 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.

  3. Qualification and Testing of a Large Hot Slumped Secondary Mirror for Schwarzschild-Couder Imaging Air Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Rodeghiero, G.; Giro, E.; Canestrari, R.; Pernechele, C.; Sironi, G.; Pareschi, G.; Lessio, L.; Conconi, P.

    2016-05-01

    Dual-mirror Schwarzschild-Couder (SC) telescopes are based on highly aspherical optics, and they represent a novel design in the world of very high energy astrophysics. This work addresses the realization and the qualification of the secondary mirror for an SC telescope, named ASTRI, developed in the context of the Cherenkov Telescope Array Observatory. The discussion surveys the overall development from the early design concept to the final acceptance optical tests.

  4. A facility to evaluate the focusing performance of mirrors for Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Canestrari, Rodolfo; Giro, Enrico; Bonnoli, Giacomo; Farisato, Giancarlo; Lessio, Luigi; Rodeghiero, Gabriele; Spiga, Rossella; Toso, Giorgio; Pareschi, Giovanni

    2016-01-01

    Cherenkov Telescopes are equipped with optical dishes of large diameter - in general based on segmented mirrors - with typical angular resolution of a few arc-minutes. To evaluate the mirror's quality specific metrological systems are required that possibly take into account the environmental conditions in which typically these telescopes operate (in open air without dome protection). For this purpose a new facility for the characterization of mirrors has been developed at the labs of the Osservatorio Astronomico di Brera of the Italian National Institute of Astrophysics. The facility allows the precise measurement of the radius of curvature and the distribution of the concentred light in terms of focused and scattered components and it works in open air. In this paper we describe the facility and report some examples of its measuring capabilities.

  5. Readout electronics for the Wide Field of view Cherenkov/Fluorescence Telescope Array

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Zhang, S.; Zhang, Y.; Zhou, R.; Bai, L.; Zhang, J.; Huang, J.; Yang, C.; Cao, Z.

    2015-08-01

    The aim of the Large High Altitude Air Shower Observatory (LHAASO), supported by IHEP of the Chinese Academy of Sciences, is a multipurpose project with a complex detectors array for high energy gamma ray and cosmic ray detection. The Wide Field of view Cherenkov Telescope Array (WFCTA), as one of the components of the LHAASO project, aim to tag each primary particle that causes an air shower. The WFCTA is a portable telescope array used to detect cosmic ray spectra. The design of the readout electronics of the WFCTA is described in this paper Sixteen photomultiplier tubes (PMTs), together with their readout electronics are integrated into a single sub-cluster. To maintain good resolution and linearity over a wide dynamic range, a dual-gain amplification configuration on an analog board is used The digital board contains two 16channel 14-bit, 50 Msps analog-to-digital converters (ADC) and its power consumption, noise level, and relative deviation are all tested.

  6. The telescope control of the ASTRI SST-2M prototype for the Cherenkov telescope Array: hardware and software design architecture

    NASA Astrophysics Data System (ADS)

    Antolini, Elisa; Cascone, Enrico; Schwarz, Joseph; Stringhetti, Luca; Tanci, Claudio; Tosti, Gino; Aisa, Damiano; Aisa, Simone; Bagaglia, Marco; Busatta, Andrea; Campeggi, Carlo; Cefala, Marco; Farnesini, Lucio; Giacomel, Stefano; Marchiori, Gianpiero; Marcuzzi, Enrico; Nucciarelli, Giuliano; Piluso, Antonfranco

    2014-07-01

    ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is a flagship project of the Italian Ministry of Research and led by the Italian National Institute of Astrophysics (INAF). One of its aims is to develop, within the Cherenkov Telescope Array (CTA) framework, an end-to-end small-sized telescope prototype in a dual-mirror configuration (SST-2M) in order to investigate the energy range E ~ 1-100 TeV. A long-term goal of the ASTRI program is the production of an ASTRI/CTA mini-array composed of seven SST-2M telescopes. The prototype, named ASTRI SST-2M, is seen as a standalone system that needs only network and power connections to work. The software system that is being developed to control the prototype is the base for the Mini-Array Software System (MASS), which has the task to make possible the operation of both the ASTRI SST-2M prototype and the ASTRI/CTA mini-array. The scope of this contribution is to give an overview of the hardware and software architecture adopted for the ASTRI SST- 2M prototype, showing how to apply state of the art industrial technologies to telescope control and monitoring systems.

  7. The ASTRI/CTA mini-array of Small Size Telescopes as a precursor of the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Pareschi, Giovanni; Agnetta, Gaetano; Antolini, Elisa; Antonelli, Lucio Angelo; Bastieri, Denis; Bellassai, Giancarlo; Belluso, Massimiliano; Bigongiari, Ciro; Billotta, Sergio; Biondo , Benedetto; Boettcher, Markus; Bonanno, Giovanni; Bonnoli, Giacomo; Bruno , Pietro; Bulgarelli, Andrea; Canestrari, Rodolfo; Capalbi, Milvia; Capobianco, G.; Caraveo, Patrizia; Carosi, Alòessandro; Cascone, Enrico; Catalano, Osvaldo; Cereda, Michele; Conconi, Paolo; Conforti, Vito; Cusumano, Giancarlo; De Caprio, Vincenzo; De Luca, Andrea; de Gouveia Dal Pino, Elisabete; Di Paola, Andrea; Di Pierro, Federico; Fantinel, Daniela; Fiorini, Mauro; Fugazza, Dino; Gardiol, Daniele; Gargano, Carmelo; Garozzo , Salvatore; Gianotti , Fulvio; Giarrusso , Salvatore; Giro, Enrico; Grillo, Aledssandro; Impiombato, Domenico; Incorvaia , Salvatore; La Barbera , Antonino; La Palombara , Nicola; La Parola , Valentina; La Rosa, Giovanni; Lessio, Luigi; Leto, Giuseppe; Lombardi , Saverio; Lucarelli, Fabrizio; Maccarone, Maria Concetta; Malaspina, Giuseppe; Marano, Davide; Martinetti , Eugenio; Melioli, C.; Millul, Rachele; Mineo , Teresa; Morello, Carlo; Morlino, Giovanni; Nemmen, R.; Perri, Luca; Rodeghiero, Gabriele; Romano, Patrizia; Romeo, Giuseppe; Russo, Francesco; Sacco, Bruno; Sartore, Nicola; Schwarz, Joseph; Alberto, Segreto; Selvestrel, Danilo; Sironi, Giorgia; Stamerra, Antonio; Strazzeri, Elisabetta; Stringhetti, Luca; Tagliaferri, Gianpiero; Tanci, Claudio; Testa, Vincenzo; Timpanaro , Maria Cristina; Toso, Giorgio; Tosti, Gino; Trifoglio, Massimo; Vallania, Piero; Vercellone, Stefano; Volpicelli, Antonio; Zitelli, Valentina

    2014-08-01

    ASTRI ("Astrofisica con Specchi a Tecnologia Replicante Italiana") is a flagship project of the Italian Ministry of Education, University and Research. Within this framework, INAF is currently developing a wide-field-of-view (9.6 degrees in diameter) end-to-end prototype of the small-size telescope (SST) of the Cherenkov Telescope Array, CTA, sensitive in the energy band from a few TeV up to hundreds TeV. The ASTRI telescope is based on a dual-mirror Schwarzschild-Couder (ASTRI SST-2M) optical design, with a compact (F# = 0.5) optical configuration named ASTRI SST-2M telescope. This allows us to adopt an innovative modular focal plane camera based on silicon photo-multipliers, with a logical pixel size of 6.2mm x 6.2mm. Moreover, planned, and already being developed, an SST mini-array based on 7 identical telescopes represents an evolution of the ASTRI SST-2M telescope. The ASTRI/CTA mini-array will be part of the CTA array, representing a precursor that will be included into the final array. With the mini-array, in addition to a technical assessment studies in the perpective of the full CTA implementation, it will be possible to perform an early scientific program. In particular we wish to start investigating the poorly known energy range between a few and 100 TeV, thus exploring e.g. the cut-off regime of cosmic accelerators. Apart from INAF, other international institutes will directly participate in the mini-array implementation, as the North-West University in South Africa and the University of Sao Paulo in Brazil. An interest about it has been expressed also by other international groups. In this talk we will report on the development status of the ASTRI prototype and ASTRI/CTA mini-array.

  8. The readout and control system of the mid-size telescope prototype of the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Oya, I.; Anguner, O.; Behera, B.; Birsin, E.; Fuessling, M.; Melkumyan, D.; Schmidt, T.; Schwanke, U.; Sternberger, R.; Wegner, P.; Wiesand, S.; Cta Consortium,the

    2014-06-01

    The Cherenkov Telescope Array (CTA) is one of the major ground-based astronomy projects being pursued and will be the largest facility for ground-based y-ray observations ever built. CTA will consist of two arrays: one in the Northern hemisphere composed of about 20 telescopes, and the other one in the Southern hemisphere composed of about 100 telescopes, both arrays containing telescopes of different type and size. A prototype for the Mid-Size Telescope (MST) with a diameter of 12 m has been installed in Berlin and is currently being commissioned. This prototype is composed of a mechanical structure, a drive system and mirror facets mounted with powered actuators to enable active control. Five Charge-Coupled Device (CCD) cameras, and a wide set of sensors allow the evaluation of the performance of the instrument. The design of the control software is following concepts and tools under evaluation within the CTA consortium in order to provide a realistic test-bed for the middleware: 1) The readout and control system for the MST prototype is implemented with the Atacama Large Millimeter/submillimeter Array (ALMA) Common Software (ACS) distributed control middleware; 2) the OPen Connectivity-Unified Architecture (OPC UA) is used for hardware access; 3) the document oriented MongoDB database is used for an efficient storage of CCD images, logging and alarm information: and 4) MySQL and MongoDB databases are used for archiving the slow control monitoring data and for storing the operation configuration parameters. In this contribution, the details of the implementation of the control system for the MST prototype telescope are described.

  9. Dark matter searches with Cherenkov telescopes: nearby dwarf galaxies or local galaxy clusters?

    NASA Astrophysics Data System (ADS)

    Sánchez-Conde, Miguel A.; Cannoni, Mirco; Zandanel, Fabio; Gómez, Mario E.; Prada, Francisco

    2011-12-01

    In this paper, we compare dwarf galaxies and galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies (Draco, Ursa Minor, Wilman 1 and Segue 1) and local galaxy clusters (Perseus, Coma, Ophiuchus, Virgo, Fornax, NGC 5813 and NGC 5846), and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman 1 appears as the best candidate in the sample. However, its mass modeling is still rather uncertain, so probably other candidates with less uncertainties and quite similar fluxes, namely Ursa Minor and Segue 1, might be better options. As for galaxy clusters, Virgo represents the one with the highest flux. However, its large spatial extension can be a serious handicap for IACT observations and posterior data analysis. Yet, other local galaxy cluster candidates with more moderate emission regions, such as Perseus, may represent good alternatives. After comparing dwarfs and clusters, we found that the former exhibit annihilation flux profiles that, at the center, are roughly one order of magnitude higher than those of clusters, although galaxy clusters can yield similar, or even higher, integrated fluxes for the whole object once substructure is taken into account. Even when any of these objects are strictly point-like according to the properties of their annihilation signals, we conclude that dwarf galaxies are best suited for observational strategies based on the search of point-like sources, while galaxy clusters represent best targets for analyses that can deal with rather extended emissions. Finally, we study the detection prospects for present and future IACTs in the framework of the constrained minimal supersymmetric standard model. We

  10. Dark Matter Searches with Cherenkov Telescopes: Nearby Dwarf Galaxies or Local Galaxy Clusters?

    SciTech Connect

    Sanchez-Conde, Miguel A.; Cannoni, Mirco; Zandanel, Fabio; Gomez, Mario E.; Prada, Francisco; /IAA, Granada

    2012-06-06

    In this paper, we compare dwarf galaxies and galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies (Draco, Ursa Minor, Wilman 1 and Segue 1) and local galaxy clusters (Perseus, Coma, Ophiuchus, Virgo, Fornax, NGC 5813 and NGC 5846), and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman 1 appears as the best candidate in the sample. However, its mass modeling is still rather uncertain, so probably other candidates with less uncertainties and quite similar fluxes, namely Ursa Minor and Segue 1, might be better options. As for galaxy clusters, Virgo represents the one with the highest flux. However, its large spatial extension can be a serious handicap for IACT observations and posterior data analysis. Yet, other local galaxy cluster candidates with more moderate emission regions, such as Perseus, may represent good alternatives. After comparing dwarfs and clusters, we found that the former exhibit annihilation flux profiles that, at the center, are roughly one order of magnitude higher than those of clusters, although galaxy clusters can yield similar, or even higher, integrated fluxes for the whole object once substructure is taken into account. Even when any of these objects are strictly point-like according to the properties of their annihilation signals, we conclude that dwarf galaxies are best suited for observational strategies based on the search of point-like sources, while galaxy clusters represent best targets for analyses that can deal with rather extended emissions. Finally, we study the detection prospects for present and future IACTs in the framework of the constrained minimal supersymmetric standard model. We

  11. Development of Gigahertz Analog Memory for Front-End Electronics of Imaging Air Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Mizukami, T.; Higashi, Y.; Nakano, S.; Nakamori, T.; Kubo, H.; Tanimori, T.; Tanaka, M.

    The night sky light is one of the major components of background for imaging air Cherenkov telescopes. It disturbs images of air shower and makes both the gamma/hadron separation and the angular resolution worse. For example, The CANGAROO-III electronics consists of charge ADCs and multi-hit TDCs. In using charge ADCs, we have to delay the signal from PMTs until the trigger signal input to ADCs. After through this delay line chip, signals from PMTs are distorted, and we have to take the signal integration time longer than Cherenkov signal time constant and more night sky light is mixed to the real signal. In order to reduce this night sky light, we are planning to replace the charge ADCs to capacitor arrays called AMC (Analog Memory Cell). AMC consists of 512 capacitors and can record the waveform of the input signal for 512 ns at high sampling rate of 1 GHz. We already developed a test type of AMC chip and its dynamic range is more than 7 bits. We will report the current status of the development of AMC.

  12. Beyond VERITAS: High-Energy Gamma-Rays with the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Williams, David A.; CTA Consortium

    2016-01-01

    The Cherenkov Telescope Array (CTA) will be a new observatory for the study of very-high-energy gamma-ray sources, designed to achieve an order of magnitude improvement in sensitivity in the ~30 GeV to ~100 TeV energy band compared to currently operating instruments: VERITAS, MAGIC, and H.E.S.S. CTA will probe known sources with unprecedented sensitivity, angular resolution, and spectral coverage, while also detecting hundreds of new sources. CTA will provide access to data in this energy band to members of the wider astronomical community for the first time. The CTA Consortium will also conduct a number of Key Science Projects, including a Galactic Plane survey and a survey of one quarter of the extragalactic sky, creating legacy data sets that will also be available to the public. This presentation will describe how CTA will bring new opportunities for the solution of astrophysical puzzles.

  13. Evaluation of Photo Multiplier Tube candidates for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Photo Multiplier Tubes (PMTs) are the most wide spread detectors for fast, faint light signals. Six years ago, an improvement program for the PMT candidates for the Cherenkov Telescope Array (CTA) project was started with the companies Hamamatsu Photonics K.K. and Electron Tubes Enterprises Ltd. (ETE). For maximizing the performance of the CTA imaging cameras we need PMTs with outstanding good quantum efficiency, high photoelectron collection efficiency, short pulse width, very low afterpulse probability and transit time spread. We will report on the measurements of PMT R-12992-100 from Hamamatsu as their final product and the PMT D573KFLSA as one of the latest test versions from ETE as candidate PMTs for the CTA project.

  14. Simulated Gamma-Ray Pulse Profile of the Crab pulsar with the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Burtovoi, A.; Zampieri, L.

    2016-04-01

    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 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 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 hours). 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 (LSTs). 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.

  15. EXPLORING THE NATURE OF THE GALACTIC CENTER {gamma}-RAY SOURCE WITH THE CHERENKOV TELESCOPE ARRAY

    SciTech Connect

    Linden, Tim; Profumo, Stefano

    2012-11-20

    Observations from multiple {gamma}-ray telescopes have uncovered a high-energy {gamma}-ray source spatially coincident with the Galactic center. Recently, a compelling model for the broadband {gamma}-ray emission has been formulated, which posits that high-energy protons emanating from Sgr A* could produce {gamma}-rays through {pi}{sup 0} decays resulting from inelastic collisions with the traversed interstellar gas in the region. Models of the gas distribution in the Galactic center region imply that the resulting {gamma}-ray morphology would be observed as a point source with all current telescopes, but that the upcoming Cherenkov Telescope Array (CTA) may be able to detect an extended emission profile with an unmistakable morphology. Here, we critically evaluate this claim, employing a three-dimensional gas distribution model and a detailed Monte Carlo simulation, and using the anticipated effective area and angular resolution of CTA. We find that the impressive angular resolution of CTA will be key to test hadronic emission models conclusively against, for example, point source or dark matter annihilation scenarios. We comment on the relevance of this result for searches for dark matter annihilation in the Galactic center region.

  16. Upper Limits from Five Years of Blazar Observations with the VERITAS Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Archambault, S.; Archer, A.; Benbow, W.; Bird, R.; Biteau, J.; Buchovecky, M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Eisch, J. D.; Errando, M.; Falcone, A.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Fortin, P.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Griffin, S.; Grube, J.; Gyuk, G.; Hütten, M.; Håkansson, N.; Hanna, D.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Krennrich, F.; Kumar, S.; Lang, M. J.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Moriarty, P.; Mukherjee, R.; Nguyen, T.; Nieto, D.; O’Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Park, N.; Perkins, J. S.; Pichel, A.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rovero, A. C.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Vincent, S.; Wakely, S. P.; Weiner, O. M.; Weinstein, A.; Williams, D. A.; Zitzer, B.; the VERITAS collaboration; Fumagalli, M.; Prochaska, J. X.

    2016-06-01

    Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energy (VHE; E > 100 GeV) γ-ray sources. In this work, we present the analysis results of a sample of 114 undetected objects. The observations constitute a total live-time of ∼570 hr. The sample includes several unidentified Fermi-Large Area Telescope (LAT) sources (located at high Galactic latitude) as well as all the sources from the second Fermi-LAT catalog that are contained within the field of view of the VERITAS observations. We have also performed optical spectroscopy measurements in order to estimate the redshift of some of these blazars that do not have spectroscopic distance estimates. We present new optical spectra from the Kast instrument on the Shane telescope at the Lick observatory for 18 blazars included in this work, which allowed for the successful measurement or constraint on the redshift of four of them. For each of the blazars included in our sample, we provide the flux upper limit in the VERITAS energy band. We also study the properties of the significance distributions and we present the result of a stacked analysis of the data set, which shows a 4σ excess.

  17. Status of the photomultiplier-based FlashCam camera for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Pühlhofer, G.; Bauer, C.; Eisenkolb, F.; Florin, D.; Föhr, C.; Gadola, A.; Garrecht, F.; Hermann, G.; Jung, I.; Kalekin, O.; Kalkuhl, C.; Kasperek, J.; Kihm, T.; Koziol, J.; Lahmann, R.; Manalaysay, A.; Marszalek, A.; Rajda, P. J.; Reimer, O.; Romaszkan, W.; Rupinski, M.; Schanz, T.; Schwab, T.; Steiner, S.; Straumann, U.; Tenzer, C.; Vollhardt, A.; Weitzel, Q.; Winiarski, K.; Zietara, K.

    2014-07-01

    The FlashCam project is preparing a camera prototype around a fully digital FADC-based readout system, for the medium sized telescopes (MST) of the Cherenkov Telescope Array (CTA). The FlashCam design is the first fully digital readout system for Cherenkov cameras, based on commercial FADCs and FPGAs as key components for digitization and triggering, and a high performance camera server as back end. It provides the option to easily implement different types of trigger algorithms as well as digitization and readout scenarios using identical hardware, by simply changing the firmware on the FPGAs. The readout of the front end modules into the camera server is Ethernet-based using standard Ethernet switches and a custom, raw Ethernet protocol. In the current implementation of the system, data transfer and back end processing rates of 3.8 GB/s and 2.4 GB/s have been achieved, respectively. Together with the dead-time-free front end event buffering on the FPGAs, this permits the cameras to operate at trigger rates of up to several ten kHz. In the horizontal architecture of FlashCam, the photon detector plane (PDP), consisting of photon detectors, preamplifiers, high voltage-, control-, and monitoring systems, is a self-contained unit, mechanically detached from the front end modules. It interfaces to the digital readout system via analogue signal transmission. The horizontal integration of FlashCam is expected not only to be more cost efficient, it also allows PDPs with different types of photon detectors to be adapted to the FlashCam readout system. By now, a 144-pixel mini-camera" setup, fully equipped with photomultipliers, PDP electronics, and digitization/ trigger electronics, has been realized and extensively tested. Preparations for a full-scale, 1764 pixel camera mechanics and a cooling system are ongoing. The paper describes the status of the project.

  18. 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

  19. Science with the ASTRI mini-array for the Cherenkov Telescope Array: blazars and fundamental physics

    NASA Astrophysics Data System (ADS)

    Bonnoli, Giacomo; Tavecchio, Fabrizio; Giuliani, Andrea; Bigongiari, Ciro; Di Pierro, Federico; Stamerra, Antonio; Pareschi, Giovanni; Vercellone, Stefano; ASTRI Collaboration; CTA Consortium

    2016-05-01

    ASTRI (“Astronomia a Specchi con Tecnologia Replicante Italiana”) is a flagship project of the Italian Ministry of Research (MIUR), devoted to the realization, operation and scientific validation of an end-to-end prototype for the Small Size Telescope (SST) envisaged to become part of the Cherenkov Telescope Array (CTA). The ASTRI SST-2M telescope prototype is characterized by a dual mirror, Schwarzschild-Couder optical design and a compact camera based on silicon photo-multipliers. It will be sensitive to multi-TeV very high energy (VHE) gamma rays up to 100 TeV, with a PSF ~ 6’ and a wide (9.6°) unaberrated optical field of view. Right after validation of the design in single-dish observations at the Serra La Nave site (Sicily, Italy) during 2015, the ASTRI collaboration will be able to start deployment, at the final CTA southern site, of the ASTRI mini-array, proposed to constitute the very first CTA precursor. Counting 9 ASTRI SST-2M telescopes, the ASTRI mini-array will overtake current IACT systems in differential sensitivity above 5 TeV, thus allowing unprecedented observations of known and predicted bright TeV emitters in this band, including some extragalactic sources such as extreme high-peaked BL Lacs with hard spectra. We exploited the ASTRI scientific simulator ASTRIsim in order to understand the feasibility of observations tackling blazar and cosmic ray physics, including discrimination of hadronic and leptonic scenarios for the VHE emission from BL Lac relativistic jets and indirect measurements of the intergalactic magnetic field and of the extragalactic background light. We selected favorable targets, outlining observation modes, exposure times, multi-wavelength coverage needed and the results expected. Moreover, the perspectives for observation of effects due to the existence of axion-like particles or to Lorentz invariance violations have been investigated.

  20. The ASTRI SST-2M telescope prototype for the Cherenkov Telescope Array: camera DAQ software architecture

    NASA Astrophysics Data System (ADS)

    Conforti, Vito; Trifoglio, Massimo; Bulgarelli, Andrea; Gianotti, Fulvio; Fioretti, Valentina; Tacchini, Alessandro; Zoli, Andrea; Malaguti, Giuseppe; Capalbi, Milvia; Catalano, Osvaldo

    2014-07-01

    ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is a Flagship Project financed by the Italian Ministry of Education, University and Research, and led by INAF, the Italian National Institute of Astrophysics. Within this framework, INAF is currently developing an end-to-end prototype of a Small Size dual-mirror Telescope. In a second phase the ASTRI project foresees the installation of the first elements of the array at CTA southern site, a mini-array of 7 telescopes. The ASTRI Camera DAQ Software is aimed at the Camera data acquisition, storage and display during Camera development as well as during commissioning and operations on the ASTRI SST-2M telescope prototype that will operate at the INAF observing station located at Serra La Nave on the Mount Etna (Sicily). The Camera DAQ configuration and operations will be sequenced either through local operator commands or through remote commands received from the Instrument Controller System that commands and controls the Camera. The Camera DAQ software will acquire data packets through a direct one-way socket connection with the Camera Back End Electronics. In near real time, the data will be stored in both raw and FITS format. The DAQ Quick Look component will allow the operator to display in near real time the Camera data packets. We are developing the DAQ software adopting the iterative and incremental model in order to maximize the software reuse and to implement a system which is easily adaptable to changes. This contribution presents the Camera DAQ Software architecture with particular emphasis on its potential reuse for the ASTRI/CTA mini-array.

  1. High Performances and Low Cost Front-End Electronics for the Cherenkov Telescope Array

    SciTech Connect

    Vincent, P.; Nayman, P.; Toussenel, F.; Delagnes, E.; Glicenstein, J.-F.; Hermann, G.

    2008-12-24

    The current Imaging Arrays of Cherenkov Telescopes (IACT) show that this technique is mature. Front-end electronics based on analogue pipelines become a popular readout solution. Slow noise and low power consumption ASICs were developed with improved dynamical range and linearity. A large bandwidth preserves the characteristics of the signal and fast readout reduces dead time. Next generation of IACT should reach an order of magnitude in sensitivity in a wide energy band, ranging from 10 GeV to more than 100 TeV. This goal can be reached with an array of 50-100 telescopes of various sizes at various spacings. With about 2 000 channels per camera a significant effort must be done to lower the overall cost and improve the performances of the electronics. Mass production will be determinant for lowering the overall cost. A gain in cost and performances can be obtained by maximising the integration of the front-end electronics in an ASIC. The amplifiers, analogue memories, digitization and first level buffering can be embedded in the same component. The first stage of the first level trigger should be also considered in this integration. Integrated electronics leads to a more compact camera and an easier maintenance on site.

  2. The single mirror small size telescope camera for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Heller, Matthieu

    2015-07-01

    The UniGe group has proposed an innovative approach for the camera of a Davies-Cotton telescope of dish diameter 4 m and focal length 5.6 m, which would require single pixel SiPM with a size exceeding any commercial device. In collaboration with Hamamatsu, we have developed a large area (93.6 mm2) hexagonal SiPM operated in Geiger Avalanche mode. Coupled to a hollow hexagonal light concentrator, the sensitive area is extended to the required pixel size. The large area and the corresponding high capacitance (> 800 pF) of these sensors poses many difficulties in terms of operation. The characterization of these devices together with the dedicated electronics will be presented.

  3. 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.

  4. High energy gamma-ray observations of the Crab Nebula and pulsar with the Solar Tower Atmospheric Cherenkov Effect Experiment

    NASA Astrophysics Data System (ADS)

    Oser, Scott Michael

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a new ground-based atmospheric Cherenkov telescope for gamma-ray astronomy. STACEE uses the large mirror area of a solar heliostat facility to achieve a low energy threshold. A prototype experiment which uses 32 heliostat mirrors with a total mirror area of ~1200 m2 has been constructed. This prototype, called STACEE-32, was used to search for high energy gamma-ray emission from the Crab Nebula and Pulsar. Observations taken between November 1998 and February 1999 yield a strong statistical excess of gamma- like events from the Crab, with a significance of +6.75σ in 43 hours of on-source observing time. No evidence for pulsed emission from the Crab Pulsar was found, and the upper limit on the pulsed fraction of the observed excess was < 5.5% at the 90% confidence level. A subset of the data was used to determine the integral flux of gamma rays from the Crab. We report an energy threshold of Eth = 190 +/- 60 GeV, and a measured integral flux of I(E > Eth) = (2.2 +/- 0.6 +/- 0.2) × 10-10 photons cm-2 s-1. The observed flux is in agreement with a continuation to lower energies of the power law spectrum seen at TeV energies.

  5. 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.

  6. Sensitivity of the Cherenkov Telescope Array to the Detection of Intergalactic Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Meyer, Manuel; Conrad, Jan; Dickinson, Hugh

    2016-08-01

    Very high energy (VHE; energy E ≳ 100 GeV) γ-rays originating from extragalactic sources undergo pair production with low-energy photons of background radiation fields. These pairs can inverse-Compton-scatter background photons, initiating an electromagnetic cascade. The spatial and temporal structure of this secondary γ-ray signal is altered as the {e}+{e}- pairs are deflected in an intergalactic magnetic field (IGMF). We investigate how VHE observations with the future Cherenkov Telescope Array, with its high angular resolution and broad energy range, can potentially probe the IGMF. We identify promising sources and simulate γ-ray spectra over a wide range of values of the IGMF strength and coherence length using the publicly available ELMAG Monte Carlo code. Combining simulated observations in a joint likelihood approach, we find that current limits on the IGMF can be significantly improved. The projected sensitivity depends strongly on the time a source has been γ-ray active and on the emitted maximum γ-ray energy.

  7. A prototype for the real-time analysis of the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Bulgarelli, Andrea; Fioretti, Valentina; Zoli, Andrea; Aboudan, Alessio; Rodríguez-Vázquez, Juan José; Maier, Gernot; Lyard, Etienne; Bastieri, Denis; Lombardi, Saverio; Tosti, Gino; De Rosa, Adriano; Bergamaschi, Sonia; Interlandi, Matteo; Beneventano, Domenico; Lamanna, Giovanni; Jacquemier, Jean; Kosack, Karl; Antonelli, Lucio Angelo; Boisson, Catherine; Burkowski, Jerzy; Buson, Sara; Carosi, Alessandro; Conforti, Vito; Contreras, Jose Luis; De Cesare, Giovanni; de los Reyes, Raquel; Dumm, Jon; Evans, Phil; Fortson, Lucy; Fuessling, Matthias; Graciani, Ricardo; Gianotti, Fulvio; Grandi, Paola; Hinton, Jim; Humensky, Brian; Knödlseder, Jürgen; Malaguti, Giuseppe; Marisaldi, Martino; Neyroud, Nadine; Nicastro, Luciano; Ohm, Stefan; Osborne, Julian; Rosen, Simon; Tacchini, Alessandro; Torresi, Eleonora; Testa, Vincenzo; Trifoglio, Massimo; Weinstein, Amanda

    2014-07-01

    The Cherenkov Telescope Array (CTA) observatory will be one of the biggest ground-based very-high-energy (VHE) γ- ray observatory. CTA will achieve a factor of 10 improvement in sensitivity from some tens of GeV to beyond 100 TeV with respect to existing telescopes. The CTA observatory will be capable of issuing alerts on variable and transient sources to maximize the scientific return. To capture these phenomena during their evolution and for effective communication to the astrophysical community, speed is crucial. This requires a system with a reliable automated trigger that can issue alerts immediately upon detection of γ-ray flares. This will be accomplished by means of a Real-Time Analysis (RTA) pipeline, a key system of the CTA observatory. The latency and sensitivity requirements of the alarm system impose a challenge because of the anticipated large data rate, between 0.5 and 8 GB/s. As a consequence, substantial efforts toward the optimization of highthroughput computing service are envisioned. For these reasons our working group has started the development of a prototype of the Real-Time Analysis pipeline. The main goals of this prototype are to test: (i) a set of frameworks and design patterns useful for the inter-process communication between software processes running on memory; (ii) the sustainability of the foreseen CTA data rate in terms of data throughput with different hardware (e.g. accelerators) and software configurations, (iii) the reuse of nonreal- time algorithms or how much we need to simplify algorithms to be compliant with CTA requirements, (iv) interface issues between the different CTA systems. In this work we focus on goals (i) and (ii).

  8. Monte-Carlo studies of the angular resolution of a future Cherenkov gamma-ray telescope

    SciTech Connect

    Funk, S.; Hinton, J. A.

    2008-12-24

    The current generation of Imaging Atmospheric telescopes (IACTs) has demonstrated the power of this observational technique, providing high sensitivity and an angular resolution of {approx}0.1 deg. per event above an energy threshold of {approx}100 GeV. Planned future arrays of IACTs such as AGIS or CTA are aiming at significantly improving the angular resolution. Preliminary results have shown that values down to {approx}1' might be achievable. Here we present the results of Monte-Carlo simulations that aim to exploring the limits of angular resolution for next generation IACTs and investigate how the resolution can be optimised by changes to array and telescope parameters such as the number of pixel in the camera, the field of view of the camera, the angular pixel size, the mirror size, and also the telescope separation.

  9. The ASTRI mini-array within the future Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Vercellone, Stefano

    2016-07-01

    The Cherenkov Telescope Array (CTA) is a large collaborative effort aimed at the design and operation of an observatory dedicated to very high-energy gamma-ray astrophysics in the energy range from a few tens of GeV to above 100 TeV, which will yield about an order of magnitude improvement in sensitivity with respect to the current major arrays (H.E.S.S., MAGIC, and VERITAS). Within this framework, the Italian National Institute for Astrophysics is leading the ASTRI project, whose main goals are the design and installation on Mt. Etna (Sicily) of an end-to-end dual-mirror prototype of the CTA small size telescope (SST) and the installation at the CTA Southern site of a dual-mirror SST mini-array composed of nine units with a relative distance of about 300 m. The innovative dual-mirror Schwarzschild-Couder optical solution adopted for the ASTRI Project allows us to substantially reduce the telescope plate-scale and, therefore, to adopt silicon photo-multipliers as light detectors. The ASTRI mini-array is a wider international effort. The mini-array, sensitive in the energy range 1-100 TeV and beyond with an angular resolution of a few arcmin and an energy resolution of about 10-15%, is well suited to study relatively bright sources (a few × 10-12 erg cm-2 s-1 at 10 TeV) at very high energy. Prominent sources such as extreme blazars, nearby well-known BL Lac objects, Galactic pulsar wind nebulae, supernovae remnants, micro-quasars, and the Galactic Center can be observed in a previously unexplored energy range. The ASTRI mini-array will extend the current IACTs sensitivity well above a few tens of TeV and, at the same time, will allow us to compare our results on a few selected targets with those of current (HAWC) and future high-altitude extensive air-shower detectors.

  10. Evolution of ground-based gamma-ray astronomy from the early days to the Cherenkov Telescope Arrays

    NASA Astrophysics Data System (ADS)

    Hillas, A. M.

    2013-03-01

    Most of what we know of cosmic gamma rays has come from spacecraft, but at energies above tens of GeV it has become possible to make observations with ground-based detectors of enormously greater collecting area. In recent years one such detector type, the cluster of imaging air Cherenkov telescopes, has reached a very productive state, whilst several alternative approaches have been explored, including converted solar power collectors and novel high-altitude particle shower detectors which promised to extend the energy range covered. Key examples of development from 1952 to 2011 are followed, noting the problems and discoveries that stimulated the current work, explaining the logic of the alternative approaches that were taken. The merits of the current major Cherenkov observatories and of other viable detectors are examined and compared, with examples of the astrophysical information they are beginning to provide. The detectors are still evolving, as we still do not understand the processes onto which the gamma rays provide a window. These include the acceleration of Galactic cosmic rays (in particular, the wide-band spectra of radiation from some individual supernova remnants are still hard to interpret), the highly relativistic and variable jets from active galactic nuclei, and aspects of the electrodynamics of pulsars. Larger groups of Cherenkov telescopes still offer the possibility of an increase in power of the technique for resolvable Galactic sources especially.

  11. A 4 V, ns-range pulse generator for the test of Cherenkov Telescopes readout electronics

    NASA Astrophysics Data System (ADS)

    Antoranz, P.; Vegas, I.; Miranda, J. M.

    2010-08-01

    We present in this paper the design, fabrication and verification of a ns-range pulse generator based on a Step Recovery Diode (SRD). This device needs only a 5 V DC power supply, delivers 1 ns pulses with peak amplitudes in excess of 4 V and features state of the art jitter figures. In addition, the pulser contains a trigger channel. The long standing problem of the SRD simulation via circuital analysis is addressed. It is shown that the dynamic properties of the Step Recovery Diode can accurately be reproduced via a small signal circuital simulation for the rise times needed in a ns-range pulser. It is also demonstrated that strong inaccuracies in the pulse shape prediction are obtained if the wave propagation through the lines typically used in this type of circuits is simulated by a simple Transverse Electromagnetic Mode (TEM) line model. Instead, it is necessary to account for non-TEM effects. By means of broadband resistive power splitters and high dynamic range amplifiers, a prototype of 4 channels was also fabricated. This prototype is particularly useful for testing the readout electronics of Cherenkov Telescopes, but additional applications to other large-scale experiments are expected, any of those where calibration or verification with compact ns-range pulsers featuring low jitter, large dynamic ranges and multichannel operation is needed. In addition, the fabrication cost of this pulser is almost negligible as compared with bulky, commercially available waveform generators, which rarely deliver ns pulses in excess of 3 V. Furthermore, the small size of the pulser presented here and its low power consumption allow an easy integration into more complex systems.

  12. ROBAST: Development of a ROOT-based ray-tracing library for cosmic-ray telescopes and its applications in the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Okumura, Akira; Noda, Koji; Rulten, Cameron

    2016-03-01

    We have developed a non-sequential ray-tracing simulation library, ROOT-basedsimulatorforraytracing (ROBAST), which is aimed to be widely used in optical simulations of cosmic-ray (CR) and gamma-ray telescopes. The library is written in C++, and fully utilizes the geometry library of the ROOT framework. Despite the importance of optics simulations in CR experiments, no open-source software for ray-tracing simulations that can be widely used in the community has existed. To reduce the dispensable effort needed to develop multiple ray-tracing simulators by different research groups, we have successfully used ROBAST for many years to perform optics simulations for the Cherenkov Telescope Array (CTA). Among the six proposed telescope designs for CTA, ROBAST is currently used for three telescopes: a Schwarzschild-Couder (SC) medium-sized telescope, one of SC small-sized telescopes, and a large-sized telescope (LST). ROBAST is also used for the simulation and development of hexagonal light concentrators proposed for the LST focal plane. Making full use of the ROOT geometry library with additional ROBAST classes, we are able to build the complex optics geometries typically used in CR experiments and ground-based gamma-ray telescopes. We introduce ROBAST and its features developed for CR experiments, and show several successful applications for CTA.

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

    SciTech Connect

    Actis, M

    2012-04-17

    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.

  14. An innovative SiPM-based camera for gamma-ray astronomy with the small size telescopes of the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Schioppa, E. J.; Heller, M.; Troyano Pujadas, I.; della Volpe, D.; Favre, Y.; Montaruli, T.; Zietara, K.; Kasperek, J.; Marszalek, A.; Rajda, P.

    2016-01-01

    A prototype camera for one of the Cherenkov Telescope Array (CTA) projects for the small size telescopes, the single mirror Small Size Telescope (SST-1M), has been designed and is under construction. The camera is a hexagonal matrix of 1296 large area (95 mm2) hexagonal silicon photomultipliers. The sensors are grouped into 108 modules of 12 pixels each, hosting a preamplifier board and a slow-control board. Among its various functions, this latter implements a compensation logic that adjusts the bias voltage of each sensor as a function of temperature. The fully digital readout and trigger system, DigiCam, is based on the latest generation of FPGAs, featuring a high number of high speed I/O interfaces, allowing high data transfer rates in an extremely compact design.

  15. Electronics for the camera of the First G-APD Cherenkov Telescope (FACT) for ground based gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Anderhub, H.; Backes, M.; Biland, A.; Boller, A.; Braun, I.; Bretz, T.; Commichau, V.; Djambazov, L.; Dorner, D.; Farnier, C.; Gendotti, A.; Grimm, O.; von Gunten, H. P.; Hildebrand, D.; Horisberger, U.; Huber, B.; Kim, K.-S.; Köhne, J.-H.; Krähenbühl, T.; Krumm, B.; Lee, M.; Lenain, J.-P.; Lorenz, E.; Lustermann, W.; Lyard, E.; Mannheim, K.; Meharga, M.; Neise, D.; Nessi-Tedaldi, F.; Overkemping, A.-K.; Pauss, F.; Renker, D.; Rhode, W.; Ribordy, M.; Rohlfs, R.; Röser, U.; Stucki, J.-P.; Thaele, J.; Tibolla, O.; Viertel, G.; Vogler, P.; Walter, R.; Warda, K.; Weitzel, Q.

    2012-01-01

    Within the FACT project, we construct a new type of camera based on Geiger-mode avalanche photodiodes (G-APDs). Compared to photomultipliers, G-APDs are more robust, need a lower operation voltage and have the potential of higher photon-detection efficiency and lower cost, but were never fully tested in the harsh environments of Cherenkov telescopes. The FACT camera consists of 1440 G-APD pixels and readout channels, based on the DRS4 (Domino Ring Sampler) analog pipeline chip and commercial Ethernet components. Preamplifiers, trigger system, digitization, slow control and power converters are integrated into the camera.

  16. Simulation studies of the high-energy component of a future imaging Cherenkov telescope array

    SciTech Connect

    Funk, S.; Hinton, J. A.

    2008-12-24

    The current generation of Imaging Atmospheric telescopes (IACTs) has demonstrated the power of the technique in an energy range between {approx}100 GeV up to several tens of TeV. At the high-energy end, these instruments are limited by photon statistics. Future arrays of IACTs such as CTA or AGIS are planned to push into the energy range beyond 100 TeV. Scientifically, this region is very promising, providing a probe of particles up to the 'knee' in the cosmic ray spectrum and access to an unexplored region in the spectra of nearby extragalactic sources. We present first results from our simulation studies of the high-energy part of a future IACT array and discuss the design parameters of such an array.

  17. Astroclimatic Characterization of Vallecitos: A Candidate Site for the Cherenkov Telescope Array at San Pedro Mártir

    NASA Astrophysics Data System (ADS)

    Tovmassian, Gagik; Hernandez, Mercedes-Stephania; Ochoa, Jose Luis; Ernenwein, Jean-Pierre; Mandat, Dusan; Pech, Miroslav; Plauchu Frayn, Ilse; Colorado, Enrique; Murillo, Jose Manuel; Ceseña, Urania; Garcia, Benjamin; Lee, William H.; Bulik, Tomasz; Garczarczyk, Markus; Fruck, Christian; Costantini, Heide; Cieslar, Marek; Aune, Taylor; Vincent, Stephane; Carr, John; Serre, Natalia; Janecek, Petr; Haefner, Dennis

    2016-03-01

    We conducted an 18 month long study of the weather conditions of the Vallecitos, a proposed site in México to harbor the northern array of the Cherenkov Telescope Array (CTA). It is located in Sierra de San Pedro Mártir (SPM) a few kilometers away from Observatorio Astronómico Nacional. The study is based on data collected by the ATMOSCOPE, a multi-sensor instrument measuring the weather and sky conditions, which was commissioned and built by the CTA Consortium. Additionally, we compare the weather conditions of the optical observatory at SPM to the Vallecitos regarding temperature, humidity, and wind distributions. It appears that the excellent conditions at the optical observatory benefit from the presence of microclimate established in the Vallecitos.

  18. The ASTRI project: Prototype status and future plans for a Cherenkov dual-mirror small-telescope array

    NASA Astrophysics Data System (ADS)

    Vercellone, S.; ASTRI Collaboration

    2012-12-01

    ASTRI ("Astrofisica con Specchi a Tecnologia Replicante Italiana") is a flagship project of the Italian Ministry of Education, University and Research. Within this framework, INAF is currently developing a wide field of view (9.6° in diameter) end-to-end prototype of the CTA smallsize telescope (SST), devoted to the investigation of the energy range from a fraction of TeV up to (possibly) hundreds of TeV, and scheduled to start data acquisition in 2014. For the first time, a dualmirror Schwarzschild-Couder optical design will be adopted on a Cherenkov telescope, in order to obtain a compact (FNo. = 0.5) optical configuration. A second challenging, but innovative technical solution consists of a focal plane camera based on Silicon photo-multipliers with a logical pixel size of 0.17° (6.2mm × 6.2mm). We will describe the current status of the project, the results obtained so far, the expected performance, and its possible evolution in terms of a SST mini-array (composed of 5-7 SSTs and developed in collaboration with CTA international partners), which could peruse not only the adopted technological solutions, but also address a few scientific test cases.

  19. The control, monitor, and alarm system for the ICT equipment of the ASTRI SST-2M telescope prototype for the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Gianotti, Fulvio; Fioretti, Valentina; Tanci, Claudio; Conforti, Vito; Tacchini, Alessandro; Leto, Giuseppe; Gallozzi, Stefano; Bulgarelli, Andrea; Trifoglio, Massimo; Malaguti, Giuseppe; Zoli, Andrea

    2014-07-01

    ASTRI is an Italian flagship project whose first goal is the realization of an end-to-end telescope prototype, named ASTRI SST-2M, for the Cherenkov Telescope Array (CTA). The prototype will be installed in Italy during Fall 2014. A second goal will be the realization of the ASTRI/CTA mini-array which will be composed of seven SST-2M telescopes placed at the CTA Southern Site. The Information and Communication Technology (ICT) equipment necessary to drive the infrastructure for the ASTRI SST-2M prototype is being designed as a complete and stand-alone computer center. The design goal is to obtain basic ICT equipment that might be scaled, with a low level of redundancy, for the ASTRI/CTA mini-array, taking into account the necessary control, monitor and alarm system requirements. The ICT equipment envisaged at the Serra La Nave observing station in Italy, where the ASTRI SST-2M telescope prototype will operate, includes computers, servers and workstations, network devices, an uninterruptable power supply system, and air conditioning systems. Suitable hardware and software tools will allow the parameters related to the behavior and health of each item of equipment to be controlled and monitored. This paper presents the proposed architecture and technical solutions that integrate the ICT equipment in the framework of the Observatory Control System package of the ASTRI/CTA Mini- Array Software System, MASS, to allow their local and remote control and monitoring. An end-toend test case using an Internet Protocol thermometer is reported in detail.

  20. Cherenkov Counters

    SciTech Connect

    Barbero, Marlon

    2012-04-19

    When a charged particle passes through an optically transparent medium with a velocity greater than the phase velocity of light in that medium, it emits prompt photons, called Cherenkov radiation, at a characteristic polar angle that depends on the particle velocity. Cherenkov counters are particle detectors that make use of this radiation. Uses include prompt particle counting, the detection of fast particles, the measurement of particle masses, and the tracking or localization of events in very large, natural radiators such as the atmosphere, or natural ice fields, like those at the South Pole in Antarctica. Cherenkov counters are used in a number of different fields, including high energy and nuclear physics detectors at particle accelerators, in nuclear reactors, cosmic ray detectors, particle astrophysics detectors and neutrino astronomy, and in biomedicine for labeling certain biological molecules.

  1. The sensitivity of Cherenkov telescopes to dark matter and astrophysical anisotropies in the diffuse gamma-ray background

    SciTech Connect

    Ripken, Joachim; Cuoco, Alessandro; Conrad, Jan; Zechlin, Hannes-S.; Horns, Dieter E-mail: cuoco@fysik.su.se E-mail: conrad@fysik.su.se

    2014-01-01

    In this article, the capability of present (H.E.S.S., MAGIC, VERITAS) and planned (CTA) ground-based Cherenkov telescope systems for detecting angular anisotropies in the diffuse gamma-ray background is investigated. Following up on a study of the impact of instrumental characteristics (effective area, field of view, angular resolution, and background rejection efficiency), the first part examines the influence of different observational strategies, i.e. whether a single deep observation or a splitting over multiple shallow fields is preferred. In the second part, the sensitivity to anisotropies generated by self-annihilating dark matter is studied for different common dark matter models. We find that a relative contribution of ∼ 10% from dark matter annihilation to the extra-galactic diffuse gamma-ray background can be detected with planned configurations of CTA. In terms of the thermally-averaged self-annihilation cross section, the sensitivity of CTA corresponds to values below the thermal freeze-out expectation (σv) = 3 × 10{sup −26} cm{sup 3} s{sup −1} for dark matter particles lighter than ∼ 200 GeV. We stress the importance of constraining anisotropies from unresolved astrophysical sources with currently operating instruments already, as a novel and complementary method for investigating the properties of TeV sources.

  2. Sensitivity of the Cherenkov Telescope Array to the detection of axion-like particles at high gamma-ray opacities

    SciTech Connect

    Meyer, Manuel; Conrad, Jan E-mail: conrad@fysik.su.se

    2014-12-01

    Extensions of the Standard Model of particles commonly predict the existence of axion(-like) particles (ALPs) that could be detected through their coupling to photons in external magnetic fields. This coupling could lead to modifications of γ-ray spectra from extragalactic sources. Above a certain energy, the γ-ray flux should be exponentially damped due to the interaction with photons of background radiations fields. ALPs, on the other hand, propagate unimpeded over cosmological distances and a reconversion into γ-rays could lead to an additional component in the spectra. Here, we present the sensitivity of the proposed Cherenkov Telescope Array (CTA) to detect this spectral hardening. Using the full instrumental response functions of CTA, a combined likelihood analysis of four γ-ray sources shows that a significant detection of the ALP signal is possible for couplings g{sub aγ} ≳ 2 × 10{sup −11} GeV{sup −1} and ALP masses m{sub a} ∼< 100 neV. We discuss the dependency of these values on different model assumptions and magnetic-field scenarios and identify the best observation strategy to search for an ALP induced boost of the γ-ray flux.

  3. Time calibration with atmospheric muon tracks in the ANTARES neutrino telescope

    NASA Astrophysics Data System (ADS)

    Adrián-Martínez, S.; Albert, A.; André, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bogazzi, C.; Bormuth, R.; Bou-Cabo, M.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Chiarusi, T.; Circella, M.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Dekeyser, I.; Deschamps, A.; De Bonis, G.; Distefano, C.; Donzaud, C.; Dornic, D.; Drouhin, D.; Dumas, A.; Eberl, T.; Elsässer, D.; Enzenhöfer, A.; Fehn, K.; Felis, I.; Fermani, P.; Flaminio, V.; Folger, F.; Fusco, L. A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Gracia-Ruiz, R.; Gómez-González, J. P.; Graf, K.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Herrero, A.; Hößl, J.; Hofestädt, J.; Hugon, C.; James, C. W.; de Jong, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kooijman, P.; Kouchner, A.; Kreykenbohm, I.; Kulikovskiy, V.; Lahmann, R.; Lambard, G.; Lattuada, D.; Lefèvre, D.; Leonora, E.; Loucatos, S.; Mangano, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Martini, S.; Mathieu, A.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Neff, M.; Nezri, E.; Păvălaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Racca, C.; Riccobene, G.; Richter, R.; Roensch, K.; Rostovtsev, A.; Saldaña, M.; Samtleben, D. F. E.; Sánchez-Losa, A.; Sanguineti, M.; Sapienza, P.; Schmid, J.; Schnabel, J.; Schulte, S.; Schüssler, F.; Seitz, T.; Sieger, C.; Spurio, M.; Steijger, J. J. M.; Stolarczyk, Th.; Taiuti, M.; Tamburini, C.; Trovato, A.; Tselengidou, M.; Tönnis, C.; Turpin, D.; Vallage, B.; Vallée, C.; Van Elewyck, V.; Visser, E.; Vivolo, D.; Wagner, S.; Wilms, J.; Zornoza, J. D.; Zúñiga, J.

    2016-05-01

    The ANTARES experiment consists of an array of photomultipliers distributed along 12 lines and located deep underwater in the Mediterranean Sea. It searches for astrophysical neutrinos collecting the Cherenkov light induced by the charged particles, mainly muons, produced in neutrino interactions around the detector. Since at energies of ∼10 TeV the muon and the incident neutrino are almost collinear, it is possible to use the ANTARES detector as a neutrino telescope and identify a source of neutrinos in the sky starting from a precise reconstruction of the muon trajectory. To get this result, the arrival times of the Cherenkov photons must be accurately measured. A to perform time calibrations with the precision required to have optimal performances of the instrument is described. The reconstructed tracks of the atmospheric muons in the ANTARES detector are used to determine the relative time offsets between photomultipliers. Currently, this method is used to obtain the time calibration constants for photomultipliers on different lines at a precision level of 0.5 ns. It has also been validated for calibrating photomultipliers on the same line, using a system of LEDs and laser light devices.

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

    SciTech Connect

    James, C. W.; Protheroe, R. J.; Ekers, R. D.; Phillips, C. J.; Roberts, P.; Alvarez-Muniz, J.; Bray, J. D.; McFadden, R. A.

    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 aim 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.

  5. FRAM telescope - monitoring of atmospheric extinction and variable star photometry

    NASA Astrophysics Data System (ADS)

    Jurysek, J.; Honkova, K.; Masek, M.

    2015-02-01

    The FRAM (F/(Ph)otometric Robotic Atmospheric Monitor) telescope is a part of the Pierre Auger Observatory (PAO) located near town Malargüe in Argentina. The main task of the FRAM telescope is the continuous night - time monitoring of the atmospheric extinction and its wavelength dependence. The current methodology of the measurement of a atmospheric extinction and for instrumentation properties also allows simultaneous observation of other interesting astronomical targets. The current observations of the FRAM telescope are focused on the photometry of eclipsing binaries, positional refinement of minor bodies of the Solar system and observations of optical counterparts of gamma ray bursts. In this contribution, we briefly describe the main purpose of the FRAM telescope for the PAO and we also present its current astrono mical observing program.

  6. The first VERITAS telescope

    NASA Astrophysics Data System (ADS)

    Holder, J.; Atkins, R. W.; Badran, H. M.; Blaylock, G.; Bradbury, S. M.; Buckley, J. H.; Byrum, K. L.; Carter-Lewis, D. A.; Celik, O.; Chow, Y. C. K.; Cogan, P.; Cui, W.; Daniel, M. K.; de la Calle Perez, I.; Dowdall, C.; Dowkontt, P.; Duke, C.; Falcone, A. D.; Fegan, S. J.; Finley, J. P.; Fortin, P.; Fortson, L. F.; Gibbs, K.; Gillanders, G.; Glidewell, O. J.; Grube, J.; Gutierrez, K. J.; Gyuk, G.; Hall, J.; Hanna, D.; Hays, E.; Horan, D.; Hughes, S. B.; Humensky, T. B.; Imran, A.; Jung, I.; Kaaret, P.; Kenny, G. E.; Kieda, D.; Kildea, J.; Knapp, J.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; LeBohec, S.; Linton, E.; Little, E. K.; Maier, G.; Manseri, H.; Milovanovic, A.; Moriarty, P.; Mukherjee, R.; Ogden, P. A.; Ong, R. A.; Petry, D.; Perkins, J. S.; Pizlo, F.; Pohl, M.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Roache, E. T.; Rose, H. J.; Schroedter, M.; Sembroski, G. H.; Sleege, G.; Steele, D.; Swordy, S. P.; Syson, A.; Toner, J. A.; Valcarcel, L.; Vassiliev, V. V.; Wakely, S. P.; Weekes, T. C.; White, R. J.; Williams, D. A.; Wagner, R.

    2006-07-01

    The first atmospheric Cherenkov telescope of VERITAS (the Very Energetic Radiation Imaging Telescope Array System) has been in operation since February 2005. We present here a technical description of the instrument and a summary of its performance. The calibration methods are described, along with the results of Monte Carlo simulations of the telescope and comparisons between real and simulated data. The analysis of TeV γ-ray observations of the Crab Nebula, including the reconstructed energy spectrum, is shown to give results consistent with earlier measurements. The telescope is operating as expected and has met or exceeded all design specifications.

  7. Telescope Formation at L2 for Observing Earth's Atmosphere

    NASA Technical Reports Server (NTRS)

    Mettler, Edward; Acikmese, Behcet; Breckenridge, William; Macenka, Steven; Hein, Randall; Tubbs, Eldred

    2007-01-01

    Two documents describe a proposed Earth-atmosphere observatory to orbit the Sun at the Sun-Earth L2 Lagrange point -- a point of unstable equilibrium in the shadow of the Earth, about 1.5 million km from the Earth along an outward projection of the Earth-Sun axis. The observatory would comprise two spacecraft flying in precision formation: (1) a primary-aperture spacecraft, from which would be deployed a 25-m diameter membrane primary mirror aimed at the Earth, and (2) a secondary-telescope spacecraft at the focal plane of the primary mirror, 125-m distant along the axis towards the Earth. The secondary telescope would be aimed at the primary mirror and slowly rotated to scan the focused annular image of the visible illuminated portion of the Earth's atmosphere during continuous occultation of the Sun.

  8. Characterization of a 6×6-mm2 75-μm cell MPPC suitable for the Cherenkov Telescope Array project

    NASA Astrophysics Data System (ADS)

    Romeo, G.; Bonanno, G.; Garozzo, S.; Grillo, A.; Marano, D.; Munari, M.; Timpanaro, M. C.; Catalano, O.; Giarrusso, S.; Impiombato, D.; La Rosa, G.; Sottile, G.

    2016-08-01

    This paper presents the latest characterization results of a novel Low Cross-Talk (LCT) large-area (6×6-mm2) Multi-Pixel Photon Counter (MPPC) detector manufactured by Hamamatsu, belonging to the recent LCT5 family and achieving a fill-factor enhancement and cross-talk reduction. In addition, the newly adopted resin coating is demonstrated to yield improved photon detection capabilities in the 290-350 nm spectral range, making the new LCT MPPC particularly suitable for emerging applications like Cherenkov Telescopes. For a 3×3-mm2 version of the new MPPC under test, a comparative analysis of the large pixel pitch (75-μm) detector versus the smaller pixel pitch (50-μm) detector is also undertaken. Furthermore, measurements of the 6×6-mm2 MPPC response versus the angle of incidence are provided for the characterized device.

  9. Photomultiplier tube selection for the Wide Field of view Cherenkov/fluorescence Telescope Array of the Large High Altitude Air Shower Observatory

    NASA Astrophysics Data System (ADS)

    Ge, Maomao; Zhang, Li; Chen, Yingtao; Cao, Zhen; Zhang, Shoushan; Wang, Chong; Bi, Baiyang

    2016-05-01

    For the purpose of selecting the most suitable photomultiplier tubes (PMTs) for the Wide Field of view Cherenkov/fluorescence Telescope Array (WFCTA), we have performed extensive tests on seven models of 25.4 mm PMTs: Hamamatsu R1924A and R7899, Beijing Hamamatsu CR303, CR332A and CR364, and HZC Photonics XP3102 and XP3182. A dedicated test system has been developed to measure the PMT characteristics such as single photo-electron spectrum, gain, linearity, and spatial uniformity of anode output. The XP3182 and CR364 (R7899) tubes both meet the pivotal requirement due to their superior pulse linearity. The PMT test system, techniques used for these measurements, and their results are also reported.

  10. Upgrading and testing the 3D reconstruction of gamma-ray air showers as observed with an array of Cherenkov telescopes

    SciTech Connect

    Naumann-Godo, Melitta; Degrange, Bernard

    2008-12-24

    Stereoscopic arrays of Imaging Cherenkov Telescopes allow to reconstruct gamma-ray-induced showers in 3 dimensions. An analysis method based on a simple 3D-model of electromagnetic showers and implemented in the framework of the H.E.S.S. experiment was recently improved by an additional quality criterion which reduces the background contamination by a factor of about 2 in the case of extended sources, while hardly affecting gamma-ray selection efficiency. Moreover, the dramatic flares of PKS 2155-304 in July 2006, which provided H.E.S.S. data with an almost pure gamma-ray sample, offered the unique opportunity of a precision test of the 3D-reconstruction method as well as of the H.E.S.S. simulations used in its calibration. An agreement at a few percent level is found between data and simulations for the distributions of all 3D shower parameters.

  11. Site selection criteria for the optical atmospheric visibility monitoring telescopes

    NASA Technical Reports Server (NTRS)

    Cowles, K.

    1989-01-01

    A description of each of the criteria used to decide where to locate the Atmospheric Visibility Monitoring (AVM) telescope systems is given, along with a weighting factor for each of them. These criteria include low probability of clouds, fog, smog, haze, low scattering, low turbulence, availability of security and maintenance, and suitability of a site for a potential optical reception station. They will be used to determine which three of several sites under consideration will be used for monitoring visibility through the atmosphere as it applies to an optical ground-based receiving network as may be used in NASA space missions in decades to come.

  12. Cryogenic infrared spectrometers and telescopes for the atmosphere: new frontiers

    NASA Astrophysics Data System (ADS)

    Kullmann, Andreas; Riese, Martin; Olschewski, Friedhelm; Stroh, Fred; Grossmann, Klaus-Ulrich

    2004-11-01

    The new airborne CRyogenic Infrared Spectrometers and Telescope for the Atmosphere experiment (CRISTA-New Frontiers) succeeds the CRISTA satellite instrument operated twice during NASA space shuttle flights in November 1994 (STS 66) and August 1997 (STS 85). The first mission of the instrument will take place aboard the high altitude research aircraft M55-Geophysica in a campaign in the tropics in 2005/06. CRISTA-NF is a limb-scanning instrument measuring thermal emissions of various atmospheric trace gases (e.g. water vapor, ozone, chlorofluorocarbons), clouds and aerosols in the mid-infrared spectral region. The incoming radiation entering the optics through a Herschel telescope is analyzed by two Ebert-Fastie grating spectrometers with moderate spectral resolution and finally registered by cryogenic semiconductor-detectors. The optical system is integrated into a compact cryostat which reaches temperatures down to 10K by cooling with supercritical helium. This allows fast measurements and provides good signal-to-noise ratio. A narrow vertical field of view (200m) results in high vertical resolution which is neccessary for the analysis of small scale dynamic processes especially in the upper troposphere and lower stratosphere. This paper gives a scientific motivation, some remarks on the measurement technique and an overview of instrument design and technology.

  13. VERITAS Distant Laser Calibration and Atmospheric Monitoring

    SciTech Connect

    Hui, C. M.

    2008-12-24

    As a calibrated laser pulse propagates through the atmosphere, the intensity of the Rayleigh scattered light arriving at the VERITAS telescopes can be calculated precisely. This allows for absolute calibration of imaging atmospheric Cherenkov telescopes (IACT) to be simple and straightforward. In these proceedings, we present the comparison between laser data and simulation to estimate the light collection efficiencies of the VERITAS telescopes, and the analysis of multiple laser data sets taken in different months for atmospheric monitoring purpose.

  14. Knee of the cosmic hydrogen and helium spectrum below 1 PeV measured by ARGO-YBJ and a Cherenkov telescope of LHAASO

    NASA Astrophysics Data System (ADS)

    Bartoli, B.; Bernardini, P.; Bi, X. J.; Cao, Z.; Catalanotti, S.; Chen, S. Z.; Chen, T. L.; Cui, S. W.; Dai, B. Z.; D'Amone, A.; Danzengluobu; De Mitri, I.; D'Ettorre Piazzoli, B.; Di Girolamo, T.; Di Sciascio, G.; Feng, C. F.; Feng, Zhaoyang; Feng, Zhenyong; Guo, Q. B.; Guo, Y. Q.; He, H. H.; Hu, Haibing; Hu, Hongbo; Iacovacci, M.; Iuppa, R.; Jia, H. Y.; Labaciren; Li, H. J.; Liu, C.; Liu, J.; Liu, M. Y.; Lu, H.; Ma, L. L.; Ma, X. H.; Mancarella, G.; Mari, S. M.; Marsella, G.; Mastroianni, S.; Montini, P.; Ning, C. C.; Perrone, L.; Pistilli, P.; Salvini, P.; Santonico, R.; Shen, P. R.; Sheng, X. D.; Shi, F.; Surdo, A.; Tan, Y. H.; Vallania, P.; Vernetto, S.; Vigorito, C.; Wang, H.; Wu, C. Y.; Wu, H. R.; Xue, L.; Yang, Q. Y.; Yang, X. C.; Yao, Z. G.; Yuan, A. F.; Zha, M.; Zhang, H. M.; Zhang, L.; Zhang, X. Y.; Zhang, Y.; Zhao, J.; Zhaxiciren; Zhaxisangzhu; Zhou, X. X.; Zhu, F. R.; Zhu, Q. Q.; Bai, Y. X.; Chen, M. J.; Feng, S. H.; Gao, B.; Gu, M. H.; Hou, C.; Liu, J.; Liu, J. L.; Wang, X.; Xiao, G.; Zhang, B. K.; Zhang, S. S.; Zhou, B.; Zuo, X.; ARGO-YBJ Collaboration

    2015-11-01

    The measurement of the cosmic ray energy spectrum, in particular for individual species of nuclei, is an important tool to investigate cosmic ray production and propagation mechanisms. The determination of the "knees" in the spectra of different species remains one of the main challenges in cosmic ray physics. In fact, experimental results are still conflicting. In this paper we report a measurement of the mixed proton and helium energy spectrum, obtained with the combined data of the ARGO-YBJ experiment and a wide field of view Cherenkov telescope, a prototype of the future LHAASO experiment. By means of a multiparameter technique, we have selected a high-purity proton plus helium sample. The reconstructed energy resolution is found to be about 25% throughout the investigated energy range from 100 TeV to 3 PeV, with a systematic uncertainty in the absolute energy scale of 9.7%. The found energy spectrum can be fitted with a broken power-law function, with a break at the energy Ek =700 ±230 (stat )±70 (sys ) TeV , where the spectral index changes from -2.56 ±0.05 to -3.24 ±0.36 . The statistical significance of the observed spectral break is 4.2 standard deviations.

  15. High-frequency-peaked BL Lacertae Objects as Spectral Candles to Measure the Extragalactic Background Light in the Fermi and Air Cherenkov Telescopes Era

    NASA Astrophysics Data System (ADS)

    Mankuzhiyil, Nijil; Persic, Massimo; Tavecchio, Fabrizio

    2010-05-01

    The extragalactic background light (EBL) is the integrated light from all the stars that have ever formed, and spans the IR-UV range. The interaction of very high-energy (VHE: E > 100 GeV) γ-rays, emitted by sources located at cosmological distances, with the intervening EBL results in e - e + pair production that leads to energy-dependent attenuation of the observed VHE flux. This introduces a fundamental ambiguity into the interpretation of measured VHE γ-ray spectra: neither the intrinsic spectrum nor the EBL are separately known—only their combination is. In this Letter, we propose a method to measure the EBL photon number density. It relies on using simultaneous observations of BL Lac objects in the optical, X-ray, high-energy (HE: E > 100 MeV) γ-ray (from the Fermi telescope), and VHE γ-ray (from Cherenkov telescopes) bands. For each source, the method involves best-fitting the spectral energy distribution from optical through HE γ-rays (the latter being largely unaffected by EBL attenuation as long as z <~ 1) with a synchrotron self-Compton model. We extrapolate such best-fitting models into the VHE regime and assume they represent the BL Lacs' intrinsic emission. Contrasting measured versus intrinsic emission leads to a determination of the γγ opacity to VHE photons. Using, for each given source, different states of emission will only improve the accuracy of the proposed method. We demonstrate this method using recent simultaneous multifrequency observations of the high-frequency-peaked BL Lac object PKS 2155-304 and discuss how similar observations can more accurately probe the EBL.

  16. HIGH-FREQUENCY-PEAKED BL LACERTAE OBJECTS AS SPECTRAL CANDLES TO MEASURE THE EXTRAGALACTIC BACKGROUND LIGHT IN THE FERMI AND AIR CHERENKOV TELESCOPES ERA

    SciTech Connect

    Mankuzhiyil, Nijil; Persic, Massimo; Tavecchio, Fabrizio

    2010-05-20

    The extragalactic background light (EBL) is the integrated light from all the stars that have ever formed, and spans the IR-UV range. The interaction of very high-energy (VHE: E > 100 GeV) {gamma}-rays, emitted by sources located at cosmological distances, with the intervening EBL results in e {sup -} e {sup +} pair production that leads to energy-dependent attenuation of the observed VHE flux. This introduces a fundamental ambiguity into the interpretation of measured VHE {gamma}-ray spectra: neither the intrinsic spectrum nor the EBL are separately known-only their combination is. In this Letter, we propose a method to measure the EBL photon number density. It relies on using simultaneous observations of BL Lac objects in the optical, X-ray, high-energy (HE: E > 100 MeV) {gamma}-ray (from the Fermi telescope), and VHE {gamma}-ray (from Cherenkov telescopes) bands. For each source, the method involves best-fitting the spectral energy distribution from optical through HE {gamma}-rays (the latter being largely unaffected by EBL attenuation as long as z {approx_lt} 1) with a synchrotron self-Compton model. We extrapolate such best-fitting models into the VHE regime and assume they represent the BL Lacs' intrinsic emission. Contrasting measured versus intrinsic emission leads to a determination of the {gamma}{gamma} opacity to VHE photons. Using, for each given source, different states of emission will only improve the accuracy of the proposed method. We demonstrate this method using recent simultaneous multifrequency observations of the high-frequency-peaked BL Lac object PKS 2155-304 and discuss how similar observations can more accurately probe the EBL.

  17. Geomagnetic Field Effects on the Imaging Air Shower Cherenkov Technique

    NASA Astrophysics Data System (ADS)

    Commichau, S.C.; Biland, A.; Kranich, D.; de los Reyes, R.; Moralejo, A.; Sobczyńska, D.

    Imaging Air Cherenkov Telescopes (IACTs) detect the Cherenkov light flashes of Extended Air Showers (EAS) triggered by VHE gamma-rays impinging on the Earth's atmosphere. Due to the overwhelming background from hadron induced EAS, the discrimination of the rare gamma-like events is rather difficult, in particular at energies below 100 GeV. The influence of the Geomagnetic Field (GF) on the EAS development can further complicate this discrimination and, in addition, also systematically affect the gamma-efficiency and energy resolution of an IACT. Here we present the results from dedicated Monte Carlo (MC) simulations for the MAGIC telescope site, show the GF effects on real data as well as possible corrections for these effects.

  18. 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.

  19. Detection of Callisto's oxygen atmosphere with the Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Cunningham, Nathaniel J.; Spencer, John R.; Feldman, Paul D.; Strobel, Darrell F.; France, Kevin; Osterman, Steven N.

    2015-07-01

    We report the result of a search for evidence of an O2-dominated atmosphere on Callisto, using the high far-ultraviolet sensitivity of the Hubble Space Telescope Cosmic Origins Spectrograph (COS). Observations of Callisto's leading/Jupiter-facing hemisphere show, for the first time, variable-strength atomic oxygen (O I) emissions with brightness up to 4.7 ± 0.7 Rayleighs for the O I 1304 Å triplet and 1.9 ± 0.4 Rayleighs for the O I 1356 Å doublet, averaged over the 2.5 arcsec. diameter COS aperture. Because the observations were made in Earth's shadow, and are brighter than expected emission from nighttime geocoronal airglow or other plausible sources, we are confident that they originate from Callisto or its immediate vicinity. In addition, COS's limited (∼1 arcsec) spatial resolution implies a 2σ detection of excess 1356 Å emission concentrated on the disk of Callisto itself, with brightness 3.2 ± 1.6 Rayleighs. The (O I 1356 Å)/(O I 1304 Å) emission ratio from Callisto's disk favors dissociative excitation of O2, suggesting that O2 is the dominant atmospheric component rather than other possible oxygen-bearing alternatives. Photoelectrons, rather than magnetospheric electrons, are the most likely source of the dissociative excitation. This detection yields an O2 column density of ∼4 × 1015 cm-2 on the leading/Jupiter facing hemisphere, which implies that Callisto's atmosphere is collisional and is the fourth-densest satellite atmosphere in the Solar System, in addition to being the second-densest O2-rich collisional atmosphere in the Solar System, after Earth. Longitudinal variations in published densities of ionospheric electrons suggest that O2 densities in Callisto's trailing hemisphere, which we did not observe, may be an order of magnitude greater. The aperture-filling emissions imply that there is also an extended corona of predominantly O I 1304 Å emission around Callisto, with observed strength of 1-4 Rayleighs, likely due to solar

  20. Deep Water Cherenkov Light Scatter Meter

    SciTech Connect

    Pappalardo, L; Petta, C.; Russo, G.V.

    2000-12-31

    The relevant parameters for the site choice of an underwater neutrino's telescope are discussed. The in situ measurement of the scattering distribution of the cherenkov light requires a suitable experimental setup. Its main features are described here.

  1. Hot Jupiter atmospheres with the Spitzer Space Telescope

    NASA Astrophysics Data System (ADS)

    Todorov, Kamen O.

    I analyze Spitzer Space Telescope observations of seven transiting hot Jupiters during the time of secondary eclipse, the portion of the planet's orbit when it is behind the star from the point of view of a Solar System observer. For six of them, HAT-P-3b, HAT-P-4b, HAT-P-6b, HAT-P-8b, HAT-P-12b and XO-4b, I analyze broadband photometric light curves at 3.6 and 4.5 microm. I compare the resulting eclipse depths, which are a measure of the planets' dayside emission, to model emergent spectra by Burrows et al. and Fortney et al. The atmosphere of XO-4b has a strong temperature inversion, HAT-P-6b has weak or no temperature inversion, HAT-P-8 has a non-inverted atmosphere. The models are inconclusive about the temperature structure of the atmospheres of HAT-P-3b and HAT-P-4b. I find that HAT-P-3b, HAT-P-4b and HAT-P-8b have relatively inefficient heat transport from their day sides to their night sides. The models suggest moderate to low heat transport for XO-4b and HAT-P-6b. I discuss the physical implications of my results in the context of theoretical and empirical hypotheses on correlations related to the temperature-pressure structures of the atmospheres and the efficiency of energy transfer to the night side of the planet. In particular, I focus on the idea by Knutson et al. that planets with chromospherically active host stars may in general not have a stratosphere-like temperature inversions, while a quiet host star may lead to an inverted atmosphere. Another hypothesis I examine is that by Cowan and Agol and Perna et al. who suggest that the hottest planets have a narrow range of permitted heat redistribution efficiencies and, thus, high day-night contrasts. The seventh object I study is HD 189733b. I examine the time series spectroscopy during 18 eclipses between wavelengths of 5 and 14 microm. This is the most extensive data set observed for the emission spectrum of any exoplanet to date. Some of these data sets have been analyzed in the past by Grillmair

  2. Study of atmospheric muons using a cosmic ray telescope

    NASA Astrophysics Data System (ADS)

    Abdollahi, S.; Bahmanabadi, M.; Purmohammad, D.

    2013-02-01

    The charge ratio of cosmic muons holds important information for both the atmospheric neutrino anomaly and hadronic interaction models. In this paper we measured the muon charge ratio (R_{\\mu }=N_{\\mu ^{+}}/N_{\\mu ^{-}}) in the cosmic ray flux in the momenta range 0.76-1.60 GeV/c by using a cosmic ray telescope. The delayed coincidence method is used based on the reduced mean lifetime of negative muons due to nuclear capture in matter. The systematic time-dependent effects of the muon charge ratio are considered by grouping the decay data into different time intervals. We compared the experimental data with the predictions of CORSIKA simulations using a high energy interaction model (QGSJET-II) and two low energy interaction models (UrQMD and GHEISHA) in the energy range 1011-1016 eV for primary particles. In addition, by considering the muon flux in different zenithal and azimuthal angles, the muon angular distribution is obtained as I(θ) = I(0)cos nθ with average n = 1.91 ± 0.07. Dependence of the muon flux on the azimuth angle (the East-West effect) is also observed, due to the influence of the geomagnetic field in particular on low energy muons.

  3. Detection and initial characterisation of an exoplanet atmosphere with small aperture telescopes

    NASA Astrophysics Data System (ADS)

    Bernt, I.; Müller, M.; Strassmeier, K. G.; Granzer, T.

    2013-09-01

    In the recent years atmospheres of exoplanets have been studied with space-based telescopes like the HST or large aperture ground-based telescopes like the Gran Telescopio Canarias. But as the number of suitable exoplanets is rising, comparative studies of atmospheres with a statistically meaningful amount of targets will follow, for which the observational time with large telescopes is limited and expensive. Our aim is to investigate whether it is possible to detect and initially characterise the atmosphere of an exoplanet with small aperture telescopes using chromatic variations in transit depths. We collected multi-color transits in the years 2011 to 2013 using the robotic 1.2m-telescope STELLA on Tenerife as well as the Nordic Optical Telescope and the 70cm-telescope at the Leibniz Institute for Astrophysics Potsdam. The highly inflated Hot Jupiter HAT-P-32 b was chosen as target for our pilot study for its favorable large atmospheric scale height and therefore enhanced atmospheric detectability. Models of the atmospheric spectra of HAT-P-32 b indicate that the STELLA-data can be used to distinguish between a dusty and a cloud-free atmosphere using the gradient in transit depth of the observations in the blue band and in the visible band. Here we want to present our project together with the first results of the transit depth analysis.

  4. Scintillation correction for astronomical photometry on large and extremely large telescopes with tomographic atmospheric reconstruction

    NASA Astrophysics Data System (ADS)

    Osborn, J.

    2015-01-01

    We describe a new concept to correct for scintillation noise on high-precision photometry in large and extremely large telescopes using telemetry data from adaptive optics (AO) systems. Most wide-field AO systems designed for the current era of very large telescopes and the next generation of extremely large telescopes require several guide stars to probe the turbulent atmosphere in the volume above the telescope. These data can be used to tomographically reconstruct the atmospheric turbulence profile and phase aberrations of the wavefront in order to assist wide-field AO correction. If the wavefront aberrations and altitude of the atmospheric turbulent layers are known from this tomographic model, then the effect of the scintillation can be calculated numerically and used to normalize the photometric light curve. We show through detailed Monte Carlo simulation that for an 8 m telescope with a 16 × 16 AO system we can reduce the scintillation noise by an order of magnitude.

  5. Use of a moiré deflectometer on a telescope for atmospheric turbulence measurements.

    PubMed

    Rasouli, Saifollah

    2010-05-01

    An instrument has been built for the study of the atmospheric turbulence by measuring the fluctuation of the angle of arrival across a telescope aperture using moiré deflectometry. A slightly divergent laser beam passes through a turbulent ground level atmosphere and enters the telescope aperture. The laser beam is recollimated behind the telescope's focal point by means of a collimator. The collimated beam passes through a moiré deflectometer. The fluctuating self-image of the first grating is formed on the second grating of the moiré deflectometer and fluctuating moiré fringes are formed. Using moiré fringe fluctuations we have calculated the fluctuations of the angle of arrival, the Fried's parameter r(0), and the atmospheric refractive index structure constant. Because of the magnifications of the telescope and moiré deflectometry, the precision of the technique can potentially be 1 order of magnitude more precise than previous methods. PMID:20436606

  6. The achromatic design of an atmospheric dispersion corrector for extremely large telescopes.

    PubMed

    Bahrami, Mehdi; Goncharov, Alexander V

    2011-08-29

    For off-zenith observations with ground-based astronomical telescopes, the effect of atmospheric dispersion relative to diffraction on image size increases with telescope diameter. Correction of atmospheric dispersion in extremely large telescopes (ELTs) might become critical. A common solution for ELTs is to use linear atmospheric dispersion correctors (ADCs). In spite of their simplicity, the intrinsic chromatic aberrations of linear ADCs could render diffraction-limited imaging impossible when used in a fast focus. The chromatic problems of the linear ADC in ELTs can be resolved by replacing the linear ADC by the achromatic ADC designs presented here, which provide diffraction-limited image quality and offer several opto-mechanical advantages over linear ADCs. PMID:21935071

  7. Hubble Space Telescope Space Telescope Imaging Spectrograph Search for an Atmosphere on Callisto: A Jovian Unipolar Inductor

    NASA Astrophysics Data System (ADS)

    Strobel, Darrell F.; Saur, Joachim; Feldman, Paul D.; McGrath, Melissa A.

    2002-12-01

    Hubble Space Telescope observations of Callisto with the Space Telescope Imaging Spectrograph were performed at both eastern and western elongations to search for the UV emissions diagnostic of the presence of O2, CO2, and/or CO atmospheres. We report upper limits of 5×10-5 photons cm-2 s-1 or 15 R for a uniform disk the diameter of Callisto on emissions of O I λ1304, O I λ1356, C I λ1561, C II λ1335, and CO fourth positive bands. These upper limits yield upper bounds on O2, CO2, and CO atmospheres far in excess of the detected CO2 atmosphere by R. W. Carlson. Our results are interpreted in terms of a strong electrodynamic interaction with the Jovian magnetosphere, which drives ~1.5×105 A through Callisto's highly conducting (~104 mho) ionosphere and generates a highly reduced ionospheric electric field, severely retarded ionospheric convection (~0.1 km s-1), and a factor of ~1500 reduction in the net electron impact emission rate. Callisto's highly conducting ionosphere renders it the most tenable unipolar inductor of the Galilean satellites.

  8. Modelling atmospheric turbulence effects on ground-based telescope systems

    SciTech Connect

    Bradford, L.W.; Flatte, S.M.; Max, C.E.

    1993-09-30

    Questions still exist concerning the appropriate model for turbulence- induced phase fluctuations seen in ground-based telescopes. Bester et al. used a particular observable (slope of the Allan variance) with an infrared interferometer in an attempt to distinguish models. The authors have calculated that observable for Kolmogorov and {open_quotes}random walk{close_quotes} models with a variety of outer scales and altitude-dependent turbulence and wind velocity. The authors have found that clear distinction between models requires good data on the vertical distribution of wind and turbulence. Furthermore, measurements at time separations of order 60 s are necessary to distinguish the {open_quotes}random walk{close_quotes} model from the Kolmogorov model.

  9. Modeling atmospheric turbulence effects on ground-based telescope systems

    SciTech Connect

    Flatte, S.M.; Bradford, L.W.; Max, C.E.

    1994-12-31

    Bester et al. report measurements of atmospheric fluctuations made with the Infrared Spatial Interferometer, which indicated behavior not in accord with the standard Kolmogorov model with only a single constant wind velocity. The numerical simulations use relatively complex models of the atmosphere to investigate both Kolmogorov and non-Kolmogorov models. The authors find that the measurements of Bester et al. for light passing through the upper atmosphere are within the limits of behavior for Kolmogorov models, but often only if the outer scale of turbulent fluctuations is between 15 to 100 meters. The possibility that the measured behavior might be non-Kolmogorov is not excluded. They also examine measurements made along short paths in the surface boundary layer, where some measurements of Bester et al. showed variations in the atmospheric fluctuations with seeing conditions which appeared to be non-Kolmogorov. These variations can perhaps be explained by standard models, but require that seeing improve with increasing wind speed in the surface layer. They discuss some other measurements which lend some support to that idea. However, they cannot exclude non-Kolmogorov behavior. They find that meteorological data is needed concurrent with astronomical observations, to help constrain the models. The size of the outer scale, the wind velocity profile and the turbulence spectrum are important to the ultimate capabilities of interferometers and other systems with adaptive optics.

  10. New optics for resolution improving of Ring Imaging Cherenkov detectors

    NASA Astrophysics Data System (ADS)

    Šulc, M.; Kramer, D.; Polak, J.; Steiger, L.; Finger, M.; Slunecka, M.

    2013-04-01

    The Ring Imaging Cherenkov detector (RICH) of the COMPASS experiment at CERN is key tool for particle identification. Two reflecting spherical mirror surfaces, covering a total area of about 21 m2 hosted in the radiator vessel, provide Cherenkov radiation focusing to photon detectors. These ones are based on the use of multi-anode photo-multiplier tubes. They are coupled to individual lens telescopes, made from special fused silica aspherical lenses. Design, construction, and Hartmann test of lenses qualities and alignment were described. The RICH detector uses C4F10 as radiator gas. The refractive index of the radiator gas is substantial parameter. It varies with temperature, atmospheric pressure and gas purity. Its accurate knowledge is essential for the particle identification performance. A modified Jamin's interferometer was proposed, constructed and tested to allow on-line refractive index measurement with accuracy better than 10-6 The new types of fused silica Cherenkov radiators was designed to the tests of electron multiplier detector too.

  11. The major upgrade of the MAGIC telescopes, Part I: The hardware improvements and the commissioning of the system

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Bangale, P.; Barceló, M.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Bitossi, M.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Cecchi, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Corti, D.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; DeAngelis, A.; De Caneva, G.; De Lotto, B.; de Oña Wilhelmi, E.; Delgado Mendez, C.; Dettlaff, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher, D.; Elsaesser, D.; Fidalgo, D.; Fink, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giavitto, G.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Haberer, W.; Hadasch, D.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hildebrand, D.; Hose, J.; Hrupec, D.; Idec, W.; Illa, J. M.; Kadenius, V.; Kellermann, H.; Knoetig, M. L.; Kodani, K.; Konno, Y.; Krause, J.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lemus, J. L.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; López-Oramas, A.; Lorca, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Negrello, M.; Neustroev, V.; Niedzwiecki, A.; Nilsson, K.; Nishijima, K.; Noda, K.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Rügamer, S.; Saito, T.; Saito, K.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schlammer, J.; Schmidl, S.; Schweizer, T.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Stamerra, A.; Steinbring, T.; Storz, J.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Tejedor, L. A.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Vogler, P.; Wetteskind, H.; Will, M.; Zanin, R.

    2016-01-01

    The MAGIC telescopes are two Imaging Atmospheric Cherenkov Telescopes (IACTs) located on the Canary island of La Palma. The telescopes are designed to measure Cherenkov light from air showers initiated by gamma rays in the energy regime from around 50 GeV to more than 50 TeV. The two telescopes were built in 2004 and 2009, respectively, with different cameras, triggers and readout systems. In the years 2011-2012 the MAGIC collaboration undertook a major upgrade to make the stereoscopic system uniform, improving its overall performance and easing its maintenance. In particular, the camera, the receivers and the trigger of the first telescope were replaced and the readout of the two telescopes was upgraded. This paper (Part I) describes the details of the upgrade as well as the basic performance parameters of MAGIC such as raw data treatment, linearity in the electronic chain and sources of noise. In Part II, we describe the physics performance of the upgraded system.

  12. Future water Cherenkov detectors

    SciTech Connect

    Bergevin, Marc

    2015-05-15

    In these proceedings a review of the current proposed large-scale Warer Cherenkov experiments is given. An argument is made that future water Cherenkov detectors would benefit in the investment in neutron detection technology. A brief overview will be given of proposed water Cherenkov experiments such as HYPER-K and MEMPHYS and other R and D experiments to demonstrate neutron capture in water Cherenkov detectors. Finally, innovation developed in the context of the now defunct LBNE Water R and D option to improve Water Cherenkov technology will be described.

  13. 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.

  14. Cosmic-Ray Accelerators in Milky Way studied with the Fermi Gamma-ray Space Telescope

    SciTech Connect

    Kamae, Tuneyoshi; /SLAC /KIPAC, Menlo Park

    2012-05-04

    High-energy gamma-ray astrophysics is now situated at a confluence of particle physics, plasma physics and traditional astrophysics. Fermi Gamma-ray Space Telescope (FGST) and upgraded Imaging Atmospheric Cherenkov Telescopes (IACTs) have been invigorating this interdisciplinary area of research. Among many new developments, I focus on two types of cosmic accelerators in the Milky-Way galaxy (pulsar, pulsar wind nebula, and supernova remnants) and explain discoveries related to cosmic-ray acceleration.

  15. Characterization of exoplanet atmospheres using future space-based infrared telescopes: challenges in detecting biomarkers

    NASA Astrophysics Data System (ADS)

    Enya, Keigo

    2014-01-01

    Characterization of exoplanet atmospheres with space-based infrared telescopes is important to detect biomarkers. A promising method is temporary differential observation. For this method, designs of a wideband infrared spectral disperser are presented. A design using a CdTe prism simultaneously covers λ=1-30 μm. Designing binary pupil masks for segmented pupils to be used in spatially resolved observations are also shown for another observational method.

  16. Characterizing exoplanet atmospheres with the 10.4m GTC telescope: New results from the world’s largest optical telescope

    NASA Astrophysics Data System (ADS)

    Wilson, Paul Anthony; Evans, Tom; Sing, David Kent; Nikolov, Nikolay; Lecavelier des Etangs, Alain; Colón, Knicole

    2015-12-01

    Exoplanet transit spectroscopy of hot Jupiters has given us the first detailed glimpses of the complex physical characteristics that govern these objects. These highly irradiated planets with their extended atmospheres lend themselves as excellent targets for probing their compositions, temperature-pressure profiles and the vertical abundance distributions.We have explored the atmospheres of several hot Jupiters using the 10.4m GTC telescope together with unique tunable filters capable of precision narrowband photometry at specific wavelengths. Using the worlds largest optical telescope we have been able to detect and characterise specific atmospheric features at higher resolutions than can be obtained with the Hubble Space Telescope. This is important as atmospheric signatures could be missed if the resolution is not sufficiently high.In this talk I will present a summary of the exoplanet atmospheres characterised with the GTC telescope. I will also present new results obtained by combining Kepler and GTC data to study the low-albedo atmosphere of TrES-2b.

  17. Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) data processing and atmospheric temperature and trace gas retrieval

    NASA Astrophysics Data System (ADS)

    Riese, M.; Spang, R.; Preusse, P.; Ern, M.; Jarisch, M.; Offermann, D.; Grossmann, K. U.

    1999-07-01

    The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment aboard the Shuttle Pallet Satellite (SPAS) was successfully flown in early November 1994 (STS 66) and in August 1997 (STS 85). This paper focuses on the first flight of the instrument, which was part of the Atmospheric Laboratory for Application and Science 3 (ATLAS 3) mission of NASA. During a free flying period of 7 days, limb scan measurements of atmospheric infrared emissions were performed in the 4 to 71 μm wavelength region. For improved horizontal resolution, three telescopes (viewing directions) were used that sensed the atmosphere simultaneously. Atmospheric pressures, temperatures, and volume mixing ratios of various trace gases were retrieved from the radiance data by using a fast onion-peeling retrieval technique. This paper gives an overview of the data system including the raw data processing and the temperature and trace gas profile retrieval. Examples of version 1 limb radiance data (level 1 product) and version 1 mixing ratios (level 2 product) of ozone, ClONO2, and CFC-11 are given. A number of important atmospheric transport processes can already be identified in the level 1 limb radiance data. Radiance data of the lower stratosphere (18 km) indicate strong upwelling in some equatorial regions, centered around the Amazon, Congo, and Indonesia. Respective data at the date line are consistent with convection patterns associated with El Niño. Very low CFC-11 mixing ratios occur inside the South Polar vortex and cause low radiance values in a spectral region sensitive to CFC-11 emissions. These low values are a result of considerable downward transport of CFC-11 poor air that occurred during the winter months. Limb radiance profiles and retrieved mixing ratio profiles of CFC-11 indicate downward transport over ˜5 km. The accuracy of the retrieved version 1 mixing ratios is rather different for the various trace gases. In the middle atmosphere the estimated

  18. A Balloon-Borne Telescope System for Planetary Atmosphere and Plasma Studies

    NASA Astrophysics Data System (ADS)

    Taguchi, M.; Yoshida, K.; Sakamoto, Y.; Kanazawa, T.; Shoji, Y.; Sawakami, T.; Takahashi, Y.; Hoshino, N.; Sato, T.; Sakanoi, T.

    2007-12-01

    A telescope floating in the polar stratosphere can continuously monitor planets for more than 24 hours. Thin, clear and stable air of the stratosphere makes it possible to observe planets in a condition free from cloud with fine seeing and high atmospheric transmittance. Moreover, a balloon-borne telescope system is less expensive compared with a huge terrestrial telescope or a direct planetary probe mission. Targets of a balloon-borne telescope system will extend over various atmospheric and plasma phenomena on almost all the planets, i.e., a sodium tail of Mercury, lightning, airglow and aurora in the atmospheres of Venus, Jupiter and Saturn, escaping atmospheres of the Earth-type planets, satellite-induced luminous events in the Jovian atmosphere, etc. The first target is global dynamics of the Venusian atmosphere by detecting cloud motion in UV and NIR imagery. A decoupling mechanism and a pair of control moment gyros (CMGs) are mounted at the top of the gondola. The decoupling mechanism isolates the gondola from a balloon and also transfers an excess angular momentum of the CMGs to the balloon. The attitude of the gondola is stabilized at a constant sun azimuthal angle so that a solar cell panel faces to the sun. A 300 mm F30 Schmidt-Cassegrain telescope is installed at the bottom of the gondola. DC/DC converters, a PC, a high voltage power supply for a piezo-electrically moving mirror and digital video recorders are contained in a sealed cell. The azimuthal angle is detected by a sun-sensor. A PC processes sensor output to control DC motors used in the decoupling mechanism and CMGs with an accuracy in azimuthal attitude of about 0.5 deg. The two-axis gimbal mount of the telescope is controlled by the same PC, guiding an object within a field-of-view of a guide telescope. Residual tracking error is detected by a position sensitive photomultiplier tube and corrected by the two-axis moving mirror installed in the optical system. The optical path is divided into

  19. Revealing the Complex Dynamics of the Atmospheres of Red Supergiants with the Very Large Telescope Interferometer

    NASA Astrophysics Data System (ADS)

    Ohnaka, K.; Weigelt, G.; Hofmann, K.-H.; Schertl, D.

    2015-12-01

    Massive stars lose a significant fraction of their initial mass when they evolve to red supergiants before they end their life in supernova explosions. The mass loss greatly affects their final fate. However, the mass loss from these dying supergiants is not yet understood well. Here we present our efforts to spatially resolve the dynamics of the atmospheres of red supergiants with the Very Large Telescope Interferometer (VLTI) and the AMBER instrument to clarify the physical mechanism behind the mass loss. The VLTI/AMBER's combination of milliarcsecond spatial resolution and high spectral resolution allows us to spatially resolve stellar atmospheres and extract the dynamical information at each position over the star and the atmosphere — just like observations of the Sun.

  20. Total absorption Cherenkov spectrometers

    NASA Astrophysics Data System (ADS)

    Malinovski, E. I.

    2015-05-01

    A short review of 50 years of work done with Cherenkov detectors in laboratories at the Lebedev Physical Institute is presented. The report considers some issues concerning the use of Cherenkov total absorption counters based on lead glass and heavy crystals in accelerator experiments.

  1. Measurement of the Muon Atmospheric Production Depth with the Water Cherenkov Detectors of the Pierre Auger Observatory

    SciTech Connect

    Molina Bueno, Laura

    2015-09-01

    Ultra-high-energy cosmic rays (UHECR) are particles of uncertain origin and composition, with energies above 1 EeV (1018 eV or 0.16 J). The measured flux of UHECR is a steeply decreasing function of energy. The largest and most sensitive apparatus built to date to record and study cosmic ray Extensive Air Showers (EAS) is the Pierre Auger Observatory. The Pierre Auger Observatory has produced the largest and finest amount of data ever collected for UHECR. A broad physics program is being carried out covering all relevant topics of the field. Among them, one of the most interesting is the problem related to the estimation of the mass composition of cosmic rays in this energy range. Currently the best measurements of mass are those obtained by studying the longitudinal development of the electromagnetic part of the EAS with the Fluorescence Detector. However, the collected statistics is small, specially at energies above several tens of EeV. Although less precise, the volume of data gathered with the Surface Detector is nearly a factor ten larger than the fluorescence data. So new ways to study composition with data collected at the ground are under investigation. The subject of this thesis follows one of those new lines of research. Using preferentially the time information associated with the muons that reach the ground, we try to build observables related to the composition of the primaries that initiated the EAS. A simple phenomenological model relates the arrival times with the depths in the atmosphere where muons are produced. The experimental confirmation that the distributions of muon production depths (MPD) correlate with the mass of the primary particle has opened the way to a variety of studies, of which this thesis is a continuation, with the aim of enlarging and improving its range of applicability. We revisit the phenomenological model which is at the root of the analysis and discuss a new way to improve some aspects of the model. We carry

  2. New method for atmospheric calibration at the Pierre Auger Observatory using FRAM, a robotic astronomical telescope

    NASA Astrophysics Data System (ADS)

    Trávníček, Petr; Benzvi, Segev; Boháčová, Martina; Connolly, Brian; Grygar, Jiří; Hrabovský, Miroslav; Kárová, Tatiana; Mandát, Dušan; Nečesal, Petr; Nosek, Dalibor; Nožka, Libor; Palatka, Miroslav; sPech, Miroslav; Prouza, Michael; Řídký, Jan; Schovánek, Petr; Šmída, Radomír; Vitale, Primo; Westerhoff, Stefan

    FRAM - F/(Ph)otometric Robotic Atmospheric Monitor is the latest addition to the atmospheric monitoring instruments of the Pierre Auger Observatory. An optical telescope equipped with CCD camera and photometer, it automatically observes a set of selected standard stars and a calibrated terrestrial source. Primarily, the wavelength dependence of the attenuation is derived and the comparison between its vertical values (for stars) and horizontal values (for the terrestrial source) is made. Further, the integral vertical aerosol optical depth can be obtained. A secondary program of the instrument, the detection of optical counterparts of gamma-ray bursts, has already proven successful. The hardware setup, software system, data taking procedures, and first analysis results are described in this paper.

  3. Stray light analysis of CRISTA - The Cryogenic Infrared Spectrometer and Telescope of the Atmosphere

    NASA Astrophysics Data System (ADS)

    Breault, Robert P.; Barthol, Peter

    1990-12-01

    The CRISTA experiment is designed to detect and analyze short term upper atmospheric waves and turbulence of the middle atmosphere. This paper presents two of the more intriguing stray light characteristics of the CRISTA instrument as revealed through a much more extensive stray light analysis. The two topics are the diffraction propagation from a series of edges, and the thermal loading characteristics of the outer baffles by the earth's radiation. The interesting parameters that play very complex roles relative to each other are: CRISTA's three different telescopes peer through a common aperture; the Center Telescope has an image plane shared by two spectrometers offset above or below the axis by 0.358 deg; the point source angles walk away from one slit but across the other; the wavelength bands vary from 4 microns to 70 microns; all of the imaging mirrors are simple spherical surfaces; the major source of stray light is the earth, which is only .5 deg from the optical axis; and the intermediate field stop is oversized.

  4. STARCaL: A Tunable Laser in Space for Telescope Calibration and Atmospheric Studies

    NASA Astrophysics Data System (ADS)

    Albert, Justin; Burgett, W.; Deustua, S.

    2006-12-01

    We propose a tunable laser-based satellite-mounted spectrophotometric and absolute flux calibration system, to be utilized by groundand space-based telescopes. As uncertainties on the photometry, due to imperfect knowledge of both telescope optics and the atmosphere, will in the near future begin to dominate the uncertainties on fundamental cosmological parameters such as ΩΛ (Omega_Lambda) and w in measurements from SNIa, weak gravitational lensing, and baryon oscillations, a method for reducing such uncertainties is needed. We propose to improve spectrophotometric calibration, currently obtained using standard stars, by placing a tunable laser and a wide-angle light source on a satellite by early next decade (perhaps included in the upgrade to the GPS satellite network) to improve absolute flux calibration to the 0.02% level and relative spectrophotometric calibration to better than 0.001% across the visible and near-infrared spectrum. As well as fundamental astrophysical applications, the system proposed here potentially has broad utility for atmospheric physics, as well as for defense and national security applications such as ground target illumination, space situational awareness, and space communication. For further details please see http://www.starcal.org/ and http://www.arxiv.org/abs/astro-ph/0604339.

  5. The Innsbruck/ESO sky models and telluric correction tools. The possibility of atmospheric monitoring for Čerenkov telescopes

    NASA Astrophysics Data System (ADS)

    Kimeswenger, S.; Kausch, W.; Noll, S.; Jones, A. M.

    2015-03-01

    Ground-based astronomical observations are influenced by scattering and absorption by molecules and aerosols in the Earth's atmosphere. They are additionally affected by background emission from scattered moonlight, zodiacal light, scattered starlight, the atmosphere, and the telescope. These influences vary with environmental parameters like temperature, humidity, and chemical composition. Nowadays, this is corrected during data processing, mainly using semi-empirical methods and calibration by known sources. Part of the Austrian ESO in-kind contribution was a new model of the sky background, which is more complete and comprehensive than previous models. While the ground based astronomical observatories just have to correct for the line-of-sight integral of these effects, the Čerenkov telescopes use the atmosphere as the primary detector. The measured radiation originates at lower altitudes and does not pass through the entire atmosphere. Thus, a decent knowledge of the profile of the atmosphere at any time is required. The latter cannot be achieved by photometric measurements of stellar sources. We show here the capabilities of our sky background model and data reduction tools for ground-based optical/infrared telescopes. Furthermore, we discuss the feasibility of monitoring the atmosphere above any observing site, and thus, the possible application of the method for Čerenkov telescopes. Based on ESO archival data and observations obtained in programme ID 491.L-0659 at ESO VLT.

  6. CHARACTERIZING THE ATMOSPHERES OF TRANSITING PLANETS WITH A DEDICATED SPACE TELESCOPE

    SciTech Connect

    Tessenyi, M.; Tinetti, G.; Swinyard, B.; Aylward, A.; Tennyson, J.; Ollivier, M.; Beaulieu, J. P.; Coude du Foresto, V.; Encrenaz, T.; Micela, G.; Ribas, I.; Swain, M. R.; Vasisht, G.; Deroo, P.; Sozzetti, A.

    2012-02-10

    Exoplanetary science is one of the fastest evolving fields of today's astronomical research, continuously yielding unexpected and surprising results. Ground-based planet-hunting surveys, together with dedicated space missions such as Kepler and CoRoT, are delivering an ever-increasing number of exoplanets, over 690, and ESA's Gaia mission will escalate the exoplanetary census into the several thousands. The next logical step is the characterization of these new worlds. What is their nature? Why are they as they are? Use of the Hubble Space Telescope and Spitzer Space Telescope to probe the atmospheres of transiting hot, gaseous exoplanets has opened perspectives unimaginable even just 10 years ago, demonstrating that it is indeed possible with current technology to address the ambitious goal of characterizing the atmospheres of these alien worlds. However, these successful measurements have also shown the difficulty of understanding the physics and chemistry of these exotic environments when having to rely on a limited number of observations performed on a handful of objects. To progress substantially in this field, a dedicated facility for exoplanet characterization, able to observe a statistically significant number of planets over time and a broad spectral range will be essential. Additionally, the instrument design (e.g., detector performances, photometric stability) will be tailored to optimize the extraction of the astrophysical signal. In this paper, we analyze the performance and tradeoffs of a 1.2/1.4 m space telescope for exoplanet transit spectroscopy from the visible to the mid-IR. We present the signal-to-noise ratio as a function of integration time and stellar magnitude/spectral type for the acquisition of spectra of planetary atmospheres for a variety of scenarios: hot, warm, and temperate planets orbiting stars ranging in spectral type from hot F- to cooler M-dwarfs. Our results include key examples of known planets (e.g., HD 189733b, GJ 436b, GJ

  7. Fractal iterative method for fast atmospheric tomography on extremely large telescopes

    NASA Astrophysics Data System (ADS)

    Tallon, Michel; Tallon-Bosc, Isabelle; Béchet, Clémentine; Momey, Fabien; Fradin, Marie; Thiébaut, Éric

    2010-07-01

    A challenge of adaptive optics (AO) on Extremely Large Telescopes (ELTs) is to overcome the difficulty of solving a huge number of equations in real time, especially when atmospheric tomography is involved. This is particularly the case for multi-conjugate or multi-objects AO systems. In addition, the quality of the wavefront estimation is crucial to optimize the performances of the future systems in a situation where measurements are missing and noises are correlated. The Fractal Iterative Method has been introduced as a fast iterative algorithm for minimum variance wavefront reconstruction and control on ELTs. This method has been successfully tested on Classical Single Conjugate AO systems on Octopus numerical simulator at ESO. But the minimum variance approach is expected to be mostly useful with atmospheric tomography. We present the first results obtained with FrIM in the context of atmospheric tomography. We recall the principle of the algorithm and we summarize the formalism used for modeling the measurements obtained from laser guide stars that entail spot elongation and tip/tilt indetermination, mixed with low order measurements from natural guide stars. We show the respective effects of tip/tilt indetermination, spot elongation, unseen modes on various configurations, as well as the usefulness of priors and correct noise models in the reconstruction. This analysis is essential for balancing the various errors that combine in a quite complex way and to optimize the configuration of the future AO systems for specific science cases and instrument requirements.

  8. Large Binocular Telescope view of the atmosphere of GJ1214b

    NASA Astrophysics Data System (ADS)

    Nascimbeni, V.; Mallonn, M.; Scandariato, G.; Pagano, I.; Piotto, G.; Micela, G.; Messina, S.; Leto, G.; Strassmeier, K. G.; Bisogni, S.; Speziali, R.

    2015-07-01

    The atmospheric composition and vertical structure of the super-Earth GJ1214b has been a subject of debate since its discovery in 2009. Recent studies have indicated that high-altitude clouds might mask the lower layers. However, some data points that were gathered at different times and facilities do not fit this picture, probably because of a combination of stellar activity and systematic errors. We observed two transits of GJ1214b with the Large Binocular Camera, the dual-channel camera at the Large Binocular Telescope. For the first time, we simultaneously measured the relative planetary radius k = Rp/R⋆ at blue and red optical wavelengths (B + R), thus constraining the Rayleigh scattering on GJ1214b after correcting for stellar activity effects. To the same purpose, a long-term photometric follow-up of the host star was carried out with WiFSIP at STELLA, revealing a rotational period that is significantly longer than previously reported. Our new unbiased estimates of k yield a flat transmission spectrum extending to shorter wavelengths, thus confirming the cloudy atmosphere scenario for GJ1214b. Based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota and University of Virginia. Partly based on STELLA WiFSIP data (Strassmeier et al. 2004).The data of the light curves are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/579/A113

  9. VERITAS: the Very Energetic Radiation Imaging Telescope Array System

    NASA Astrophysics Data System (ADS)

    Weekes, T. C.; Badran, H.; Biller, S. D.; Bond, I.; Bradbury, S.; Buckley, J.; Carter-Lewis, D.; Catanese, M.; Criswell, S.; Cui, W.; Dowkontt, P.; Duke, C.; Fegan, D. J.; Finley, J.; Fortson, L.; Gaidos, J.; Gillanders, G. H.; Grindlay, J.; Hall, T. A.; Harris, K.; Hillas, A. M.; Kaaret, P.; Kertzman, M.; Kieda, D.; Krennrich, F.; Lang, M. J.; LeBohec, S.; Lessard, R.; Lloyd-Evans, J.; Knapp, J.; McKernan, B.; McEnery, J.; Moriarty, P.; Muller, D.; Ogden, P.; Ong, R.; Petry, D.; Quinn, J.; Reay, N. W.; Reynolds, P. T.; Rose, J.; Salamon, M.; Sembroski, G.; Sidwell, R.; Slane, P.; Stanton, N.; Swordy, S. P.; Vassiliev, V. V.; Wakely, S. P.

    2002-05-01

    The Very Energetic Radiation Imaging Telescope Array System (VERITAS) represents an important step forward in the study of extreme astrophysical processes in the universe. It combines the power of the atmospheric Cherenkov imaging technique using a large optical reflector with the power of stereoscopic observatories using arrays of separated telescopes looking at the same shower. The seven identical telescopes in VERITAS, each of aperture 10 m, will be deployed in a filled hexagonal pattern of side 80 m; each telescope will have a camera consisting of 499 pixels with a field of view of 3.5°. VERITAS will substantially increase the catalog of very high energy ( E>100 GeV) γ-ray sources and greatly improve measurements of established sources.

  10. The effect of the atmospheric condition on the extensive air shower analysis at the Telescope Array experiment

    SciTech Connect

    Kobayashi, Y.; Tsunesada, Y.; Tokuno, H.; Kakimoto, F.; Tomida, T.

    2011-09-22

    The accuracies in determination of air shower parameters such as longitudinal profiles or primary energies with the fluorescence detection technique are strongly dependent on atmospheric conditions of the molecular and aerosol components. Moreover, air fluorescence photon yield depends on the atmospheric density, and the transparency of the air for fluorescence photons depends on the atmospheric conditions from EAS to FDs. In this paper, we describe the atmospheric monitoring system in the Telescope Array (TA experiment), and the impact of the atmospheric conditions in air shower reconstructions. The systematic uncertainties of the determination of the primary cosmic ray energies and of the measurement of depth of maximum development (X{sub max}) of EASs due to atmospheric variance are evaluated by Monte Carlo simulation.

  11. Wavelength-shifted Cherenkov radiators

    NASA Technical Reports Server (NTRS)

    Krider, E. P.; Jacobson, V. L.; Pifer, A. E.; Polakos, P. A.; Kurz, R. J.

    1976-01-01

    The scintillation and Cherenkov responses of plastic Cherenkov radiators containing different wavelength-shifting fluors in varying concentrations have been studied in beams of low energy protons and pions. For cosmic ray applications, where large Cherenkov to scintillation ratios are desired, the optimum fluor concentrations are 0.000025 by weight or less.

  12. Observations in the 1.3 and 1.5 THz atmospheric windows with the Receiver Lab Telescope

    NASA Technical Reports Server (NTRS)

    Marrone, Daniel P.; Blundell, Raymond; Tong, Edward; Paine, Scott N.; Loudkov, Denis; Kawamura, Jonathan H.; Luhr, Daniel; Barrientos, Claudio

    2005-01-01

    The Receiver Lab Telescope (RLT) is a groundbased terahertz telescope; it is currently the only instrument producing astronomical data between 1 and 2 THz. The capabilities of the RLT have been expanding since observations began in late 2002. Initial observations were limited to the 850 GHz and 1.03 THz windows due to the availability of solid state local oscillators. In the last year we have begun observations with new local oscillators for the 1.3 and 1.5 THz atmospheric windows.

  13. Search for Primordial Black Holes with the Whipple Atmospheric Cerenkov Telescope

    NASA Astrophysics Data System (ADS)

    Linton, Eric

    2005-04-01

    Stephen Hawking's prediction that black holes should radiate like black bodies has several important consequences, including the possibility for the detection of small (˜10^15 g) black holes created in the very early universe. The detection of such primordial black holes (PBHs) would not only validate Hawking's theory, but would provide useful insights into the history of the early universe. A search through 5.5 years of archival data from the Whipple Atmospheric Cerenkov Telescope was made for TeV gamma-ray bursts on 1 s, 3 s, and 5 s timescales. Based on a null result, an upper-limit on the evaporation rate of PBHs of 2.69 x10^6 pc-3 yr^- 1 (99% CL) was made, assuming the Standard Model of particle physics. When combined with the results of an earlier search through Whipple data, this limit was lowered to 1.33 x10^6 pc-3 yr-1, which is nearly a factor of 2 better than the previous limit at this energy range.

  14. A method of observing cherenkov light from extensive air shower at Yakutsk EAS array

    NASA Astrophysics Data System (ADS)

    Timofeev, Lev; Anatoly, Ivanov

    2016-07-01

    Proposed a new method for measuring the cherenkov light from the extensive air shower (EAS) of cosmic rays (CR), which allows to determine not only the primary particle energy and angle of arrival, but also the parameters of the shower in the atmosphere - the maximum depth and "age". For measurements Cherenkov light produced by EAS is proposed to use a ground network of wide-angle telescopes which are separated from each other by a distance 100-300 m depending on the total number of telescopes operating in the coincidence signals, acting autonomously, or includes a detector of the charged components, radio waves, etc. as part of EAS. In a results such array could developed, energy measurement and CR angle of arrival data on the depth of the maximum and the associated mass of the primary particle generating by EAS. This is particularly important in the study of galactic cosmic ray in E> 10^14 eV, where currently there are no direct measurements of the maximum depth of the EAS.

  15. Fermi large area telescope observations of the cosmic-ray induced γ-ray emission of the Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; de Palma, F.; Digel, S. W.; Do Couto E Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Rodriguez, A. Y.; Roth, M.; Sadrozinski, H. F.-W.; Sander, A.; Saz Parkinson, P. M.; Sgrò, C.; Share, G. H.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2009-12-01

    We report on measurements of the cosmic-ray induced γ-ray emission of Earth’s atmosphere by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The Large Area Telescope has observed the Earth during its commissioning phase and with a dedicated Earth limb following observation in September 2008. These measurements yielded ˜6.4×106 photons with energies >100MeV and ˜250 hours total live time for the highest quality data selection. This allows the study of the spatial and spectral distributions of these photons with unprecedented detail. The spectrum of the emission—often referred to as Earth albedo gamma-ray emission—has a power-law shape up to 500 GeV with spectral index Γ=2.79±0.06.

  16. Optical aperture synthesis with electronically connected telescopes.

    PubMed

    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

  17. 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

  18. Space Telescopes

    NASA Technical Reports Server (NTRS)

    Clampin, Mark; Flanagan, Kathryn A.

    2012-01-01

    Space telescopes have been a dominant force in astrophysics and astronomy over the last two decades. As Lyman Spitzer predicted in 1946, space telescopes have opened up much of the electromagnetic spectrum to astronomers, and provided the opportunity to exploit the optical performance of telescopes uncompromised by the turbulent atmosphere. This special section of Optical Engineering is devoted to space telescopes. It focuses on the design and implementation of major space observatories from the gamma-ray to far-infrared, and highlights the scientific and technical breakthroughs enabled by these telescopes. The papers accepted for publication include reviews of major space telescopes spanning the last two decades, in-depth discussions of the design considerations for visible and x-ray telescopes, and papers discussing concepts and technical challenges for future space telescopes.

  19. Trigger rate simulation study for the MACE telescope

    NASA Astrophysics Data System (ADS)

    Thoudam, S.; Rannot, R. C.; Koul, R.

    The MACE (Major Atmospheric Cherenkov Experiment) gamma-ray telescope is a Cherenkov imaging telescope going to be installed at Hanle (4200 m asl) in the Ladakh region of Jammu and kashmir. The telescope consists of a parabolic basket of f/dsim 1.2 with focal length f=25 m giving a total light collection area of sim 340 m^2 and a (40times 40) camera pixels of individual pixel size of sim 0.1^circ. The telescope which is expected to be operated in the energy range of triangle Esim (10 GeV-10 TeV) will be capable of observing various galactic and extragalactic gamma-ray sources. The present work discusses the trigger rates due to the light of night sky (LONS) background for different trigger schemes. We consider 2, 3, 4 and 5 pixels trigger configuration. Finally, the system energy threshold for the Crab-like gamma-ray signal is estimated for the 4 pixels trigger scheme (Nearest neighbour quadruplet). Application of the same analysis to the main cosmic-ray background components like protons, electrons, positrons, alphas and the low energy muons are still underway.

  20. Atmospheric modeling for co-located VLBI antennas and twin telescopes

    NASA Astrophysics Data System (ADS)

    Nilsson, Tobias; Karbon, Maria; Soja, Benedikt; Heinkelmann, Robert; Lu, Cuixian; Schuh, Harald

    2015-07-01

    In the next generation VLBI network, the VLBI global observing system (VGOS), there will be several twin telescopes, i.e. stations equipped with a pair of VLBI telescopes with identical design. In this work we test the possibility of combining the tropospheric parameters of these two telescopes within the VLBI data analysis. This is done through simulations of a possible future VGOS network containing one twin telescope. We simulate the tropospheric delays with the help of a turbulence model, approximately taking into account the distance between the antennas. The results show that the combination of tropospheric delays can improve the station position repeatability by about 15 % as long as the distance is smaller than 1 km. The main improvement is in the repeatability of the baseline vector between the antennas. However, the results are strongly dependent on how the observations are scheduled for the twin telescope. The simulation results are confirmed by an analysis of the CONT14 campaign, where the tropospheric parameters of the two Hobart antennas are combined. Furthermore, we also discuss the study of combining other parameters for the twin telescope, i.e. the clocks and/or the station positions.

  1. Hubble space telescope far-ultraviolet observations of Io: Determining atmospheric abundances, mapping the sulfur dioxide distribution, and correlating the molecular and atomic atmosphere

    NASA Astrophysics Data System (ADS)

    Feaga, Lori Michelle

    2006-05-01

    Io's molecular and atomic atmosphere has been studied via far-ultraviolet spectroscopy obtained with the Hubble Space Telescope . Examination of an extensive data set reveals a sunlit SO 2 atmosphere which is temporally stable on a global scale, with only small local changes. An anti-/sub-Jovian asymmetry in the SO 2 distribution persists in all of the observations. The atmosphere is densest in the anti-Jovian equatorial regions, with a maximum column density of 5.0 × 10^16 cm -2 at 140° longitude. The SO 2 atmosphere also has greater latitudinal extent on the anti-Jovian hemisphere as compared to the sub-Jovian. The atmospheric distribution is best correlated with the location of known volcanic plumes. Theoretical sublimation atmosphere models cannot reproduce the asymmetry alone. Atomic S, O and Cl are also detected. Their abundances are derived and compared to the SO 2 . Sulfur is measured at a relative abundance of 9 × 10^-3 compared to SO 2 , oxygen at 0.05, and chlorine at 3-8.5 × 10^-4 .

  2. Transforming Cherenkov radiation in metamaterials

    NASA Astrophysics Data System (ADS)

    Ginis, Vincent; Danckaert, Jan; Veretennicoff, Irina; Tassin, Philippe

    2015-08-01

    In this contribution, we explore the generation of light in transformation-optical media. When charged particles move through a transformation-optical material with a speed larger than the phase velocity of light in the medium, Cherenkov light is emitted. We show that the emitted Cherenkov cone can be modified with longitudinal and transverse stretching of the coordinates. Transverse coordinates stretching alters only the dimensions of the cone, whereas longitudinal stretching also changes the apparent velocity of the charged particle. These results demonstrate that the geometric formalism of transformation optics can be used not only for the manipulation of light beam trajectories, but also for controlling the emission of light, here for describing the Cherenkov cone in an arbitrary anisotropic medium. Subsequently, we illustrate this point by designing a radiator for a ring imaging Cherenkov radiator. Cherenkov radiators are used to identify unknown elementary particles by determining their mass from the Cherenkov radiation cone that is emitted as they pass through the detector apparatus. However, at higher particle momentum, the angle of the Cherenkov cone saturates to a value independent of the mass of the generating particle, making it difficult to effectively distinguish between different particles. Using our transformation optics description, we show how the Cherenkov cone and the cut-off can be controlled to yield a radiator medium with enhanced sensitivity for particle identification at higher momentum [Phys. Rev. Lett. 113, 167402 (2014)].

  3. Semiconductor film Cherenkov lasers

    NASA Astrophysics Data System (ADS)

    Walsh, John E.

    1994-12-01

    The technical achievements for the project 'Semiconductor Film Cherenkov Lasers' are summarized. Described in the fourteen appendices are the operation of a sapphire Cherenkov laser and various grating-coupled oscillators. These coherent radiation sources were operated over the spectral range extending from 3 mm down to 400 micrometers. The utility of various types of open, multi-grating resonators and mode-locked operation were also demonstrated. In addition to these experiments, which were carried out with a 10-100 kV pulse generator, a low-energy (3-3.6 MeV) Van de Graaff generator and a low-energy RF linac (2.8 MeV) were used to investigate the properties of continuum incoherent Smith-Purcell radiation. It was shown that levels of intensity comparable to the infrared beam lines on a synchrotron could be obtained and thus that grating-coupled sources are potentially an important new source for Fourier transform spectroscopy. Finally, a scanning electron microscope was adapted for investigating mu-electron-beam-driven far-infrared sources. At the close of the project, spontaneous emission over the 288-800 micrometers band had been observed. Intensity levels were in accord with expectations based on theory. One or more of the Appendices address these topics in detail.

  4. Off-axis response measurement of the sounding of the atmosphere using broadband emission radiometry (SABER) telescope

    NASA Astrophysics Data System (ADS)

    Stauder, John L.; Bates, Lynne R.; Dyer, James S.; Esplin, Roy W.; Miles, Duane O.

    2002-09-01

    The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument is a 10-channel earth limb-viewing sensor that measures atmospheric emissions in the spectral range of 1.27 μm to 16.9 μm. SABER is part of NASA's Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) mission, which was successfully launched in December 2001. Uncommon among limb-viewing sensors, SABER employs an on-axis telescope design with reimaging optics to allow for an intermediate field stop and a Lyot stop. Additional stray light protection is achieved by an innovative inner Lyot stop, which is placed conjugate to the secondary obscuration and support structure. Presented in this paper is the off-axis response of SABER as measured in the Terrestrial Black Hole off-axis scatter facility at the Space Dynamics Laboratory. The measurement was made at visible wavelengths; thus, the response is only representative of SABER's short wavelength channels. The measurement validated the stray light design and complemented the APART software model, which predicts that mirror scatter is the dominant stray light mechanism at short wavelengths. In addition, estimates of the mirror bi-directional reflectance distribution function (BRDF) were made. The off-axis response measurement indicates that SABER is an exceptional stray light suppression telescope.

  5. Differential measurement of atmospheric refraction using a telescope with double fields of view

    NASA Astrophysics Data System (ADS)

    Yu, Yong; Cao, Jian-Jun; Tang, Zheng-Hong; Luo, Hao; Zhao, Ming

    2015-10-01

    For the sake of advancing theoretical research about atmospheric refraction, the atmospheric refraction observed at lower angles of elevation is still worth analyzing and exploring. In some engineering applications, objects with a larger zenith distance must sometimes be observed. Carrying out observational research on atmospheric refraction at lower angles of elevation has an important significance. However, it has been considered difficult to measure the atmospheric refraction at lower angles of elevation. A new idea for determining atmospheric refraction by utilizing differential measurement with double fields of view is proposed. Taking the observational principle used by the HIPPARCOS satellite as a reference, a prototype with double fields of view was developed. In August 2013, experimental observations were carried out and atmospheric refractions at lower angles of elevation were obtained by the prototype. The measured value of atmospheric refraction at a zenith distance of 78.8° was 240.23″ ± 0.27″, and the feasibility of differential measurement of atmospheric refraction with double fields of view was verified. Limitations of the prototype, such as inadequate ability to gather light, lack of accurate meteorological data recording, and a low level of automation in observation and data processing, are pointed out, which need to be improved in subsequent work.

  6. Spatially resolving the atmospheric dynamics over the surface of red supergiants with the Very Large Telescope Interferometer

    NASA Astrophysics Data System (ADS)

    Ohnaka, K.

    2013-05-01

    The mass-loss mechanism in red supergiants is a long-stand-ing problem. The milliarcsecond angular resolution achieved by infrared long-baseline interferometry provides us with the only way to spatially resolve the region where the material is accelerated. For this goal, the 2.3 μm CO lines are important, because they form in the upper photosphere and the outer atmosphere (so-called MOLsphere). We present high-spatial and high-spectral resolution observations of the 2.3 μm CO lines in the red supergiants Betelgeuse and Antares using the Very Large Telescope Interferometer (VLTI). This has enabled us to spatially resolve the gas dynamics in the photosphere (and the MOLsphere) for the first time other than the Sun. We have detected vigorous motions of large CO gas clumps with velocities of up to 20-30 km s-1. Comparison of the CO line data taken 1 year apart shows a significant change in the dynamics of the atmosphere. In contrast to the CO line data, the continuum data reveal no or only marginal time variations. The observationally estimated gas density in the outer atmosphere at 1.3-1.4 R⋆ is higher than the values predicted by the current 3-D convection simulations by 6 to 11 orders of magnitude. Therefore, at the moment, convection alone cannot explain the detected vigorous gas motions in the extended outer atmosphere of Betelgeuse and Antares.

  7. Pulsar observations with the MAGIC telescopes

    NASA Astrophysics Data System (ADS)

    Fidalgo, David

    2016-07-01

    The vast majority of spectra of gamma-ray pulsars exhibit an exponential cut-off at a few GeV, as seen by the Large Area Telescope (LAT) on board of the Fermi satellite. Due to this cut-off, current Imaging Atmospheric Cherenkov Telescopes (IACTs) with an energy threshold as low as 30 GeV, struggle to detect pulsars. So far, emission above 50 GeV has been confirmed only for the Crab and Vela pulsars. In the case of the former, the spectrum even extends up to about 1 TeV firmly revealing a second emission component. To further understand the emission mechanism of gamma-ray pulsars, the MAGIC collaboration continues the search of pulsars above 50 GeV. In this talk we report on recent results on the Crab and Geminga Pulsar obtained with the MAGIC telescopes, including the analysis of data taken with a new trigger system lowering the energy threshold of the MAGIC telescopes.

  8. Recent results from the ANTARES neutrino telescope

    SciTech Connect

    Eberl, Thomas; Collaboration: ANTARES Collaboration

    2014-11-18

    The ANTARES detector, located in the deep sea 40 km off the French coast, is the largest neutrino telescope in the northern hemisphere. It consists of an array of 885 photomultipliers detecting the Cherenkov light induced by charged leptons created in neutrino interactions in and around the detector. The main goal of ANTARES is to search for astrophysical neutrinos in the TeV-PeV range. This comprises searches for a diffuse cosmic neutrino flux and for fluxes from possible galactic and extragalactic sources of neutrinos. The search program also includes multi-messenger analyses based on time and/or space coincidences with other cosmic probes. The ANTARES detector is sensitive to a wide range of other phenomena, from atmospheric neutrino oscillations to dark matter annihilation or potential exotics such as nuclearites and magnetic monopoles.

  9. Recent Results from the ANTARES Neutrino Telescope

    NASA Astrophysics Data System (ADS)

    Kouchner, Antoine

    2014-10-01

    The ANTARES detector, located 40 km off the French coast, is the largest deep-sea neutrino telescope in the world. It consists of an array of 885 photomultipliers detecting the Cherenkov light induced by charged leptons produced by neutrino interactions in and around the detector. The primary goal of ANTARES is to search for astrophysical neutrinos in the TeV-PeV range. This comprises generic searches for any diffuse cosmic neutrino flux as well as more specific searches for astrophysical sources such as active galactic nuclei or galactic sources. The search program also includes multi-messenger analyses based on time and/or space coincidences with other cosmic probes. The ANTARES observatory is sensitive to a wide range of other phenomena, from atmospheric neutrino oscillations to dark matter annihilation or potential exotics such as nuclearites and magnetic monopoles. The most recent results are reported.

  10. Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters

    NASA Astrophysics Data System (ADS)

    Cenarro, A. J.; Peletier, R. F.; Sánchez-Blázquez, P.; Selam, S. O.; Toloba, E.; Cardiel, N.; Falcón-Barroso, J.; Gorgas, J.; Jiménez-Vicente, J.; Vazdekis, A.

    2007-01-01

    We present a homogeneous set of stellar atmospheric parameters (Teff, logg, [Fe/H]) for MILES, a new spectral stellar library covering the range λλ 3525-7500Å at 2.3Å (FWHM) spectral resolution. The library consists of 985 stars spanning a large range in atmospheric parameters, from super-metal-rich, cool stars to hot, metal-poor stars. The spectral resolution, spectral type coverage and number of stars represent a substantial improvement over previous libraries used in population synthesis models. The atmospheric parameters that we present here are the result of a previous, extensive compilation from the literature. In order to construct a homogeneous data set of atmospheric parameters we have taken the sample of stars of Soubiran, Katz & Cayrel, which has very well determined fundamental parameters, as the standard reference system for our field stars, and have calibrated and bootstrapped the data from other papers against it. The atmospheric parameters for our cluster stars have also been revised and updated according to recent metallicity scales, colour-temperature relations and improved set of isochrones.

  11. Telescope-optical system performance analysis for the Cryogenic Limb Array Etalon Spectrometer (CLAES) on the Upper Atmospheric Research Satellite

    NASA Technical Reports Server (NTRS)

    Roche, A. E.; Forney, P. B.; Morrow, H. E.; Anapol, M.

    1983-01-01

    A first-order performance analysis of the CLAES telescope-optical system is presented. The experiment involves the passive measurement of earth-limb radiance over a 10-60 km tangent altitude range, and is based on a solid Fabry-Perot spectrometer which provides spectral resolution of 0.25/cm for atmospheric emission spectroscopy over the 3.5-12 micron IR range. The optical system is required to provide a high degree of off-axis rejection and stray-light control, primarily to suppress intense emission from the earth surface. The astigmatism and other geometric aberrations are corrected by a secondary mirror which produces an excellent image of the primary one, allowing for location of a diffraction control or Lyot stop. The off-axis scattering performance of the telescope is examined in terms of the mirror scatter coefficient and point source rejection ratio. A mirror bidirectional reflectance distribution function of 0.0001 at 1 deg with a 1/theta-squared roll-off between 1 and 0.2 deg is realizable based on recent measurements. This results in an off-axis radiance term that is generally small in comparison with the system-limiting NER.

  12. Useful receiver telescope diameter of ground-based and airborne 1-, 2-, and 10-micron coherent lidars in the presence of atmospheric refractive turbulence

    NASA Technical Reports Server (NTRS)

    Chan, Kin P.; Killinger, Dennis K.

    1992-01-01

    Calculations of the integrated effect of atmospheric refractive turbulence on 1-, 2-, and 10-micron coherent lidar performance are presented for a series of different lidar propagation geometries. The effective lidar receiver telescope diameter is evaluated for each case. The results indicate that atmospheric turbulence should not be a significant factor in the performance of a downward-looking high-altitude or satellite-borne coherent lidar system. It is also shown that ground-based 1-2-micron coherent lidars may be limited in their useful telescope aperture, especially for horizontal or nearly horizontal path measurements near the ground.

  13. Gamma-ray burst observations with new generation imaging atmospheric Cerenkov Telescopes in the FERMI era

    SciTech Connect

    Covino, S.; Campana, S.; Galante, N.; Gaug, M.; Longo, F.; Scapin, V.

    2009-04-08

    After the launch and successful beginning of operations of the FERMI satellite, the topics related to high-energy observations of gamma-ray bursts have obtained a considerable attention by the scientific community. Undoubtedly, the diagnostic power of high-energy observations in constraining the emission processes and the physical conditions of gamma-ray burst is relevant. We briefly discuss how gamma-ray burst observations with ground-based imaging array Cerenkov telescopes, in the GeV-TeV range, can compete and cooperate with FERMI observations, in the MeV-GeV range, to allow researchers to obtain a more detailed and complete picture of the prompt and afterglow phases of gamma-ray bursts.

  14. A threshold gas Cherenkov detector for the Spin Asymmetries of the Nucleon Experiment

    NASA Astrophysics Data System (ADS)

    Armstrong, Whitney R.; Choi, Seonho; Kaczanowicz, Ed; Lukhanin, Alexander; Meziani, Zein-Eddine; Sawatzky, Brad

    2015-12-01

    We report on the design, construction, commissioning, and performance of a threshold gas Cherenkov counter in an open configuration, which operates in a high luminosity environment and produces a high photo-electron yield. Part of a unique open geometry detector package called the Big Electron Telescope Array (BETA), this Cherenkov counter served to identify scattered electrons and reject produced pions in an inclusive scattering experiment known as the Spin Asymmetries of the Nucleon Experiment (SANE), E07-003 at Jefferson Lab. The experiment consisted of a measurement of double spin asymmetries A∥ and A⊥ of a polarized electron beam impinging on a polarized ammonia target. The Cherenkov counter's performance is characterised by a yield of about 20 photoelectrons per electron or positron track. Thanks to this large number of photoelectrons per track, the Cherenkov counter had enough resolution to identify electron-positron pairs from the conversion of photons resulting mainly from π0 decays.

  15. Atmospheric characterization of five hot Jupiters with the wide field Camera 3 on the Hubble space telescope

    SciTech Connect

    Ranjan, Sukrit; Charbonneau, David; Désert, Jean-Michel; Madhusudhan, Nikku; Deming, Drake; Wilkins, Ashlee; Mandell, Avi M.

    2014-04-20

    We probe the structure and composition of the atmospheres of five hot Jupiter exoplanets using the Hubble Space Telescope Wide Field Camera 3 (WFC3) instrument. We use the G141 grism (1.1-1.7 μm) to study TrES-2b, TrES-4b, and CoRoT-1b in transit; TrES-3b in secondary eclipse; and WASP-4b in both. This wavelength region includes a predicted absorption feature from water at 1.4 μm, which we expect to be nondegenerate with the other molecules that are likely to be abundant for hydrocarbon-poor (e.g., solar composition) hot Jupiter atmospheres. We divide our wavelength regions into 10 bins. For each bin we produce a spectrophotometric light curve spanning the time of transit or eclipse. We correct these light curves for instrumental systematics without reference to an instrument model. For our transmission spectra, our mean 1σ precision per bin corresponds to variations of 2.1, 2.8, and 3.0 atmospheric scale heights for TrES-2b, TrES-4b, and CoRoT-1b, respectively. We find featureless spectra for these three planets. We are unable to extract a robust transmission spectrum for WASP-4b. For our dayside emission spectra, our mean 1σ precision per bin corresponds to a planet-to-star flux ratio of 1.5 × 10{sup –4} and 2.1 × 10{sup –4} for WASP-4b and TrES-3b, respectively. We combine these estimates with previous broadband measurements and conclude that for both planets isothermal atmospheres are disfavored. We find no signs of features due to water. We confirm that WFC3 is suitable for studies of transiting exoplanets, but in staring mode multivisit campaigns are necessary to place strong constraints on water abundance.

  16. Transit Observations of Venus's Atmosphere in 2012 from Terrestrial and Space Telescopes as Exoplanet Analogs

    NASA Astrophysics Data System (ADS)

    Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.; Penn, M. J.; Jaeggli, S. A.; Galayda, E.; Reardon, K. P.; Widemann, T.; Tanga, P.; Ehrenreich, D.; Vidal-Madjar, A.; Nicholson, P. D.; Dantowitz, R.

    2013-06-01

    We extensively observed the 8 June 2012 transit of Venus from several sites on Earth; we provide this interim status report about this and about two subsequent ToVs observed from space. From Haleakala Obs., we observed the entire June transit over almost 7 h with a coronagraph of the Venus Twilight Experiment B filter) and with a RED Epic camera to compare with simultaneous data from ESA's Venus Express, to study the Cytherean mesosphere; from Kitt Peak, we have near-IR spectropolarimetry at 1.6 µm from the aureole and during the disk crossing that compare well with carbon dioxide spectral models; from Sac Peak/IBIS we have high-resolution imaging of the Cytherean aureole for 22 min, starting even before 1st contact; from Big Bear, we have high-resolution imaging of Venus's atmosphere and the black-drop effect through 2nd contact; and we had 8 other coronagraphs around the world. For the Sept 21 ToV as seen from Jupiter, we had 14 orbits of HST to use Jupiter's clouds as a reflecting surface to search for an 0.01% diminution in light and a differential drop that would result from Venus's atmosphere by observing in both IR/UV, for which we have 170 HST exposures. As of this writing, preliminary data reduction indicates that variations in Jovian clouds and the two periods of Jupiter's rotation will be too great to allow extraction of the transit signal. For the December 20 ToV as seen from Saturn, we had 22 hours of observing time with VIMS on Cassini, for which we are looking for a signal of the 10-hr transit in total solar irradiance and of Venus's atmosphere in IR as an exoplanet-transit analog. Our Maui & Sac Peak expedition was sponsored by National Geographic Society's Committee for Research and Exploration; HST data reduction by NASA: HST-GO-13067. Some of the funds for the carbon dioxide filter for Sac Peak provided by NASA through AAS's Small Research Grant Program. We thank Rob Ratkowski of Haleakala Amateur Astronomers; Rob Lucas, Aram Friedman, Eric

  17. Josephson-vortex Cherenkov radiation

    SciTech Connect

    Mints, R.G.; Snapiro, I.B.

    1995-10-01

    We predict the Josephson-vortex Cherenkov radiation of an electromagnetic wave. We treat a long one-dimensional Josephson junction. We consider the wavelength of the radiated electromagnetic wave to be much less than the Josephson penetration depth. We use for calculations the nonlocal Josephson electrodynamics. We find the expression for the radiated power and for the radiation friction force acting on a Josephson vortex and arising due to the Cherenkov radiation. We calculate the relation between the density of the bias current and the Josephson vortex velocity.

  18. Cherenkov radiation oscillator without reflectors

    SciTech Connect

    Li, D.; Wang, Y.; Wei, Y.; Yang, Z.; Hangyo, M.; Miyamoto, S.

    2014-05-12

    This Letter presents a Cherenkov radiation oscillator with an electron beam travelling over a finitely thick plate made of negative-index materials. In such a scheme, the external reflectors required in the traditional Cherenkov oscillators are not necessary, since the electromagnetic energy flows backward in the negative-index materials, leading to inherent feedback. We theoretically analyzed the interaction between the electron beam and the electromagnetic wave, and worked out the growth rate and start current through numerical calculations. With the help of particle-in-cell simulation, the theoretical predictions are well demonstrated.

  19. Cherenkov Radiation from e+e- Pairs and Its Effect on nu e InducedShowers

    SciTech Connect

    Mandal, Sourav K.; Klein, Spencer R.; Jackson, J. David

    2005-06-08

    We calculate the Cherenkov radiation from an e{sup +}e{sup -} pair at small separations, as occurs shortly after a pair conversion. The radiation is reduced (compared to that from two independent particles) when the pair separation is smaller than the wavelength of the emitted light. We estimate the reduction in light in large electromagnetic showers, and discuss the implications for detectors that observe Cherenkov radiation from showers in the Earth's atmosphere, as well as in oceans and Antarctic ice.

  20. Progress in Cherenkov femtosecond fiber lasers

    NASA Astrophysics Data System (ADS)

    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.

  1. Transient Small-Scale Magnetic Flux Emergence and Atmospheric Response Observed with New Solar Telescope and SDO

    NASA Astrophysics Data System (ADS)

    Vargas Domínguez, Santiago; Kosovichev, Alexander G.

    2014-06-01

    State-of-the art solar instrumentation is now revealing the activity of the Sun at the highest temporal and spatial resolution. Granular-scale magnetic flux emergence and the response of the solar atmosphere is one of the key topics. Observations with the 1.6m aperture New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO) are making next steps in our understanding of the solar surface structure. On August 7, 2013, NST observed active region NOAA 11810 in different photospheric and chromospheric wavelengths. The region displays a group of solar pores, in the vicinity of which we detected a site of emerging magnetic flux accompanied by intense and very confined abnormal granulation dynamics, observed in the photospheric TiO 7057 A with a resolution of 0.034 “/pix. Following the expansion of exploding granules in this site, we observed a sudden appearance of an extended surge in the HeI 10830A data (bandpass of 0.05 A). The SDO/HMI data used to study the evolution of the magnetic field and Doppler velocities reveal a short-lived emerging loop-like structure with strong upflows. We used the SDO/AIA data to investigate the response of the transition region and corona to the transient emerging flux phenomenon. We compare the results with previous observations, and propose a scenario for the production of plasma surges by the transient magnetic flux emergence events.

  2. Cherenkov Source for PMT Calibrations

    NASA Astrophysics Data System (ADS)

    Kaptanoglu, Tanner; SNO+ at UC Berkeley Collaboration

    2013-10-01

    My research is focused on building a deployable source for PMT calibrations in the SNO+ detector. I work for the SNO+ group at UC Berkeley headed by Gabriel Orebi Gann. SNO+ is an addition to the SNO project, and its main goal is to search for neutrinoless double beta decay. The detector will be monitored by over 9500 photomultiplier tubes (PMTs). In order to characterize the PMTs, several calibration sources are being constructed. One of which, the Cherenkov Source, will provide a well-understood source of non-isotropic light for calibrating the detector response. My goal is to design and construct multiple aspects of the Cherenkov Source. However, there are multiple questions that arose with its design. How do we keep the scintillation light inside the Cherenkov source so it does not contaminate calibration? How do we properly build the Cherenkov source: a hollow acrylic sphere with a neck? Can we maintain a clean source throughout these processes? These are some of the problems I have been working on, and will continue to work on, until the deployment of the source. Additionally, I have worked to accurately simulate the physics inside the source, mainly the energy deposition of alphas.

  3. HARPS Observes the Earth Transiting the Sun — A Method to Study Exoplanet Atmospheres Using Precision Spectroscopy on Large Ground-based Telescopes

    NASA Astrophysics Data System (ADS)

    Yan, F.; Fosbury, R.; Petr-Gotzens, M.; Pallé, E.; Zhao, G.

    2015-09-01

    Exoplanetary transits offer the opportunity to measure the transmission of long, tangential pathlengths through their atmospheres. Since the fraction of the observed stellar light taking these paths is very small, transit photometric and spectrophotometric measurements of light curves require very high levels of measurement stability, favouring the use of intrinsically stable space telescopes. By studying the Rossiter-McLaughlin effect on the radial velocity of the transited star, pure, high-precision radial velocity measurements can be used to estimate the changes in planetary atmospheric transmission with wavelength: a promising method for future studies of small planets with very large ground-based telescopes since it removes the requirement for extreme photometric stability. This article describes a successful feasibility experiment using the HARPS instrument to measure reflected moonlight during the penumbral phases of a Lunar eclipse, effectively providing an observation of an Earth transit.

  4. Measurement of the atmospheric ν μ energy spectrum from 100 GeV to 200 TeV with the ANTARES telescope

    NASA Astrophysics Data System (ADS)

    Adrián-Martínez, S.; Albert, A.; Al Samarai, I.; André, M.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Astraatmadja, T.; Aubert, J.-J.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bigongiari, C.; Bogazzi, C.; Bouhou, B.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Cârloganu, C.; Carr, J.; Cecchini, S.; Charif, Z.; Charvis, Ph.; Chiarusi, T.; Circella, M.; Classen, F.; Core, L.; Costantini, H.; Coyle, P.; Creusot, A.; Curtil, C.; Dekeyser, I.; Deschamps, A.; De Bonis, G.; Decowski, M. P.; Distefano, C.; Donzaud, C.; Dornic, D.; Dorosti, Q.; Drouhin, D.; Dumas, A.; Eberl, T.; Emanuele, U.; Enzenhöfer, A.; Ernenwein, J.-P.; Escoffier, S.; Fehn, K.; Fermani, P.; Flaminio, V.; Folger, F.; Fritsch, U.; Fusco, L. A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giacomelli, G.; Giordano, V.; Gleixner, A.; Gómez-González, J. P.; Graf, K.; Guillard, G.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Herold, B.; Hößl, J.; James, C. W.; de Jong, M.; Kadler, M.; Kalekin, O.; Kappes, A.; Katz, U.; Kooijman, P.; Kouchner, A.; Kreykenbohm, I.; Kulikovskiy, V.; Lahmann, R.; Lambard, E.; Lambard, G.; Larosa, G.; Lattuada, D.; Lefèvre, D.; Leonora, E.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Louis, F.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martínez-Mora, J. A.; Martini, S.; Michael, T.; Montaruli, T.; Morganti, M.; Motz, H.; Mueller, C.; Neff, M.; Nezri, E.; Palioselitis, D.; Păvălaş, G. E.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Racca, C.; Richter, R.; Rivière, C.; Robert, A.; Roensch, K.; Rostovtsev, A.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Schmid, J.; Schnabel, J.; Schulte, S.; Schüssler, F.; Seitz, T.; Shanidze, R.; Sieger, C.; Simeone, F.; Spies, A.; Spurio, M.; Steijger, J. J. M.; Stolarczyk, Th.; Sánchez-Losa, A.; Taiuti, M.; Tamburini, C.; Tayalati, Y.; Trovato, A.; Vallage, B.; Vallée, C.; Van Elewyck, V.; Vernin, P.; Visser, E.; Wagner, S.; Wilms, J.; de Wolf, E.; Yatkin, K.; Yepes, H.; Zornoza, J. D.; Zúñiga, J.

    2013-10-01

    Atmospheric neutrinos are produced during cascades initiated by the interaction of primary cosmic rays with air nuclei. In this paper, a measurement of the atmospheric energy spectrum in the energy range 0.1-200 TeV is presented, using data collected by the ANTARES underwater neutrino telescope from 2008 to 2011. Overall, the measured flux is ˜25 % higher than predicted by the conventional neutrino flux, and compatible with the measurements reported in ice. The flux is compatible with a single power-law dependence with spectral index γ meas=3.58±0.12. With the present statistics the contribution of prompt neutrinos cannot be established.

  5. Modeling the diurnal tide for the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) 1 time period

    NASA Astrophysics Data System (ADS)

    Oberheide, Jens; Hagan, Maura E.; Ward, William E.; Riese, Martin; Offermann, Dirk

    2000-11-01

    High-resolution stratospheric and mesospheric temperature measurements from the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment taken during the space shuttle mission STS 66 in November 1994 show large tidal signatures in the day/night temperature differences. Previous comparisons with the predictions of the global-scale wave model (GSWM-95) for equinox conditions have shown these differences to be in very good qualitative agreement with GSWM results for the diurnal component of the migrating solar tide, although quantitative differences in the tidal amplitudes and phases did exist. In this paper the source of these differences is examined. Background fields corresponding to the flight conditions are derived from the CRISTA data and used as input to an updated version of the GSWM. The updated GSWM includes revised tidal heating and dissipation schemes. The background fields from CRISTA include temperature, ozone, pressure, mass density, and derived geostrophic wind (in geostrophic balance with the CRISTA temperatures). These model updates significantly improve the agreement with the CRISTA observations at all latitudes and altitudes. Modeled and observed phases match to within 1 hour at the equator. The amplitudes agree within 1 K for most altitudes. Above 75 km, however, the CRISTA measurements show a decrease in the tidal amplitude which is not present in the GSWM results, suggesting that the model underestimates the equatorial gravity wave dissipation in the form of eddy diffusivity and wave stress in the upper mesosphere. The mesospheric wind field update accounts for the most profound improvement in the phase distributions of the diurnal tide. The results show the strengths of the GSWM but also indicate the need for some model improvements. Our determination of the GSWM capability for reliable predictions of phases and amplitudes of the migrating diurnal tide when realistic atmospheric background conditions are used

  6. Deployment of a Pair of 3 M telescopes in Utah

    SciTech Connect

    Finnegan, G.; Adams, B.; Butler, K.; Cardoza, J.; Colin, P.; Hui, C. M.; Kieda, D.; Kirkwood, D.; Kress, D.; Kress, M.; LeBohec, S.; McGuire, C.; Newbold, M.; Nunez, P.; Pham, K.

    2008-12-24

    Two 3 m telescopes are being installed in Grantsville Utah. They are intended for the testing of various approaches to the implementation of intensity interferometry using Cherenkov Telescopes in large arrays as receivers as well as for the testing of novel technology cameras and electronics for ground based gamma-ray astronomy.

  7. Aerogel Cherenkov detectors in colliding beam experiments

    NASA Astrophysics Data System (ADS)

    Danilyuk, A. F.; Kononov, S. A.; Kravchenko, E. A.; Onuchin, A. P.

    2015-05-01

    This review discusses the application of aerogel Cherenkov detectors in colliding beam experiments. Such detectors are used for charged particle identification at velocities at which other methods are ineffective. The paper examines aerogel production technology and how the aerogel optical parameters are measured. Data on threshold Cherenkov counters with direct light collection and on those using wavelength shifters are evaluated. Also presented are data on Ring Image Cherenkov detectors with single and multilayer focusing aerogel radiators.

  8. Observations in the 1.3 and 1.5 THz atmospheric windows with the Receiver Lab Telescope

    NASA Technical Reports Server (NTRS)

    Marrone, Daniel P.; Blundell, Raymond; Tong, Edward; Paine, Scott N.; Loudkov, Denis; Kawamura, Jonathan H.; Luhr, Daniel; Barrientos, Claudio

    2005-01-01

    The Receiver Lab Telescope (RLT) is a ground-based terahertz telescope; it is currently the only instrument producing astronmical data between 1 and 2 THz. We report on our first measurements o the high CO transitions, which represent the highest frequency detection ever made from the ground. We also present initial observations of {N II} and discuss the implications of this non-detection for the standard estimates of the strength of this line.

  9. The Advanced Gamma-ray Imaging System (AGIS) Telescope Optical System Designs

    SciTech Connect

    Bugaev, V.; Buckley, J.; Krawczynski, H.; Diegel, S.; Romani, R.; Falcone, A.; Fegan, S.; Vassiliev, V.; Finley, J.; Guarino, V.; Hanna, D.; Kaaret, P.; Konopelko, A.; Ramsey, B.; Weekes, T.

    2008-12-24

    AGIS is a conceptual design for a future ground-based gamma-ray observatory operating in the energy range 25 GeV-100 TeV, which is based on an array of {approx}20-100 imaging atmospheric Cherenkov telescopes (IACTs). The desired improvement in sensitivity, angular resolution, and reliability of operation of AGIS imposes demanding technological and cost requirements on the design of the IACTs. We are considering several options for the optical system (OS) of the AGIS telescopes, which include the traditional Davies-Cotton design as well as novel two-mirror design. Emerging mirror production technologies based on replication processes such as cold and hot glass slumping, cured carbon fiber reinforced plastic (CFRP), and electroforming provide new opportunities for cost-effective solutions for the design of the OS.

  10. SkyProbe: Real-Time Precision Monitoring in the Optical of the Absolute Atmospheric Absorption on the Telescope Science and Calibration Fields

    NASA Astrophysics Data System (ADS)

    Cuillandre, J.-C.; Magnier, E.; Sabin, D.; Mahoney, B.

    2016-05-01

    Mauna Kea is known for its pristine seeing conditions but sky transparency can be an issue for science operations since at least 25% of the observable (i.e. open dome) nights are not photometric, an effect mostly due to high-altitude cirrus. Since 2001, the original single channel SkyProbe mounted in parallel on the Canada-France-Hawaii Telescope (CFHT) has gathered one V-band exposure every minute during each observing night using a small CCD camera offering a very wide field of view (35 sq. deg.) encompassing the region pointed by the telescope for science operations, and exposures long enough (40 seconds) to capture at least 100 stars of Hipparcos' Tycho catalog at high galactic latitudes (and up to 600 stars at low galactic latitudes). The measurement of the true atmospheric absorption is achieved within 2%, a key advantage over all-sky direct thermal infrared imaging detection of clouds. The absolute measurement of the true atmospheric absorption by clouds and particulates affecting the data being gathered by the telescope's main science instrument has proven crucial for decision making in the CFHT queued service observing (QSO) representing today all of the telescope time. Also, science exposures taken in non-photometric conditions are automatically registered for a new observation at a later date at 1/10th of the original exposure time in photometric conditions to ensure a proper final absolute photometric calibration. Photometric standards are observed only when conditions are reported as being perfectly stable by SkyProbe. The more recent dual color system (simultaneous B & V bands) will offer a better characterization of the sky properties above Mauna Kea and should enable a better detection of the thinnest cirrus (absorption down to 0.01 mag., or 1%).

  11. Optic detectors calibration for measuring ultra-high energy extensive air showers Cherenkov radiation by 532 nm laser

    NASA Astrophysics Data System (ADS)

    Knurenko, Stanislav; Petrov, Igor; Egorov, Yuri

    2015-08-01

    Calibration of a PMT matrix is crucial for the treatment of the data obtained with Cherenkov tracking detector. Furthermore, due to high variability of the aerosol abundance in the atmosphere depending on season, weather etc. A constant monitoring of the atmospheric transparency is required during the measurements. For this purpose, besides traditional methods, a station for laser atmospheric probing is used.

  12. Anomalous Cherenkov spin-orbit sound

    SciTech Connect

    Smirnov, Sergey

    2011-02-15

    The Cherenkov effect is a well-known phenomenon in the electrodynamics of fast charged particles passing through transparent media. If the particle is faster than the light in a given medium, the medium emits a forward light cone. This beautiful phenomenon has an acoustic counterpart where the role of photons is played by phonons and the role of the speed of light is played by the sound velocity. In this case the medium emits a forward sound cone. Here, we show that in a system with spin-orbit interactions in addition to this normal Cherenkov sound there appears an anomalous Cherenkov sound with forward and backward sound propagation. Furthermore, we demonstrate that the transition from the normal to anomalous Cherenkov sound happens in a singular way at the Cherenkov cone angle. The detection of this acoustic singularity therefore represents an alternative experimental tool for the measurement of the spin-orbit coupling strength.

  13. Recent multiwave Cherenkov generator experiments

    SciTech Connect

    Adler, R.; Richter-Sand, R.; Hacker, F.; Walsh, J.; Arman, M.

    1994-12-31

    The initial operating characteristics of the North Star Research Corporation (NSRC) multiwave generator experiment are discussed. The first radiation from the NSRC apparatus has now been observed and the immediate goal is to optimize the power output by providing a beam which is better matched to the field profile (a thinner beam propagating closer to the vanes). When this has been accomplished a detailed comparison of the performance of MWCG/MWDG (multiwave diffraction generator/multiwave Cherenkov generator) structures with BWO structures of the same interaction length will be undertaken.

  14. VERTICAL ATMOSPHERIC STRUCTURE IN A VARIABLE BROWN DWARF: PRESSURE-DEPENDENT PHASE SHIFTS IN SIMULTANEOUS HUBBLE SPACE TELESCOPE-SPITZER LIGHT CURVES

    SciTech Connect

    Buenzli, Esther; Apai, Daniel; Flateau, Davin; Morley, Caroline V.; Showman, Adam P.; Lewis, Nikole K.; Burrows, Adam; Marley, Mark S.; Reid, I. Neill

    2012-12-01

    Heterogeneous clouds or temperature perturbations in rotating brown dwarfs produce variability in the observed flux. We report time-resolved simultaneous observations of the variable T6.5 brown dwarf 2MASS J22282889-431026 over the wavelength ranges 1.1-1.7 {mu}m and broadband 4.5 {mu}m. Spectroscopic observations were taken with Wide Field Camera 3 on board the Hubble Space Telescope and photometry with the Spitzer Space Telescope. The object shows sinusoidal infrared variability with a period of 1.4 hr at most wavelengths with peak-to-peak amplitudes between 1.45% and 5.3% of the mean flux. While the light curve shapes are similar at all wavelengths, their phases differ from wavelength to wavelength with a maximum difference of more than half of a rotational period. We compare the spectra with atmospheric models of different cloud prescriptions, from which we determine the pressure levels probed at different wavelengths. We find that the phase lag increases with decreasing pressure level, or higher altitude. We discuss a number of plausible scenarios that could cause this trend of light curve phase with probed pressure level. These observations are the first to probe heterogeneity in an ultracool atmosphere in both horizontal and vertical directions, and thus are an ideal test case for realistic three-dimensional simulations of the atmospheric structure with clouds in brown dwarfs and extrasolar planets.

  15. Simulating a measurement of the 2nd knee in the cosmic ray spectrum with an atmospheric fluorescence telescope tower array.

    PubMed

    Liu, Jiali; Yang, Qunyu; Bai, Yunxiang; Cao, Zhen

    2014-01-01

    A fluorescence telescope tower array has been designed to measure cosmic rays in the energy range of 10(17)-10(18) eV. A full Monte Carlo simulation, including air shower production, light generation and propagation, detector response, electronics, and trigger system, has been developed for that purpose. Using such a simulation tool, the detector configuration, which includes one main tower array and two side-trigger arrays, 24 telescopes in total, has been optimized. The aperture and the event rate have been estimated. Furthermore, the performance of the X max technique in measuring composition has also been studied. PMID:24737964

  16. Simulating a Measurement of the 2nd Knee in the Cosmic Ray Spectrum with an Atmospheric Fluorescence Telescope Tower Array

    PubMed Central

    Liu, Jiali; Yang, Qunyu; Bai, Yunxiang; Cao, Zhen

    2014-01-01

    A fluorescence telescope tower array has been designed to measure cosmic rays in the energy range of 1017–1018 eV. A full Monte Carlo simulation, including air shower production, light generation and propagation, detector response, electronics, and trigger system, has been developed for that purpose. Using such a simulation tool, the detector configuration, which includes one main tower array and two side-trigger arrays, 24 telescopes in total, has been optimized. The aperture and the event rate have been estimated. Furthermore, the performance of the Xmax⁡ technique in measuring composition has also been studied. PMID:24737964

  17. TARGET: A multi-channel digitizer chip for very-high-energy gamma-ray telescopes

    SciTech Connect

    Bechtol, K.; Funk, S.; Okumura, A.; Ruckman, L.; Simons, A.; Tajima, H.; Vandenbroucke, J.; Varner, G.; /Hawaii U.

    2011-08-11

    The next-generation very-high-energy (VHE) gamma-ray observatory, the Cherenkov Telescope Array, will feature dozens of imaging atmospheric Cherenkov telescopes (IACTs), each with thousands of pixels of photosensors. To be affordable and reliable, reading out such a mega-channel array requires event recording technology that is highly integrated and modular, with a low cost per channel. We present the design and performance of a chip targeted to this application: the TeV Array Readout with GSa/s sampling and Event Trigger (TARGET). This application-specific integrated circuit (ASIC) has 16 parallel input channels, a 4096-sample buffer for each channel, adjustable input termination, self-trigger functionality, and tight window-selected readout. We report the performance of TARGET in terms of sampling frequency, power consumption, dynamic range, current-mode gain, analog bandwidth, and cross talk. The large number of channels per chip allows a low cost per channel ($10 to $20 including front-end and back-end electronics but not including photosensors) to be achieved with a TARGET-based IACT readout system. In addition to basic performance parameters of the TARGET chip itself, we present a camera module prototype as well as a second-generation chip (TARGET 2), both of which have been produced.

  18. Radio telescopes as the detectors of super-high-energy neutrinos

    NASA Technical Reports Server (NTRS)

    Dagkesamansky, R. D.; Zheleznykh, I. M.

    1991-01-01

    The registration of super high energy neutrinos is a very difficult and also very important problem that requires construction of detectors with large effective target masses. Askaryan pointed out the possibility of registering cascades in dense media by the Cherenkov radio emission of an excess of negative charges in the cascades which arose in interaction between high energy particles and the atoms of medium. The telescopes for cosmic high energy neutrino detection by radioemission of cascades induced underground, but whose development continues in the atmosphere were proposed by others. The effective target masses of such detectors could be approx. 10(exp 9) tons and more. The properties of Cherenkov radio emission of cascades and the properties of ice in the Antarctic Region make it possible to propose Radio Antarctic Muon and Neutrino Detection (RAMAND): antennas should be placed on the ice surface of approx. 10 sq km to search for radio signals for neutrino (muon) cascades of energy. It is evident from data given that the largest radio telescopes gives the opportunity for registration of the cascades induced by neutrinos with the energies E is greater than or = 10(exp 20) eV.

  19. 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

  20. All-fiber femtosecond Cherenkov radiation source.

    PubMed

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe; Tu, Haohua; Boppart, Stephen A; Turchinovich, Dmitry

    2012-07-01

    An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave-conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580-630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such an all-fiber Cherenkov radiation source is promising for practical applications in biophotonics such as bioimaging and microscopy. PMID:22743523

  1. Performance evaluation of trigger algorithm for the MACE telescope

    NASA Astrophysics Data System (ADS)

    Yadav, Kuldeep; Yadav, K. K.; Bhatt, N.; Chouhan, N.; Sikder, S. S.; Behere, A.; Pithawa, C. K.; Tickoo, A. K.; Rannot, R. C.; Bhattacharyya, S.; Mitra, A. K.; Koul, R.

    The MACE (Major Atmospheric Cherenkov Experiment) telescope with a light collector diameter of 21 m, is being set up at Hanle (32.80 N, 78.90 E, 4200m asl) India, to explore the gamma-ray sky in the tens of GeV energy range. The imaging camera of the telescope comprises 1088 pixels covering a total field-of-view of 4.30 × 4.00 with trigger field-of-view of 2.60 × 3.00 and an uniform pixel resolution of 0.120. In order to achieve low energy trigger threshold of less than 30 GeV, a two level trigger scheme is being designed for the telescope. The first level trigger is generated within 16 pixels of the Camera Integrated Module (CIM) based on 4 nearest neighbour (4NN) close cluster configuration within a coincidence gate window of 5 ns while the second level trigger is generated by combining the first level triggers from neighbouring CIMs. Each pixel of the telescope is expected to operate at a single pixel threshold between 8-10 photo-electrons where the single channel rate dominated by the after- pulsing is expected to be ˜500 kHz. The hardware implementation of the trigger logic is based on complex programmable logic devices (CPLD). The basic design concept, hardware implementation and performance evaluation of the trigger system in terms of threshold energy and trigger rate estimates based on Monte Carlo data for the MACE telescope will be presented in this meeting.

  2. The HERA-B ring imaging Cherenkov counter

    NASA Astrophysics Data System (ADS)

    Ariño, I.; Bastos, J.; Broemmelsiek, D.; Carvalho, J.; Chmeissani, M.; Conde, P.; Davila, J.; Dujmić, D.; Eckmann, R.; Garrido, L.; Gascon, D.; Hamacher, T.; Gorišek, A.; Ivaniouchenkov, I.; Ispirian, M.; Karabekian, S.; Kim, M.; Korpar, S.; Križan, P.; Kupper, S.; Lau, K.; Maas, P.; McGill, J.; Miquel, R.; Murthy, N.; Peralta, D.; Pestotnik, R.; Pyrlik, J.; Ramachandran, S.; Reeves, K.; Rosen, J.; Schmidt-Parzefall, W.; Schwarz, A.; Schwitters, R. F.; Siero, X.; Starič, M.; Stanovnik, A.; Škrk, D.; Živko, T.

    2004-01-01

    The HERA-B RICH uses a radiation path length of 2.8 m in C 4F 10 gas and a large 24 m2 spherical mirror for imaging Cherenkov rings. The photon detector consists of 2240 Hamamatsu multi-anode photomultipliers with about 27 000 channels. A 2:1 reducing two-lens telescope in front of each photomultiplier tube increases the sensitive area at the expense of increased pixel size, resulting in a contribution to the resolution which roughly matches that of dispersion. The counter was completed in January of 1999, and its performance has been steady and reliable over the years it has been in operation. The design performance of the Ring Imaging Cherenkov counter was fully reached: the average number of detected photons in the RICH for a β=1 particle was found to be 33 with a single-hit resolution of 0.7 and 1 mrad in the fine and coarse granularity regions, respectively.

  3. Neutron Detection via the Cherenkov Effect

    SciTech Connect

    Bell, Zane W; Boatner, Lynn A

    2010-01-01

    We have incorporated neutron-absorbing elements in transparent, nonscintillating glasses and used the Cherenkov effect to convert neutron-induced beta-gamma radiation directly into light. Use of the Cherenkov effect requires glasses with a high index of refraction (to lower the threshold and increase the number of Cherenkov photons) and neutron absorbers resulting in radioactive products emitting high-energy beta or gamma radiation. In this paper, we present a brief description of the requirements for developing efficient Cherenkov-based neutron detectors, show the results of measurements of the response of representative samples to thermal and fast neutron fluxes, and give the results of a calculation of the expected response of a detector to a moderated fission spectrum.

  4. Stray light design and analysis of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) telescope

    NASA Astrophysics Data System (ADS)

    Stauder, John L.; Esplin, Roy W.

    1998-11-01

    The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument is a 10-channel earth limb- viewing sensor that is to measure atmospheric emissions in the spectral range of 1.27 micrometer to 16.9 micrometer. Presented in this paper is the stray light design and analysis of SABER. Unwanted radiation from the earth and atmosphere are suppressed by the use of stray light features that are critical to mission success. These include the use of an intermediate field stop, an inner and outer Lyot stop, and super-polished mirrors. The point source normalized irradiance transmission (PSNIT) curve, which characterizes the sensor's off-axis response, was computed using the stray light analysis program APART. An initial calculation of the non-rejected radiance (NRR) due to emissions and scatter from the earth and atmosphere was made using the PSNIT data. The results indicate that stray light will not impede the mission objectives.

  5. The solar optical telescope

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Objectives of the Solar Optical Telescope are to study the physics of the Sun on the scale at which many of the important physical processes occur and to attain a resolution of 73km on the Sun or 0.1 arc seconds of angular resolution. Topics discussed in this overview of the Solar Optical Telescope include: why is the Solar Optical Telescope needed; current picture of the Sun's atmosphere and convection zone; scientific problems for the Solar Optical Telescope; a description of the telescope; the facility - science management, contamination control, and accessibility to the instruments; the scientific instruments - a coordinated instrument package for unlocking the Sun's secrets; parameters of the coordinated instrument package; science operations from the Space Shuttle; and the dynamic solar atmosphere.

  6. Asymmetric Cherenkov acoustic reverse in topological insulators

    NASA Astrophysics Data System (ADS)

    Smirnov, Sergey

    2014-09-01

    A general phenomenon of the Cherenkov radiation known in optics or acoustics of conventional materials is a formation of a forward cone of, respectively, photons or phonons emitted by a particle accelerated above the speed of light or sound in those materials. Here we suggest three-dimensional topological insulators as a unique platform to fundamentally explore and practically exploit the acoustic aspect of the Cherenkov effect. We demonstrate that by applying an in-plane magnetic field to a surface of a three-dimensional topological insulator one may suppress the forward Cherenkov sound up to zero at a critical magnetic field. Above the critical field the Cherenkov sound acquires pure backward nature with the polar distribution differing from the forward one generated below the critical field. Potential applications of this asymmetric Cherenkov reverse are in the design of low energy electronic devices such as acoustic ratchets or, in general, in low power design of electronic circuits with a magnetic field control of the direction and magnitude of the Cherenkov dissipation.

  7. Space Telescope.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.

    This pamphlet describes the Space Telescope, an unmanned multi-purpose telescope observatory planned for launch into orbit by the Space Shuttle in the 1980s. The unique capabilities of this telescope are detailed, the major elements of the telescope are described, and its proposed mission operations are outlined. (CS)

  8. A Combined Very Large Telescope and Gemini Study of the Atmosphere of the Directly Imaged Planet, Beta Pictoris b

    NASA Technical Reports Server (NTRS)

    Currie, Thayne; Burrows, Adam; Madhusudhan, Nikku; Fukagawa, Misato; Girard, Julien H.; Dawson, Rebekah; Murray-Clay, Ruth; Kenyon, Scott; Kuchner, Marc J.; Matsumura, Soko; Jayawardhana, Ray; Chambers, John; Bromley, Ben

    2013-01-01

    We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet Beta Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While Beta Pic b's near-IR colors mimic those of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects-i.e., ? And b and 1RXJ 1609B-match Beta Pic b's JHKsL photometry and its 3.1 micron and 5 micron photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large (approx. 60 micron)dust grains fail to reproduce the Beta Pic b spectrum. However, models incorporating thick clouds similar to those found forHR8799 bcde, but also with small (a fewmicrons) modal particle sizes, yield fits consistent with the data within the uncertainties. Assuming solar abundance models, thick clouds, and small dust particles (a = 4 micron), we derive atmosphere parameters of log(g) = 3.8 +/- 0.2 and Teff = 1575-1650 K, an inferred mass of 7+4 -3 MJ, and a luminosity of log(L/L) approx. -3.80 +/- 0.02. The best-estimated planet radius, is approx. equal to 1.65 +/- 0.06 RJ, is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if Beta Pic b is younger than is approx. equal to 7 Myr, consistent with a late formation well after its host star's birth approx. 12+8 -4 Myr ago.

  9. A Combined Very Large Telescope and Gemini Study of the Atmosphere of the Directly Imaged Planet, β Pictoris b

    NASA Astrophysics Data System (ADS)

    Currie, Thayne; Burrows, Adam; Madhusudhan, Nikku; Fukagawa, Misato; Girard, Julien H.; Dawson, Rebekah; Murray-Clay, Ruth; Kenyon, Scott; Kuchner, Marc; Matsumura, Soko; Jayawardhana, Ray; Chambers, John; Bromley, Ben

    2013-10-01

    We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet β Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While β Pic b's near-IR colors mimic those of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects—i.e., κ And b and 1RXJ 1609B—match β Pic b's JHKsL' photometry and its 3.1 μm and 5 μm photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large (~60 μm) dust grains fail to reproduce the β Pic b spectrum. However, models incorporating thick clouds similar to those found for HR 8799 bcde, but also with small (a few microns) modal particle sizes, yield fits consistent with the data within the uncertainties. Assuming solar abundance models, thick clouds, and small dust particles (langarang = 4 μm), we derive atmosphere parameters of log (g) = 3.8 ± 0.2 and T eff = 1575-1650 K, an inferred mass of 7^{+4}_{-3} MJ , and a luminosity of log(L/L ⊙) ~-3.80 ± 0.02. The best-estimated planet radius, ≈1.65 ± 0.06 RJ , is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if β Pic b is younger than ≈7 Myr, consistent with a late formation well after its host star's birth ~12^{+8}_{-4} Myr ago.

  10. Cherenkov TOF PET with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Dolenec, R.; Korpar, S.; Križan, P.; Pestotnik, R.

    2015-12-01

    As previously demonstrated, an excellent timing resolution below 100 ps FWHM is possible in time-of-flight positron emission tomography (TOF PET) if the detection method is based on the principle of detecting photons of Cherenkov light, produced in a suitable material and detected by microchannel plate photomultipliers (MCP PMTs). In this work, the silicon photomultipliers (SiPMs) were tested for the first time as the photodetectors in Cherenkov TOF PET. The high photon detection efficiency (PDE) of SiPMs led to a large improvement in detection efficiency. On the other hand, the time response of currently available SiPMs is not as good as that of MCP PMTs. The SiPM dark counts introduce a new source of random coincidences in Cherenkov method, which would be overwhelming with present SiPM technology at room temperature. When the apparatus was cooled, its performance significantly improved.

  11. Telescope Adaptive Optics Code

    SciTech Connect

    Phillion, D.

    2005-07-28

    The Telescope AO Code has general adaptive optics capabilities plus specialized models for three telescopes with either adaptive optics or active optics systems. It has the capability to generate either single-layer or distributed Kolmogorov turbulence phase screens using the FFT. Missing low order spatial frequencies are added using the Karhunen-Loeve expansion. The phase structure curve is extremely dose to the theoreUcal. Secondly, it has the capability to simulate an adaptive optics control systems. The default parameters are those of the Keck II adaptive optics system. Thirdly, it has a general wave optics capability to model the science camera halo due to scintillation from atmospheric turbulence and the telescope optics. Although this capability was implemented for the Gemini telescopes, the only default parameter specific to the Gemini telescopes is the primary mirror diameter. Finally, it has a model for the LSST active optics alignment strategy. This last model is highly specific to the LSST

  12. Metamaterials for Cherenkov Radiation Based Particle Detectors

    SciTech Connect

    Tyukhtin, A. V.; Schoessow, P.; Kanareykin, A.; Antipov, S.

    2009-01-22

    Measurement of Cherenkov radiation (CR) has long been a useful technique for charged particle detection and beam diagnostics. We are investigating metamaterials engineered to have refractive indices tailored to enhance properties of CR that are useful for particle detectors and that cannot be obtained using conventional media. Cherenkov radiation in dispersive media with a large refractive index differs significantly from the same effect in conventional detector media, like gases or aerogel. The radiation pattern of CR in dispersive metamaterials presents lobes at very large angles with respect to particle motion. Moreover, the frequency and particle velocity dependence of the radiated energy can differ significantly from CR in a conventional dielectric medium.

  13. The Ring Imaging Cherenkov detectors of DELPHI

    SciTech Connect

    Adam, W.; Albrecht, E.; Allen, D.

    1995-08-01

    A Ring Imaging Cherenkov (RICH) detector system has been built and is now in full operation within the DELPHI experiment. Large data samples of Z{sup 0} decays are being collected with good resolution on the observed Cherenkov angles. Several studies of Z{sup 0} decays using the RICH have already been performed on limited samples. Disturbance of the detector operation caused by shrinkage of polymeric construction materials and by migration of radiator substance is reported. These effects have been counteracted and do not endanger the quality of the data.

  14. A COMBINED VERY LARGE TELESCOPE AND GEMINI STUDY OF THE ATMOSPHERE OF THE DIRECTLY IMAGED PLANET, β PICTORIS b

    SciTech Connect

    Currie, Thayne; Jayawardhana, Ray; Burrows, Adam; Madhusudhan, Nikku; Fukagawa, Misato; Girard, Julien H.; Dawson, Rebekah; Murray-Clay, Ruth; Kenyon, Scott; Kuchner, Marc; Matsumura, Soko; Chambers, John; Bromley, Ben

    2013-10-10

    We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet β Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While β Pic b's near-IR colors mimic those of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects—i.e., κ And b and 1RXJ 1609B—match β Pic b's JHK{sub s}L' photometry and its 3.1 μm and 5 μm photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large (∼60 μm) dust grains fail to reproduce the β Pic b spectrum. However, models incorporating thick clouds similar to those found for HR 8799 bcde, but also with small (a few microns) modal particle sizes, yield fits consistent with the data within the uncertainties. Assuming solar abundance models, thick clouds, and small dust particles ((a) = 4 μm), we derive atmosphere parameters of log (g) = 3.8 ± 0.2 and T{sub eff} = 1575-1650 K, an inferred mass of 7{sup +4}{sub -3} M{sub J} , and a luminosity of log(L/L{sub ☉}) ∼–3.80 ± 0.02. The best-estimated planet radius, ≈1.65 ± 0.06 R{sub J} , is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if β Pic b is younger than ≈7 Myr, consistent with a late formation well after its host star's birth ∼12{sup +8}{sub -4} Myr ago.

  15. Lear jet telescope system

    NASA Technical Reports Server (NTRS)

    Erickson, E. F.; Goorvitch, D.; Dix, M. G.; Hitchman, M. J.

    1974-01-01

    The telescope system was designed as a multi-user facility for observations of celestial objects at infrared wavelengths, where ground-based observations are difficult or impossible due to the effects of telluric atmospheric absorption. The telescope is mounted in a Lear jet model 24B which typically permits 70 min. of observing per flight at altitudes in excess of 45,000 ft (13 km). Telescope system installation is discussed, along with appropriate setup and adjustment procedures. Operation of the guidance system is also explained, and checklists are provided which pertain to the recommended safe operating and in-flight trouble-shooting procedures for the equipment.

  16. TRANSMISSION SPECTRA OF TRANSITING PLANET ATMOSPHERES: MODEL VALIDATION AND SIMULATIONS OF THE HOT NEPTUNE GJ 436b FOR THE JAMES WEBB SPACE TELESCOPE

    SciTech Connect

    Shabram, Megan; Fortney, Jonathan J.; Greene, Thomas P.; Freedman, Richard S.

    2011-02-01

    We explore the transmission spectrum of the Neptune-class exoplanet GJ 436b, including the possibility that its atmospheric opacity is dominated by a variety of nonequilibrium chemical products. We also validate our transmission code by demonstrating close agreement with analytic models that use only Rayleigh scattering or water vapor opacity. We find broad disagreement with radius variations predicted by another published model. For GJ 436b, the relative coolness of the planet's atmosphere, along with its implied high metallicity, may make it dissimilar in character compared to 'hot Jupiters'. Some recent observational and modeling efforts suggest low relative abundances of H{sub 2}O and CH{sub 4} present in GJ 436b's atmosphere, compared to calculations from equilibrium chemistry. We include these characteristics in our models and examine the effects of absorption from methane-derived higher-order hydrocarbons. To our knowledge, the effects of these nonequilibrium chemical products on the spectra of close-in giant planets have not previously been investigated. Significant absorption from HCN and C{sub 2}H{sub 2} is found throughout the infrared, while C{sub 2}H{sub 4} and C{sub 2}H{sub 6} are less easily seen. We perform detailed simulations of James Webb Space Telescope observations, including all likely noise sources, and find that we will be able to constrain chemical abundance regimes from this planet's transmission spectrum. For instance, the width of the features at 1.5, 3.3, and 7 {mu}m indicates the amount of HCN versus C{sub 2}H{sub 2} present. The NIRSpec prism mode will be useful due to its large spectral range and the relatively large number of photo-electrons recorded per spectral resolution element. However, extremely bright host stars like GJ 436 may be better observed with a higher spectroscopic resolution mode in order to avoid detector saturation. We find that observations with the MIRI low-resolution spectrograph should also have high signal

  17. The major upgrade of the MAGIC telescopes, Part II: A performance study using observations of the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Bangale, P.; Barceló, M.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Bitossi, M.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Cecchi, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Corti, D.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; de Oña Wilhelmi, E.; Delgado Mendez, C.; Dettlaff, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher, D.; Elsaesser, D.; Fidalgo, D.; Fink, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giavitto, G.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Haberer, W.; Hadasch, D.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hildebrand, D.; Hose, J.; Hrupec, D.; Idec, W.; Illa, J. M.; Kadenius, V.; Kellermann, H.; Knoetig, M. L.; Kodani, K.; Konno, Y.; Krause, J.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lemus, J. L.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; López-Oramas, A.; Lorca, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Negrello, M.; Neustroev, V.; Niedzwiecki, A.; Nilsson, K.; Nishijima, K.; Noda, K.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Rügamer, S.; Saito, T.; Saito, K.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schlammer, J.; Schmidl, S.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Stamerra, A.; Steinbring, T.; Storz, J.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Tejedor, L. A.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Vogler, P.; Wetteskind, H.; Will, M.; Zanin, R.

    2016-01-01

    MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes located in the Canary island of La Palma, Spain. During summer 2011 and 2012 it underwent a series of upgrades, involving the exchange of the MAGIC-I camera and its trigger system, as well as the upgrade of the readout system of both telescopes. We use observations of the Crab Nebula taken at low and medium zenith angles to assess the key performance parameters of the MAGIC stereo system. For low zenith angle observations, the standard trigger threshold of the MAGIC telescopes is ∼ 50 GeV. The integral sensitivity for point-like sources with Crab Nebula-like spectrum above 220 GeV is (0.66 ± 0.03)% of Crab Nebula flux in 50 h of observations. The angular resolution, defined as the σ of a 2-dimensional Gaussian distribution, at those energies is ≲ 0.07°, while the energy resolution is 16%. We also re-evaluate the effect of the systematic uncertainty on the data taken with the MAGIC telescopes after the upgrade. We estimate that the systematic uncertainties can be divided in the following components: < 15% in energy scale, 11%-18% in flux normalization and ± 0.15 for the energy spectrum power-law slope.

  18. The large binocular telescope.

    PubMed

    Hill, John M

    2010-06-01

    The Large Binocular Telescope (LBT) Observatory is a collaboration among institutions in Arizona, Germany, Italy, Indiana, Minnesota, Ohio, and Virginia. The telescope on Mount Graham in Southeastern Arizona uses two 8.4 m diameter primary mirrors mounted side by side. A unique feature of the LBT is that the light from the two Gregorian telescope sides can be combined to produce phased-array imaging of an extended field. This cophased imaging along with adaptive optics gives the telescope the diffraction-limited resolution of a 22.65 m aperture and a collecting area equivalent to an 11.8 m circular aperture. This paper describes the design, construction, and commissioning of this unique telescope. We report some sample astronomical results with the prime focus cameras. We comment on some of the technical challenges and solutions. The telescope uses two F/15 adaptive secondaries to correct atmospheric turbulence. The first of these adaptive mirrors has completed final system testing in Firenze, Italy, and is planned to be at the telescope by Spring 2010. PMID:20517352

  19. The mechanism of Vavilov-Cherenkov radiation

    NASA Astrophysics Data System (ADS)

    Kobzev, A. P.

    2010-05-01

    The mechanism of generation of Vavilov-Cherenkov radiation is discussed in this article. The developers of the theory of the Vavilov-Cherenkov effect, I.E. Tamm and I.M. Frank, attributed this effect to their discovery of a new mechanism of radiation when a charged particle moves uniformly and rectilinearly in the medium. As such a mechanism presupposes the violation of the laws of conservation of energy and momentum, they proposed the abolition of these laws to account for the Vavilov-Cherenkov radiation mechanism. This idea has received a considerably wide acceptance in the creation of other theories, for example, transition radiation theory. In this paper, the radiation mechanism for the charge constant motion is demonstrated to be incorrect, because it contradicts not only the laws of conservation of energy and momentum, but also the very definitions of uniform and rectilinear motion (Newton's First Law). A consistent explanation of the Vavilov-Cherenkov radiation microscopic mechanism that does not contradict the basic laws is proposed. It is shown that the radiation arises from the interaction of the moving charge with bound charges that are spaced fairly far away from its trajectory. The Vavilov-Cherenkov radiation mechanism bears a slowing down character, but it differs fundamentally from bremsstrahlung, primarily because the Vavilov-Cherenkov radiation onset results from a two-stage process. First, the moving particle polarizes the medium; then, the already polarized atoms radiate coherently, provided that the particle velocity exceeds the phase speed of light in the medium. If the particle velocity is less than the phase speed of light in the medium, the polarized atoms return energy to the outgoing particle. In this case, radiation is not observed. Special attention is given to the relatively constant particle velocity as the condition of the coherent composition of waves. However, its motion cannot be designated as a uniform and rectilinear one in the

  20. Reverse surface-polariton cherenkov radiation.

    PubMed

    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

  1. Reverse surface-polariton cherenkov radiation

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  2. HAWC - The High Altitude Water Cherenkov Detector

    NASA Astrophysics Data System (ADS)

    Tepe, Andreas; HAWC Collaboration

    2012-07-01

    The high altitude water Cherenkov observatory (HAWC) is an instrument for the detection of high energy cosmic gamma-rays. Its predecessor Milagro has successfully proven that the water Cherenkov technology for gamma-ray astronomy is a useful technique. HAWC is currently under construction at Sierra Negra in Mexico at an altitude of 4100 m and will include several improvements compared to Milagro. Two complementary DAQ systems of the HAWC detector allow for the observation of a large fraction of the sky with a very high duty cycle and independent of environmental conditions. HAWC will observe the gamma-ray sky from about 100 GeV up to 100 TeV. Also the cosmic ray flux anisotropy on different angular length scales is object of HAWC science. Because of HAWC's large effective area and field of view, we describe its prospects to observe gamma-ray bursts (GRBs) as an example for transient sources.

  3. 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

  4. Particle identification via Cherenkov correlated timing

    NASA Astrophysics Data System (ADS)

    Honscheid, K.; Selen, M.; Sivertz, M.

    1994-04-01

    We describe a new particle-identification technique based on precision timing measurements to determine the Cherenkov angle of photons emitted by particles passing through a quartz radiator. A Monte Carlo simulation indicates that good π-K separation can be obtained for a large range of particle momenta and incident angles. A prototype detector to demonstrate the feasibility of the concept is under construction.

  5. Study of TOF PET using Cherenkov light

    NASA Astrophysics Data System (ADS)

    Korpar, S.; Dolenec, R.; Križan, P.; Pestotnik, R.; Stanovnik, A.

    We report on measurements of coincident 511 keV annihilation photons via detection of Cherenkov radiation in PbF2 crystals attached to a microchannel plate photomultiplier. Back to back timing resolution has been studied with segmented crystals. The detection efficiency has also been measured and compared to the simulation results. We have also searched for the optimum radiator parameters by simulating timing resolution and effciency as a function of crystal thickness and transmission cut-off.

  6. Latest results on searches for dark matter signatures in galactic and extragalactic selected targets by the MAGIC Telescopes

    NASA Astrophysics Data System (ADS)

    Giammaria, P.; Aleksić, J.; Lombardi, S.; Maggio, C.; Palacio, J.; Rico, J.; Vanzo, G.; Vazquez Acosta, M.; MAGIC Collaboration

    2016-05-01

    Discovering the nature of Dark Matter (DM) is one of the fundamental challenges of the modern physics. Indirect searches of DM are devoted to look for non-gravitational signals of its presence in the highly DM dominated cosmic regions. Within the weakly interacting massive particles (WIMPs) scenario, we expect very high energy (VHE) gamma-ray emissions resulting from annihilation and/or decay of DM particles. Since the beginning of operations, the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes are carrying out deep observations of several promising DM targets, with the aim of detecting such signals or alternatively setting stringent constrains to DM particle models in the TeV mass region. In this contribution we present the latest indirect DM search results achieved by MAGIC on several targets, such as dwarf satellites – where MAGIC reached the strongest constraints on DM annihilation searches above few hundreds of GeV –, galaxy clusters, and the Galactic Center.

  7. Measuring module of the Cherenkov water detector NEVOD

    NASA Astrophysics Data System (ADS)

    Kindin, V. V.; Amelchakov, M. B.; Barbashina, N. S.; Bogdanov, A. G.; Burtsev, V. D.; Chernov, D. V.; Khokhlov, S. S.; Khomyakov, V. A.; Kokoulin, R. P.; Kompaniets, K. G.; Kovylyaeva, E. A.; Kruglikova, V. S.; Ovchinnikov, V. V.; Petrukhin, A. A.; Shulzhenko, I. A.; Shutenko, V. V.; Yashin, I. I.; Zadeba, E. A.

    2015-08-01

    Quasispherical Module (QSM) of Cherenkov water detector NEVOD represents six low-noise FEU-200 photomultipliers with flat photocathodes (15 cm in diameter), oriented along the axes of orthogonal coordinate system. Such configuration allows to register Cherenkov radiation arriving from any direction with almost equal efficiency. The results of measurements of QSM characteristics in the sensitive volume of the NEVOD detector during the registration of Cherenkov radiation of single muons at different distances and angles are discussed.

  8. Air Cherenkov methods in cosmic rays: Review and some history

    NASA Astrophysics Data System (ADS)

    Lidvansky, A. S.

    2006-08-01

    Radiation first discovered by Pavel Cherenkov is used for developing a variety of methods in cosmic-ray studies. Among them, air Cherenkov methods form a separate area with several lines of research. Numerous applications of air Cherenkov radiation in studies of extensive air showers, in γ-astronomy and neutrino physics are reviewed. A tribute is given to Alexander Chudakov whose pioneer ideas and experimental skill laid foundation for the present-day progress.

  9. Why Space Telescopes Are Amazing

    NASA Technical Reports Server (NTRS)

    Rigby, Jane R.

    2012-01-01

    One of humanity's best ideas has been to put telescopes in space. The dark stillness of space allows telescopes to perform much better than they can on even the darkest and clearest of Earth's mountaintops. In addition, from space we can detect colors of light, like X-rays and gamma rays, that are blocked by the Earth's atmosphere I'll talk about NASA's team of great observatories: the Hubble Space Telescope, Spitzer Space Telescope, and Chandra X-ray Observatory} and how they've worked together to answer key questions: When did the stars form? Is there really dark matter? Is the universe really expanding ever faster and faster?

  10. Hubble Space Telescope Configuration

    NASA Technical Reports Server (NTRS)

    1985-01-01

    This image illustrates the overall Hubble Space Telescope (HST) configuration. The HST is the product of a partnership between NASA, European Space Agency Contractors, and the international community of astronomers. It is named after Edwin P. Hubble, an American Astronomer who discovered the expanding nature of the universe and was the first to realize the true nature of galaxies. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The HST detects objects 25 times fainter than the dimmest objects seen from Earth and provides astronomers with an observable universe 250 times larger than visible from ground-based telescopes, perhaps as far away as 14 billion light-years. The HST views galaxies, stars, planets, comets, possibly other solar systems, and even unusual phenomena such as quasars, with 10 times the clarity of ground-based telescopes. The major elements of the HST are the Optical Telescope Assembly (OTA), the Support System Module (SSM), and the Scientific Instruments (SI). The HST is approximately the size of a railroad car, with two cylinders joined together and wrapped in a silvery reflective heat shield blanket. Wing-like solar arrays extend horizontally from each side of these cylinders, and dish-shaped anternas extend above and below the body of the telescope. The HST was deployed from the Space Shuttle Discovery (STS-31 mission) into Earth orbit in April 1990. The Marshall Space Flight Center had responsibility for design, development, and construction of the HST. The Perkin-Elmer Corporation, in Danbury, Connecticut, developed the optical system and guidance sensors. The Lockheed Missile and Space Company of Sunnyvale, California produced the protective outer shroud and spacecraft systems, and assembled and tested the finished telescope.

  11. RF Cherenkov picosecond timing technique for high energy physics applications

    SciTech Connect

    Margaryan, Amur; Hashimoto, Osamu; Majewski, Stanislaw; Tang, Liguang

    2008-09-01

    The Cherenkov time-of-propagation (TOP) detector and Cherenkov time-of-flight (TOF) detector in a ?head-on? geometry based on the recently proposed time measuring technique with radio frequency (RF) phototube are considered. Results of the Monte Carlo simulations are presented.

  12. The endcap Cherenkov ring imaging detector at SLD

    SciTech Connect

    Abe, K.; Hasegawa, K.; Hawegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H.; Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dolinsky, S.

    1995-05-01

    The authors present the Cherenkov Ring Imaging Detector in the endcap regions of the SLD detector and report initial performance. The endcap CRID was completed and commissioned in 1993 and is fully operational for the 1994 run. First Cherenkov rings have been observed. The endcap CRID detectors and fluid systems are described and initial operational experience is discussed.

  13. Space Telescopes

    NASA Technical Reports Server (NTRS)

    Rigby, Jane R.

    2011-01-01

    The science of astronomy depends on modern-day temples called telescopes. Astronomers make pilgrimages to remote mountaintops where these large, intricate, precise machines gather light that rains down from the Universe. Bit, since Earth is a bright, turbulent planet, our finest telescopes are those that have been launched into the dark stillness of space. These space telescopes, named after heroes of astronomy (Hubble, Chandra, Spitzer, Herschel), are some of the best ideas our species has ever had. They show us, over 13 billion years of cosmic history, how galaxies and quasars evolve. They study planets orbiting other stars. They've helped us determine that 95% of the Universe is of unknown composition. In short, they tell us about our place in the Universe. The next step in this journey is the James Webb Space Telescope, being built by NASA, Europe, and Canada for a 2018 launch; Webb will reveal the first galaxies that ever formed.

  14. SNAP telescope

    SciTech Connect

    Lampton, Michael L.; Akerlof, C.W.; Aldering, G.; Amanullah, R.; Astier, P.; Barrelet, E.; Bebek, C.; Bergstrom, L.; Bercovitz, J.; Bernstein, G.; Bester, M.; Bonissent, A.; Bower, C.; Carithers Jr., W.C.; Commins, E.D.; Day, C.; Deustua, S.E.; DiGennaro, R.; Ealet, A.; Ellis,R.S.; Eriksson, M.; Fruchter, A.; Genat, J.-F.; Goldhaber, G.; Goobar,A.; Groom, D.; Harris, S.E.; Harvey, P.R.; Heetderks, H.D.; Holland,S.E.; Huterer, D.; Karcher, A.; Kim, A.G.; Kolbe, W.; Krieger, B.; Lafever, R.; Lamoureux, J.; Levi, M.E.; Levin, D.S.; Linder, E.V.; Loken,S.C.; Malina, R.; Massey, R.; McKay, T.; McKee, S.P.; Miquel, R.; Mortsell, E.; Mostek, N.; Mufson, S.; Musser, J.; Nugent, P.; Oluseyi,H.; Pain, R.; Palaio, N.; Pankow, D.; Perlmutter, S.; Pratt, R.; Prieto,E.; Refregier, A.; Rhodes, J.; Robinson, K.; Roe, N.; Sholl, M.; Schubnell, M.; Smadja, G.; Smoot, G.; Spadafora, A.; Tarle, G.; Tomasch,A.; von der Lippe, H.; Vincent, R.; Walder, J.-P.; Wang, G.; Wang, G.

    2002-07-29

    The SuperNova/Acceleration Probe (SNAP) mission will require a two-meter class telescope delivering diffraction limited images spanning a one degree field in the visible and near infrared wavelength regime. This requirement, equivalent to nearly one billion pixel resolution, places stringent demands on its optical system in terms of field flatness, image quality, and freedom from chromatic aberration. We discuss the advantages of annular-field three-mirror anastigmat (TMA) telescopes for applications such as SNAP, and describe the features of the specific optical configuration that we have baselined for the SNAP mission. We discuss the mechanical design and choice of materials for the telescope. Then we present detailed ray traces and diffraction calculations for our baseline optical design. We briefly discuss stray light and tolerance issues, and present a preliminary wavefront error budget for the SNAP Telescope. We conclude by describing some of tasks to be carried out during the upcoming SNAP research and development phase.

  15. Teaching Telescopes

    ERIC Educational Resources Information Center

    Reid, John S.

    1974-01-01

    Discusses experience of teaching optical experiments with emphasis upon the student's design and construction of refracting and reflecting telescopes. Concludes that the student's interest and acquired knowledge are greatly enhanced through the use of realistic experiments. (CC)

  16. Cherenkov detector for beam quality measurement

    NASA Astrophysics Data System (ADS)

    Orfanelli, S.

    2016-07-01

    A new detector to measure the machine induced background at larger radii has been developed and installed in the CMS experiment at the LHC. It consists of forty modules, each comprising a quartz bar read out by a photomultiplier tube. Since Cherenkov radiation is emitted in a forward cone around the charged particle trajectory, these detectors can distinguish between the arrival directions of the machine induced background and the collision products. The back-end electronics consists of a uTCA readout with excellent time resolution. The installation in the CMS is described and first commissioning measurements with the LHC beams in Run II are presented.

  17. Current state of ring imaging Cherenkov detectors

    SciTech Connect

    Coutrakon, G.B.

    1984-02-01

    This paper reviews several ring imaging Cherenkov detectors which are being used or developed to identify particles in high energy physics experiments. These detectors must have good detection efficiency for single photon-electrons and good spatial resolution over a large area. Emphasis is placed on the efficiencies and resolutions of these detectors as determined from ring imaging beam tests and other experiments. Following a brief review of the ring imaging technique, comparative evaluations are made of different forms of detectors and their respective materials.

  18. Cherenkov radiation as a serendipitous phenomenon

    NASA Astrophysics Data System (ADS)

    Kadmensky, S. G.

    2015-05-01

    A brief account is given of P A Cherenkov's Voronezh years, a period during which the future Nobel laureate in physics attended school (in the village of Novaya Chigla near Voronezh) and studied at Voronezh State University. The history of the serendipitous discovery of the radiation which was to be named after him is described and its importance for modern science is discussed. Possible modern approaches are considered to explain — without using the concept of 'cold nuclear synthesis' — some other unexpected experimental results on the nonthermonuclear fusion of light nuclei stimulated by electron beams and by laser and gamma radiations.

  19. Cherenkov-Vavilov Formulation of X Waves

    SciTech Connect

    Walker, S. C.; Kuperman, W. A.

    2007-12-14

    The field from a supersonic (or equivalently superluminal) point source in uniform motion [i.e., the Cherenkov-Vavilov (CV) effect] is shown to be equivalent to the diffractionless X-wave field. It is demonstrated that the power required to support an X wave is equivalent to the power dissipated by a CV source. In the context of the CV solution, it is clear that any supersonic or superluminal properties exhibited by X waves are purely phase effects. As a consequence, X waves cannot propagate a signal faster than the speed of waves, and thus necessarily obey the law on the finiteness of information transfer.

  20. Data Aquisition System of the CANGAROO-III Telescope

    NASA Astrophysics Data System (ADS)

    Kubo, H.; CANGAROO Collaboration

    2001-08-01

    We report the development of the data acquisition system of the CANGAROO-III imaging Cherenkov telescope. Multi-pixel cameras consisting of 552 and 427 PMTs are placed at the prime focus of the first and second telescopes respectively. The charge and hit timings of each PMT are measured with ADCs and TDCs respectively via a fast VME-bus which is selected to reduce the data acquisition time. The VME-bus data are read by computers running a linux OS. Furthermore a module to select hit pattern in hardware whether triggered PMTs are adjacent or not will be installed to the second telescope. In CANGAROO-III observations, a global trigger is generated by the coincidence of the local triggers of the four telescopes, and the event data is collected via fast-ethernet, and analyzed with the central event-builder. The data acquisition system of each telescope is designed to accept triggers up to 100 Hz.

  1. Signal acquisition in Cherenkov-type diagnostics of electron beams within tokamak facilities

    NASA Astrophysics Data System (ADS)

    Rabiński, Marek; Jakubowski, Lech; Sadowski, Marek J.; Żebrowski, Jarosław; Jakubowski, Marcin J.; Malinowski, Karol; Mirowski, Robert

    2015-09-01

    The paper presents feasibility and design studies of Cherenkov-type probes, a development of the measuring head construction designed for different tokamak devices, and in particular the acquisition of optical signals to a data storage system. In order to lower the energy threshold of the electron detection the authors applied radiators with the highest values of the refractive index. Different radiator materials, such as aluminium nitride and CVD diamond were applied. Several versions of measuring heads and different manipulators, e.g., a movable vacuum-tight shaft or a fast-moving reciprocating probe, were manufactured and used. The practical application of the Cherenkov probes required also a consideration of spectral characteristics of optical fibres and photomultipliers. The Cherenkov radiation, as generated inside the radiators, is lead out through separate fibres (optical cables) to the atmospheric pressure side. The emitted radiation in the blue (near ultraviolet) spectrum range should be collected and delivered through appropriate optical cables to a control room, amplified within photomultipliers and recorded in a digital form. In order to investigate an electron energy distribution the multi-channel probes have also been designed and applied.

  2. The South Pole Telescope

    SciTech Connect

    Ruhl, J.E.; Ade, P.A.R.; Carlstrom, J.E.; Cho, H.M.; Crawford,T.; Dobbs, M.; Greer, C.H.; Halverson, N.W.; Holzapfel, W.L.; Lanting,T.M.; Lee, A.T.; Leitch, E.M.; Leong, J.; Lu, W.; Lueker, M.; Mehl, J.; Meyer, S.S.; Mohr, J.J.; Padin, S.; Plagge, T.; Pryke, C.; Runyan, M.C.; Schwan, D.; Sharp, M.K.; Spieler, H.; Staniszewski, Z.; Stark, A.A.

    2004-11-04

    A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs an off-axis primary with a 10 m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and will feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key project will be to conduct a survey over 4000 degrees for galaxy clusters using the Sunyaev-Zeldovich Effect. This survey should find many thousands of clusters with a mass selection criteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable significant constraints to be placed on the equation of state of the dark energy.

  3. Telescope Adaptive Optics Code

    Energy Science and Technology Software Center (ESTSC)

    2005-07-28

    The Telescope AO Code has general adaptive optics capabilities plus specialized models for three telescopes with either adaptive optics or active optics systems. It has the capability to generate either single-layer or distributed Kolmogorov turbulence phase screens using the FFT. Missing low order spatial frequencies are added using the Karhunen-Loeve expansion. The phase structure curve is extremely dose to the theoreUcal. Secondly, it has the capability to simulate an adaptive optics control systems. The defaultmore » parameters are those of the Keck II adaptive optics system. Thirdly, it has a general wave optics capability to model the science camera halo due to scintillation from atmospheric turbulence and the telescope optics. Although this capability was implemented for the Gemini telescopes, the only default parameter specific to the Gemini telescopes is the primary mirror diameter. Finally, it has a model for the LSST active optics alignment strategy. This last model is highly specific to the LSST« less

  4. 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.

  5. The High Altitude Water Cherenkov Observatory

    NASA Astrophysics Data System (ADS)

    Mostafa, Miguel; HAWC Collaboration

    2016-03-01

    The High Altitude Water Cherenkov (HAWC) Observatory is a continuously operated, wide field of view experiment comprised of an array of 300 water Cherenkov detectors (WCDs) to study transient and steady emission of TeV gamma and cosmic rays. Each 200000 l WCD is instrumented with 4 PMTs providing charge and timing information. The array covers ~22000 m2 at an altitude of 4100 m a.s.l. inside the Pico de Orizaba national park in Mexico. The high altitude, large active area, and optical isolation of the PMTs allows us to reliably estimate the energy and determine the arrival direction of gamma and cosmic rays with significant sensitivity over energies from several hundred GeV to a hundred TeV. Continuously observing 2 / 3 of the sky every 24 h, HAWC plays a significant role as a survey instrument for multi-wavelength studies. The performance of HAWC makes possible the detection of both transient and steady emissions, the study of diffuse emission and the measurement of the spectra of gamma-ray sources at TeV energies. HAWC is also sensitive to the emission from GRBs above 100 GeV. I will highlight the results from the first year of operation of the full HAWC array, and describe the ongoing site work to expand the array by a factor of 4 to explore the high energy range.

  6. The High Altitude Water Cherenkov (HAWC) Observatory

    NASA Astrophysics Data System (ADS)

    Springer, Wayne

    2014-06-01

    The High Altitude Water Cherenkov (HAWC) observatory is a continuously operated, wide field of view detector based upon a water Cherenkov technology developed by the Milagro experiment. HAWC observes, at an elevation of 4100 m on Sierra Negra Mountain in Mexico, extensive air showers initiated by gamma and cosmic rays. The completed detector will consist of 300 closely spaced water tanks each instrumented with four photomultiplier tubes that provide timing and charge information used to reconstruct energy and arrival direction. HAWC has been optimized to observe transient and steady emission from point as well as diffuse sources of gamma rays in the energy range from several hundred GeV to several hundred TeV. Studies in solar physics as well as the properties of cosmic rays will also be performed. HAWC has been making observations at various stages of deployment since completion of 10% of the array in summer 2012. A discussion of the detector design, science capabilities, current construction/commissioning status, and first results will be presented...

  7. The High-Altitude Water Cherenkov Observatory

    NASA Astrophysics Data System (ADS)

    Mostafá, Miguel A.

    2014-10-01

    The High-Altitude Water Cherenkov (HAWC) observatory is a large field of view, continuously operated, TeV γ-ray experiment under construction at 4,100 m a.s.l. in Mexico. The HAWC observatory will have an order of magnitude better sensitivity, angular resolution, and background rejection than its predecessor, the Milagro experiment. The improved performance will allow us to detect both the transient and steady emissions, to study the Galactic diffuse emission at TeV energies, and to measure or constrain the TeV spectra of GeV γ-ray sources. In addition, HAWC will be the only ground-based instrument capable of detecting prompt emission from γ-ray bursts above 50 GeV. The HAWC observatory will consist of an array of 300 water Cherenkov detectors (WCDs), each with four photomultiplier tubes. This array is currently under construction on the flanks of the Sierra Negra volcano near the city of Puebla, Mexico. The first 30 WCDs (forming an array approximately the size of Milagro) were deployed in Summer 2012, and 100 WCDs will be taking data by May, 2013. We present in this paper the motivation for constructing the HAWC observatory, the status of the deployment, and the first results from the constantly growing array.

  8. Progress in Cherenkov ring imaging. Part 2: Identification of charged hadrons at 200 GeV/c

    NASA Astrophysics Data System (ADS)

    Mangeot, Ph.; Coutrakon, G.; Hubbard, J. R.; M´, J.; Tichit, J.; Zadra, A.; Bouclier, R.; Charpak, G.; Million, J.; Peisert, A.; Santiard, J. C.; Sauli, F.; Brown, C. N.; Finley, D.; Glass, H.; Kirz, J.; McCarthy, R. L.

    1983-10-01

    We have used a ring-imaging Cherenkov detector to separate π's, K's, and antiprotons in a 200 GeV/ c beam at Fermilab. This device was built as a prototype for a large-aperture counter now in operation in Fermilab experiment E605. The radiator consisted of 8 m of atmospheric-pressure helium gas. The photon detector was a multistep proportional chamber. Cherenkov photons near 8 eV were detected by photoionization of triethylamine (TEA) vapor in the chamber. An average of 2.5 to 2.7 Cherenkov photons were observed per event, corresponding to a figure of merit N 0 ⋍ 45 per cm. A single-photon radius uncertainty of 0.47 mm was obtained with a helium/TEA/CH 4 gas mixture in the photon detector. The rms uncertainty in the determination of the Cherenkov angle was ΔΘ c/Θ max = 0.006 , corresponding to one-standard-deviation π/K separation at 500 GeV/ c. At 200 GeV/ c, the particle identification efficiency in a beam containing 95.2% π -, 4.3% K -, and 0.5% antiprotons was 92% for the π's, 83% for the K's, and 90% for the antiprotons.

  9. The Greenland Telescope

    NASA Astrophysics Data System (ADS)

    Grimes, Paul; Blundell, Raymond

    2012-09-01

    In the spring of 2010, the Academia Sinica Institute of Astronomy and Astrophysics, and the Smithsonian Astrophysical Observatory, acquired the ALMA North America prototype antenna - a state-of-the-art 12-m diameter dish designed for submillimeter astronomy. Together with the MIT-Haystack Observatory and the National Radio Astronomy Observatory, the plan is to retrofit this antenna for cold-weather operation and equip it with a suite of instruments designed for a variety of scientific experiments and observations. The primary scientific goal is to image the shadow of the Super-Massive Black Hole in M87 in order to test Einstein’s theory of relativity under extreme gravity. This requires the highest angular resolution, which can only be achieved by linking this antenna with others already in place to form a telescope almost the size of the Earth. We are therefore developing plans to install this antenna at the peak of the Greenland ice-sheet. This location will produce an equivalent North-South separation of almost 9,000 km when linked to the ALMA telescope in Northern Chile, and an East-West separation of about 6,000 km when linked to SAO and ASIAA’s Submillimeter Array on Mauna Kea, Hawaii, and will provide an angular resolution almost 1000 times higher than that of the most powerful optical telescopes. Given the quality of the atmosphere at the proposed telescope location, we also plan to make observations in the atmospheric windows at 1.3 and 1.5 THz. We will present plans to retrofit the telescope for cold-weather operation, and discuss potential instrumentation and projected time-line.

  10. Quenching the scintillation in CF4 Cherenkov gas radiator

    NASA Astrophysics Data System (ADS)

    Blake, T.; D`Ambrosio, C.; Easo, S.; Eisenhardt, S.; Fitzpatrick, C.; Forty, R.; Frei, C.; Gibson, V.; Gys, T.; Harnew, N.; Hunt, P.; Jones, C. R.; Lambert, R. W.; Matteuzzi, C.; Muheim, F.; Papanestis, A.; Perego, D. L.; Piedigrossi, D.; Plackett, R.; Powell, A.; Topp-Joergensen, S.; Ullaland, O.; Websdale, D.; Wotton, S. A.; Wyllie, K.

    2015-08-01

    CF4 is used as a Cherenkov gas radiator in one of the Ring Imaging Cherenkov detectors at the LHCb experiment at the CERN Large Hadron Collider. CF4 is well known to have a high scintillation photon yield in the near and far VUV, UV and in the visible wavelength range. A large flux of scintillation photons in our photon detection acceptance between 200 and 800 nm could compromise the particle identification efficiency. We will show that this scintillation photon emission system can be effectively quenched, consistent with radiationless transitions, with no significant impact on the photons resulting from Cherenkov radiation.

  11. Cherenkov neutron detector for fusion reaction and runaway electron diagnostics.

    PubMed

    Cheon, MunSeong; Kim, Junghee

    2015-08-01

    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. PMID:26329194

  12. Cherenkov neutron detector for fusion reaction and runaway electron diagnostics

    SciTech Connect

    Cheon, MunSeong 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.

  13. Cherenkov Light-based Beam Profiling for Ultrarelativistic Electron Beams

    SciTech Connect

    Adli, E.; Gessner, S. J.; Corde, S.; Hogan, M. J.; Bjerke, H. H.

    2015-02-09

    We describe a beam profile monitor design based on Cherenkov light emitted from a charged particle beam in an air gap. The main components of the profile monitor are silicon wafers used to reflect Cherenkov light onto a camera lens system. The design allows for measuring large beam sizes, with large photon yield per beam charge and excellent signal linearity with beam charge. Furthermore, the profile monitor signal is independent of the particle energy for ultrarelativistic particles. Different design and parameter considerations are discussed. A Cherenkov light-based profile monitor has been installed at the FACET User Facility at SLAC. Finally, we report on the measured performance of this profile monitor.

  14. Infrared telescope

    NASA Technical Reports Server (NTRS)

    Karr, G. R.; Hendricks, J. B.

    1985-01-01

    The development of the Infrared Telescope for Spacelab 2 is discussed. The design, development, and testing required to interface a stationary superfluid helium dewar with a scanning cryostate capable of operating in the zero-g environment in the space shuttle bay is described.

  15. Selecting Your First Telescope.

    ERIC Educational Resources Information Center

    Harrington, Sherwood

    1982-01-01

    Designed for first-time telescope purchasers, provides information on how a telescope works; major telescope types (refractors, reflectors, compound telescopes); tripod, pier, altazimuth, and equatorial mounts; selecting a telescope; visiting an astronomy club; applications/limitations of telescope use; and tips on buying a telescope. Includes a…

  16. An innovative telescope control system architecture for SST-GATE telescopes at the CTA Observatory

    NASA Astrophysics Data System (ADS)

    Fasola, Gilles; Mignot, Shan; Laporte, Philippe; Abchiche, Abdel; Buchholtz, Gilles; Jégouzo, Isabelle

    2014-07-01

    SST-GATE (Small Size Telescope - GAmma-ray Telescope Elements) is a 4-metre telescope designed as a prototype for the Small Size Telescopes (SST) of the Cherenkov Telescope Array (CTA), a major facility for the very high energy gamma-ray astronomy of the next three decades. In this 100-telescope array there will be 70 SSTs, involving a design with an industrial view aiming at long-term service, low maintenance effort and reduced costs. More than a prototype, SST-GATE is also a fully functional telescope that shall be usable by scientists and students at the Observatoire de Meudon for 30 years. The Telescope Control System (TCS) is designed to work either as an element of a large array driven by an array controller or in a stand-alone mode with a remote workstation. Hence it is built to be autonomous with versatile interfacing; as an example, pointing and tracking —the main functions of the telescope— are managed onboard, including astronomical transformations, geometrical transformations (e.g. telescope bending model) and drive control. The core hardware is a CompactRIO (cRIO) featuring a real-time operating system and an FPGA. In this paper, we present an overview of the current status of the TCS. We especially focus on three items: the pointing computation implemented in the FPGA of the cRIO —using CORDIC algorithms— since it enables an optimisation of the hardware resources; data flow management based on OPCUA with its specific implementation on the cRIO; and the use of an EtherCAT field-bus for its ability to provide real-time data exchanges with the sensors and actuators distributed throughout the telescope.

  17. Nonlinear theory of a plasma Cherenkov maser

    SciTech Connect

    Choi, J.S.; Heo, E.G.; Choi, D.I.

    1995-12-31

    The nonlinear saturation state in a plasma Cherenkov maser (PCM) propagating the intense relativistic electron beam through a circular waveguide partially filled with a dense annular plasma, is analyzed from the nonlinear formulation based on the cold fluid-Maxwell equations. We obtain the nonlinear efficiency and the final operation frequency under consideration of the effects of the beam current, the beam energy and the slow wave structure. We show that the saturation mechanism of a PCM instablity is a close correspondence in that of the relativistic two stream instability by the coherent trapping of electrons in a single most-ustable wave. And the optimal conditions in PCM operation are also obtained from performing our nonliear analysis together with computer simulations.

  18. Cherenkov radiation from short relativistic bunches: general approach.

    PubMed

    Baturin, S S; Kanareykin, A D

    2014-11-21

    In recent years new interest in Cherenkov radiation has arisen based on progress in its new applications like biomedical imaging, photonic structures, metamaterials, and beam physics. These new applications require Cherenkov radiation theory of short bunches to be extended to rather more complicated media and structures than considered originally. We present a new general approach to the analysis of Cherenkov fields and loss factors for relativistic short bunches in arbitrary slow wave guiding systems. This new formalism is obtained by considering a general integral relation that allows calculation of the fields in the vicinity of the charge. The proposed approach dramatically simplifies simulations using analytical fields near the moving source of Cherenkov radiation. PMID:25479498

  19. CHERCAM: The Cherenkov imager of the CREAM experiment

    NASA Astrophysics Data System (ADS)

    Sallaz-Damaz, Y.; Barrau, A.; Bazer-Bachi, R.; Bourrion, O.; Bouvier, J.; Boyer, B.; Buénerd, M.; Derome, L.; Eraud, L.; Foglio, R.; Gallin-Martel, L.; Ganel, O.; Han, J. H.; Kim, K. C.; Lee, M. H.; Lutz, L.; Mangin-Brinet, M.; Malinine, A.; Menchaca-Rocha, A.; Périé, J. N.; Putze, A.; Scordilis, J.-P.; Seo, E. S.; Walpole, P.; Yoo, J. H.; Yoon, Y. S.; Zinn, S. Y.

    2008-09-01

    A Cherenkov imager, CHERCAM (CHERenkov CAMera), has been designed and built for the CREAM (Cosmic-Ray Energetic and Mass) balloon-borne experiment. The instrument will perform charge measurements of nuclear cosmic-ray over a range extending from proton to iron. It will achieve individual charge separation of the elements over this range [M. Buénerd, et al., in: 28th ICRC, Tsukuba, Japan, OG 1.5, 2003, p. 2157. [2

  20. Electron Beam Diagnostics using Coherent Cherenkov Radiation in Aerogel

    SciTech Connect

    Tikhoplav, R.; Knyazik, A.; Rosenzweig, J. B.; Ruelas, M.

    2009-01-22

    The use of coherent Cherenkov radiation as a diagnostic tool for longitudinal distribution of an electron beam is studied in this paper. Coherent Cherenkov radiation is produced in an aerogel with an index of refraction close to unity. An aerogel spectral properties are experimentally studied and analyzed. This method will be employed for the helical IFEL bunching experiment at Neptune linear accelerator facility at UCLA.

  1. Telescopic limiting magnitudes

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.

    1990-01-01

    The prediction of the magnitude of the faintest star visible through a telescope by a visual observer is a difficult problem in physiology. Many prediction formulas have been advanced over the years, but most do not even consider the magnification used. Here, the prediction algorithm problem is attacked with two complimentary approaches: (1) First, a theoretical algorithm was developed based on physiological data for the sensitivity of the eye. This algorithm also accounts for the transmission of the atmosphere and the telescope, the brightness of the sky, the color of the star, the age of the observer, the aperture, and the magnification. (2) Second, 314 observed values for the limiting magnitude were collected as a test of the formula. It is found that the formula does accurately predict the average observed limiting magnitudes under all conditions.

  2. Orthogonal Cherenkov sound in spin-orbit coupled systems

    NASA Astrophysics Data System (ADS)

    Smirnov, Sergey

    2015-06-01

    Conventionally the Cherenkov sound is governed by orbital degrees of freedom and is excited by supersonic particles. Additionally, it usually has a forward nature with a conic geometry known as the Cherenkov cone whose axis is oriented along the supersonic particle motion. Here we predict Cherenkov sound of a unique nature entirely resulting from the electronic spin degree of freedom and demonstrate a fundamentally distinct Cherenkov effect originating from essentially subsonic electrons in two-dimensional gases with both Bychkov-Rashba and Dresselhaus spin-orbit interactions. Specifically, we show that the axis of the conventional forward Cherenkov cone gets a nontrivial quarter-turn and at the same time the sound distribution strongly localizes around this rotated axis being now orthogonal to the subsonic particle motion. Apart from its fundamentally appealing nature, the orthogonal Cherenkov sound could have applications in planar semiconductor technology combining spin and acoustic phenomena to develop, e.g., acoustic amplifiers or sound sources with a flexible spin dependent orientation of the sound propagation.

  3. Atmospheric Sciences Meet Astronomy: Mutual Benefits from two Different Approaches

    NASA Astrophysics Data System (ADS)

    Kausch, Wolfgang; Noll, Stefan; Kimeswenger, Stefan; Kondrak, Matthias; Unterguggenberger, Stefanie; Przybilla, Norbert; Lakićević, Maša; Zeilinger, Werner

    2016-04-01

    ENVISAT (MIPAS instrument), Aura (MLS), and TIMED (SABER), and modelled data from the Global Data Assimilation System (GDAS), and the ERA/MACC reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF). In this presentation we give an overview on our methods to link these various data, the impact/application of these data on atmospheric sciences and observations with classical and future astro-particle Cherenkov telescopes, and present recent results.

  4. Sensitivity of the High Altitude Water Cherenkov Experiment to observe Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    González, M. M.

    Ground based telescopes have marginally observed very high energy emission (>100GeV) from gamma-ray bursts(GRB). For instance, Milagrito observed GRB970417a with a significance of 3.7 sigmas over the background. Milagro have not yet observed TeV emission from a GRB with its triggered and untriggered searches or GeV emission with a triggered search using its scalers. These results suggest the need of new observatories with higher sensitivity to transient sources. The HAWC (High Altitute Water Cherenkov) observatory is proposed as a combination of the Milagro tecnology with a very high altitude (>4000m over see level) site. The expected HAWC sensitivity for GRBs is at least >10 times the Milagro sensitivity. In this work HAWC sensitivity for GRBs is discussed for different detector configurations such as altitude, distance between PMTs, depth under water of PMTs, number of PMTs required for a trigger, etc.

  5. 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

  6. Robotic Telescopes

    NASA Astrophysics Data System (ADS)

    Akerlof, C. W.

    2001-05-01

    Since the discovery of gamma-ray bursts, a number of groups have attempted to detect correlated optical transients from these elusive objects. Following the flight of the BATSE instrument on the Compton Gamma-Ray Observatory in 1991, a prompt burst coordinate alert service, BACODINE (now GCN) became available to ground-based telescopes. Several instruments were built to take advantage of this facility, culminating in the discovery of a bright optical flash associated with GRB990123. To date, that single observation remains unique - no other prompt flashes have been seen for a dozen or so other bursts observed with comparably short response times. Thus, GRB prompt optical luminosities may be considerably dimmer than observed for the GRB990123 event or even absent altogether. A new generation of instruments is prepared to explore these possibilties using burst coordinates provided by HETE-2, Swift, Ballerina, Agile and other satellite missions. These telescopes have response times as short as a few seconds and reach limiting magnitudes, m_v 20, guaranteeing a sensitivity sufficient to detect the afterglow many hours later. Results from these experiments should provide important new data about the dynamics and locale of GRBs.

  7. Hubble Space Telescope satellite

    NASA Technical Reports Server (NTRS)

    Mitchell, R. E.

    1985-01-01

    The Hubble Space Telescope, named for the American astronomer Edwin Powell Hubble, will be the largest and most powerful astronomical instrument ever orbited. Placed above the obscuring effects of the earth's atmosphere in a 600-km orbit, this remotely-controlled, free-flying satellite observatory will expand the terrestrial-equivalent resolution of the universe by a factor of seven, or a volumetric factor of 350. This telescope has a 2.4-m primary mirror and can accommodate five scientific instruments (cameras, spectrographs and photometers). The optics are suitable for a spectral range from 1100 angstrom to 1 mm wavelength. With a projected service life of fifteen years, the spacecraft can be serviced on-orbit for replacement of degraded systems, to insert advanced scientific instruments, and to reboost the telescope from decayed altitudes. The anticipated image quality will be a result of extremely precise lambda/20 optics, stringent cleanliness, and very stable pointing: jitter will be held to less than 0.01 arcsecond for indefinite observation periods, consistent with instrument apertures as small as 0.1 arcsecond.

  8. INSTRUMENTS AND METHODS OF INVESTIGATION: Vavilov-Cherenkov amplifiers with irregular electrodynamic structures

    NASA Astrophysics Data System (ADS)

    Gulyaev, Yurii V.; Kravchenko, Viktor F.; Kuraev, Aleksandr A.

    2004-06-01

    Optimal control theory-based methods for improving the efficiency of Cherenkov microwave amplifiers with irregular electrodynamic structures are reviewed. The physics of optimal processes in amplifiers and oscillators with Cherenkov- and combined-type interactions is discussed.

  9. Characteristics of Cherenkov radiation in naturally occurring ice

    NASA Astrophysics Data System (ADS)

    Mikkelsen, R. E.; Poulsen, T.; Uggerhøj, U. I.; Klein, S. R.

    2016-03-01

    We revisit the theory of Cherenkov radiation in uniaxial crystals. Historically, a number of flawed attempts have been made at explaining this radiation phenomenon, and a consistent error-free description is nowhere available. We apply our calculation to a large modern day telescope—IceCube. Located in Antarctica, this detector makes use of the naturally occurring ice as a medium to generate Cherenkov radiation. However, due to the high pressure at the depth of the detector site, large volumes of hexagonal ice crystals are formed. We calculate how this affects the Cherenkov radiation yield and angular dependence. We conclude that the effect is small, at most about a percent, and would only be relevant in future high-precision instruments like e.g. Precision IceCube Next Generation Upgrade (PINGU). For radio-Cherenkov experiments which use the presence of a clear Cherenkov cone to determine the arrival direction, any variation in emission angle will directly and linearly translate into a change in apparent neutrino direction. In closing, we also describe a simple experiment to test this formalism and calculate the impact of anisotropy on light yields from lead tungstate crystals as used, for example, in the CMS calorimeter at the CERN LHC.

  10. Improved Detection of Cherenkov Radiation using Wavelength-Shifting Paints

    NASA Astrophysics Data System (ADS)

    Schmookler, Barak; Ou, Longwu

    2014-03-01

    Photomultiplier Tubes (PMTs) are often used to detect Cherenkov radiation in accelerator-based physics experiments. Since the Cherenkov spectrum is inversely proportional to the square of the photon's wavelength, PMTs with relatively good quantum efficiencies in the ultraviolet region can produce on average a higher number of photoelectrons. The application of certain paints, which absorb light at ultraviolet wavelengths and emit in the visible spectrum, to the surface of some PMTs allows for better sampling of the Cherenkov spectrum. The effects of various wavelength-shifting (WLS) paints designed by Eljen Technologies were tested on ET Enterprises, Model: 9390KB PMTs. Using a 106Ru β-source, Cherenkov light was produced in disks of fused silica. The charge spectrums of the PMTs were measured before and after application of the paint. The average number of photoelectrons produced from the Cherenkov radiation could be determined by knowing the value of the single-photoelectron peak and the mean of the charge spectrum. Four paints were tested, and the gain in the number photoelectrons produced varied from 10-35% for the different paints. Work Conducted at Thomas Jefferson National Accelerator Facility.

  11. Neutrino telescopes

    SciTech Connect

    Costantini, H.

    2012-09-15

    Neutrino astrophysics offers a new possibility to observe our Universe: high-energy neutrinos, produced by the most energetic phenomena in our Galaxy and in the Universe, carry complementary (if not exclusive) information about the cosmos: this young discipline extends in fact the conventional astronomy beyond the usual electromagnetic probe. The weak interaction of neutrinos with matter allows them to escape from the core of astrophysical objects and in this sense they represent a complementary messenger with respect to photons. However, their detection on Earth due to the small interaction cross section requires a large target mass. The aim of this article is to review the scientific motivations of the high-energy neutrino astrophysics, the detection principles together with the description of a running apparatus, the experiment ANTARES, the performance of this detector with some results, and the presentation of other neutrino telescope projects.

  12. Separation of scintillation and Cherenkov lights in linear alkyl benzene

    NASA Astrophysics Data System (ADS)

    Li, Mohan; Guo, Ziyi; Yeh, Minfang; Wang, Zhe; Chen, Shaomin

    2016-09-01

    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. The scintillation light yield was measured to be (1.01 ± 0.12) ×103 photons / MeV .

  13. Spin-Cherenkov effect and magnonic Mach cones

    NASA Astrophysics Data System (ADS)

    Yan, Ming; Kákay, Attila; Andreas, Christian; Hertel, Riccardo

    2013-12-01

    We report on the Cherenkov-type excitation of spin waves (SWs) in ferromagnets. Our micromagnetic simulations show that a localized magnetic field pulse moving sufficiently fast along the surface of a ferromagnet generates a SW boom, with a Mach-type cone of propagating wave fronts. The SWs are formed when the velocity of the source exceeds the propagation speed of SWs. Unlike the single cone of the usual Cherenkov effect, we find that the magnetic Mach cone consists of two wave fronts with different wave numbers. In patterned thin strips, this magnetic analog of the Cherenkov effect should enable the excitation of SWs with well-defined and velocity-dependent frequency. It thereby provides a promising route towards tunable SW generation, with important potential for applications in magnonic devices.

  14. Cherenkov Light-based Beam Profiling for Ultrarelativistic Electron Beams

    DOE PAGESBeta

    Adli, E.; Gessner, S. J.; Corde, S.; Hogan, M. J.; Bjerke, H. H.

    2015-02-09

    We describe a beam profile monitor design based on Cherenkov light emitted from a charged particle beam in an air gap. The main components of the profile monitor are silicon wafers used to reflect Cherenkov light onto a camera lens system. The design allows for measuring large beam sizes, with large photon yield per beam charge and excellent signal linearity with beam charge. Furthermore, the profile monitor signal is independent of the particle energy for ultrarelativistic particles. Different design and parameter considerations are discussed. A Cherenkov light-based profile monitor has been installed at the FACET User Facility at SLAC. Finally,more » we report on the measured performance of this profile monitor.« less

  15. Quantitative Cherenkov emission spectroscopy for tissue oxygenation assessment

    PubMed Central

    Axelsson, Johan; Glaser, Adam K.; Gladstone, David J.; Pogue, Brian W.

    2012-01-01

    Measurements of Cherenkov emission in tissue during radiation therapy are shown to enable estimation of hemoglobin oxygen saturation non-invasively, through spectral fitting of the spontaneous emissions from the treated tissue. Tissue oxygenation plays a critical role in the efficacy of radiation therapy to kill tumor tissue. Yet in-vivo measurement of this has remained elusive in routine use because of the complexity of oxygen measurement techniques. There is a spectrally broad emission of Cherenkov light that is induced during the time of irradiation, and as this travels through tissue from the point of the radiation deposition, the tissue absorption and scatter impart spectral changes. These changes can be quantified by diffuse spectral fitting of the signal. Thus Cherenkov emission spectroscopy is demonstrated for the first time quantitatively in vitro and qualitatively in vivo, and has potential for real-time online tracking of tissue oxygen during radiation therapy when fully characterized and developed. PMID:22418319

  16. A New Event Reconstruction Algorithm for Super-Kamiokande Water Cherenkov Detector

    NASA Astrophysics Data System (ADS)

    Tobayama, Shimpei

    2012-10-01

    Super-Kamiokande is the world's largest water Cherenkov particle detector located underground in Kamioka-mine, Gifu, Japan. The detector has been used for proton decay search, and observation of atmospheric, solar and supernova neutrinos. It also serves as the far detector for T2K long baseline neutrino oscillation experiment. The detector consists of a cylindrical tank filled with 50kt of ultra-pure water, and an array of 11,000 photomultiplier tubes (PMT) installed on the tank's inner wall record the time and intensity of the Cherenkov light emitted by charged particles traveling in the water. Using the information from the PMTs, particle type, interaction vertex, direction and momentum can be reconstructed. A new reconstruction algorithm is being developed which performs a simultaneous maximum likelihood determination of such parameters. Through Monte Carlo studies, it was found that the new algorithm has a significantly better particle identification performance and vertex/momentum resolutions, compared to the existing reconstruction software. In this talk, an outline of the new algorithm, its performance and implications on physics analyses will be presented.

  17. Cherenkov Radiation from Jets in Heavy-ion Collisions

    SciTech Connect

    Koch, Volker; Majumder, Abhijit; Wang, Xin-Nian

    2005-07-26

    The possibility of Cherenkov-like gluon bremsstrahlung in dense matter is studied. We point out that the occurrence of Cherenkov radiation in dense matter is sensitive to the presence of partonic bound states. This is illustrated by a calculation of the dispersion relation of a massless particle in a simple model in which it couples to two different massive resonance states. We further argue that detailed spectroscopy of jet correlations can directly probe the index of refraction of this matter, which in turn will provide information about the mass scale of these partonic bound states.

  18. Fast timing and trigger Cherenkov detector for collider experiments

    NASA Astrophysics Data System (ADS)

    Grigoryev, V. A.; Kaplin, V. A.; Karavicheva, T. L.; Konevskikh, A. S.; Kurepin, A. B.; Loginov, V. A.; Melikyan, Yu A.; Morozov, I. V.; Reshetin, A. I.; Serebryakov, D. V.; Shabanov, A. I.; Slupecki, M.; Trzaska, W. H.; Tykmanov, E. M.

    2016-02-01

    Analysis of fast timing and trigger Cherenkov detector's design for its use in collider experiments is presented. Several specific requirements are taken into account - necessity of the radiator's placement as close to the beam pipe as possible along with the requirement of gapless (solid) radiator's design. Characteristics of the Cherenkov detector's laboratory prototype obtained using a pion beam at the CERN Proton Synchrotron are also presented, showing the possibility of obtaining sufficiently high geometrical efficiency along with good enough time resolution (50 ps sigma).

  19. 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.

  20. Hubble Space Telescope-Concept

    NASA Technical Reports Server (NTRS)

    1986-01-01

    This is an artist's concept of the Hubble Space Telescope (HST). The HST is the product of a partnership between NASA, European Space Agency Contractors, and the international community of astronomers. It is named after Edwin P. Hubble, an American Astronomer who discovered the expanding nature of the universe and was the first to realize the true nature of galaxies. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The HST detects objects 25 times fainter than the dimmest objects seen from Earth and provides astronomers with an observable universe 250 times larger than is visible from ground-based telescopes, perhaps as far away as 14 billion light-years. The HST views galaxies, stars, planets, comets, possibly other solar systems, and even unusual phenomena such as quasars, with 10 times the clarity of ground-based telescopes. The major elements of the HST are the Optical Telescope Assembly (OTA), the Support System Module (SSM), and the Scientific Instruments (SI). The HST is approximately the size of a railroad car, with two cylinders joined together and wrapped in a silvery reflective heat shield blanket. Wing-like solar arrays extend horizontally from each side of these cylinders, and dish-shaped anternas extend above and below the body of the telescope. The HST was deployed from the Space Shuttle Discovery (STS-31 mission) into Earth orbit in April 1990. The Marshall Space Flight Center had responsibility for design, development, and construction of the HST. The Perkin-Elmer Corporation, in Danbury, Connecticut, developed the optical system and guidance sensors. The Lockheed Missile and Space Company of Sunnyvale, California produced the protective outer shroud and spacecraft systems, and assembled and tested the finished telescope.

  1. Hubble Space Telescope observations of Europa in and out of eclipse

    USGS Publications Warehouse

    Sparks, W.B.; McGrath, M.; Hand, K.; Ford, H.C.; Geissler, P.; Hough, J.H.; Turner, E.L.; Chyba, C.F.; Carlson, R.; Turnbull, M.

    2010-01-01

    Europa is a prime target for astrobiology and has been prioritized as the next target for a National Aeronautics and Space Administration flagship mission. It is important, therefore, that we advance our understanding of Europa, its ocean and physical environment as much as possible. Here, we describe observations of Europa obtained during its orbital eclipse by Jupiter using the Hubble Space Telescope. We obtained Advanced Camera for Surveys Solar Blind Channel far ultraviolet low-resolution spectra that show oxygen line emission both in and out of eclipse. We also used the Wide-Field and Planetary Camera-2 and searched for broad-band optical emission from fluorescence of the surface material, arising from the very high level of incident energetic particle radiation on ices and potentially organic substances. The high-energy particle radiation at the surface of Europa is extremely intense and is responsible for the production of a tenuous oxygen atmosphere and associated FUV line emission. Approximately 50% of the oxygen emission lasts at least a few hours into the eclipse. We discuss the detection limits of the optical emission, which allow us to estimate the fraction of incident energy reradiated at optical wavelengths, through electron-excited emission, Cherenkov radiation in the ice and fluorescent processes. ?? 2010 Cambridge University Press.

  2. The Data Acquisition of the MAGIC Telescope

    NASA Astrophysics Data System (ADS)

    Goebel, F.; Coarasa, J. A.; Stiehler, R.; Volkov, S.; MAGIC Collaboration

    2003-07-01

    The data acquisition system of the MAGIC telescope processes the Cherenkov signals registered in the high resolution camera consisting of 577 PMTs. The analog signals are transmitted via optical fibers to the electronics hut where they are stretched, split into high and low gain channels and digitized with 300 MHz 8 bit Flash ADCs. The digital data is read out by a multipro cessor PC which saves it to a RAID system and a tap e library. The system has been designed to process data at a rate of 20 MBytes/sec which is required by the maximum envisaged trigger rate of 1 kHz. Tests of the complete readout chain show that the achieved dynamic range is more than 1000.

  3. Noise and spurious pulses for Cherenkov light detection with 10-inch and 3-inch photomultipliers

    SciTech Connect

    Giordano, V.; Aiello, S.; Leonora, E. E-mail: Valentina.Giordano@ct.infn.it; Collaboration: KM3NeT Collaboration

    2014-11-18

    A large number of large photocathode area 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. The glass sphere serves as mechanical protection while ensuring good light transmission. The performance of the telescope is largely dependent on the presence of noise pulses present on the anode of the photomultipliers. A study was conducted of noise pulses of Hamamatsu 10-inch and 3-inch diameter photomultipliers measuring time and charge distributions of dark pulses, pre-pulses, delayed pulses, and after-pulses. In particular, an analysis on multiple after-pulses was performed on both photomultiplier models. A digital oscilloscope was used to acquire all the pulses after the main pulse during a time window of 16μs for an off-line analysis to determine the charge and time spectra and a correlation between the arrival times and the charge of each after-pulse.

  4. Global Astrophysical Telescope System - telescope No. 2

    NASA Astrophysics Data System (ADS)

    Kamiński, Krzysztof; Baranowski, Roman; Fagas, Monika; Borczyk, Wojciech; Dimitrov, Wojciech; Polińska, Magdalena

    2014-02-01

    We present the new, second spectroscopic telescope of Poznań Astronomical Observatory. The telescope allows automatic simultaneous spectroscopic and photometric observations and is scheduled to begin operation from Arizona in autumn 2013. Together with the telescope located in Borowiec, Poland, it will constitute a perfect instrument for nearly continuous spectroscopic observations of variable stars. With both instruments operational, the Global Astrophysical Telescope System will be established.

  5. Opportunities for Fundamental and New Physics with Very High Energy Gamma-ray Telescopes

    NASA Astrophysics Data System (ADS)

    Bechtol, Keith

    2016-04-01

    Astronomical observations with the highest energy gamma rays enable a wide range of fundamental physics measurements as well as searches for new physics beyond the Standard Model. In this presentation, I will discuss indirect dark matter searches, intergalactic magnetic field constraints, and tests of Lorentz invariance with an emphasis on sensitivity gains that could be achieved with two new ground-based gamma-ray telescopes operating at the TeV energy scale: the High-Altitude Water Cherenkov observatory (HAWC) and the Cherenkov Telescope Array (CTA). Multiwavelength and multimessenger observations are an essential component of these studies needed to characterize the environments in which the highest energy gamma rays are produced, the conditions encountered while traversing interstellar and intergalactic distances, and "conventional" astrophysical backgrounds.

  6. Characterizing the radiation response of Cherenkov glass detectors with isotopic sources

    SciTech Connect

    Hayward, J P; Hobbs, C. L.; Bell, Zane W; Boatner, Lynn A; Johnson, Rose E; Ramey, Joanne Oxendine; Jellison Jr, Gerald Earle; Lillard, Cole R; Ramey, Lucas A

    2012-01-01

    Abstract Cherenkov detectors are widely used for particle identification and threshold detectors in high-energy physics. Glass Cherenkov detectors that are sensitive to beta emissions originating from neutron activation have been demonstrated recently as a potential replacement for activation foils. In this work, we set the groundwork to evaluate large Cherenkov glass detectors for sensitivity to MeV photons through first understanding the measured response of small Cherenkov glass detectors to isotopic gamma-ray sources. Counting and pulse height measurements are acquired with reflected glass Cherenkov detectors read out with a photomultiplier tube. Simulation was used to inform our understanding of the measured results. This simulation included radioactive source decay, radiation interaction, Cherenkov light generation, optical ray tracing, and photoelectron production. Implications for the use of Cherenkov glass detectors to measure low energy gammaray response are discussed.

  7. The operation of a pressurized ultraviolet photoionization threshold cherenkov counter

    NASA Astrophysics Data System (ADS)

    Harnew, N.; Meyer, D. I.

    We have successfully tested an ultraviolet photoionization Cherenkov counter in a 10 GeV/ c pion beam. The counter has been tested to 11 atm pressure for use as a π-K separator. The design and operation of the counter is described.

  8. The C 4F 10 Cherenkov detector for DIRAC-II

    NASA Astrophysics Data System (ADS)

    Horikawa, S.; Allkofer, Y.; Amsler, C.; Brekhovskikh, V.; Kuptsov, A.; Pentia, M.; Zhabitsky, M.

    2008-09-01

    A new threshold Cherenkov detector using C 4F 10 gas radiator was built and put into operation in the DIRAC-II experiment at CERN. Running on the C 4F 10 at room temperature and atmospheric pressure, the detector discriminates between pions and kaons in the momentum range of 4- 8 GeV/c. A compact radiator-gas recirculation system including a gas-liquid separation unit, hollow-fibre membranes and molecular sieves ensures gas purity for a long term of operation without a significant loss of the gas. The system is robust and stable and the pressure in the two detector vessels is regulated in the range of ±0.5 mbar. We report on the design and the technical aspects of the detector and its response in the DIRAC 2007 run.

  9. A hybrid version of the Whipple observatory's air Cherenkov imaging camera for use in moonlight

    NASA Astrophysics Data System (ADS)

    Chantell, M. C.; Akerlof, C. W.; Badran, H. M.; Buckley, J.; Carter-Lewis, D. A.; Cawley, M. F.; Connaughton, V.; Fegan, D. J.; Fleury, P.; Gaidos, J.; Hillas, A. M.; Lamb, R. C.; Pare, E.; Rose, H. J.; Rovero, A. C.; Sarazin, X.; Sembroski, G.; Schubnell, M. S.; Urban, M.; Weekes, T. C.; Wilson, C.

    1997-02-01

    A hybrid version of the Whipple Observatory's atmospheric Cherenkov imaging camera that permits observation during periods of bright moonlight is described. The hybrid camera combines a blue-light blocking filter with the standard Whipple imaging camera to reduce sensitivity to wavelengths greater than 360 nm. Data taken with this camera are found to be free from the effects of the moonlit night-sky after the application of simple off-line noise filtering. This camera has been used to successfully detect TeV gamma rays, in bright moon light, from both the Crab Nebula and the active galactic nucleus Markarian 421 at the 4.9σ and 3.9σ levels of statistical significance, respectively. The energy threshold of the camera is estimated to be 1.1 ( +0.6/-0.3) TeV from Monte Carlo simulations.

  10. Sensitivity of ground-based Cherenkov telescopes for anisotropics in the cosmic gamma-ray background

    SciTech Connect

    Ripken, Joachim; Horns, Dieter; Elsaesser, Dominik; Mannheim, Karl

    2008-12-24

    Self-annihilating dark matter contributes to the extra galactic very high-energy {gamma}-ray background. This contribution is expected to be anisotropic following the density distribution of non-baryonic dark matter. We explore the possibilities to search for these anisotropies with present and future ground-based gamma-ray experiments like H.E.S.S., MAGIC, or CTA. A multipole-expansion of simulated events is used to investigate the sensitivity for anisotropies detectable with narrow field of view observations.

  11. Coherent large telescopes

    NASA Astrophysics Data System (ADS)

    Nelson, J. E.

    Present ground-based telescopes are compared with those of the future. The inherent limitations of ground-based telescopes are reviewed, and existing telescopes and their evolution are briefly surveyed in order to see the trends that led to the present period of innovative telescope design. The major telescope types and the critical design factors that must be considered in designing large telescopes for the future are reviewed, emphasizing economicality. As an example, the Ten Meter Telescope project at the University of California is discussed in detail, including the telescope buildings, domes, and apertures, the telescope moving weights, the image quality, and the equipment. Finally, a brief review of current work in progress on large telescopes is given.

  12. Search for muon-neutrino emission from GeV and TeV gamma-ray flaring blazars using five years of data of the ANTARES telescope

    NASA Astrophysics Data System (ADS)

    The ANTARES Collaboration

    2015-12-01

    The ANTARES telescope is well-suited for detecting astrophysical transient neutrino sources as it can observe a full hemisphere of the sky at all times with a high duty cycle. The background due to atmospheric particles can be drastically reduced, and the point-source sensitivity improved, by selecting a narrow time window around possible neutrino production periods. Blazars, being radio-loud active galactic nuclei with their jets pointing almost directly towards the observer, are particularly attractive potential neutrino point sources, since they are among the most likely sources of the very high-energy cosmic rays. Neutrinos and gamma rays may be produced in hadronic interactions with the surrounding medium. Moreover, blazars generally show high time variability in their light curves at different wavelengths and on various time scales. This paper presents a time-dependent analysis applied to a selection of flaring gamma-ray blazars observed by the FERMI/LAT experiment and by TeV Cherenkov telescopes using five years of ANTARES data taken from 2008 to 2012. The results are compatible with fluctuations of the background. Upper limits on the neutrino fluence have been produced and compared to the measured gamma-ray spectral energy distribution.

  13. Radium-228 analysis of natural waters by Cherenkov counting of Actinium-228.

    PubMed

    Aleissa, Khalid A; Almasoud, Fahad I; Islam, Mohammed S; L'Annunziata, Michael F

    2008-12-01

    The activities of (228)Ra in natural waters were determined by the Cherenkov counting of the daughter nuclide (228)Ac. The radium was pre-concentrated on MnO(2) and the radium purified via ion exchange and, after a 2-day period of incubation to allow for secular equilibrium between the parent-daughter (228)Ra((228)Ac), the daughter nuclide (228)Ac was isolated by ion exchange according to the method of Nour et al. [2004. Radium-228 determination of natural waters via concentration on manganese dioxide and separation using Diphonix ion exchange resin. Appl. Radiat. Isot. 61, 1173-1178]. The Cherenkov photons produced by (228)Ac were counted directly without the addition of any scintillation reagents. The optimum Cherenkov counting window, sample volume, and vial type were determined experimentally to achieve optimum Cherenkov photon detection efficiency and lowest background count rates. An optimum detection efficiency of 10.9+/-0.1% was measured for (228)Ac by Cherenkov counting with a very low Cherenkov photon background of 0.317+/-0.013cpm. The addition of sodium salicylate into the sample counting vial at a concentration of 0.1g/mL yielded a more than 3-fold increase in the Cherenkov detection efficiency of (228)Ac to 38%. Tests of the Cherenkov counting technique were conducted with several water standards of known activity and the results obtained compared closely with a conventional liquid scintillation counting technique. The advantages and disadvantages of Cherenkov counting compared to liquid scintillation counting methods are discussed. Advantages include much lower Cherenkov background count rates and consequently lower minimal detectable activities for (228)Ra and no need for expensive environmentally unfriendly liquid scintillation cocktails. The disadvantages of the Cherenkov counting method include the need to measure (228)Ac Cherenkov photon detection efficiency and optimum Cherenkov counting volume, which are not at all required when liquid

  14. The Spacelab Wide Angle Telescope (SWAT)

    NASA Technical Reports Server (NTRS)

    West, R. M.; Gull, T. R.; Henize, K. G.; Bertola, F.

    1979-01-01

    A fast wide angle telescope that will be capable of imaging to the darker sky limit and in the ultraviolet wavelength region available above the atmosphere is described. The telescope (SWAT) has a resolution comparable to that of the large ground-based Schmidt telescope and a field of at least five degrees. A number of astrophysically important investigations can only be accomplished with such a telescope, e.g., detection of hidden, hot objects like hot white dwarfs and subwarfs in stellar binary systems, and energetic regions in globular clusters and galaxy nuclei. It permits unique studies of the UV-morphology of extended objects and allows discovery of very faint extensions, halos, jets, and filaments in galaxies. It can contribute to the investigation of dust in the Milky Way and in other galaxies and, with an objective prism, spectra of very faint objects can be obtained. The SWAT will localize objects for further study with the narrow-field Space Telescope.

  15. An autonomous underwater telescope for measuring the scattering of light in the deep sea

    NASA Astrophysics Data System (ADS)

    Balasi, K. G.; Domvoglou, T.; Kiskiras, I.; Lenis, D.; Maniatis, M.; Maragos, N.; Stavropoulos, G.

    2016-05-01

    The KM3NeT research infrastructure will be a deep sea multidisciplinary observatory in the Mediterranean Sea housing a neutrino telescope. Accurate knowledge of the optical properties of the sea water is important for the performance evaluation of the telescope. In this work we describe the deployment of the equipment that we had previously examined by Monte Carlo (MC) simulationsl, in the context of the scattering experiment in order to evaluate the parameters describing the scattering characteristics of the sea water. Four photomultipliers (PMTs) were used to measure in situ the scattered light emitted by six laser diodes in three different wavelengths covering the Cherenkov radiation spectrum.

  16. Analysis of telescope performance: MTF approach

    NASA Astrophysics Data System (ADS)

    Vítek, Stanislav; Páta, Petr

    2006-03-01

    Small robotic telescopes (like BOOTES in Spain, BART in Czech Republic or FRAM in Argentina) are constructed for continuous galactic survey and fast reactions to GRB (Gamma Ray Burts) alerts. Due subtile construction performance of those instruments strongly depends on temperature, atmosphere scintillations etc. In this article will be discussed possibilities of performance improvement based on knowledge of any transfer characteristic like modulation transfer function MTF (or Point Spread Function PSF of course) of imaging system introducing a robotic telescope.

  17. Measuring Neutrinos with the ANTARES Telescope

    SciTech Connect

    Reed, Corey

    2009-12-17

    The ANTARES underwater neutrino telescope has been taking data since construction began in 2006. The telescope, completed in May of 2008, detects the Cerenkov radiation of charged leptons produced by high energy neutrinos interacting in or around the detector. The lepton trajectory is reconstructed with high precision, revealing the direction of the incoming neutrino. The performance of the detector will be discussed and recent data showing muons, electromagnetic showers and atmospheric neutrinos will be presented. Studies have been underway to search for neutrino point sources in the ANTARES data since 2007. Results from these studies will be presented, and the sensitivity of the telescope will be discussed.

  18. Multi-Spectral Solar Telescope Array

    NASA Technical Reports Server (NTRS)

    Walker, Arthur B. C., Jr.; Lindblom, Joakim F.; O'Neal, Ray H.; Allen, Maxwell J.; Barbee, Troy W., Jr.; Hoover, Richard B.

    1990-01-01

    This paper descibes the design and the characteristics of the Multispectral Solar Telescope Array (MSSTA), a new rocket spectroheliograph to be launched in August 1990. The MSSTA includes five multilayer Ritchey-Chretien telescopes covering the spectral range 150-300 A and eight multilayer Herschelian telescopes covering the spectral range 40-1550 A, making it possible to obtain spectrohelipgrams over the soft X-ray/extreme UV/FUV spectral range. The MSSTA is expected to obtain information regarding the structure and dynamics of the solar atmosphere in the temperature range 10 to the 4th-10 to the 7th K.

  19. The ANTARES neutrino telescope: Status and first results

    NASA Astrophysics Data System (ADS)

    Brown, Anthony M.

    2009-10-01

    Completed in May 2008, the ANTARES neutrino telescope is located in the Mediterranean Sea, 40 km off the coast of Toulon, at a depth of about 2500 m. Consisting of 12 detector lines housing nearly 900 optical modules, the ANTARES telescope is currently the largest neutrino detector in the northern hemisphere. Utilising the Mediterranean Sea as a detecting medium, the detection principle of ANTARES relies on the observation of Cherenkov photons emitted by charged relativistic leptons, produced through neutrino interactions with the surrounding water and seabed, using a 3 dimensional lattice of photomultiplier tubes. In this paper we review the current status of the ANTARES experiment, highlighting some of the results from its first year of full operation.

  20. Measuring a Cherenkov ring in the radio emission from air showers at 110-190 MHz with LOFAR

    NASA Astrophysics Data System (ADS)

    Nelles, A.; Schellart, P.; Buitink, S.; Corstanje, A.; de Vries, K. D.; Enriquez, J. E.; Falcke, H.; Frieswijk, W.; Hörandel, J. R.; Scholten, O.; ter Veen, S.; Thoudam, S.; van den Akker, M.; Anderson, J.; Asgekar, A.; Bell, M. E.; Bentum, M. J.; Bernardi, G.; Best, P.; Bregman, J.; Breitling, F.; Broderick, J.; Brouw, W. N.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Deller, A.; Duscha, S.; Eislöffel, J.; Fallows, R. A.; Garrett, M. A.; Gunst, A. W.; Hassall, T. E.; Heald, G.; Horneffer, A.; Iacobelli, M.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; Maat, P.; Mann, G.; Mevius, M.; Norden, M. J.; Paas, H.; Pandey-Pommier, M.; Pietka, G.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Röttgering, H.; Scaife, A. M. M.; Schwarz, D.; Smirnov, O.; Stappers, B. W.; Steinmetz, M.; Stewart, A.; Tagger, M.; Tang, Y.; Tasse, C.; Vermeulen, R.; Vocks, C.; van Weeren, R. J.; Wijnholds, S. J.; Wucknitz, O.; Yatawatta, S.; Zarka, P.

    2015-05-01

    Measuring radio emission from air showers offers a novel way to determine properties of the primary cosmic rays such as their mass and energy. Theory predicts that relativistic time compression effects lead to a ring of amplified emission which starts to dominate the emission pattern for frequencies above ∼ 100 MHz. In this article we present the first detailed measurements of this structure. Ring structures in the radio emission of air showers are measured with the LOFAR radio telescope in the frequency range of 110-190 MHz. These data are well described by CoREAS simulations. They clearly confirm the importance of including the index of refraction of air as a function of height. Furthermore, the presence of the Cherenkov ring offers the possibility for a geometrical measurement of the depth of shower maximum, which in turn depends on the mass of the primary particle.

  1. Study of a Cherenkov TOF-PET module

    NASA Astrophysics Data System (ADS)

    Korpar, S.; Dolenec, R.; Križan, P.; Pestotnik, R.; Stanovnik, A.

    2013-12-01

    An apparatus, consisting of two PbF2 crystals, each coupled to a multichannel plate photomultiplier (MCP-PMT), has been constructed in order to measure the time-of-flight (TOF) of the two 511 keV annihilation photons produced in positron emission tomography (PET). Excellent timing is achieved by detecting the prompt Cherenkov photons produced by the absorption of the 511 keV gamma photons. The present work describes the measurement and image reconstruction of two 22Na point sources. In addition, the influence of the radiator thickness and the Cherenkov light absorption cut-off of the crystal on the efficiency and the timing resolution have been studied by Monte Carlo simulation.

  2. Data analysis for solar neutrinos observed by water Cherenkov detectors⋆

    NASA Astrophysics Data System (ADS)

    Koshio, Yusuke

    2016-04-01

    A method of analyzing solar neutrino measurements using water-based Cherenkov detectors is presented. The basic detection principle is that the Cherenkov photons produced by charged particles via neutrino interaction are observed by photomultiplier tubes. A large amount of light or heavy water is used as a medium. The first detector to successfully measure solar neutrinos was Kamiokande in the 1980's. The next-generation detectors, i.e., Super-Kamiokande and the Sudbury Neutrino Observatory (SNO), commenced operation from the mid-1990's. These detectors have been playing the critical role of solving the solar neutrino problem and determining the neutrino oscillation parameters over the last decades. The future prospects of solar neutrino analysis using this technique are also described.

  3. Nonlinear saturation characteristics of a dielectric Cherenkov maser

    SciTech Connect

    Choi, J.S.; Heo, E.G.; Choi, D.I.

    1995-12-31

    The nonlinear saturation state in a dielectric Cherenkov maser (DCM) with the TM mode and the intense relativistic electron beam is analyzed from the nonlinear formulation based on the cold fluid-Maxwell equations. We obtain the nonlinear efficiency and the final operation frequency under consideration of the effects of the beam current, the beam energy and the dielectric materials and show that the characteristics of a DCM instablity has a strong resemblance to that of the relativistic two stream instability by the coherent trapping of electrons in a single most-ustable wave. Finally, the nonlinear analysis shows that the Cherenkov maser operation with a lower-energy beam can be more efficient in the higher frequency regime for the case of the high power DCM with a high current.

  4. A ring imaging Cherenkov detector for CLAS12

    SciTech Connect

    Montgomery, Rachel A.

    2013-12-01

    The energy increase of Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) to 12 GeV promises to greatly extend the physics reach of its experiments. This will include an upgrade of the CEBAF Large Acceptance Spectrometer (CLAS) to CLAS12, offering unique possibilities to study internal nucleon dynamics. For this excellent hadron identification over the full kinematical range of 3–8 GeV/c is essential. This will be achieved by the installation of a Ring Imaging CHerenkov (RICH) detector. A novel hybrid imaging design incorporating mirrors, aerogel radiators and Hamamatsu H8500 multianode photomultiplier tubes is proposed. Depending on the incident particle track angle, Cherenkov light will either be imaged directly or after two reflections and passes through the aerogel. The detector design is described, along with preliminary results on individual detector components tests and from recent testbeam studies.

  5. GEANT4 simulations of Cherenkov reaction history diagnostics.

    PubMed

    Rubery, M S; Horsfield, C J; Herrmann, H W; Kim, Y; Mack, J M; Young, C S; Caldwell, S E; Evans, S C; Sedilleo, T J; McEvoy, A; Miller, E K; Stoeffl, W; Ali, Z; Toebbe, J

    2010-10-01

    This paper compares the results from a GEANT4 simulation of the gas Cherenkov detector 1 (GCD1) with previous simulations and experimental data from the Omega laser facility. The GCD1 collects gammas emitted during a deuterium-tritium capsule implosion and converts them, through several processes, to Cherenkov light. Photon signals are recorded using subnanosecond photomultiplier tubes, producing burn reaction histories. The GEANT4 GCD1 simulation is first benchmarked against ACCEPT, an integrated tiger series code, with good agreement. The simulation is subsequently compared with data from the Omega laser facility, where experiments have been performed to measure the effects of Hohlraum materials on reaction history signals, in preparation for experiments at the National Ignition Facility. PMID:21033850

  6. GEANT4 simulations of Cherenkov reaction history diagnostics

    SciTech Connect

    Rubery, M. S.; Horsfield, C. J.; Herrmann, H. W.; Kim, Y.; Mack, J. M.; Young, C. S.; Caldwell, S. E.; Evans, S. C.; Sedilleo, T. J.; McEvoy, A.; Miller, E. K.; Stoeffl, W.; Ali, Z.

    2010-10-15

    This paper compares the results from a GEANT4 simulation of the gas Cherenkov detector 1 (GCD1) with previous simulations and experimental data from the Omega laser facility. The GCD1 collects gammas emitted during a deuterium-tritium capsule implosion and converts them, through several processes, to Cherenkov light. Photon signals are recorded using subnanosecond photomultiplier tubes, producing burn reaction histories. The GEANT4 GCD1 simulation is first benchmarked against ACCEPT, an integrated tiger series code, with good agreement. The simulation is subsequently compared with data from the Omega laser facility, where experiments have been performed to measure the effects of Hohlraum materials on reaction history signals, in preparation for experiments at the National Ignition Facility.

  7. Optical Cherenkov radiation in ultrafast cascaded second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Bache, M.; Bang, O.; Zhou, B. B.; Moses, J.; Wise, F. W.

    2010-12-01

    We show through theory and numerics that when few-cycle femtosecond solitons are generated through cascaded (phase-mismatched) second-harmonic generation, these broadband solitons can emit optical Cherenkov radiation in the form of linear dispersive waves located in the red part of the spectrum. The beating between the dispersive wave and the soliton generates trailing temporal oscillations on the compressed soliton. Insertion of a simple short-wave pass filter after the crystal can restore a clean soliton. On the other hand, bandpass filtering around the dispersive wave peak results in near-transform-limited ultrashort mid-IR pulses with pulse durations much shorter than the input near-IR pulse. The Cherenkov radiation for the crystal considered (β-barium borate) is found for pump wavelengths in the range λ=0.95-1.45μm, and is located in the regime λ=1.5-3.5μm. For shorter pump wavelengths, the phase-matching point is located in the absorption region of the crystal, effectively absorbing the generated dispersive wave. By calculating the phase-matching curves for typically used frequency conversion crystals, we point out that the mid-IR absorption in the crystal in many cases automatically will filter away the dispersive wave. Finally, an investigation of recent experimental results uncovers a four-wave-mixing phenomenon related to Cherenkov radiation that is an additional generation mechanism of long-wavelength radiation that can occur during soliton compression. We discuss the conditions that lead to this alternative dynamics rather than generation of Cherenkov radiation.

  8. Cherenkov-type diagnostics of fast electrons within tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Jakubowski, Lech; Sadowski, Marek J.; Zebrowski, Jaroslaw; Malinowski, Karol; Rabinski, Marek; Jakubowski, Marcin J.; Mirowski, Robert

    2014-05-01

    This paper presents a summary of the most important results of fast electron measurements performed so far within different tokamaks by means of Cherenkov-type detectors. In the ISTTOK tokamak (IPFN, IST, Lisboa, Portugal), two measuring heads were applied, each equipped with four radiators made of different types of alumina-nitrate poly-crystals. A two-channel measuring head equipped with diamond radiators was also used. Within the COMPASS tokamak (IPP AS CR, Prague, Czech Republic) some preliminary measurements have recently been performed by means of a new single-channel Cherenkov-type detector. The experimental data from the TORE SUPRA tokamak (CEA, IFRM, Cadarache, France), which were collected by means of a DENEPR-2 probe during two recent experimental campaigns, have been briefly analyzed. A new Cherenkov probe (the so-called DENEPR-3) has been mounted within the TORE SUPRA machine, but the electron measurements could not be performed because of the failure of this facility. Some conclusions concerning the fast electron emission are presented.

  9. Hubble Space Telescope Solar Array

    NASA Technical Reports Server (NTRS)

    1985-01-01

    This is a view of a solar cell blanket deployed on a water table during the Solar Array deployment test. The Hubble Space Telescope (HST) Solar Arrays provide power to the spacecraft. The arrays are mounted on opposite sides of the HST, on the forward shell of the Support Systems Module. Each array stands on a 4-foot mast that supports a retractable wing of solar panels 40-feet (12.1-meters) long and 8.2-feet (2.5-meters) wide, in full extension. The arrays rotate so that the solar cells face the Sun as much as possible to harness the Sun's energy. The Space Telescope Operations Control Center at the Goddard Space Center operates the array, extending the panels and maneuvering the spacecraft to focus maximum sunlight on the arrays. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The HST Solar Array was designed by the European Space Agency and built by British Aerospace. The Marshall Space Flight Center had overall responsibility for design, development, and construction of the HST.

  10. Detection of Sub-TeV gamma-rays from the Galactic Center with the CANGAROO-II telescope

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Ken'ichi

    2005-02-01

    The Galactic Center has been observed with the CANGAROO-II imaging atmospheric Cherenkov telescope in 2001 and 2002. We detected a statistically significant excess at energies greater than 250GeV. This is the first detection of sub-TeV gamma rays from the Galactic Center region. The signal direction is consistent with the Galactic Center, which includes the massive black hole Sgr A* and supernova remnant Sgr A East. The resultant flux is 1 order of magnitude lower than that of the Crab Nebula at 1 TeV. The differential flux has a steep spectrum and the power law index is observed to be -4.6 +/- 0.5, although it could flatten to -3.4 if the uncertainty in energy determination is included. Here, the analysis for reduction of night sky background effects and the radiation mechanism of sub-TeV gamma rays are reported. The most probable radiation mechanism is π0 decays. The maximum energy of the inferred cosmic rays is 1-3 TeV and the total cosmic-ray luminosity corresponds to 1 ~ 10 supernova remnants. We also obtain an upper limit on the cold dark matter density in the galactic halo.

  11. Data analysis method for the search of point sources of gamma rays with the HAGAR telescope array

    NASA Astrophysics Data System (ADS)

    Britto, R. J.; Acharya, B. S.; Anupama, G. C.; Bhattacharjee, P.; Chitnis, V. R.; Cowsik, R.; Dorji, N.; Duhan, S. K.; Gothe, K. S.; Kamath, P. U.; Mahesh, P. K.; Manoharan, J.; Nagesh, B. K.; Parmar, N. K.; Prabhu, T. P.; Rao, S. K.; Saha, L.; Saleem, F.; Saxena, A. K.; Sharma, S. K.; Shukla, A.; Singh, B. B.; Srinivasan, R.; Srinivasulu, G.; Sudersanan, P. V.; Tsewang, D.; Upadhya, S. S.; Vishwanath, P. R.

    2011-12-01

    The High Altitude GAmma-Ray (HAGAR) experiment is the highest altitude atmospheric Cherenkov sampling array, set up at 4300 m amsl in the Himalayas (Northern India). It constitutes 7 telescopes, each one with seven 90 cm-diameter mirrors, a field of view of 3 degrees, and was designed to reach a relatively low threshold (currently around 200 GeV) with quite a low total mirror area (31 m^2). In order to remove the strong isotropic background of charged cosmic rays, data are collected by tracking separately ON-source followed by OFF-source regions, or vice-versa. Typical observations period is about 30-40 min. ON-OFF data pairs are then selected according to quality parameters such as stability of the trigger rate and the comparison of average trigger rates between ON and OFF-source data sets. Signal extraction from point sources is done by performing analysis cuts on the count rate excess, rejecting off-axis events. Validation of method and systematics are evaluated through the analysis of fake sources (OFF-OFF pairs) located at similar declination as the observed point sources. Spurious signal, if any, would show up in this study.

  12. Toward the construction of a medium size prototype Schwarzschild-Couder telescope for CTA

    NASA Astrophysics Data System (ADS)

    Rousselle, J.; Byrum, K.; Cameron, R.; Connaughton, V.; Errando, M.; Griffiths, S.; Guarino, V.; Humensky, T. B.; Jenke, P.; Kaaret, P.; Kieda, D.; Limon, M.; Mognet, I.; Mukherjee, R.; Nieto, D.; Okumura, A.; Peck, A.; Petrashyk, A.; Ribeiro, D.; Stevenson, B.; Vassiliev, V.; Yu, P.

    2015-09-01

    The construction of a prototype Schwarzschild-Couder telescope (pSCT) started in early June 2015 at the Fred Lawrence Whipple Observatory in Southern Arizona, as a candidate medium-sized telescope for the Cherenkov Telescope Array (CTA). Compared to current Davies-Cotton telescopes, this novel instrument with an aplanatic two-mirror optical system will offer a wider field-of-view and improved angular resolution. In addition, the reduced plate scale of the camera allows the use of highly-integrated photon detectors such as silicon photo multipliers. As part of CTA, this design has the potential to greatly improve the performance of the next generation ground-based observatory for very high-energy (E>60 GeV) gamma-ray astronomy. In this contribution we present the design and performance of both optical and alignment systems of the pSCT.

  13. Applications of Cherenkov Light Emission for Dosimetry in Radiation Therapy

    NASA Astrophysics Data System (ADS)

    Glaser, Adam Kenneth

    Since its discovery in the 1930's, the Cherenkov effect has been paramount in the development of high-energy physics research. It results in light emission from charged particles traveling faster than the local speed of light in a dielectric medium. The ability of this emitted light to describe a charged particle's trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, only recently has the phenomenon been considered in the practical context of medical physics and radiation therapy dosimetry, where Cherenkov light is induced by clinical x-ray photon, electron, and proton beams. To investigate the relationship between this phenomenon and dose deposition, a Monte Carlo plug-in was developed within the Geant4 architecture for medically-oriented simulations (GAMOS) to simulate radiation-induced optical emission in biological media. Using this simulation framework, it was determined that Cherenkov light emission may be well suited for radiation dosimetry of clinically used x-ray photon beams. To advance this application, several novel techniques were implemented to realize the maximum potential of the signal, such as time-gating for maximizing the signal to noise ratio (SNR) and Cherenkov-excited fluorescence for generating isotropic light release in water. Proof of concept experiments were conducted in water tanks to demonstrate the feasibility of the proposed method for two-dimensional (2D) projection imaging, three-dimensional (3D) parallel beam tomography, large field of view 3D cone beam tomography, and video-rate dynamic imaging of treatment plans for a number of common radiotherapy applications. The proposed dosimetry method was found to have a number of unique advantages, including but not limited to its non-invasive nature, water-equivalence, speed, high-resolution, ability to provide full 3D data, and potential to yield data in-vivo. Based on

  14. Telescopes and space exploration

    NASA Technical Reports Server (NTRS)

    Brandt, J. C.; Maran, S. P.

    1976-01-01

    The necessity for different types of telescopes for astronomical investigations is discussed. Major findings in modern astronomy by ground-based and spaceborne telescopes are presented. Observations of the Crab Nebula, solar flares, interstellar gas, and the Black Hole are described. The theory of the oscillating universe is explored. Operating and planned telescopes are described.

  15. The Green Bank Telescope

    NASA Astrophysics Data System (ADS)

    Prestage, R. M.; Constantikes, K. T.; Hunter, T. R.; King, L. J.; Lacasse, R. J.; Lockman, F. J.; Norrod, R. D.

    2009-08-01

    The Robert C. Byrd Green Bank Telescope of the National Radio Astronomy Observatory is the world's premiere single-dish radio telescope operating at centimeter to long millimeter wavelengths. This paper describes the history, construction, and main technical features of the telescope.

  16. Coma-compensation telescope

    NASA Technical Reports Server (NTRS)

    MacFarlane, Malcolm J. (Inventor)

    1986-01-01

    A telescope for eliminating on axis coma due to tilt of the secondary mirror in infrared astronomy. The secondary mirror of a reflecting telescope is formed to cause field coma to always be equal and opposite at the optical axis of the telescope to tilt coma regardless of the angle through the secondary mirror is tilted with respect to the optical axis.

  17. The space telescope

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Papers concerning the development of the Space Telescope which were presented at the Twenty-first Annual Meeting of the American Astronautical Society in August, 1975 are included. Mission planning, telescope performance, optical detectors, mirror construction, pointing and control systems, data management, and maintenance of the telescope are discussed.

  18. ATST telescope mount: telescope of machine tool

    NASA Astrophysics Data System (ADS)

    Jeffers, Paul; Stolz, Günter; Bonomi, Giovanni; Dreyer, Oliver; Kärcher, Hans

    2012-09-01

    The Advanced Technology Solar Telescope (ATST) will be the largest solar telescope in the world, and will be able to provide the sharpest views ever taken of the solar surface. The telescope has a 4m aperture primary mirror, however due to the off axis nature of the optical layout, the telescope mount has proportions similar to an 8 meter class telescope. The technology normally used in this class of telescope is well understood in the telescope community and has been successfully implemented in numerous projects. The world of large machine tools has developed in a separate realm with similar levels of performance requirement but different boundary conditions. In addition the competitive nature of private industry has encouraged development and usage of more cost effective solutions both in initial capital cost and thru-life operating cost. Telescope mounts move relatively slowly with requirements for high stability under external environmental influences such as wind buffeting. Large machine tools operate under high speed requirements coupled with high application of force through the machine but with little or no external environmental influences. The benefits of these parallel development paths and the ATST system requirements are being combined in the ATST Telescope Mount Assembly (TMA). The process of balancing the system requirements with new technologies is based on the experience of the ATST project team, Ingersoll Machine Tools who are the main contractor for the TMA and MT Mechatronics who are their design subcontractors. This paper highlights a number of these proven technologies from the commercially driven machine tool world that are being introduced to the TMA design. Also the challenges of integrating and ensuring that the differences in application requirements are accounted for in the design are discussed.

  19. Workshop on Mars Telescopic Observations

    NASA Technical Reports Server (NTRS)

    Bell, J. F., III (Editor); Moersch, J. E. (Editor)

    1995-01-01

    The Mars Telescopic Observations Workshop, held August 14-15, 1995, at Cornell University in Ithaca, New York, was organized and planned with two primary goals in mind: The first goal was to facilitate discussions among and between amateur and professional observers and to create a workshop environment fostering collaborations and comparisons within the Mars observing community. The second goal was to explore the role of continuing telescopic observations of Mars in the upcoming era of increased spacecraft exploration. The 24 papers presented at the workshop described the current NASA plans for Mars exploration over the next decade, current and recent Mars research being performed by professional astronomers, and current and past Mars observations being performed by amateur observers and observing associations. The workshop was divided into short topical sessions concentrating on programmatic overviews, groundbased support of upcoming spacecraft experiments, atmospheric observations, surface observations, modeling and numerical studies, and contributions from amateur astronomers.

  20. India's National Large Solar Telescope

    NASA Astrophysics Data System (ADS)

    Hasan, S. S.

    2012-12-01

    India's 2-m National Large Solar Telescope (NLST) is aimed primarily at carrying out observations of the solar atmosphere with high spatial and spectral resolution. A comprehensive site characterization program, that commenced in 2007, has identified two superb sites in the Himalayan region at altitudes greater than 4000-m that have extremely low water vapor content and are unaffected by monsoons. With an innovative optical design, the NLST is an on-axis Gregorian telescope with a low number of optical elements to reduce the number of reflections and yield a high throughput with low polarization. In addition, it is equipped with a high-order adaptive optics to produce close to diffraction limited performance. To control atmospheric and thermal perturbations of the observations, the telescope will function with a fully open dome, to achieve its full potential atop a 25 m tower. Given its design, NLST can also operate at night, without compromising its solar performance. The post-focus instruments include broad-band and tunable Fabry-Pérot narrow-band imaging instruments; a high resolution spectropolarimeter and an Echelle spectrograph for night time astronomy. This project is led by the Indian Institute of Astrophysics and has national and international partners. Its geographical location will fill the longitudinal gap between Japan and Europe and is expected to be the largest solar telescope with an aperture larger than 1.5 m till the ATST and EST come into operation. An international consortium has been identified to build the NLST. The facility is expected to be commissioned by 2016.

  1. Adaptive-optics performance of Antarctic telescopes.

    PubMed

    Lawrence, Jon S

    2004-02-20

    The performance of natural guide star adaptive-optics systems for telescopes located on the Antarctic plateau is evaluated and compared with adaptive-optics systems operated with the characteristic mid-latitude atmosphere found at Mauna Kea. A 2-m telescope with tip-tilt correction and an 8-m telescope equipped with a high-order adaptive-optics system are considered. Because of the large isoplanatic angle of the South Pole atmosphere, the anisoplanatic error associated with an adaptive-optics correction is negligible, and the achievable resolution is determined only by the fitting error associated with the number of corrected wave-front modes, which depends on the number of actuators on the deformable mirror. The usable field of view of an adaptive-optics equipped Antarctic telescope is thus orders of magnitude larger than for a similar telescope located at a mid-latitude site; this large field of view obviates the necessity for multiconjugate adaptive-optics systems that use multiple laser guide stars. These results, combined with the low infrared sky backgrounds, indicate that the Antarctic plateau is the best site on Earth at which to perform high-resolution imaging with large telescopes, either over large fields of view or with appreciable sky coverage. Preliminary site-testing results obtained recently from the Dome Concordia station indicate that this site is far superior to even the South Pole. PMID:15008551

  2. Observations of the magnetars 4U 0142+61 and 1E 2259+586 with the MAGIC telescopes

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Antonelli, L. A.; Antoranz, P.; Asensio, M.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Borla Tridon, D.; Bretz, T.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Cea del Pozo, E.; De Lotto, B.; Delgado Mendez, C.; Diago Ortega, A.; Doert, M.; 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 Terrats, D.; Gaug, M.; Giavitto, G.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Hadamek, A.; Hadasch, D.; Häfner, D.; Herrero, A.; Hose, J.; Hrupec, D.; Huber, B.; Jankowski, F.; Jogler, T.; Kadenius, V.; Klepser, S.; Knoetig, M. L.; Krähenbühl, T.; Krause, J.; Kushida, J.; La Barbera, A.; Lelas, D.; Leonardo, E.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López-Coto, 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.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Partini, S.; Persic, M.; Pilia, M.; Pochon, J.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; 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.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamatescu, V.; Stamerra, A.; Steinke, B.; Storz, J.; Sun, S.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Uellenbeck, M.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.; Rea, N.; Backes, M.

    2013-01-01

    Context. Magnetars are an extreme, highly magnetized class of isolated neutron stars whose large X-ray luminosity is believed to be driven by their high magnetic field. Aims: We study for the first time the possible very high energy γ-ray emission above 100 GeV from magnetars, observing the sources 4U 0142+61 and 1E 2259+586. Methods: We observed the two sources with atmospheric Cherenkov telescopes in the very high energy range (E > 100 GeV). 4U 0142+61 was observed with the MAGIC I telescope in 2008 for about 25 h and 1E 2259+586 was observed with the MAGIC stereoscopic system in 2010 for about 14 h. The data were analyzed with the standard MAGIC analysis software. Results: Neither magnetar was detected. Upper limits to the differential and integral flux above 200 GeV were computed using the Rolke algorithm. We obtain integral upper limits to the flux of 1.52 × 10-12 cm-2 s-1 and 2.7 × 10-12 cm-2 s-1 with a confidence level of 95% for 4U 0142+61 and 1E 2259+586, respectively. The resulting differential upper limits are presented together with X-ray data and upper limits in the GeV energy range. FITS files are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/549/A23

  3. Status of the Southern Utah Observatory (SUO) 32" Telescope

    NASA Astrophysics Data System (ADS)

    Kieda, David; Springer, R. Wayne; Gondolo, Paolo

    2007-10-01

    The University of Utah is building a new Astronomical Observatory at a high altitude site in Southern Utah. The Southern Utah Observatory (SUO) Telescope will be outfitted with a 32" R-C telescope manufactured by DFM, and will feature optical and IR focal plane instrumentation as well as capability for remote/robotic operations. In this talk, I will describe the status of SUO Telescope Project, including surveys of atmospheric seeing and night sky darkness measured at potential observatory locations.

  4. Baseline design of the SUNRISE Telescope

    NASA Astrophysics Data System (ADS)

    Bittner, Hermann; Erdmann, Matthias; Haberler, Peter; Härtel, Klaus-Ruediger; Barthol, Peter; Curdt, Werner

    2004-10-01

    The SUNRISE telescope is part of a balloon-borne instrument for spectro-polarimetric high-resolution observations of the solar atmosphere, to be flown 2007/2008 in the Antarctic summer stratosphere. It is a 1-m UV-VIS Gregory type telescope, operating close to the VIS diffraction limit. The telescope has a steel central frame and a lightweight CFRP trusswork structure with Serrurier properties, providing proper alignment of the optical elements over the varying eleva-tion angle. Mechanisms allow a fine adjustment of the optics. Aberrations caused by residual deformations of the stiff silicon carbide (Cesic) primary mirror are lowered by a dedicated offset in the secondary mirror polish (imprint). The telescope is subjected to the changing heat loads caused by the sun and earth radiation, necessitating measures to provide thermal conditions suitable for high-performance observations. Adequate preliminary solutions for an effective baffling are outlined.

  5. A fast ring-imaging Cherenkov counter for a fixed-target heavy-quark experiment

    SciTech Connect

    Kaplan, D.M.; Isenhower, L.D.; Atac, M. |; Brown, C.N.; Darden, C.W.

    1993-06-01

    We present a design for a fast ring-imaging Cherenkov counter operating in the visible. The Cherenkov photons are imaged on an array of small Winston cones and read out with optical fibers and VLPCs. the design is optimized for {pi}/K/p separation in the range 10 < p < 100 GeV/c.

  6. π/K/p identification with a large-aperture ring-imaging cherenkov counter

    NASA Astrophysics Data System (ADS)

    Adams, M.; Bastin, A.; Coutrakon, G.; Glass, H.; Jaffe, D.; Kirz, J.; McCarthy, R.; Hubbard, J. R.; Mangeot, Ph.; Mullie, J.; Peisert, A.; Tichit, J.; Bouclier, R.; Charpak, G.; Santiard, J. C.; Sauli, F.; Crittenden, J.; Hsiung, Y.; Kaplan, D.; Brown, C.; Childress, S.; Finley, D.; Ito, A.; Jonckheere, A.; Jöstlein, H.; Lederman, L.; Orava, R.; Smith, S.; Sugano, K.; Ueno, K.; Maki, A.; Hemmi, Y.; Miyake, K.; Nakamura, T.; Sasao, N.; Sakai, Y.; Gray, R.; Plaag, R.; Rothberg, J.; Rutherfoord, J.; Young, K.

    1983-11-01

    The operating large aperture ring-imaging Cherenkov detector from the FNAL experiment E605 is described. Cherenkov ultraviolet photons are detected with a multi-step avalanche chamber using a He/TEA gas mixture and π/K/p separation is obtained from 50 to 200 GeV/ c.

  7. SST-GATE: an innovative telescope for very high energy astronomy

    NASA Astrophysics Data System (ADS)

    Laporte, Philippe; Dournaux, Jean-Laurent; Sol, Hélène; Blake, Simon; Boisson, Catherine; Chadwick, Paula; Dumas, Delphine; Fasola, Gilles; de Frondat, Fatima; Greenshaw, Tim; Hervet, Olivier; Hinton, James; Horville, David; Huet, Jean-Michel; Jégouzo, Isabelle; Schmoll, Jürgen; White, Richard; Zech, Andreas

    2012-09-01

    The Cherenkov Telescope Array (CTA) is an international collaboration that aims to create the world's largest (ever) Very High Energy gamma-ray telescope array, consisting of more than 100 telescopes covering an area of several square kilometers to observe the electromagnetic showers generated by incoming cosmic gamma-rays with very high energies (from a few tens of GeV up to over 100 TeV). Observing such sources requires - amongst many other things - a large FoV (Field of View). In the framework of CTA, SST-GATE (Small Size Telescope - GAmma-ray Telescope Elements) aims to investigate and to build one of the two first CTA prototypes based on the Schwarzschild-Couder (SC) optical design that delivers a FoV close to 10 degrees in diameter. To achieve the required performance per unit cost, many improvements in mirror manufacturing and in other technologies are required. We present in this paper the current status of our project. After a brief introduction of the very high energy context, we present the opto-mechanical design, discuss the technological tradeoffs and explain the electronics philosophy that will ensure the telescopes cost is minimised without limiting its capabilities. We then describe the software nedeed to operate the telescope and conclude by presenting the expected telescope performance and some management considerations.

  8. Perception for a large deployable reflector telescope

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. M.; Swanson, P. N.; Meinel, A. B.; Meinel, M. P.

    1984-01-01

    Optical science and technology concepts for a large deployable reflector for far-infrared and submillimeter astronomy from above the earth's atmosphere are discussed. Requirements given at the Asilomar Conference are reviewed. The technical challenges of this large-aperture (about 20-meter) telescope, which will be diffraction limited in the infrared, are highlighted in a brief discussion of one particular configuration.

  9. Cosmic ray studies with a gas Cherenkov counter in association with an ionization spectrometer

    NASA Technical Reports Server (NTRS)

    Balasubrahmanyan, V. K.; Ormes, J. F.; Arens, J. F.; Siohan, F.; Yodh, G. B.; Simon, M.; Spiegelhauer, H.

    1980-01-01

    The results from a balloon-borne gas Cherenkov counter (threshold 16.5 GeV/nucleon) and an ionization spectrometer are presented. The gas Cherenkov counter provides an absolute energy distribution for the response of the calorimeter for 5 or = Z 26 nuclei of cosmic rays. The contribution of scintillation to the gas Cherenkov pulse height was obtained by independently selecting particles below the gas Cherenkov threshold using the ionization spectrometer. Energy spectra were derived by minimizing the chi squared between Monte Carlo simulted data and flight data. Best fit power laws, dN/dE = AE-gamma, were determined for C, N, O, Ne, Mg, and Si. The power laws, all consistent with E (-2.7) are not good fits to the data. A better fit is obtained using the spectrum derived from the spectrometer. The data from the ionization calorimeter and the gas Cherenkov are thus completely self-consistent.

  10. Study of Cherenkov Light Lateral Distribution Function Around the Knee Region in Extensive Air Showers

    NASA Astrophysics Data System (ADS)

    Al-Rubaiee, A.; Hashim, U.; Marwah, M.; Al-Douri, Y.

    2015-06-01

    The Cherenkov light lateral distribution function (LDF) was simulated with the CORSIKA code in the energy range (10^{13} - 10^{16}) eV. This simulation was performed for conditions and configurations of the Tunka EAS Cherenkov array for the two primary particles (p and Fe). Basing on the simulated results, many approximated functions are structured for two primary particles and different zenith angles. This allowed us to reconstruct the EAS events, which is, to determine the type and energy of the primary particles that produced showers from signal amplitudes of Cherenkov radiation measured by the Tunka Cherenkov array experiment. Comparison of the calculated LDF of Cherenkov radiation with that measured at the Tunka EAS array shows the ability to identify the primary particle that initiated the EAS cascades by determining its primary energy around the knee region of the cosmic ray spectrum.

  11. Cherenkov Ring Imaging Detector front-end electronics

    SciTech Connect

    Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.; Marshall, D.; Muller, D.; Nagamine, T.; Oxoby, G.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Suekane, F.; Toge, N.; Va'Vra, J.; Williams, S. ); Wilson, R.J.; Whitaker, J.S. . Dept.

    1990-10-01

    The SLD Cherenkov Ring Imaging Detector use a proportional wire detector for which a single channel hybrid has been developed. It consists of a preamplifier, gain selectable amplifier, load driver amplifier, power switching, and precision calibrator. For this hybrid, a bipolar, semicustom integrated circuit has been designed which includes video operational amplifiers for two of the gain stages. This approach allows maximization of the detector volume, allows DC coupling, and enables gain selection. System tests show good noise performance, calibration precision, system linearity, and signal shape uniformity over the full dynamic range. 10 refs., 8 figs.

  12. The ring imaging Cherenkov detector for Fermilab experiment 665

    SciTech Connect

    Coutrakon, G.B.; Dhawan, S.; Schuler, P.

    1988-02-01

    The authors describe a ring imaging Cherenkov counter (RICH) which uses a multiwire proportional chamber (MWPC) with cathode pad readout as a UV photon detector. The detector has 10800 pads, each connected to a charge sensitive amplifier, within an area of 55 x 95 cm/sup 2/. The detector offers high data rate capability and a chamber sensitive time of less than 250 nsec. In addition, the detector has 1 mm spatial resolution and a multi-hit capability of about 50 photons/event.

  13. Modified energy-momentum conservation laws and vacuum Cherenkov radiation

    NASA Astrophysics Data System (ADS)

    Carmona, J. M.; Cortés, J. L.; Romeo, B.

    2015-12-01

    We present a general parametrization for the leading order terms in a momentum power expansion of a non-universal Lorentz-violating, but rotational invariant, kinematics and its implications for two-body decay thresholds. The considered framework includes not only modified dispersion relations for particles, but also modified energy-momentum conservation laws, something which goes beyond effective field theory. As a particular and relevant example, bounds on the departures from special relativistic kinematics from the non-observation of vacuum Cherenkov radiation are discussed and compared with those obtained within the effective field theory scenario.

  14. The fluid systems for the SLD Cherenkov ring imaging detector

    SciTech Connect

    Abe, K.; Hasegawa, K.; Hasegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H.; Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dolinsky, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.W.G.S.; McCulloch, M.; McShurley, D.; Mueller, G.; Muller, D.; Nagamine, T.; Pavel, T.J.; Peterson, H.; Ratcliff, B.; Reif, R.; Rensing, P.; Schultz, D.; Shapiro, S.; Shaw, H.; Simopoulos, C.; Solodov, E.; Toge, N.; Vavra, J.; Watt, R.; Weber, T.; Williams, S.H.; Baird, K.; Jacques, P.; Kalelkar, M.; Plano, R.; Stamer, P.; Word, G.; Bean, A.; Caldwell, D.O.; Duboscq, J.; Huber, J.; Lu, A.; Mathys, L.; McHugh, S.; Yellin, S.; Ben-David, R.; Manly, S.; Snyder, J.; Turk, J.; Cavalli-Sforza, M.; Coyle, P.; Coyne, D.; Gagnon, P.; Liu, X.; Schneider, M.; Williams, D.A.; Coller, J.; Shank, J.T.; Whitaker, J.S.; d`Oliveira, A.; Johnson, R.A.; Martinez, J.; Nussbaum, M.; Santha, A.K.S.; Sokoloff, M.D.; Stockdale, I.; Wilson, R.J.

    1992-10-01

    We describe the design and operation of the fluid delivery, monitor and control systems for the SLD barrel Cherenkov Ring Imaging Detector (CRID). The systems deliver drift gas (C{sub 2}H{sub 6} + TMAE), radiator gas (C{sub 5}F{sub 12} + N{sub 2}) and radiator liquid (C{sub 6}F{sub 14}). Measured critical quantities such as electron lifetime in the drift gas and ultra-violet (UV) transparencies of the radiator fluids, together with the operational experience, are also reported.

  15. A high-efficiency focusing Cherenkov radiation detector

    SciTech Connect

    Lewis, K.; Moran, M.J.; Hall, J. ); Graser, M. )

    1992-03-01

    A new design uses advanced technology to produce an efficient, high-bandwidth Cherenkov detector for relativistic charged particles. The detector consists of a diamond-lathe machined ultraviolet-grade Lucite radiator, a parabolic focusing mirror, and a photodiode with an S-20 cathode. This article discusses some details of the detector design and describes preliminary measurements of its response characteristics. The data show the detector to have an overall gain of {approx}76 signal electrons per incident electron and a photodiode-limited response time of {approx}450 ps.

  16. Corrugated capillary as THz Cherenkov Smith-Purcell radiator

    NASA Astrophysics Data System (ADS)

    Lekomtsev, K. V.; Aryshev, A. S.; Tishchenko, A. A.; Ponomarenko, A. A.; Sukharev, V. M.; Terunuma, N.; Urakawa, J.; Strikhanov, M. N.

    2016-07-01

    In this article we discussed Particle In Cell electromagnetic simulations and mechanical design of dielectric capillaries that produce THz Cherenkov Smith-Purcell radiation (ChSPR), arising when a femtosecond electron multi-bunch beam propagates through corrugated and non-corrugated dielectric capillaries with metallic radiation reflectors. We investigated the influence of the four-bunch beam on the SPR field spectrum and on the ChSPR power spectrum, and the influence of the non-central beam propagation on the ChSPR power spectrum. We also discussed the design and assembly of the capillaries, constructed as sets of cylindrical rings.

  17. Hubble Telescope Detects 'Sunscreen' Layer on Distant Planet

    NASA Video Gallery

    Using NASA’s Hubble Telescope, scientists detected a stratosphere on the planet WASP-33b. A stratosphere occurs when molecules in the atmosphere absorb ultraviolet and visible light from the star. ...

  18. JWST Pathfinder Telescope Integration

    NASA Technical Reports Server (NTRS)

    Matthews, Gary W.; Kennard, Scott H.; Broccolo, Ronald T.; Ellis, James M.; Daly, Elizabeth A.; Hahn, Walter G.; Amon, John N.; Mt. Pleasant, Stephen M.; Texter, Scott; Atkinson, Charles B.; McKay, Andrew; Levi, Joshua; Keski-Kuha, Ritva; Feinberg, Lee

    2015-01-01

    The James Webb Space Telescope (JWST) is a 6.5m, segmented, IR telescope that will explore the first light of the universe after the big bang. In 2014, a major risk reduction effort related to the Alignment, Integration, and Test (AI&T) of the segmented telescope was completed. The Pathfinder telescope includes two Primary Mirror Segment Assemblies (PMSA's) and the Secondary Mirror Assembly (SMA) onto a flight-like composite telescope backplane. This pathfinder allowed the JWST team to assess the alignment process and to better understand the various error sources that need to be accommodated in the flight build. The successful completion of the Pathfinder Telescope provides a final integration roadmap for the flight operations that will start in August 2015.

  19. JWST pathfinder telescope integration

    NASA Astrophysics Data System (ADS)

    Matthews, Gary W.; Kennard, Scott H.; Broccolo, Ronald T.; Ellis, James M.; Daly, Elizabeth A.; Hahn, Walter G.; Amon, John N.; Mt. Pleasant, Stephen M.; Texter, Scott; Atkinson, Charles B.; McKay, Andrew; Levi, Joshua; Keski-Kuha, Ritva; Feinberg, Lee

    2015-08-01

    The James Webb Space Telescope (JWST) is a 6.5m, segmented, IR telescope that will explore the first light of the universe after the big bang. In 2014, a major risk reduction effort related to the Alignment, Integration, and Test (AI and T) of the segmented telescope was completed. The Pathfinder telescope includes two Primary Mirror Segment Assemblies (PMSA's) and the Secondary Mirror Assembly (SMA) onto a flight-like composite telescope backplane. This pathfinder allowed the JWST team to assess the alignment process and to better understand the various error sources that need to be accommodated in the flight build. The successful completion of the Pathfinder Telescope provides a final integration roadmap for the flight operations that will start in August 2015.

  20. Automated telescope scheduling

    NASA Technical Reports Server (NTRS)

    Johnston, Mark D.

    1988-01-01

    With the ever increasing level of automation of astronomical telescopes the benefits and feasibility of automated planning and scheduling are becoming more apparent. Improved efficiency and increased overall telescope utilization are the most obvious goals. Automated scheduling at some level has been done for several satellite observatories, but the requirements on these systems were much less stringent than on modern ground or satellite observatories. The scheduling problem is particularly acute for Hubble Space Telescope: virtually all observations must be planned in excruciating detail weeks to months in advance. Space Telescope Science Institute has recently made significant progress on the scheduling problem by exploiting state-of-the-art artificial intelligence software technology. What is especially interesting is that this effort has already yielded software that is well suited to scheduling groundbased telescopes, including the problem of optimizing the coordinated scheduling of more than one telescope.

  1. Automated telescope scheduling

    NASA Astrophysics Data System (ADS)

    Johnston, Mark D.

    1988-08-01

    With the ever increasing level of automation of astronomical telescopes the benefits and feasibility of automated planning and scheduling are becoming more apparent. Improved efficiency and increased overall telescope utilization are the most obvious goals. Automated scheduling at some level has been done for several satellite observatories, but the requirements on these systems were much less stringent than on modern ground or satellite observatories. The scheduling problem is particularly acute for Hubble Space Telescope: virtually all observations must be planned in excruciating detail weeks to months in advance. Space Telescope Science Institute has recently made significant progress on the scheduling problem by exploiting state-of-the-art artificial intelligence software technology. What is especially interesting is that this effort has already yielded software that is well suited to scheduling groundbased telescopes, including the problem of optimizing the coordinated scheduling of more than one telescope.

  2. Next Generation Space Telescope

    NASA Astrophysics Data System (ADS)

    Smith, E.; Murdin, P.

    2002-01-01

    The Next Generation Space Telescope (NGST) will be an 8 m class deployable, radiatively cooled telescope, optimized for the 1-5 μm band, with zodiacal background limited sensitivity from 0.6 to 10 μm or longer, operating for 10 yr near the Earth-Sun second LAGRANGIAN POINT (L2). It will be a general-purpose observatory, operated by the SPACE TELESCOPE SCIENCE INSTITUTE (STScI) for competitively s...

  3. South Pole Telescope optics.

    PubMed

    Padin, S; Staniszewski, Z; Keisler, R; Joy, M; Stark, A A; Ade, P A R; Aird, K A; Benson, B A; Bleem, L E; Carlstrom, J E; Chang, C L; Crawford, T M; Crites, A T; Dobbs, M A; Halverson, N W; Heimsath, S; Hills, R E; Holzapfel, W L; Lawrie, C; Lee, A T; Leitch, E M; Leong, J; Lu, W; Lueker, M; McMahon, J J; Meyer, S S; Mohr, J J; Montroy, T E; Plagge, T; Pryke, C; Ruhl, J E; Schaffer, K K; Shirokoff, E; Spieler, H G; Vieira, J D

    2008-08-20

    The South Pole Telescope is a 10 m diameter, wide-field, offset Gregorian telescope with a 966-pixel, millimeter-wave, bolometer array receiver. The telescope has an unusual optical system with a cold stop around the secondary. The design emphasizes low scattering and low background loading. All the optical components except the primary are cold, and the entire beam from prime focus to the detectors is surrounded by cold absorber. PMID:18716649

  4. The Antarctic Submillimetre Telescope

    NASA Astrophysics Data System (ADS)

    Minier, V.; Olmi, L.; Durand, G.; Daddi, E.; Israel, F.; Kramer, C.; Lagage, P.-O.; de Petris, M.; Sabbatini, L.; Spinoglio, L.; Schneider, N.; Tothill, N.; Tremblin, P.; Valenziano, L.; Veyssière, C.

    This report aims to provide a summary of the status of our Antarctic Submillimetre Telescope (AST) project up to date. It is a very new project for Antarctic astronomy. Necessary prerequisites for a future deployment of a large size telescope infrastructure have been tested in years 2007 and 2008. The knowledge of the transmission, frost formation and temperature gradient were fundamental parameters before starting a feasibility study. The telescope specifications and requirements are currently discussed with the industrial partnership.

  5. LISA Telescope Sensitivity Analysis

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    The results of a LISA telescope sensitivity analysis will be presented, The emphasis will be on the outgoing beam of the Dall-Kirkham' telescope and its far field phase patterns. The computed sensitivity analysis will include motions of the secondary with respect to the primary, changes in shape of the primary and secondary, effect of aberrations of the input laser beam and the effect the telescope thin film coatings on polarization. An end-to-end optical model will also be discussed.

  6. EUSO-TA prototype telescope

    NASA Astrophysics Data System (ADS)

    Bisconti, Francesca

    2016-07-01

    EUSO-TA is one of the prototypes developed for the JEM-EUSO project, a space-based large field-of-view telescope to observe the fluorescence light emitted by cosmic ray air showers in the atmosphere. EUSO-TA is a ground-based prototype located at the Telescope Array (TA) site in Utah, USA, where an Electron Light Source and a Central Laser Facility are installed. The purpose of the EUSO-TA project is to calibrate the prototype with the TA fluorescence detector in presence of well-known light sources and cosmic ray air showers. In 2015, the detector started the first measurements and tests using the mentioned light sources have been performed successfully. A first cosmic ray candidate has been observed, as well as stars of different magnitude and color index. Since Silicon Photo-Multipliers (SiPMs) are very promising for fluorescence telescopes of next generation, they are under consideration for the realization of a new prototype of EUSO Photo Detector Module (PDM). The response of this sensor type is under investigation through simulations and laboratory experimentation.

  7. The Multiple Mirror Telescope

    NASA Astrophysics Data System (ADS)

    Beckers, J. M.; Ulich, B. L.; Shannon, R. R.; Carleton, N. P.; Geary, J. C.; Latham, D. W.; Angel, J. R. P.; Hoffmann, W. F.; Low, F. J.; Weymann, R. J.

    The Multiple Mirror Telescope (MMT), located on top of Mount Hopkins (2600 m) in Arizona, consists of six main telescope systems, each of which is a classical Cassegrain with a 1.8 m diameter parabolic primary with focal ratio f/2.7, and a hyperbolic secondary producing a final f/31.6 for each of the individual telescopes. The most significant departures of the MMT from conventional optical telescope technology are (1) the use of light-weight 'egg-crate' mirrors, which reduced the telescope weight, (2) the use of an alt-azimuth mount, which simplifies the gravitational effects on the structure, (3) the use of a ball-bearing support rather than hydrostatic bearings, resulting in cost savings and less maintenance, (4) the use of spur gear drives rather than worm gears, and (5) the use of multiple coaligned light collectors rather than a single monolithic mirror. Early multiple objective telescopes are discussed, and the early history of the MMT project is given. The design and performance of the telescope are explained, and MMT instrumentation (spectrograph, optical design, detector, infrared photometer, SAO CCD camera) is given. Astronomical research with the telescope is discussed, along with plans for future multiple objective telescopes.

  8. ATST telescope pier

    NASA Astrophysics Data System (ADS)

    Jeffers, Paul; Manuel, Eric; Dreyer, Oliver; Kärcher, Hans

    2012-09-01

    The Advanced Technology Solar Telescope (ATST) will be the largest solar telescope in the world with a 4m aperture primary mirror. The off axis nature of the telescope optical layout, has the proportions of an 8 metre class telescope. Accordingly the instrumentation for solar observations a 16m diameter co-rotating laboratory (Coude Rotator) is also located within the telescope pier. The pier has a lower cylindrical profile with an upper conical section to support both the telescope mount with a 9m bearing diameter and contain the 16m diameter Coudé rotator. The performance of this pier cannot be considered in isolation but must account for ancillary equipment, access and initial installation. The Coude rotator structure and bearing system are of similar size to the telescope base structure and therefore this is the proverbial 'ship in a bottle' problem. This paper documents the competing requirements on the pier design and the balancing of these as the design progresses. Also summarized is the evolution of the design from a conceptual traditional reinforced concrete pier to a composite concrete and steel framed design. The stiffness requirements of the steel frame was a unique challenge for both the theoretical performance and overall design strategy considering constructability. The development of design acceptance criteria for the pier is discussed along with interfacing of the AandE firm responsible for the pier design and the telescope designer responsible for the telescope performance.

  9. Telescope performance verification

    NASA Astrophysics Data System (ADS)

    Swart, Gerhard P.; Buckley, David A. H.

    2004-09-01

    While Systems Engineering appears to be widely applied on the very large telescopes, it is lacking in the development of many of the medium and small telescopes currently in progress. The latter projects rely heavily on the experience of the project team, verbal requirements and conjecture based on the successes and failures of other telescopes. Furthermore, it is considered an unaffordable luxury to "close-the-loop" by carefully analysing and documenting the requirements and then verifying the telescope's compliance with them. In this paper the authors contend that a Systems Engineering approach is a keystone in the development of any telescope and that verification of the telescope's performance is not only an important management tool but also forms the basis upon which successful telescope operation can be built. The development of the Southern African Large Telescope (SALT) has followed such an approach and is now in the verification phase of its development. Parts of the SALT verification process will be discussed in some detail to illustrate the suitability of this approach, including oversight by the telescope shareholders, recording of requirements and results, design verification and performance testing. Initial test results will be presented where appropriate.

  10. Tagging spallation backgrounds with showers in water Cherenkov detectors

    NASA Astrophysics Data System (ADS)

    Li, Shirley Weishi; Beacom, John F.

    2015-11-01

    Cosmic-ray muons and especially their secondaries break apart nuclei ("spallation") and produce fast neutrons and beta-decay isotopes, which are backgrounds for low-energy experiments. In Super-Kamiokande, these beta decays are the dominant background in 6-18 MeV, relevant for solar neutrinos and the diffuse supernova neutrino background. In a previous paper, we showed that these spallation isotopes are produced primarily in showers, instead of in isolation. This explains an empirical spatial correlation between a peak in the muon Cherenkov light profile and the spallation decay, which Super-Kamiokande used to develop a new spallation cut. However, the muon light profiles that Super-Kamiokande measured are grossly inconsistent with shower physics. We show how to resolve this discrepancy and how to reconstruct accurate profiles of muons and their showers from their Cherenkov light. We propose a new spallation cut based on these improved profiles and quantify its effects. Our results can significantly benefit low-energy studies in Super-Kamiokande, and will be especially important for detectors at shallower depths, like the proposed Hyper-Kamiokande.

  11. 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.

  12. NRO 10-m submillimeter telescope

    NASA Astrophysics Data System (ADS)

    Ukita, Nobuharu; Kawabe, Ryohei; Ishiguro, Masato; Ezawa, Hajime; Sekimoto, Yutaro; Hasegawa, Tatsuo; Yamamoto, Satoshi; Miyawaki, Keizo; Matsumoto, Soichi

    2000-07-01

    A 10-m submillimeter telescope designed for interferometric observations at bands from 3 to 0.3 mm has constructed at Nobeyama Radio Observatory. The telescope is an engineering model for a large millimeter and sub-millimeter array, and will be operated for developments of sub-millimeter observation techniques at a remote site. We have fabricated lightweight machined aluminum panels (15 kg m-2) that have a surface accuracy of 5 micrometer rms. They have a typical size of 0.8 m X 0.6 m, and are supported with three motorized screws. The back-up structure is constructed of a central hub of low thermal expansion alloy, and CFRP honeycomb boards and tubes. Holography measurements will be made with a nearby transmitter at 3 mm. The overall surface accuracy is expected to be < 25 micrometer rms; the goal being 17 micrometer rms. We have achieved an accuracy of 0.03' rms for angle encoders. The drive and control system is designed to achieve a pointing error of 1'.0 rms with no wind and at night. Under a wind velocity of 7 m s-1, the pointing error increases to 2'.0 rms. An optical telescope of 10-cm diameter mounted on the center hub will be used to characterize pointing and tracking accuracy. Thermal effects on the pointing and surface accuracy will be investigated using temperature measurements and FEM analyses. The fast position switching capability is also demanded to cancel atmospheric fluctuations. The antenna is able to drive both axes at a maximum velocity of 3 deg s-2 with a maximum acceleration of 6 deg. s-2. The telescope is currently equipped with SIS receivers for 100, 150, 230, and 345 GHz and a continuum backend and an FX-type digital autocorrelator with an instantaneous bandwidth of 512 MHz and 1024 channel outputs.

  13. LUTE telescope structural design

    NASA Technical Reports Server (NTRS)

    Ruthven, Gregory

    1993-01-01

    The major objective of the Lunar Ultraviolet Transit Experiment (LUTE) Telescope Structural Design Study was to investigate the feasibility of designing an ultralightweight 1-m aperture system within optical performance requirements and mass budget constraints. This study uses the results from our previous studies on LUTE as a basis for further developing the LUTE structural architecture. After summarizing our results in Section 2, Section 3 begins with the overall logic we used to determine which telescope 'structural form' should be adopted for further analysis and weight estimates. Specific telescope component analysis showing calculated fundamental frequencies and how they compare with our derived requirements are included. 'First-order' component stress analyses to ensure telescope optical and structural component (i.e. mirrors & main bulkhead) weights are realistic are presented. Layouts of both the primary and tertiary mirrors showing dimensions that are consistent with both our weight and frequency calculations also form part of Section 3. Section 4 presents our calculated values for the predicted thermally induced primary-to-secondary mirror despace motion due to the large temperature range over which LUTE must operate. Two different telescope design approaches (one which utilizes fused quartz metering rods and one which assumes the entire telescope is fabricated from beryllium) are considered in this analysis. We bound the secondary mirror focus mechanism range (in despace) based on these two telescope configurations. In Section 5 we show our overall design of the UVTA (Ultraviolet Telescope Assembly) via an 'exploded view' of the sub-system. The 'exploded view' is annotated to help aid in the understanding of each sub-assembly. We also include a two view layout of the UVTA from which telescope and telescope component dimensions can be measured. We conclude our study with a set of recommendations not only with respect to the LUTE structural architecture

  14. Grid-Observing: Creating a Global Network of Telescopes

    NASA Astrophysics Data System (ADS)

    Hessman, F. V.; Gelderman, R.; Naylor, T.; Pennypacker, C.; Steele, I.

    2004-12-01

    With the increasing switch from classical observing campaigns to service observations, the decreasing pressure on a large number of 1 - 2m telescopes, and the rapid growth in the number of robotic, autonomous telescopes, it has become possible to create a truly global network of telescopes - what we call ``Grid-Observing." Such a network would permit a variety of photometric and spectroscopic monitoring and temporal survey projects which cannot be performed either with current or proposed larger telescopes (e.g. LSST) or with individual telescopes operated by a single institution. Participating observatories can be ``paid" for the services they provide to the network by being able to extract an equivalent amount of time on other telescopes, scaled by aperture, spectral resolution, atmospheric conditions, and the costs of operation or willingness to provide such a service. An XML interface - Remote Telescope Markup Language - insures that communications within the network are simple and relatively easily adapted to existent observatory software and procedures. An eBay-like mechanism for the automatic scheduling of telescopes can provide the necessary flexibility needed to perform time-critical projects as well as insure that the participating institutions retain full control over their telescopes. We are planning on networking several robotic telescope in the near future and expect that many other robotic and non-robotic telescopes will follow.

  15. Observations of Mars using Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    James, Philip B.; Clancy, R. Todd; Lee, Steven W.; Kahn, Ralph; Zurek, Richard; Martin, Leonard; Singer, Robert

    1992-01-01

    The lack of a continuous record of Martian meteorology or of volatile cycles on Mars for extended periods of several Martian years seriously hinders efforts to understand the physics of the Martian atmosphere and surface system. The spacecraft observations are limited to only a few isolated time periods, and the Earth based record is limited by the relatively short periods surrounding oppositions when telescopic observations can yield useful data. To remedy this situation, the authors have embarked on a three year program of Mars observations using the Hubble Space Telescope (HST). Several scientific investigations are being carried out using the images, including: a study of the albedo variations; unit mapping of spectral reflectances; determination of optical depths due to aerosols and condensates; a study of the properties of condensate clouds and hoods; comparison of surface and atmospheric features; observation of size and shape of the polar caps; and investigation of surface atmospheric phenomena.

  16. ANTARES deep sea neutrino telescope results

    SciTech Connect

    Mangano, Salvatore; Collaboration: ANTARES Collaboration

    2014-01-01

    The ANTARES experiment is currently the largest underwater neutrino telescope in the Northern Hemisphere. It is taking high quality data since 2007. Its main scientific goal is to search for high energy neutrinos that are expected from the acceleration of cosmic rays from astrophysical sources. This contribution reviews the status of the detector and presents several analyses carried out on atmospheric muons and neutrinos. For example it shows the results from the measurement of atmospheric muon neutrino spectrum and of atmospheric neutrino oscillation parameters as well as searches for neutrinos from steady cosmic point-like sources, for neutrinos from gamma ray bursts and for relativistic magnetic monopoles.

  17. Video Telescope Operating Microscopy.

    PubMed

    Divers, Stephen J

    2015-09-01

    Exotic pet veterinarians frequently have to operate on small animals, and magnification is commonly used. Existing endoscopy equipment can be used with a mechanical arm and telescope to enable video telescope operating microscopy. The additional equipment items and their specifics are described, and several case examples are provided. PMID:26117519

  18. High resolution telescope

    DOEpatents

    Massie, Norbert A.; Oster, Yale

    1992-01-01

    A large effective-aperture, low-cost optical telescope with diffraction-limited resolution enables ground-based observation of near-earth space objects. The telescope has a non-redundant, thinned-aperture array in a center-mount, single-structure space frame. It employs speckle interferometric imaging to achieve diffraction-limited resolution. The signal-to-noise ratio problem is mitigated by moving the wavelength of operation to the near-IR, and the image is sensed by a Silicon CCD. The steerable, single-structure array presents a constant pupil. The center-mount, radar-like mount enables low-earth orbit space objects to be tracked as well as increases stiffness of the space frame. In the preferred embodiment, the array has elemental telescopes with subaperture of 2.1 m in a circle-of-nine configuration. The telescope array has an effective aperture of 12 m which provides a diffraction-limited resolution of 0.02 arc seconds. Pathlength matching of the telescope array is maintained by an electro-optical system employing laser metrology. Speckle imaging relaxes pathlength matching tolerance by one order of magnitude as compared to phased arrays. Many features of the telescope contribute to substantial reduction in costs. These include eliminating the conventional protective dome and reducing on-site construction activites. The cost of the telescope scales with the first power of the aperture rather than its third power as in conventional telescopes.

  19. High resolution telescope

    SciTech Connect

    Massie, N.A.; Oster, Y.

    1990-01-01

    A large effective-aperture, low-cost optical telescope with diffraction-limited resolution enables ground-based observation of near-earth space objects. The telescope has a non-redundant, thinned-aperture array in a center-mount, single-structure space frame. It employs speckle interferometric imaging to achieve diffraction-limited resolution. The signal-to-noise ratio problem is mitigated by moving the wavelength of operation to the near-IR, and the image is sensed by a Silicon CCD. The steerable, single-structure array presents a constant pupil. The center-mount, radar-like mount enables low-earth orbit space objects to be tracked as well as increases stiffness of the space frame. In the preferred embodiment, the array has elemental telescopes with subaperture of 2.1m in a circle-of-nine configuration. The telescope array has an effective aperture of 12m which provides a diffraction-limited resolution of 0.02 arc seconds. Pathlength matching of the telescope array is maintained by an electro-optical system employing laser metrology. Speckle imaging relaxes pathlength matching tolerance by one order of magnitude as compared to phased arrays. Many features of the telescope contribute to substantial reduction in costs. These include eliminating the conventional protective dome and reducing on-site construction activities. The cost of the telescope scales with the first power of the aperture rather than its third power as in conventional telescopes. 9 figs., 1 tab.

  20. High resolution telescope

    SciTech Connect

    Massie, N.A.; Oster, Y.

    1990-12-31

    A large effective-aperture, low-cost optical telescope with diffraction-limited resolution enables ground-based observation of near-earth space objects. The telescope has a non-redundant, thinned-aperture array in a center-mount, single-structure space frame. It employs speckle interferometric imaging to achieve diffraction-limited resolution. The signal-to-noise ratio problem is mitigated by moving the wavelength of operation to the near-IR, and the image is sensed by a Silicon CCD. The steerable, single-structure array presents a constant pupil. The center-mount, radar-like mount enables low-earth orbit space objects to be tracked as well as increases stiffness of the space frame. In the preferred embodiment, the array has elemental telescopes with subaperture of 2.1m in a circle-of-nine configuration. The telescope array has an effective aperture of 12m which provides a diffraction-limited resolution of 0.02 arc seconds. Pathlength matching of the telescope array is maintained by an electro-optical system employing laser metrology. Speckle imaging relaxes pathlength matching tolerance by one order of magnitude as compared to phased arrays. Many features of the telescope contribute to substantial reduction in costs. These include eliminating the conventional protective dome and reducing on-site construction activities. The cost of the telescope scales with the first power of the aperture rather than its third power as in conventional telescopes. 9 figs., 1 tab.

  1. Inherent small telescope projects

    NASA Astrophysics Data System (ADS)

    Charles, P. A.

    2001-01-01

    As we stand on the verge of substantial access to the new generation of giant telescopes (Gemini, VLT and others) it is timely to consider the range of science that can be undertaken with the substantial number of smaller telescopes that are spread around the globe. While providing survey science input to the giant telescopes, or simultaneous monitoring capability for space missions, is a clearly important role (see previous contributions), it should not be forgotten that there are still many outstanding scientific programmes that can be undertaken on smaller telescopes in their own right. There is a danger of these opportunities being overlooked in the stampede to abandon the smaller telescope 'baggage' in the hope of acquiring access to more giant telescope time. I will try to demonstrate that the most effective and efficient use of all our telescope time requires access to a broad range of complementary facilities. I will therefore describe here some of the projects currently being undertaken with smaller telescopes as well as some of those planned for future facilities such as ROBONET.

  2. Telescope With Reflecting Baffle

    NASA Technical Reports Server (NTRS)

    Linlor, W. I.

    1985-01-01

    Telescope baffle made from combination of reflecting surfaces. In contrast with previous ellipsoidal reflecting baffles, new baffle reflects skew rays more effectively and easier to construct. For infrared telescopes, reflecting baffles better than absorbing baffles because heat load reduced, and not necessary to contend with insufficiency of infrared absorption exhibited by black coatings.

  3. Goddard Robotic Telescope

    SciTech Connect

    Sakamoto, Takanori; Donato, Davide; Gehrels, Neil; Okajima, Takashi; Ukwatta, Tilan N.

    2009-05-25

    We are constructing the 14'' fully automated optical robotic telescope, Goddard Robotic Telescope (GRT), at the Goddard Geophysical and Astronomical Observatory. The aims of our robotic telescope are 1) to follow-up the Swift/Fermi Gamma-Ray Bursts (GRBs) and 2) to perform the coordinated optical observations of the Fermi/Large Area Telescope (LAT) Active Galactic Nuclei (AGN). Our telescope system consists of the 14'' Celestron Optical Telescope Assembly (OTA), the Astro-Physics 1200GTO mount, the Apogee U47 CCD camera, the JMI's electronic focuser, and the Finger Lake Instrumentation's color filter wheel with U, B, V, R and I filters. With the focal reducer, 20'x20' field of view has been achieved. The observatory dome is the Astro Haven's 7 ft clam-shell dome. We started the scientific observations on mid-November 2008. While not observing our primary targets (GRBs and AGNs), we are planning to open our telescope time to the public for having a wider use of our telescope in both a different research field and an educational purpose.

  4. Oscillation of Very Low Energy Atmospheric Neutrinos

    SciTech Connect

    Peres, Orlando L. G.

    2010-03-30

    We discuss the oscillation effects of sub-sub-GeV atmospheric neutrinos, the sample with energies E < or approx. 100 MeV. The energy spectra of the e-like events in water Cherenkov detectors are computed and dependence of the spectra on the 2-3 mixing angle, theta{sub 23}, the 1-3 mixing and CP-violation phase are studied.

  5. Development of the ACS+OPC UA based control system for a CTA medium size telescope prototype

    NASA Astrophysics Data System (ADS)

    Behera, Bagmeet; Oya, Igor; Birsin, Emrah; Köppel, Hendryk; Melkumyan, David; Schlenstedt, Stefan; Schmidt, Torsten; Schwanke, Ullrich; Wegner, Peter; Wiesand, Stephan; Winde, Michael

    2012-09-01

    The Cherenkov Telescope Array (CTA) is the next generation Very High Energy (VHE, defined as > 50GeV to several 100TeV) telescope facility, currently in the design and prototyping phase, and expected to come on-line around 2016. The array would have both a Northern and Southern hemisphere site, together delivering nearly complete sky coverage. The CTA array is planned to have ~100 telescopes of several different sizes to fulfill the sensitivity and energy coverage needs. Each telescope has a number of subsystems with varied hardware and control mechanisms; a drive system that gets commands and inputs via OPC UA (OPC Unified Architecture), mirror alignment systems based on XBee/ZigBee protocol and/or CAN bus, weather monitor accessed via serial/Ethernet ports, CCD cameras for calibration, Cherenkov camera, and the data read out electronics, etc. Integrating the control and data-acquisitions of such a distributed heterogeneous system calls for a framework that can handle such a multi-platform, multi-protocol scenario. The CORBA based ALMA Common software satisfies these needs very well and is currently being evaluated as the base software for developing the control system for CTA. A prototype for a Medium Size Telescope (MST, ~12m) is being developed and will be deployed in Berlin, by end of 2012. We present the development being carried out to integrate and control the various hardware subsystems of this MST prototype using ACS.

  6. Surveys with the New KOSMA Telescope

    NASA Astrophysics Data System (ADS)

    Kramer, C.; Beuther, H.; Simon, R.; Stutzki, J.; Winnewisser, G.

    The Kölner Observatorium für Submillimeter-Astronomie (KOSMA) has recently been equipped with a new 3m submm telescope. The current surface accuracy of the primary dish of ~30 microns, the excellent weather conditions at the telescope site, the Gornergrat in the Swiss Alps at 3150m altitude, and the dual-channel SIS receivers, allow to efficiently conduct observations between 210 and 820 GHz, covering all the high atmospheric windows accessible from ground based telescopes. Currently, we are concentrating on observing low- J and mid- J transitions of CO and its isotopomers to analyze the excitation conditions of the cold and warm interstellar medium. I will present maps of Cepheus B and other clouds, made in the newly implemented, very efficient, on-the-fly observing modus. The effect of continuously sampling the source will be discussed, in comparison to the traditional point-by-point raster mapping mode. In addition, I will present a method to correct for the emission detected in the extended errorbeam of a large telescope, e.g. the IRAM 30m telescope, by additional observations with e.g. the KOSMA 3m telescope. Furtheron, a flat fielding algorithm, developed to improve the calibration consistency of large raster maps made with single pixel receivers, may also serve to improve maps of multi-beam array receivers (Urs Graf, this conference) in the future.

  7. The 3.5-meter telescope enclosure

    NASA Astrophysics Data System (ADS)

    Brady, Michael H.

    1994-04-01

    The 3.5-m telescope enclosure is designed to perform two functions as part of the U.S. Air Force's 3.5-m telescope system: (1) to provide weather and temperature protection when the telescope is not in use and (2) to permit open-air operation of the telescope while minimizing atmospheric disturbances in the field of view (FOV). The use of a standard rotating dome is impractical because of the large telescope and its high rotational rate and acceleration. The enclosure is a 40-ft tall cylinder with a diameter of 72 ft. This steel and aluminum structure does not rotate but collapses vertically to fully expose the telescope to the open air and to provide it with an unobscured view of the horizon at all azimuthal angles. To lessen wind disturbances in the FOV, the enclosure has a moderately sloped roof and smooth, vertical walls. To minimize thermal flow, the outer surface has a high-reflectivity, low-emissivity coating and ambient air is forced through the double-skinned walls and roof. These measures make it possible to keep the enclosure surface temperature near that of the ambient air during viewing. With these features, the enclosure adds minimal degradation to the seeing.

  8. Ultra-high resolution of radiocesium distribution detection based on Cherenkov light imaging

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Ogata, Yoshimune; Kawachi, Naoki; Suzui, Nobuo; Yin, Yong-Gen; Fujimaki, Shu

    2015-03-01

    After the nuclear disaster in Fukushima, radiocesium contamination became a serious scientific concern and research of its effects on plants increased. In such plant studies, high resolution images of radiocesium are required without contacting the subjects. Cherenkov light imaging of beta radionuclides has inherently high resolution and is promising for plant research. Since 137Cs and 134Cs emit beta particles, Cherenkov light imaging will be useful for the imaging of radiocesium distribution. Consequently, we developed and tested a Cherenkov light imaging system. We used a high sensitivity cooled charge coupled device (CCD) camera (Hamamatsu Photonics, ORCA2-ER) for imaging Cherenkov light from 137Cs. A bright lens (Xenon, F-number: 0.95, lens diameter: 25 mm) was mounted on the camera and placed in a black box. With a 100-μm 137Cs point source, we obtained 220-μm spatial resolution in the Cherenkov light image. With a 1-mm diameter, 320-kBq 137Cs point source, the source was distinguished within 2-s. We successfully obtained Cherenkov light images of a plant whose root was dipped in a 137Cs solution, radiocesium-containing samples as well as line and character phantom images with our imaging system. Cherenkov light imaging is promising for the high resolution imaging of radiocesium distribution without contacting the subject.

  9. Hubble Space Telescope overview

    NASA Technical Reports Server (NTRS)

    Polidan, Ronald S.

    1991-01-01

    A general overview of the performance and current status of the Hubble Space Telescope is presented. Most key spacecraft subsystems are operating well, equaling or exceeding specifications. Spacecraft thermal properties, power, and communications, are superb. The only spacecraft subsystem to have failed, a gyro, is briefly discussed. All science instruments are functioning extremely well and are returning valuable scientific data. The two significant problems effecting the Hubble Space Telescope science return, the pointing jitter produced by thermally induced bending of the solar array wings and the optical telescope assembly spherical aberration, are discussed and plans to repair both problems are mentioned. The possible restoration of full optical performance of the axial scientific instruments through the use of the Corrective Optics Space Telescope Axial Replacement, currently under study for the 1993 servicing mission, is discussed. In addition, an overview of the scientific performance of the Hubble Space Telescope is presented.

  10. Recent results from the ANTARES neutrino telescope

    NASA Astrophysics Data System (ADS)

    Van Elewyck, Véronique

    2014-04-01

    The ANTARES neutrino telescope is currently the largest operating water Cherenkov detector and the largest neutrino detector in the Northern Hemisphere. Its main scientific target is the detection of high-energy (TeV and beyond) neutrinos from cosmic accelerators, as predicted by hadronic interaction models, and the measurement of the diffuse neutrino flux. Its location allows for surveying a large part of the Galactic Plane, including the Galactic Centre. In addition to the standalone searches for point-like and diffuse high-energy neutrino signals, ANTARES has developed a range of multi-messenger strategies to exploit the close connection between neutrinos and other cosmic messengers such as gamma-rays, charged cosmic rays and gravitational waves. This contribution provides an overview of the recently conducted analyses, including a search for neutrinos from the Fermi bubbles region, searches for optical counterparts with the TAToO program, and searches for neutrinos in correlation with gamma-ray bursts, blazars, and microquasars. Further topics of investigation, covering e.g. the search for neutrinos from dark matter annihilation, searches for exotic particles and the measurement of neutrino oscillations, are also reviewed.

  11. Large Binocular Telescope Project

    NASA Astrophysics Data System (ADS)

    Hill, John M.; Salinari, Piero

    1998-08-01

    The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, Germany, Italy, and Ohio. With the addition of the partners from Ohio State and Germany in February 1997, the Large Binocular Telescope Corporation has the funding required to build the full telescope populated with both 8.4 meter optical trans. The first of two 8.4 meter borosilicate honeycomb primary mirrors for LBT was cast at the Steward Observatory Mirror Lab in 1997. The baseline optical configuration of LBT includes adaptive infrared secondaries of a Gregorian design. The F/15 secondaries are undersized to provide a low thermal background focal plane. The interferometric focus combining the light from the two 8.4 meter primaries will reimage the two folded Gregorian focal planes to three central locations. The telescope elevation structure accommodates swing arms which allow rapid interchange of the various secondary and tertiary mirrors. Maximum stiffness and minimal thermal disturbance were important drivers for the design of the telescope in order to provide the best possible images for interferometric observations. The telescope structure accommodates installation of a vacuum bell jar for aluminizing the primary mirrors in-situ on the telescope. The detailed design of the telescope structure was completed in 1997 by ADS Italia (Lecco) and European Industrial Engineering (Mestre). A series of contracts for the fabrication and machining of the telescope structure had been placed at the end of 1997. The final enclosure design was completed at M3 Engineering & Technology (Tucson), EIE and ADS Italia. During 1997, the telescope pier and the concrete ring wall for the rotating enclosure were completed along with the steel structure of the fixed portion of the enclosure. The erection of the steel structure for the rotating portion of the enclosure will begin in the Spring of 1998.

  12. Daniel K. Inouye Solar Telescope Science Operations

    NASA Astrophysics Data System (ADS)

    Tritschler, Alexandra; Rimmele, Thomas R.; Berukoff, Steven

    2016-05-01

    The Daniel K. Inouye Solar Telescope (DKIST) is a versatile high resolution ground-based solar telescope designed to explore the dynamic Sun and its magnetism throughout the solar atmosphere from the photosphere to the faint corona. The DKIST is currently under construction on Haleakala, Maui, Hawai'i, and expected to commence with science operations in 2019. In this contribution we provide an overview of the high-level science operations concepts from proposal preparation and submission to the flexible and dynamic planning and execution of observations.

  13. The Reflecting Surface of the MAGIC Telescope

    NASA Astrophysics Data System (ADS)

    Bastieri, D.; Bigongiari, C.; Galante, N.; Lorenz, E.; Mariotti, M.; Mirzoyan, R.; Moralejo, A.; Pepato, A.; Peruzzo, L.; Saggion, A.; Scalzotto, V.; Tonello, N.; MAGIC Collaboration

    2003-07-01

    ˇ The MAGIC Collab oration is starting to operate the Cerenkov telescope with the largest reflecting surface, in order to lower the energy threshold well ˇ below 100 GeV. The MAGIC (Ma jor Atmospheric Gamma Imaging Cerenkov) telescope has a 17 m diameter parab olic surface F/1, consisting of 956 spherical aluminium mirrors (50 × 50 cm2 each). In this contribution, we describe the technology adopted to produce metallic mirrors and the methods used to measure the optical quality in terms of: reflectivity, radius of curvature, spot dimension and geometry.

  14. Studies of extended planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hunten, D. M.

    1991-01-01

    The following topics are covered: (1) telescopic observations and analysis of planetary atmospheres (including the Moon and Mars) and the Io torus; (2) occultation observations; and (3) supporting laboratory studies.

  15. First Year Operational Experience with the Cherenkov Detector (DIRC) of BaBar

    SciTech Connect

    Spanier, Stefane

    2000-04-21

    The DIRC (acronym for Detection of Internally Reflected Cherenkov (light)) is a new type of Cherenkov ring imaging detector based on total internal reflection that is used for the first time in the BaBar detector at PEP-II ring of SLAC. The Cherenkov radiators are long rectangular bars made of synthetic fused silica. The photon detector is a water tank equipped with an array of 10,752 conventional photomultipliers. The first year operational experience in the BaBar detector is presented using cosmic data and collision data in the energy region of the Upsilon(4S) resonance.

  16. First year operational experience with the Cherenkov Detector (DIRC) of BaBar

    SciTech Connect

    Adam, I.; BaBar Collaboration

    2000-04-01

    The DIRC (acronym for Detection of Internally Reflected Cherenkov (light)) is a new type of Cherenkov ring imaging detector based on total internal reflection that is used for the first time in the BaBar detector at PEP-II ring of SLAC. The Cherenkov radiators are long rectangular bars made of synthetic fused silica. The photon detector is a water tank equipped with an array of 10,752 conventional photomultipliers. The first year operational experience in the BaBar detector is presented using cosmic data and collision data in the energy region of the Y(4s) resonance.

  17. Design, transport, and installation of autonomous Cherenkov detectors at high altitude

    NASA Astrophysics Data System (ADS)

    Rubén Calderón Cueva, Mario; Alejandro Vasquez, Nicolas; Martínez, Oscar; Carrera, Edgar; Cazar, Dennis; Audelo, Mario; Mantilla, Cristina; Quishpe, Raquel

    2015-08-01

    Ecuador, as a member of the Latin American Giant Observatory (LAGO), wishes to expand the understanding of astroparticle physics and space weather by the installation of Water Cherenkov detectors at high altitude. The challenge for such devices lies on their transport to the remote areas of operation, the autonomy of their electrical power supply, the robustness of their data transmission system, their remote operation stability, and the reliability of the water integrity for long periods of time. LAGO Ecuador features several studies of gamma ray bursts and high energy astrophysical sources, as well as of space weather. Based on these studies, we develop a feasibility study for the design, installation, operation and maintenance of the aforementioned devices in Papallacta, Chimborazo and Cruz Loma in the Ecuadorean highlands. As the atmospheric absorption, and so the area of detection to be instrumented, is significantly reduced with the altitude, the easy access to locations higher than 4000 m a.s.l. is one of the main advantages of the Ecuadorean Andes for the installation of these facilities.

  18. Selective Filtration of Gadolinium Trichloride for Use in Neutron Detection in Large Water Cherenkov Detectors

    SciTech Connect

    Vagins, Mark R.

    2013-04-10

    Water Cherenkov detectors have been used for many years as inexpensive, effective detectors for neutrino interactions and nucleon decay searches. While many important measurements have been made with these detectors a major drawback has been their inability to detect the absorption of thermal neutrons. We believe an inexpensive, effective technique could be developed to overcome this situation via the addition to water of a solute with a large neutron cross section and energetic gamma daughters which would make neutrons detectable. Gadolinium seems an excellent candidate especially since in recent years it has become very inexpensive, now less than $8 per kilogram in the form of commercially-available gadolinium trichloride, GdCl{sub 3}. This non-toxic, non-reactive substance is highly soluble in water. Neutron capture on gadolinium yields a gamma cascade which would be easily seen in detectors like Super-Kamiokande. We have been investigating the use of GdCl{sub 3} as a possible upgrade for the Super-Kamiokande detector with a view toward improving its performance as a detector for atmospheric neutrinos, supernova neutrinos, wrong-sign solar neutrinos, reactor neutrinos, proton decay, and also as a target for the coming T2K long-baseline neutrino experiment. This focused study of selective water filtration and GdCl{sub 3} extraction techniques, conducted at UC Irvine, followed up on highly promising benchtop-scale and kiloton-scale work previously carried out with the assistance of 2003 and 2005 Advanced Detector Research Program grants.

  19. Two Easily Made Astronomical Telescopes.

    ERIC Educational Resources Information Center

    Hill, M.; Jacobs, D. J.

    1991-01-01

    The directions and diagrams for making a reflecting telescope and a refracting telescope are presented. These telescopes can be made by students out of plumbing parts and easily obtainable, inexpensive, optical components. (KR)

  20. The GREGOR Solar Telescope

    NASA Astrophysics Data System (ADS)

    Denker, C.; Lagg, A.; Puschmann, K. G.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier, K. G.; Volkmer, R.; von der Luehe, O.; Solanki, S. K.; Balthasar, H.; Bello Gonzalez, N.; Berkefeld, T.; Collados Vera, M.; Hofmann, A.; Kneer, F.

    2012-12-01

    The 1.5-meter GREGOR solar telescope is a new facility for high-resolution observations of the Sun. The telescope is located at the Spanish Observatorio del Teide on Tenerife. The telescope incorporates advanced designs for a foldable-tent dome, an open steel-truss telescope structure, and active and passive means to minimize telescope and mirror seeing. Solar fine structure can be observed with a dedicated suite of instruments: a broad-band imaging system, the "GREGOR Fabry-Perot Interferometer", and the "Grating Infrared Spectrograph". All post-focus instruments benefit from a high-order (multi-conjugate) adaptive optics system, which enables observations close to the diffraction limit of the telescope. The inclusion of a spectrograph for stellar activity studies and the search for solar twins expands the scientific usage of the GREGOR to the nighttime domain. We report on the successful commissioning of the telescope until the end of 2011 and the first steps towards science verification in 2012.

  1. Telescopic vision contact lens

    NASA Astrophysics Data System (ADS)

    Tremblay, Eric J.; Beer, R. Dirk; Arianpour, Ashkan; Ford, Joseph E.

    2011-03-01

    We present the concept, optical design, and first proof of principle experimental results for a telescopic contact lens intended to become a visual aid for age-related macular degeneration (AMD), providing magnification to the user without surgery or external head-mounted optics. Our contact lens optical system can provide a combination of telescopic and non-magnified vision through two independent optical paths through the contact lens. The magnified optical path incorporates a telescopic arrangement of positive and negative annular concentric reflectors to achieve 2.8x - 3x magnification on the eye, while light passing through a central clear aperture provides unmagnified vision.

  2. Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    1990-02-01

    An overview of the mission of the Hubble Space Telescope, a joint project between NASA and the European Space Agency which will be used to study deep space, as well as our solar system is presented. The video contains animations depicting the Hubble Space Telescope in orbit, as well as footage of scientists at the Space Telescope Science Institute making real time observations. The images Hubble acquires will be downloaded into a database that contains images of over 19,000,0000 celestial objects called the Star Catalog.

  3. Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    1990-01-01

    An overview of the mission of the Hubble Space Telescope, a joint project between NASA and the European Space Agency which will be used to study deep space, as well as our solar system is presented. The video contains animations depicting the Hubble Space Telescope in orbit, as well as footage of scientists at the Space Telescope Science Institute making real time observations. The images Hubble acquires will be downloaded into a database that contains images of over 19,000,000 celestial objects called the Star Catalog.

  4. Ritchey-Chretien Telescope

    NASA Technical Reports Server (NTRS)

    Rosin, S.; Amon, M. (Inventor)

    1973-01-01

    A Ritchey-Chretien telescope is described which was designed to respond to images located off the optical axis by using two transparent flat plates positioned in the ray path of the image. The flat plates have a tilt angle relative to the ray path to compensate for astigmatism introduced by the telescope. The tilt angle of the plates is directly proportional to the off axis angle of the image. The plates have opposite inclination angles relative to the ray paths. A detector which is responsive to the optical image as transmitted through the plates is positioned approximately on the sagittal focus of the telescope.

  5. Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings

    NASA Astrophysics Data System (ADS)

    van de Bruck, Carsten; Burrage, Clare; Morrice, Jack

    2016-08-01

    The simplest way to modify gravity is to extend the gravitational sector to include an additional scalar degree of freedom. The most general metric that can be built in such a theory includes disformal terms, so that standard model fields move on a metric which is the sum of the space time metric and a tensor constructed from first derivatives of the scalar. In such a theory gravitational waves and photons can propagate at different speeds, and these can in turn be different from the maximum speed limit for matter particles. In this work we show that disformal couplings can cause charged particles to emit Cherenkov radiation and bremsstrahlung apparently in vacuum, depending on the background evolution of the scalar field. We discuss the implications of this for observations of cosmic rays, and the constraints that arise for models of dark energy with disformal couplings.

  6. Status of Coherent Cherenkov Wakefield Experiment at UCLA

    SciTech Connect

    Cook, A. M.; Knyazik, A.; Rosenzweig, J. B.; Tikhoplav, R.; Travish, G.; Williams, O. B.

    2009-01-22

    Coherent Cherenkov radiation (CCR) wakefields are produced when a compressed electron beam travels along the axis of a hollow cylindrical dielectric tube. In a dielectric wakefield accelerator (DWA) these wakefields accelerate either a trailing electron bunch or the tail of the driving bunch, depending on the modal structure of the radiation. For an appropriate choice of dielectric structure geometry and beam parameters the device operates in a single-mode regime, producing sinusoidal wakefields with wavelengths in the THz range. We report on preliminary results of an experiment at UCLA studying the potential of a DWA structure to produce high-power, narrow-band THz radiation. First measurements include observation of 1 MW peak-power pulses of coherent broadband radiation from a compact dipole beam dump magnet.

  7. Suppressing the numerical Cherenkov radiation in the Yee numerical scheme

    NASA Astrophysics Data System (ADS)

    Nuter, Rachel; Tikhonchuk, Vladimir

    2016-01-01

    The next generation of laser facilities will routinely produce relativistic particle beams from the interaction of intense laser pulses with solids and/or gases. Their modeling with Particle-In-Cell (PIC) codes needs dispersion-free Maxwell solvers in order to properly describe the interaction of electromagnetic waves with relativistic particles. A particular attention is devoted to the suppression of the numerical Cherenkov instability, responsible for the noise generation. It occurs when the electromagnetic wave is artificially slowed down because of the finite mesh size, thus allowing for the high energy particles to propagate with super-luminous velocities. In the present paper, we show how a slight increase of the light velocity in the Maxwell's equations enables to suppress this instability while keeping a good overall precision of calculations.

  8. Coherent Cherenkov radiation as an intense THz source

    NASA Astrophysics Data System (ADS)

    Bleko, V.; Karataev, P.; Konkov, A.; Kruchinin, K.; Naumenko, G.; Potylitsyn, A.; Vaughan, T.

    2016-07-01

    Diffraction and Cherenkov radiation of relativistic electrons from a dielectric target has been proposed as mechanism for production of intense terahertz (THz) radiation. The use of an extremely short high-energy electron beam of a 4th generation light source (X-ray free electron laser) appears to be very promising. A moderate power from the electron beam can be extracted and converted into THz radiation with nearly zero absorption losses. The initial experiment on THz observation will be performed at CLARA/VELA FEL test facility in the UK to demonstrate the principle to a wider community and to develop the radiator prototype. In this paper, we present our theoretical predictions (based on the approach of polarization currents), which provides the basis for interpreting the future experimental measurements. We will also present our hardware design and discuss a plan of the future experiment.

  9. Application of Geiger-mode photosensors in Cherenkov detectors

    NASA Astrophysics Data System (ADS)

    Gamal, Ahmed; Paul, Bühler; Michael, Cargnelli; Roland, Hohler; Johann, Marton; Herbert, Orth; Ken, Suzuki

    2011-05-01

    Silicon-based photosensors (SiPMs) working in the Geiger-mode represent an elegant solution for the readout of particle detectors working at low-light levels like Cherenkov detectors. Especially the insensitivity to magnetic fields makes this kind of sensors suitable for modern detector systems in subatomic physics which are usually employing magnets for momentum resolution. We are characterizing SiPMs of different manufacturers for selecting sensors and finding optimum operating conditions for given applications. Recently we designed and built a light concentrator prototype with 8×8 cells to increase the active photon detection area of an 8×8 SiPM (Hamamatsu MPPC S10931-100P) array. Monte Carlo studies, measurements of the collection efficiency, and tests with the MPPC were carried out. The status of these developments are presented.

  10. Cherenkov sound on a surface of a topological insulator

    NASA Astrophysics Data System (ADS)

    Smirnov, Sergey

    2013-11-01

    Topological insulators are currently of considerable interest due to peculiar electronic properties originating from helical states on their surfaces. Here we demonstrate that the sound excited by helical particles on surfaces of topological insulators has several exotic properties fundamentally different from sound propagating in nonhelical or even isotropic helical systems. Specifically, the sound may have strictly forward propagation absent for isotropic helical states. Its dependence on the anisotropy of the realistic surface states is of distinguished behavior which may be used as an alternative experimental tool to measure the anisotropy strength. Fascinating from the fundamental point of view backward, or anomalous, Cherenkov sound is excited above the critical angle π/2 when the anisotropy exceeds a critical value. Strikingly, at strong anisotropy the sound localizes into a few forward and backward beams propagating along specific directions.

  11. About a Gadolinium-doped Water Cherenkov LAGUNA Detector

    NASA Astrophysics Data System (ADS)

    Labarga, Luis

    2010-11-01

    Water Cherenkov (wC) detectors are extremely powerful apparatuses for scientific research. Nevertheless they lack of neutron tagging capabilities, which translates, mainly, into an inability to identify the anti-matter nature of the reacting incoming anti-neutrino particles. A solution was proposed by R. Beacon and M. Vagins back in 2004: by dissolving in the water a compound with nucleus with very large cross section for neutron capture like the Gadolinium, with a corresponding emission of photons of enough energy to be detected, they can tag thermal neutrons with an efficiency larger than 80%. In this talk we detail the technique and its implications in the measurement capabilities and, as well, the new backgrounds induced. We discuss the improvement on their physics program, also for the case of LAGUNA type detectors. We comment shortly the status of the pioneering R&D program of the Super-Kamiokande Collaboration towards dissolving a Gadolinium compound in its water.

  12. About a Gadolinium-doped Water Cherenkov LAGUNA Detector

    SciTech Connect

    Labarga, Luis

    2010-11-24

    Water Cherenkov (wC) detectors are extremely powerful apparatuses for scientific research. Nevertheless they lack of neutron tagging capabilities, which translates, mainly, into an inability to identify the anti-matter nature of the reacting incoming anti-neutrino particles. A solution was proposed by R. Beacon and M. Vagins back in 2004: by dissolving in the water a compound with nucleus with very large cross section for neutron capture like the Gadolinium, with a corresponding emission of photons of enough energy to be detected, they can tag thermal neutrons with an efficiency larger than 80%. In this talk we detail the technique and its implications in the measurement capabilities and, as well, the new backgrounds induced. We discuss the improvement on their physics program, also for the case of LAGUNA type detectors. We comment shortly the status of the pioneering R and D program of the Super-Kamiokande Collaboration towards dissolving a Gadolinium compound in its water.

  13. The Ring Imaging Cherenkov Detector of the NA62 Experiment

    NASA Astrophysics Data System (ADS)

    Bucci, F.

    2012-08-01

    The NA62 experiment is designed to measure the branching ratio of the decay K+ -> π +ν bar {ν } with a 10% accuracy at the CERN SPS. To suppress the main background coming from the K+ → μ+ν decay, a Ring Imaging Cherenkov detector (RICH), able to separate π and μ in the momentum range between 15 and 35 GeV/c with a muon contamination in a pion sample < 10-2 is needed. The RICH must also have an unprecedented time resolution (100 ps) to disentangle accidental time 115sociatioDll of beam particles with pions. The last updates of the detector layout are presented along with the results of the beam tests of the RICH prototype: the muon misidentification probability was found to be 0. 7% and the time resolution < 100 ps in all the momentum range.

  14. Multi-use lunar telescopes

    NASA Technical Reports Server (NTRS)

    Genet, Russell M.; Genet, David R.; Talent, David L.; Drummond, Mark; Hine, Butler P.; Boyd, Louis J.; Trueblood, Mark

    1992-01-01

    The objective of multi-use telescopes is to reduce the initial and operational costs of space telescopes to the point where a fair number of telescopes, a dozen or so, would be affordable. The basic approach is to develop a common telescope, control system, and power and communications subsystem that can be used with a wide variety of instrument payloads, i.e., imaging CCD cameras, photometers, spectrographs, etc. By having such a multi-use and multi-user telescope, a common practice for earth-based telescopes, development cost can be shared across many telescopes, and the telescopes can be produced in economical batches.

  15. Multi-use lunar telescopes

    NASA Technical Reports Server (NTRS)

    Drummond, Mark; Hine, Butler; Genet, Russell; Genet, David; Talent, David; Boyd, Louis; Trueblood, Mark; Filippenko, Alexei V. (Editor)

    1991-01-01

    The objective of multi-use telescopes is to reduce the initial and operational costs of space telescopes to the point where a fair number of telescopes, a dozen or so, would be affordable. The basic approach is to develop a common telescope, control system, and power and communications subsystem that can be used with a wide variety of instrument payloads, i.e., imaging CCD cameras, photometers, spectrographs, etc. By having such a multi-use and multi-user telescope, a common practice for earth-based telescopes, development cost can be shared across many telescopes, and the telescopes can be produced in economical batches.

  16. Solar Rejection Filter for Large Telescopes

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Lesh, James

    2009-01-01

    front aperture filter is integrated with the telescope dome, it will reject heat from the dome and will significantly reduce dome temperature regulation requirements and costs. Also, the filter will protect the telescope optics from dust and other contaminants in the atmosphere. It will be simpler to clean or replace this filter than the telescope primary mirror. It may be necessary to paint the support grid with a highly reflective material to avoid overheating.

  17. Characterization study of silica aerogel for Cherenkov imaging

    NASA Astrophysics Data System (ADS)

    Sallaz-Damaz, Y.; Derome, L.; Mangin-Brinet, M.; Loth, M.; Protasov, K.; Putze, A.; Vargas-Trevino, M.; Véziant, O.; Buénerd, M.; Menchaca-Rocha, A.; Belmont, E.; Vargas-Magaña, M.; Léon-Vargas, H.; Ortiz-Velàsquez, A.; Malinine, A.; Baraõ, F.; Pereira, R.; Bellunato, T.; Matteuzzi, C.; Perego, D. L.

    2010-03-01

    Different methods to measure the characteristics of silica aerogel tiles used as Cherenkov radiator in the CREAM and AMS experiments have been investigated to optimize the detector performances. The measurement accuracy dictated by the physics objectives on the velocity and charge resolutions set stringent requirements on the aerogel refractive index determination, namely Δn˜1.5×10-4 and Δn˜5×10-4 for the AMS and CREAM imagers, respectively. The matching of such accuracies for this material turned out to be a metrological challenge, and finally led to a full R&D program, to develop an appropriate characterization procedure. Preliminary studies performed with a standard refractive index measurement technique (laser beam deviation by a prism) have revealed a significant systematic index nonuniformity for the AMS tiles at a level (10-3), not acceptable considering the aimed accuracy. These large variations were confirmed in a beam test. A second method, mapping the transverse index gradient by deflection of a laser beam entering normally to the tile has then been developed. It is shown that this procedure is suitable to reach the required accuracy, at the price of using both methods combined. The several hundreds of tiles of the radiator plane of the CREAM and AMS Cherenkov imagers were characterized using a simplified procedure, however, appropriate for each case, compromising between the amount of work and the time available. The experimental procedures and set-ups used are described in the text, and the obtained results are reported.

  18. Optical properties of water for the Yangbajing water cherenkov detector

    NASA Astrophysics Data System (ADS)

    Gao, Shang-qi; Sun, Zhi-bin; Jiang, Yuan-da; Wang, Chao; Du, Ke-ming

    2011-08-01

    Cherenkov radiation is used to study the production of particles during collisions, cosmic rays detections and distinguishing between different types of neutrinos and electrons. The optical properties of water are very important to the research of Cherenkov Effect. Lambert-beer law is a method to study the attenuation of light through medium. In this paper, optical properties of water are investigated by use of a water attenuation performance test system. The system is composed of the light-emitting diode (LED) light source and the photon receiver models. The LED light source model provides a pulse light signal which frequency is 1 kHz and width is 100ns. In photon receiver model, a high sensitivity photomultiplier tube (PMT) is used to detect the photons across the water. Because the output voltage amplitude of PMT is weak which is from 80mv to 120mV, a low noise pre-amplifier is used to improve the detector precise. An effective detector maximum time window of PMT is 100ns for a long lifetime, so a peak holder circuit is used to hold the maximum peak amplitude of PMT for the induced photons signal before the digitalization. In order to reduce the noise of peak holder, a multi-pulse integration is used before the sampling of analog to digital converter. At last, the detector of photons from the light source to the PMT across the water is synchronized to the pulse width of the LED. In order to calculate the attenuation coefficient and attenuation length of water precisely, the attenuation properties of air-to-water boundary is considered in the calculation.

  19. Ionization and pulse lethargy effects in inverse Cherenkov accelerators

    SciTech Connect

    Sprangle, P.; Hubbard, R.F.,; Hafizi, B.,

    1997-05-01

    Ionization processes limit the accelerating gradient and place an upper limit on the pulse duration of the electromagnetic driver in the inverse Cherenkov accelerator (ICA). Group velocity slippage, i.e., pulse lethargy, on the other hand, imposes a lower limit on the pulse duration. These limits are obtained for two ICA configurations in which the electromagnetic driver (e.g., laser or millimeter wave source) is propagated in a waveguide that is (i) lined with a dielectric material or (ii) filled with a neutral gas. In either configuration the electromagnetic driving field is guided and has an axial electric field with phase velocity equal to the speed of light in vacuum, c. The intensity of the driver in the ICA, and therefore the acceleration gradient, is limited by tunneling and collisional ionization effects. Partial ionization of the dielectric liner or gas can lead to significant modification of the dispersive properties of the waveguide, altering the phase velocity of the accelerating field and causing particle slippage, thus disrupting the acceleration process. An additional limitation on the pulse duration is imposed since the group velocity of the driving pulse is less than c and the pulse slips behind the accelerated electrons. Hence for sufficiently short pulses the electrons outrun the pulse, terminating the acceleration. Limitations on the driver pulse duration and accelerating gradient, due to ionization and pulse lethargy, are estimated for the two ICA configurations. Maximum accelerating gradients and pulse durations are presented for a 10 {mu}m, 1 mm, and 1 cm wavelength electromagnetic driver. The combination of ionization and pulse lethargy effects impose severe limitations on the maximum energy gain in inverse Cherenkov accelerators. {copyright} {ital 1997} {ital The American Physical Society}

  20. Applying artificial intelligence to the control of space telescopes (extended abstract)

    NASA Technical Reports Server (NTRS)

    Drummond, Mark; Swanson, Keith; Bresina, John; Philips, Andrew; Levinson, Rich

    1992-01-01

    The field of astronomy has recently benefited from the availability of space telescopes. The Hubble Space Telescope (HST), for instance, despite its problems, provides a unique and valuable view of the universe. However, unlike HST, a telescope need not be in low Earth orbit to escape our thickening atmosphere: it is currently technologically feasible to put a telescope on the moon, and there are excellent reasons for doing this. Either in low Earth orbit or on the moon, a space telescope represents an expensive and sought-after resource. Thus, the planning, scheduling, and control of these telescopes is an important problem that must be seriously studied.

  1. Composite Space Telescope Truss

    NASA Video Gallery

    NASA engineers are recycling an idea for a lightweight, compact space telescope structure from the early 1990s. The 315 struts and 84 nodes were originally designed to enable spacewalking astronaut...

  2. Hubble Space Telescope Image

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This photograph is a Hubble Space Telescope (HST) image of a sky full of glittering jewels. The HST peered into the Sagittarius star cloud, a narrow dust free region, providing this spectacular glimpse of a treasure chest full of stars.

  3. Webb Telescope: Planetary Evolution

    NASA Video Gallery

    Stars and planets form in the dark, inside vast, cold clouds of gas and dust. The James Webb Space Telescope's large mirror and infrared sensitivity will let astronomers peer inside dusty knots whe...

  4. Building a Telescope.

    ERIC Educational Resources Information Center

    Linas, Chris F.

    1988-01-01

    Provides information on the parts, materials, prices, dimensions, and tools needed for the construction of a telescope that can be used in high school science laboratories. Includes step-by-step directions and a diagram for assembly. (RT)

  5. Telescopes and space exploration

    NASA Technical Reports Server (NTRS)

    Brandt, J. C.; Maran, S. P.

    1982-01-01

    Progress in contemporary astronomy and astrophysics is shown to depend on complementary investigations with sensitive telescopes operating in several wavelength regions, some of which can be on the Earth's surface and others of which must be in space.

  6. Very high energy emission of Crab-like pulsars driven by the Cherenkov drift radiation

    NASA Astrophysics Data System (ADS)

    Osmanov, Z.

    2016-02-01

    In this paper, we study the generation of very high energy (VHE) emission in Crab-like pulsars driven by means of the feedback of Cherenkov drift waves on distribution of magnetospheric electrons. We have found that the unstable Cherenkov drift modes lead to the quasi-linear diffusion, keeping the pitch angles from vanishing, which in turn, maintains the synchrotron mechanism. Considering the Crab-like pulsars it has been shown that the growth rate of the Cherenkov drift instability is quite high, indicating high efficiency of the process. Analysing the mechanism for the typical parameters we have found that the Cherenkov drift emission from the extreme UV to hard X-rays is strongly correlated with the VHE synchrotron emission in the GeV band.

  7. Silica aerogel threshold Cherenkov counters for the JLab Hall A spectrometers: improvements and proposed modifications

    SciTech Connect

    Luigi Lagamba; Evaristo Cisbani; S. Colilli; R. Crateri; R. De Leo; Salvatore Frullani; Franco Garibaldi; F. Giuliani; M. Gricia; Mauro Iodice; Riccardo Iommi; A. Leone; M. Lucentini; A. Mostarda; E. Nappi; Roberto Perrino; L. Pierangeli; F. Santavenere; Guido M. Urciuoli

    2001-10-01

    Recently approved experiments at Jefferson Lab Hall A require a clean kaon identification in a large electron, pion, and proton background environment. To this end, improved performance is required of the silica aerogel threshold Cherenkov counters installed in the focal plane of the two Hall A spectrometers. In this paper we propose two strategies to improve the performance of the Cherenkov counters which presently use a hydrophilic aerogel radiator, and convey Cherenkov photons towards the photomultipliers by means of mirrors with a parabolic shape in one direction and flat in the other. The first strategy is aerogel baking. In the second strategy we propose a modification of the counter geometry by replacing the mirrors with a planar diffusing surface and by displacing in a different way the photomultipliers. Tests at CERN with a 5GeV/c multiparticle beam revealed that both the strategies are able to increase significantly the number of the detected Cherenkov photons and, therefore, the detector performance.

  8. Extension of Cherenkov Light LDF Parametrization for Tunka and Yakutsk EAS Arrays

    NASA Astrophysics Data System (ADS)

    Al-Rubaiee, A. A.

    2014-12-01

    The Cherenkov light Lateral Distribution Function (LDF) from particles initiated Extensive Air Showers (EAS) with ultrahigh energies (E > 1016 eV) was simulated using CORSIKA program for configuration of Tunka and Yakutsk EAS arrays for different primary particles (p, Fe and O2) and different zenith angles. By depending on the Breit-Wigner function, a parametrization of the Cherenkov light LDF was reconstructed on the basis of this simulation as a function of the primary energy. The comparison of the approximated Cherenkov light LDF with that measured on Tunka and Yakutsk EAS arrays gives the possibility of identification of energy spectrum and mass composition of particles initiating EAS about the knee region of the cosmic ray spectrum. The extrapolation of approximated Cherenkov light LDF for energies 20, 30 and 50 PeV was obtained for different primary particles and different zenith angles.

  9. Low-Noise Operation of All-Fiber Femtosecond Cherenkov Laser

    PubMed Central

    Liu, Xiaomin; Villanueva, Guillermo E.; Lægsgaard, Jesper; Møller, Uffe; Tu, Haohua; Boppart, Stephen A.; Turchinovich, Dmitry

    2013-01-01

    We investigate the noise properties of a femtosecond all-fiber Cherenkov radiation source with emission wavelength 600 nm, based on an Yb-fiber laser and a highly nonlinear photonic crystal fiber. A relative intensity noise as low as 103 dBc/Hz, corresponding to 2.48% pulse-to-pulse fluctuation in energy, is observed at the Cherenkov radiation output power of 4.3 mW, or 150 pJ-pulse energy. This pulse-to-pulse fluctuation is at least 10.6-dB lower compared to spectrally sliced supercontinuum sources traditionally used for ultrafast fiber-based generation at visible wavelengths. Low noise makes all-fiber Cherenkov sources promising for biophotonics applications such as multiphoton microscopy, where minimum pulse-to-pulse energy fluctuation is required. We present the dependency of the noise figure on both the Cherenkov radiation output power and its spectrum. PMID:24532961

  10. Simulated response of Cherenkov glass detectors to MeV photons

    SciTech Connect

    Hayward, J P; Bell, Zane W; Boatner, Lynn A; Hobbs, C. L.; Johnson, Rose E; Ramey, Joanne Oxendine; Jellison Jr, Gerald Earle

    2012-01-01

    Cherenkov detectors are widely used for par ticle identification in high-energy physics and for track imaging in astrophysics. Glass Cherenkov detectors that are sensitive to beta emissions originating from neutron activation have been demonstrated recently as a potential replacement for activation foils. In this work, we evaluate Cherenkov glass detectors for sensitivity and specificity to MeV photons through simulations using Geant4. The model has been previously compared with measurements of isotopic gamma sources. It includes Cherenkov gener ation, light transport, light collection, photoelectron pro duction and time response in photomultiplier tubes. The model incorporates measured, wavelength-dependent absorption and refractive index data. Simulations are con ducted for glasses the size of fabricated samples and also for the same glasses in monolithic, square-meter-size. Implications for selective detection of MeV photons are discussed.

  11. Large Binocular Telescope Project

    NASA Astrophysics Data System (ADS)

    Hill, John M.

    1997-03-01

    The large binocular telescope (LBT) project have evolved from concepts first proposed in 1985. The present partners involved in the design and construction of this 2 by 8.4 meter binocular telescope are the University of Arizona, Italy represented by the Osservatorio Astrofisico di Arcetri and the Research Corporation based in Tucson, Arizona. These three partners have committed sufficient funds to build the enclosure and the telescope populated with a single 8.4 meter optical train -- approximately 40 million dollars (1989). Based on this commitment, design and construction activities are now moving forward. Additional partners are being sought. The next mirror to be cast at the Steward Observatory Mirror Lab in the fall of 1996 will be the first borosilicate honeycomb primary for LBT. The baseline optical configuration of LBT includes wide field Cassegrain secondaries with optical foci above the primaries to provide a corrected one degree field at F/4. The infrared F/15 secondaries are a Gregorian design to allow maximum flexibility for adaptive optics. The F/15 secondaries are undersized to provide a low thermal background focal plane which is unvignetted over a 4 arcminute diameter field-of-view. The interferometric focus combining the light from the two 8.4 meter primaries will reimage two folded Gregorian focal planes to a central location. The telescope elevation structure accommodates swing arms which allow rapid interchange of the various secondary and tertiary mirrors. Maximum stiffness and minimal thermal disturbance continue to be important drivers for the detailed design of the telescope. The telescope structure accommodates installation of a vacuum bell jar for aluminizing the primary mirrors in-situ on the telescope. The detailed design of the telescope structure will be completed in 1996 by ADS Italia (Lecco) and European Industrial Engineering (Mestre). The final enclosure design is now in progress at M3 Engineering (Tucson), EIE and ADS Italia

  12. Optical tracking telescope compensation

    NASA Technical Reports Server (NTRS)

    Gilbart, J. W.

    1973-01-01

    In order to minimize the effects of parameter variations in the dynamics of an optical tracking telescope, a model referenced parameter adaptive control system is described that - in conjunction with more traditional forms of compensation - achieves a reduction of rms pointing error by more than a factor of six. The adaptive compensation system utilizes open loop compensation, closed loop compensation, and model reference compensation to provide the precise input to force telescope axis velocity to follow the ideal velocity.

  13. LISA Telescope Sensitivity Analysis

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Krebs, Carolyn (Technical Monitor)

    2002-01-01

    The Laser Interferometer Space Antenna (LISA) for the detection of Gravitational Waves is a very long baseline interferometer which will measure the changes in the distance of a five million kilometer arm to picometer accuracies. As with any optical system, even one with such very large separations between the transmitting and receiving, telescopes, a sensitivity analysis should be performed to see how, in this case, the far field phase varies when the telescope parameters change as a result of small temperature changes.

  14. Atmospheric and adaptive optics

    NASA Astrophysics Data System (ADS)

    Hickson, Paul

    2014-11-01

    Atmospheric optics is the study of optical effects induced by the atmosphere on light propagating from distant sources. Of particular concern to astronomers is atmospheric turbulence, which limits the performance of ground-based telescopes. The past two decades have seen remarkable growth in the capabilities and performance of adaptive optics (AO) systems. These opto-mechanical systems actively compensate for the blurring effect of the Earth's turbulent atmosphere. By sensing, and correcting, wavefront distortion introduced by atmospheric index-of-refraction variations, AO systems can produce images with resolution approaching the diffraction limit of the telescope at near-infrared wavelengths. This review highlights the physical processes and fundamental relations of atmospheric optics that are most relevant to astronomy, and discusses the techniques used to characterize atmospheric turbulence. The fundamentals of AO are then introduced and the many types of advanced AO systems that have been developed are described. The principles of each are outlined, and the performance and limitations are examined. Aspects of photometric and astrometric measurements of AO-corrected images are considered. The paper concludes with a discussion of some of the challenges related to current and future AO systems, particularly those that will equip the next generation of large, ground-based optical and infrared telescopes.

  15. Hubble Space Telescope: The Telescope, the Observations & the Servicing Mission

    NASA Astrophysics Data System (ADS)

    1999-11-01

    Hubble's success is the advantage of being in orbit, beyond the Earth's atmosphere. From there it enjoys a crystal-clear view of the universe - without clouds and atmospheric disturbances to blur its vision. European astronomer Guido De Marchi from ESO in Munich has been using Hubble since the early days of the project. He explains: "HST can see the faintest and smallest details and lets us study the stars with great accuracy, even where they are packed together - just as with those in the centre of our Galaxy". Dieter Reimers from Hamburg Observatory adds: "HST has capabilities to see ultraviolet light, which is not possible from the ground due to the blocking effect of the atmosphere. And this is really vital to our work, the main aim of which is to discover the chemical composition of the Universe." The Servicing Missions In the early plans for telescope operations, maintenance visits were to have been made every 2.5 years. And every five years HST should have been transported back to the ground for thorough overhaul. This plan has changed somewhat over time and a servicing scheme, which includes Space Shuttle Servicing Missions every three years, was decided upon. The two first Servicing Missions, in December 1993 (STS-61) and February 1997 (STS-82) respectively, were very successful. In the first three years of operations HST did not meet expectations because its primary mirror was 2 microns too flat at the edge. The first Servicing Mission in 1993 (on which the European astronaut Claude Nicollier flew) dealt with this problem by installing a new instrument with corrective optics (COSTAR - Corrective Optics Space Telescope Axial Replacement). With this pair of "glasses" HST's golden age began. The images were as sharp as originally hoped and astonishing new results started to emerge on a regular basis. The first Servicing Mission also replaced the solar panels and installed a new camera (Wide Field and Planetary Camera 2 - WFPC2). The High-Speed Photometer (HSP) was

  16. Angular width of the Cherenkov radiation with inclusion of multiple scattering

    NASA Astrophysics Data System (ADS)

    Zheng, Jian

    2016-06-01

    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.

  17. Search for very high energy gamma-rays from the z = 0.896 quasar 4C +55.17 with the MAGIC telescopes

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Bangale, P.; de Almeida, U. Barres; Barrio, J. A.; González, J. Becerra; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Fidalgo, D. Carreto; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; Mendez, C. Delgado; Doert, M.; Domínguez, A.; Prester, D. Dominis; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher, D.; Elsaesser, D.; Farina, E.; Ferenc, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; López, R. J. García; Garczarczyk, M.; Terrats, D. Garrido; Gaug, M.; Giavitto, G.; Godinović, N.; Muñoz, A. González; Gozzini, S. R.; Hadasch, D.; Hayashida, M.; Herrero, A.; Hildebrand, D.; Hose, J.; Hrupec, D.; Idec, W.; Kadenius, V.; Kellermann, H.; Knoetig, M. L.; Kodani, K.; Konno, Y.; Krause, J.; Kubo, H.; Kushida, J.; Barbera, A. La; Lelas, D.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Niedzwiecki, A.; Nilsson, K.; Nishijima, K.; Nowak, N.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Partini, S.; Persic, M.; Prada, F.; Moroni, P. G. Prada; Prandini, E.; Preziuso, S.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Garcia, J. Rodriguez; Rügamer, S.; Saggion, A.; Saito, T.; Saito, K.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Stamatescu, V.; Stamerra, A.; Steinbring, T.; Storz, J.; Sun, S.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Vogler, P.; Wagner, R. M.; Zandanel, F.; Zanin, R.

    2014-05-01

    The bright gamma-ray quasar 4C +55.17 is a distant source (z = 0.896) with a hard spectrum at GeV energies as observed by the Large Area Telescope (LAT) on board the Fermi satellite. This source is identified as a good source candidate for very high energy (VHE; >30 GeV) gamma-rays. In general, VHE gamma-rays from distant sources provide a unique opportunity to study the extragalactic background light (EBL) and underlying astrophysics. The flux intensity of this source in the VHE range is investigated. Then, constraints on the EBL are derived from the attenuation of gamma-ray photons coming from the distant blazar. We searched for a gamma-ray signal from this object using the 35 h observations taken by the MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescopes between 2010 November and 2011 January. No significant VHE gamma-ray signal was detected. We computed the upper limits of the integrated gamma-ray flux at the 95 per cent confidence level of 9.4 × 10-12 and 2.5 × 10-12 cm-2 s-1 above 100 and 200 GeV, respectively. The differential upper limits in four energy bins in the range from 80 to 500 GeV are also derived. The upper limits are consistent with the attenuation predicted by low-flux EBL models on the assumption of a simple power-law spectrum extrapolated from LAT data.

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

    NASA Astrophysics Data System (ADS)

    Bogdanov, O. V.; Fiks, E. I.; Pivovarov, Yu. L.

    2012-09-01

    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 quantity 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.

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

    SciTech Connect

    Bogdanov, O. V. 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 quantity 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.

  20. Hubble Space Telescope Deployment-Artist's Concept

    NASA Technical Reports Server (NTRS)

    1980-01-01

    This artist's concept depicts the Hubble Space Telescope after being released into orbit, with the high gain anternas and solar arrays deployed and the aperture doors opened. The HST is the product of a partnership between NASA, European Space Agency Contractors, and the international community of astronomers. It is named after Edwin P. Hubble, an American Astronomer who discovered the expanding nature of the universe and was the first to realize the true nature of galaxies. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The HST detects objects 25 times fainter than the dimmest objects seen from Earth and provides astronomers with an observable universe 250 times larger than visible from ground-based telescopes, perhaps as far away as 14 billion light-years. The HST views galaxies, stars, planets, comets, possibly other solar systems, and even unusual phenomena such as quasars, with 10 times the clarity of ground-based telescopes. The major elements of the HST are the Optical Telescope Assembly (OTA), the Support System Module (SSM), and the Scientific Instruments (SI). The HST is 42.5-feet (13-meters) long and weighs about 25,000 pounds (11,600 kilograms). The HST was deployed from the Space Shuttle Discovery (STS-31 mission) into Earth orbit in April 1990. The Marshall Space Flight Center had responsibility for design, development, and construction of the HST. The Perkin-Elmer Corporation, in Danbury, Connecticut, developed the optical system and guidance sensors. The Lockheed Missile and Space Company of Sunnyvale, California produced the protective outer shroud and spacecraft systems, and assembled and tested the finished telescope.

  1. Hubble Space Telescope Deployment-Artist's Concept

    NASA Technical Reports Server (NTRS)

    1980-01-01

    This artist's concept depicts the Hubble Space Telescope (HST) being positioned for release from the Space Shuttle orbiter by the Remote Manipulator System (RMS). The HST is the product of a partnership between NASA, European Space Agency Contractors, and the international community of astronomers. It is named after Edwin P. Hubble, an American Astronomer who discovered the expanding nature of the universe and was the first to realize the true nature of galaxies. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The HST detects objects 25 times fainter than the dimmest objects seen from Earth and provides astronomers with an observable universe 250 times larger than visible from ground-based telescopes, perhaps as far away as 14 billion light-years. The HST views galaxies, stars, planets, comets, possibly other solar systems, and even unusual phenomena such as quasars, with 10 times the clarity of ground-based telescopes. The major elements of the HST are the Optical Telescope Assembly (OTA), the Support System Module (SSM), and the Scientific Instruments (SI). The HST is 42.5-feet (13- meters) long and weighs about 25,000 pounds (11,600 kilograms). The HST was deployed from the Space Shuttle Discovery (STS-31 mission) into Earth orbit in April 1990. The Marshall Space Flight Center had responsibility for design, development, and construction of the HST. The Perkin-Elmer Corporation, in Danbury, Cornecticut, developed the optical system and guidance sensors. The Lockheed Missile and Space Company of Sunnyvale, California produced the protective outer shroud and spacecraft systems, and assembled and tested the finished telescope.

  2. Hubble Space Telescope Deployment-Artist's Concept

    NASA Technical Reports Server (NTRS)

    1980-01-01

    This artist's concept depicts the Hubble Space Telescope (HST) being raised to a vertical position in the cargo bay of the Space Shuttle orbiter. The HST is the product of a partnership between NASA, European Space Agency Contractors, and the international community of astronomers. It is named after Edwin P. Hubble, an American Astronomer who discovered the expanding nature of the universe and was the first to realize the true nature of galaxies. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The HST detects objects 25 times fainter than the dimmest objects seen from Earth and provides astronomers with an observable universe 250 times larger than visible from ground-based telescopes, perhaps as far away as 14 billion light-years. The HST views galaxies, stars, planets, comets, possibly other solar systems, and even unusual phenomena such as quasars, with 10 times the clarity of ground-based telescopes. The major elements of the HST are the Optical Telescope Assembly (OTA), the Support System Module (SSM), and the Scientific Instruments (SI). The HST is 42.5-feet (13-meters) long and weighs about 25,000 pounds (11,600 kilograms). The HST was deployed from the Space Shuttle Discovery (STS-31 mission) into Earth orbit in April 1990. The Marshall Space Flight Center had responsibility for design, development, and construction of the HST. The Perkin-Elmer Corporation, in Danbury, Cornecticut, developed the optical system and guidance sensors. The Lockheed Missile and Space Company of Sunnyvale, California produced the protective outer shroud and spacecraft systems, and assembled and tested the finished telescope.

  3. Adaptive Optics for Large Telescopes

    SciTech Connect

    Olivier, S

    2008-06-27

    The use of adaptive optics was originally conceived by astronomers seeking to correct the blurring of images made with large telescopes due to the effects of atmospheric turbulence. The basic idea is to use a device, a wave front corrector, to adjust the phase of light passing through an optical system, based on some measurement of the spatial variation of the phase transverse to the light propagation direction, using a wave front sensor. Although the original concept was intended for application to astronomical imaging, the technique can be more generally applied. For instance, adaptive optics systems have been used for several decades to correct for aberrations in high-power laser systems. At Lawrence Livermore National Laboratory (LLNL), the world's largest laser system, the National Ignition Facility, uses adaptive optics to correct for aberrations in each of the 192 beams, all of which must be precisely focused on a millimeter scale target in order to perform nuclear physics experiments.

  4. The Multiple-Mirror Telescope

    ERIC Educational Resources Information Center

    Carleton, Nathaniel P.; Hoffmann, William F.

    1978-01-01

    Describes the basic design and principle of operating an optical-infrared telescope, the MMT. This third largest telescope in the world represents a new stage in telescope design; it uses a cluster of six reflecting telescopes, and relies on an automatic sensing and control system. (GA)

  5. Investigating the Cherenkov light lateral distribution function for primary proton and iron nuclei in extensive air showers

    NASA Astrophysics Data System (ADS)

    Al-Rubaiee, A. A.; Hashim, U.; Al-Douri, Y.

    2015-11-01

    The lateral distribution function (LDF) of Cherenkov radiation in extensive air showers (EAS) was simulated by CORSIKA program for the conditions of Yakutsk Cherenkov array at the high energy range (1013-1016) eV for two primary particles (p and Fe) for different zenith angles. By depending on Breit-Wigner function for analyzing of Cherenkov light LDF, a parameterization of Cherenkov light LDF was reconstructed by depending on CORSIKA simulation as a function of primary energy. The comparison between the estimated Cherenkov light LDF with the LDF that measured on the Yakutsk EAS array gives the ability of particle identification that initiated the shower and determination of particle's energy around the knee region. The extrapolation of approximated Cherenkov light LDF for energies 20 and 30 PeV was obtained for primary particles (p and Fe).

  6. Hubble Space Telescope: The Telescope, the Observations & the Servicing Mission

    NASA Astrophysics Data System (ADS)

    1999-11-01

    Hubble's success is the advantage of being in orbit, beyond the Earth's atmosphere. From there it enjoys a crystal-clear view of the universe - without clouds and atmospheric disturbances to blur its vision. European astronomer Guido De Marchi from ESO in Munich has been using Hubble since the early days of the project. He explains: "HST can see the faintest and smallest details and lets us study the stars with great accuracy, even where they are packed together - just as with those in the centre of our Galaxy". Dieter Reimers from Hamburg Observatory adds: "HST has capabilities to see ultraviolet light, which is not possible from the ground due to the blocking effect of the atmosphere. And this is really vital to our work, the main aim of which is to discover the chemical composition of the Universe." The Servicing Missions In the early plans for telescope operations, maintenance visits were to have been made every 2.5 years. And every five years HST should have been transported back to the ground for thorough overhaul. This plan has changed somewhat over time and a servicing scheme, which includes Space Shuttle Servicing Missions every three years, was decided upon. The two first Servicing Missions, in December 1993 (STS-61) and February 1997 (STS-82) respectively, were very successful. In the first three years of operations HST did not meet expectations because its primary mirror was 2 microns too flat at the edge. The first Servicing Mission in 1993 (on which the European astronaut Claude Nicollier flew) dealt with this problem by installing a new instrument with corrective optics (COSTAR - Corrective Optics Space Telescope Axial Replacement). With this pair of "glasses" HST's golden age began. The images were as sharp as originally hoped and astonishing new results started to emerge on a regular basis. The first Servicing Mission also replaced the solar panels and installed a new camera (Wide Field and Planetary Camera 2 - WFPC2). The High-Speed Photometer (HSP) was

  7. Monolithic afocal telescope

    NASA Technical Reports Server (NTRS)

    Roberts, William T. (Inventor)

    2010-01-01

    An afocal monolithic optical element formed of a shallow cylinder of optical material (glass, polymer, etc.) with fast aspheric surfaces, nominally confocal paraboloids, configured on the front and back surfaces. The front surface is substantially planar, and this lends itself to deposition of multi-layer stacks of thin dielectric and metal films to create a filter for rejecting out-of-band light. However, an aspheric section (for example, a paraboloid) can either be ground into a small area of this surface (for a Cassegrain-type telescope) or attached to the planar surface (for a Gregorian-type telescope). This aspheric section of the surface is then silvered to create the telescope's secondary mirror. The rear surface of the cylinder is figured into a steep, convex asphere (again, a paraboloid in the examples), and also made reflective to form the telescope's primary mirror. A small section of the rear surface (approximately the size of the secondary obscuration, depending on the required field of the telescope) is ground flat to provide an unpowered surface through which the collimated light beam can exit the optical element. This portion of the rear surface is made to transmit the light concentrated by the reflective surfaces, and can support the deposition of a spectral filter.

  8. The Travelling Telescope

    NASA Astrophysics Data System (ADS)

    Murabona Oduori, Susan

    2015-08-01

    The telescope has been around for more than 400 years, and through good use of it scientists have made many astonishing discoveries and begun to understand our place in the universe. Most people, however, have never looked through one. Yet it is a great tool for cool science and observation especially in a continent and country with beautifully dark skies. The Travelling Telescope project aims to invite people outside under the stars to learn about those curious lights in the sky.The Travelling Telescope aims to promote science learning to a wide range of Kenyan schools in various locations exchanging knowledge about the sky through direct observations of celestial bodies using state of the art telescopes. In addition to direct observing we also teach science using various hands-on activities and astronomy software, ideal for explaining concepts which are hard to understand, and for a better grasp of the sights visible through the telescope. We are dedicated to promoting science using astronomy especially in schools, targeting children from as young as 3 years to the youth, teachers, their parents and members of the public. Our presentation focuses on the OAD funded project in rural coastal Kenya.

  9. Spectroradiometry with space telescopes

    NASA Astrophysics Data System (ADS)

    Pauluhn, Anuschka; Huber, Martin C. E.; Smith, Peter L.; Colina, Luis

    2015-12-01

    Radiometry, i.e. measuring the power of electromagnetic radiation—hitherto often referred to as "photometry"—is of fundamental importance in astronomy. We provide an overview of how to achieve a valid laboratory calibration of space telescopes and discuss ways to reliably extend this calibration to the spectroscopic telescope's performance in space. A lot of effort has been, and still is going into radiometric "calibration" of telescopes once they are in space; these methods use celestial primary and transfer standards and are based in part on stellar models. The history of the calibration of the Hubble Space Telescope serves as a platform to review these methods. However, we insist that a true calibration of spectroscopic space telescopes must directly be based on and traceable to laboratory standards, and thus be independent of the observations. This has recently become a well-supported aim, following the discovery of the acceleration of the cosmic expansion by use of type-Ia supernovae, and has led to plans for launching calibration rockets for the visible and infrared spectral range. This is timely, too, because an adequate exploitation of data from present space missions, such as Gaia, and from many current astronomical projects like Euclid and WFIRST demands higher radiometric accuracy than is generally available today. A survey of the calibration of instruments observing from the X-ray to the infrared spectral domains that include instrument- or mission-specific estimates of radiometric accuracies rounds off this review.

  10. Flight performance of BESS PolarII Aerogel Cherenkov Counter

    NASA Astrophysics Data System (ADS)

    Sakai, Kenichi

    The second scientific flight of the BESS-Polar experiment was performed in December 2007. The objective is understanding elementary particle phenomena in the early universe and propagation mechanism in the Galaxy through a search for antiparticles and antimatter in the cosmic radiation and mesurement of cosmic-ray nuclei. The BESS-Polar II scientific balloon was launched from Williams Field near the US McMurdo station in Antarctica and recorded more than 46x108 cosmic-ray events dualing a scientific balloon flight of 24.5 days. In addition to secondly production, there could be other, more exotic antiproton sources such as the evapolation of primordial black holes . Since the secondly antiproton spectrum has a sharp peak around 2 GeV, antiproton contributions well above or below this peak from other sources could cause an apparent flattening of the spectrum. For clear indentification of antiprotons against electron and muon background around the 0.2GeV 3.0GeV region, a threshold-type aerogel cherenkov counter(ACC) had been adopted. However, its performance was not high enough in the Polar I flight. The number of photoelectrons (N.pe.) was only 6 and the rejection power was 600 against more than 103 times electron and muon background. In BESS-Polar II which aims at precision measurement by vast statistics, the ACC was thoroughly redesigned to increase its rejection power while maintaining low systematic error. Improvements are described below. 1.Changing the aerogel refractive index(1.02 to 1.03): Because the focus of BESS-Polar II was on particle identification in lower energy region, the index was changed and this produced an improvement of 1.5 times N.pe. 2.Redesign of ACC Box Optimization of ACC optical geometry using Monte-Carlo simulation tuned with beam-test data gave 1.2 times N.pe. 3.Changing Aerogel block size (100x100x10mm3 to 190x280x20mm3 ) Larger aerogel blocks were adopted to reduce the inefficient area and N.pe. grew 1.1times. As a result of these

  11. Ultrathin zoom telescopic objective.

    PubMed

    Li, Lei; Wang, Di; Liu, Chao; Wang, Qiong-Hua

    2016-08-01

    We report an ultrathin zoom telescopic objective that can achieve continuous zoom change and has reduced compact volume. The objective consists of an annular folded lens and three electrowetting liquid lenses. The annular folded lens undertakes the main part of the focal power of the lens system. Due to a multiple-fold design, the optical path is folded in a lens with the thickness of ~1.98mm. The electrowetting liquid lenses constitute a zoom part. Based on the proposed objective, an ultrathin zoom telescopic camera is demonstrated. We analyze the properties of the proposed objective. The aperture of the proposed objective is ~15mm. The total length of the system is ~18mm with a tunable focal length ~48mm to ~65mm. Compared with the conventional zoom telescopic objective, the total length has been largely reduced. PMID:27505830

  12. Configurable Aperture Space Telescope

    NASA Technical Reports Server (NTRS)

    Ennico, Kimberly; Bendek, Eduardo

    2015-01-01

    In December 2014, we were awarded Center Innovation Fund to evaluate an optical and mechanical concept for a novel implementation of a segmented telescope based on modular, interconnected small sats (satlets). The concept is called CAST, a Configurable Aperture Space Telescope. With a current TRL is 2 we will aim to reach TLR 3 in Sept 2015 by demonstrating a 2x2 mirror system to validate our optical model and error budget, provide straw man mechanical architecture and structural damping analyses, and derive future satlet-based observatory performance requirements. CAST provides an alternative access to visible and/or UV wavelength space telescope with 1-meter or larger aperture for NASA SMD Astrophysics and Planetary Science community after the retirement of HST

  13. Control of optical performance on the Space Telescope

    NASA Technical Reports Server (NTRS)

    Jones, C. O.

    1977-01-01

    A large astronomical telescope, termed the Space Telescope, is expected to be placed in orbit in the early 1980's. It will be operated as an international observatory that will enable astronomers to detect electromagnetic radiation over a much broader spectrum than is possible from ground observatories. The image quality (not degraded by atmospheric effects) will be limited only by the quality of the optics and by aperture diffraction. This opportunity to approach diffraction-limited imagery on an astronomical telescope of this size (2.4-m aperture) sets unusually stringent tolerances on the optical quality. The budgeting and control of these qualities throughout the design, fabrication, assembly, and operation of the Space Telescope is described. A feedback control system which will maintain the telescope at peak performance in the orbital environment is examined.

  14. Auxiliary control systems for Pachmarhi array of Cverenkov telescopes

    NASA Astrophysics Data System (ADS)

    Gothe, K. S.; Acharya, B. S.; Bhat, P. N.; Chitnis, V. R.; D'Souza, A. I.; Francis, P. J.; John, A. V.; Joshi, S. R.; Majumdar, P.; Nagesh, B. K.; Pose, M. S.; Purohit, P. N.; Rahman, M. A.; Rao, K. K.; Rao, S. K.; Sharma, S. K.; Singh, B. B.; Stanislaus, A. J.; Sudershanan, P. V.; Upadhya, S. S.; Venkateshmurthy, B. L.; Vishwanath, P. R.

    2002-03-01

    Pachmarhi Array of Cverenkov Telescopes (PACT) consists of 25 Telescopes deployed over an area of 100m x 80m. The experiment is based on atmospheric Cverenkov technique to detect Very High Energy celestial gamma-rays using wavefront sampling method. Each telescope consists of 7 large area parabolic mirrors mounted para-axially on an equatorial mount and a fast photo-multiplier tube at the focus of each mirror. For efficient operation of the experiment 3 automated control systems were developed and installed, viz. Automated Computerized Telescope Orientation System (ACTOS) to control the pointing and tracking of individual telescopes, Automatic Photo-multiplier Exposure System (APES) to facilitate the exposure of photo-tubes only during observations, and Computerized Automated Rate Adjustment and Monitoring System (CARAMS) to ensure uniform gains for all the phototube - mirror systems. The design features and performance of each of these systems are discussed.

  15. The Discovery Channel Telescope

    NASA Astrophysics Data System (ADS)

    Millis, R. L.; Dunham, E. W.; Sebring, T. A.; Smith, B. W.; de Kock, M.; Wiecha, O.

    2004-11-01

    The Discovery Channel Telescope (DCT) is a 4.2-m telescope to be built at a new site near Happy Jack, Arizona. The DCT features a large prime focus mosaic CCD camera with a 2-degree-diameter field of view especially designed for surveys of KBOs, Centaurs, NEAs and other moving or time-variable targets. The telescope can be switched quickly to a Ritchey-Chretien configuration for optical/IR spectroscopy or near-IR imaging. This flexibility allows timely follow-up physical studies of high priority objects discovered in survey mode. The ULE (ultra-low-expansion) meniscus primary and secondary mirror blanks for the telescope are currently in fabrication by Corning Glass. Goodrich Aerospace, Vertex RSI, M3 Engineering and Technology Corp., and e2v Technologies have recently completed in-depth conceptual design studies of the optics, mount, enclosure, and mosaic focal plane, respectively. The results of these studies were subjected to a formal design review in July, 2004. Site testing at the 7760-ft altitude Happy Jack site began in 2001. Differential image motion observations from 117 nights since January 1, 2003 gave median seeing of 0.84 arcsec FWHM, and the average of the first quartile was 0.62 arcsec. The National Environmental Policy Act (NEPA) process for securing long-term access to this site on the Coconino National Forest is nearing completion and ground breaking is expected in the spring of 2005. The Discovery Channel Telescope is a project of the Lowell Observatory with major financial support from Discovery Communications, Inc. (DCI). DCI plans ongoing television programming featuring the construction of the telescope and the research ultimately undertaken with the DCT. An additional partner can be accommodated in the project. Interested parties should contact the lead author.

  16. Telescoping tube assembly

    NASA Technical Reports Server (NTRS)

    Sturm, Albert J. (Inventor); Marrinan, Thomas E. (Inventor)

    1995-01-01

    An extensible and retractable telescoping tube positions test devices that inspect large stationary objects. The tube has three dimensional adjustment capabilities and is vertically suspended from a frame. The tube sections are independently supported with each section comprising U-shaped housing secured to a thicker support plate. Guide mechanisms preferably mounted only to the thicker plates guide each tube section parallel to a reference axis with improved accuracy so that the position of the remote end of the telescoping tube is precisely known.

  17. Virtual Telescopes in Education

    NASA Astrophysics Data System (ADS)

    Hoban, S.; Des Jardins, M.; Farrell, N.; Rathod, P.; Sachs, J.; Sansare, S.; Yesha, Y.; Keating, J.; Busschots, B.; Means, J.; Clark, G.; Mayo, L.; Smith, W.

    Virtual Telescopes in Education is providing the services required to operate a virtual observatory comprising distributed telescopes, including an interactive, constraint-based scheduling service, data and resource archive, proposal preparation and review environment, and a VTIE Journal. A major goal of VTIE is to elicit from learners questions about the nature of celestial objects and the physical processes that give rise to the spectacular imagery that catches their imaginations. Generation of constrained science questions will assist learners in the science process. To achieve interoperability with other NSDL resources, our approach follows the Open Archives Initiative and the W3C Semantic Web activity.

  18. SU-E-I-87: Calibrating Cherenkov Emission to Match Superficial Dose in Tissue

    SciTech Connect

    Zhang, R; Pogue, B; Glaser, A; Gladstone, D

    2015-06-15

    Purpose: Through Monte Carlo simulations and phantom studies, the dominant factors affecting the calibration of superficial Cherenkov intensity to absolute surface dose was investigated, including tissue optical properties, curvatures, beam properties and imaging angle. Methods: The phasespace files for the TrueBeam system from Varian were used in GAMOS (a GEANT4 based Monte Carlo simulation toolkit) to simulate surface emission Cherenkov signals and the correlated deposited dose. The parameters examined were: i) different tissue optical properties (skin color from light to dark), ii) beam types (X-ray and electron beam), iii) beam energies, iv) thickness of tissues (2.5 cm to 20 cm), v) SSD (80 cm to 120 cm), vi) field sizes (0.5×0.5 cm2 to 20×20 cm2), vii) entrance/exit sides, viii) curvatures (cylinders with diameters from 2.5 cm to 20cm) and ix) imaging angles (0 to 90 degrees). In a specific case, for any Cherenkov photon emitted from the surface, the original position and direction, final position and direction and energy were recorded. Similar experimental measurements were taken in a range of the most pertinent parameters using tissue phantoms. Results: Combining the dose distribution and sampling sensitivity of Cherenkov emission, quantitatively accurate calibration factors (the amount of radiation dose represented by a single Cherenkov photon) were calculated. The data showed relatively large dependence upon different optical properties, curvature, entrance/exit and beam types. For a diffusive surface, the calibration factor was insensitive to imaging angles smaller than 60 degrees. Normalization with the reflectance image was experimentally validated as a simple and accurate method for calibrations of different optical properties. Conclusion: This study sheds light on how and to what extent different conditions affect the calibration from Cherenkov intensity to absolute superficial dose and provides practical solutions to allow quantitative Cherenkov

  19. Gadolinium Doped Water Cherenkov Detector for use as Neutron Detector

    NASA Astrophysics Data System (ADS)

    Davis, Patrick; Woltman, Brian; Mei, Dongming; Sun, Yongchen; Thomas, Keenan; Perevozchikov, Oleg

    2010-11-01

    Background characterization is imperative to the success of rare event physics research such as neutrinoless double-beta decay and dark matter searches. There are a number of different ways to measure backgrounds from muon-induced processes and other forms of high energy events. In our current research, we are constructing a research and development project for the feasibility of a Gadolinium doped water Cherenkov detector as a neutron detector. We are constructing a 46 liter acrylic housing for the Gd-doped water consisting of two acrylic cone sections connected to a middle acrylic cylinder to increase volume while still using 5 inch photo multiplier tubes (PMTs) on either end. I will present the challenges of a Gd-doped water detector and the reasons why our design should be much more successful than past metal housed detectors. I will also discuss our current progress and future goals of our detector including its use in characterizing the background in the future underground laboratory in the Sanford Lab, soon to be DUSEL.

  20. Time-domain measurement of broadband coherent Cherenkov radiation

    SciTech Connect

    Miocinovic, P.; Gorham, P. W.; Guillian, E.; Milincic, R.; Field, R. C.; Walz, D.; Saltzberg, D.; Williams, D.

    2006-08-15

    We report on further analysis of coherent microwave Cherenkov impulses emitted via the Askaryan mechanism from high-energy electromagnetic showers produced at the Stanford Linear Accelerator Center (SLAC). In this report, the time-domain based analysis of the measurements made with a broadband (nominally 1-18 GHz) log periodic dipole array antenna is described. The theory of a transmit-receive antenna system based on time-dependent effective height operator is summarized and applied to fully characterize the measurement antenna system and to reconstruct the electric field induced via the Askaryan process. The observed radiation intensity and phase as functions of frequency were found to agree with expectations from 0.75-11.5 GHz within experimental errors on the normalized electric field magnitude and the relative phase; {sigma}{sub RvertcalbarEverticalbar}=0.039 {mu}V/MHz/TeV and {sigma}{sub {phi}}=17 deg. This is the first time this agreement has been observed over such a broad bandwidth, and the first measurement of the relative phase variation of an Askaryan pulse. The importance of validation of the Askaryan mechanism is significant since it is viewed as the most promising way to detect cosmogenic neutrino fluxes at E{sub {nu}}(greater-or-similar sign)10{sup 15} eV.

  1. Cherenkov radiation with massive, C P T -violating photons

    NASA Astrophysics Data System (ADS)

    Colladay, Don; McDonald, Patrick; Potting, Robertus

    2016-06-01

    The source of C P T violation in the photon sector of the Standard Model Extension arises from a Chern-Simons-like contribution that involves a coupling to a fixed background vector field kAF μ . These Lorentz- and C P T -violating photons have well-known theoretical issues that arise from missing states at low momenta when kAF μ is timelike. In order to make the theory consistent, a tiny mass for the photon can be introduced, well below current experimental bounds. The implementation of canonical quantization can then be implemented as in the C P T -preserving case by using the Stückelberg mechanism. We explicitly construct a covariant basis of properly normalized polarization vectors at fixed three-momentum satisfying the momentum space field equations, in terms of which the vector field can be expanded. As an application of the theory, we calculate the Cherenkov radiation rate for the case of purely timelike kAF μ and find a radiation rate at high energies that has a contribution that does not depend on the mass used to regulate the photons.

  2. Time-Domain Measurement of Broadband Coherent Cherenkov Radiation

    SciTech Connect

    Miocinovic, P.; Field, R.C.; Gorham, P.W.; Guillian, E.; Milincic, R.; Saltzberg, D.; Walz, D.; Williams, D.; /UCLA

    2006-03-13

    We report on further analysis of coherent microwave Cherenkov impulses emitted via the Askaryan mechanism from high-energy electromagnetic showers produced at the Stanford Linear Accelerator Center (SLAC). In this report, the time-domain based analysis of the measurements made with a broadband (nominally 1-18 GHz) log periodic dipole antenna (LPDA) is described. The theory of a transmit-receive antenna system based on time-dependent effective height operator is summarized and applied to fully characterize the measurement antenna system and to reconstruct the electric field induced via the Askaryan process. The observed radiation intensity and phase as functions of frequency were found to agree with expectations from 0.75-11.5 GHz within experimental errors on the normalized electric field magnitude and the relative phase; {sigma}{sub R|E|} = 0.039 {micro}V/MHz/TeV and {sigma}{sub {phi}} = 17{sup o}. This is the first time this agreement has been observed over such a broad bandwidth, and the first measurement of the relative phase variation of an Askaryan pulse. The importance of validation of the Askaryan mechanism is significant since it is viewed as the most promising way to detect cosmogenic neutrino fluxes at E{sub v} {ge} 10{sup 15} eV.

  3. Charged Kaon Mass Measurement using the Cherenkov Effect

    SciTech Connect

    Graf, N.; Lebedev, A.; Abrams, R.J.; Akgun, U.; Aydin, G.; Baker, W.; Barnes, P.D., Jr.; Bergfeld, T.; Beverly, L.; Bujak, A.; Carey, D.; /Fermilab /Virginia U. /Iowa U.

    2009-09-01

    The two most recent and precise measurements of the charged kaon mass use X-rays from kaonic atoms and report uncertainties of 14 ppm and 22 ppm yet differ from each other by 122 ppm. We describe the possibility of an independent mass measurement using the measurement of Cherenkov light from a narrow-band beam of kaons, pions, and protons. This technique was demonstrated using data taken opportunistically by the Main Injector Particle Production experiment at Fermi National Accelerator Laboratory which recorded beams of protons, kaons, and pions ranging in momentum from +37 GeV/c to +63 GeV/c. The measured value is 491.3 {+-} 1.7 MeV/c{sup 2}, which is within 1.4{sigma} of the world average. An improvement of two orders of magnitude in precision would make this technique useful for resolving the ambiguity in the X-ray data and may be achievable in a dedicated experiment.

  4. Latest news from the High Altitude Water Cherenkov Observatory

    NASA Astrophysics Data System (ADS)

    González Muñoz, A.; HAWC Collaboration

    2016-07-01

    The High Altitude Water Cherenkov Observatory is an air shower detector designed to study very-high-energy gamma rays (∼ 100 GeV to ∼ 100 TeV). It is located in the Pico de Orizaba National Park, Mexico, at an elevation of 4100 m. HAWC started operations since August 2013 with 111 tanks and in April of 2015 the 300 tanks array was completed. HAWC's unique capabilities, with a field of view of ∼ 2 sr and a high duty cycle of 5%, allow it to survey 2/3 of the sky every day. These features makes HAWC an excellent instrument for searching new TeV sources and for the detection of transient events, like gamma-ray bursts. Moreover, HAWC provides almost continuous monitoring of already known sources with variable gamma-ray fluxes in most of the northern and part of the southern sky. These observations will bring new information about the acceleration processes that take place in astrophysical environments. In this contribution, some of the latest scientific results of the observatory will be presented.

  5. Status of the James Webb Space Telescope Observatory

    NASA Technical Reports Server (NTRS)

    Clampin, Mark

    2013-01-01

    The James Webb Space Telescope (JWST) is the largest cryogenic, space telescope ever built, and will address a broad range of scientific goals from first light in the universe and re-ionization, to characterization of the atmospheres of extrasolar planets. Recently, significant progress has been made in the construction of the observatory with the completion of all 21 flight mirrors that comprise the telescope's optical chain, and the start of flight instrument deliveries to the Goddard Space Flight Center. In this paper we discuss the design of the observatory, and focus on the recent milestone achievements in each of the major observatory sub-systems.

  6. An Event Reconstruction Method for the Telescope Array Fluorescence Detectors

    SciTech Connect

    Fujii, T.; Ogio, S.; Yamazaki, K.; Fukushima, M.; Ikeda, D.; Sagawa, H.; Takahashi, Y.; Tameda, Y.; Hayashi, K.; Ishimori, R.; Kobayashi, Y.; Tokuno, H.; Tsunesada, Y.; Honda, K.; Tomida, T.; Udo, S.

    2011-09-22

    We measure arrival directions, energies and mass composition of ultra-high energy cosmic rays with air fluorescence detector telescopes. The longitudinal profile of the cosmic ray induced extensive air shower cascade is imaged on focal plane of the telescope camera. Here, we show an event reconstruction method to obtain the primary information from data collected by the Telescope Array Fluorescence Detectors. In particular, we report on an ''Inverse Monte Carlo (IMC)'' method in which the reconstruction process searches for an optimum solution via repeated Monte Carlo simulations including characteristics of all detectors, atmospheric conditions, photon emission and scattering processes.

  7. Sensitivity of {gamma}-ray telescopes for detection of magnetic fields in the intergalactic medium

    SciTech Connect

    Neronov, A.; Semikoz, D. V.

    2009-12-15

    We explore potential of current and next-generation {gamma}-ray telescopes for the detection of weak magnetic fields in the intergalactic medium. We demonstrate that using two complementary techniques, observation of extended emission around point sources and observation of time delays in {gamma}-ray flares, one would be able to probe most of the cosmologically and astrophysically interesting part of the 'magnetic field strength' vs 'correlation length' parameter space. This implies that {gamma}-ray observations with Fermi and ground-based Cherenkov telescopes will allow to (a) strongly constrain theories of the origin of magnetic fields in galaxies and galaxy clusters and (b) discover, constrain or rule out the existence of weak primordial magnetic field generated at different stages of evolution of the Early Universe.

  8. Recent results from operation of the ANTARES deep-sea neutrino telescope

    NASA Astrophysics Data System (ADS)

    Hallewell, G. D.

    2014-12-01

    The ANTARES neutrino telescope is currently the largest operating water Cherenkov detector and the largest neutrino detector in the Northern hemisphere. It comprises 885 optical modules distributed on 12 detection lines anchored at a depth of 2.5 km in the Mediterranean Sea near Toulon, France; at a latitude that accesses a large part of the Galactic Plane, including the Galactic Centre. Its main scientific target is the detection of multi-TeV neutrinos predicted in charged cosmic particle acceleration mechanisms. In addition, ANTARES has developed a range of multi-messenger search strategies to look for correlations with optical counterparts and other cosmic messengers including γ-rays and charged cosmic rays. Other topics of investigation include the search for neutrinos from dark matter annihilation, searches for exotic particles and the measurement of neutrino oscillations. Details of the telescope are discussed together with examples of recently-conducted searches.

  9. Extragalactic Science with the Next Generation of Ground Based TeV {gamma}-Ray Telescopes

    SciTech Connect

    Krawczynski, Henric

    2008-12-24

    The ground based Cherenkov telescope experiments H.E.S.S., MAGIC, and VERITAS, and the space borne Fermi Gamma-Ray Space Telescope are currently exploring the galactic and extragalactic Universe in {gamma}-rays. At the time of writing this article, a large number of Active Galactic Nuclei have been studied in great detail and the {gamma}-ray observations have had a major impact on our understanding of the structure of jets from these objects. In this contribution, the status of ground based {gamma}-ray observations of AGN and other extragalactic source classes is reviewed as of October, 2008. After discussing source classes that could be detected with next generation ground based experiments like AGIS, CTA, and HAWC, the potential impact of the observations on the fields of high energy astrophysics, structure formation, observational cosmology, and fundamental physics is reviewed. We close with a discussion of the technical requirements that arise from the science drivers.

  10. 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.

  11. TELESCOPES: Astronomers Overcome 'Aperture Envy'.

    PubMed

    Irion, R

    2000-07-01

    Many users of small telescopes are disturbed by the trend of shutting down smaller instruments in order to help fund bigger and bolder ground-based telescopes. Small telescopes can thrive in the shadow of giant new observatories, they say--but only if they are adapted to specialized projects. Telescopes with apertures of 2 meters or less have unique abilities to monitor broad swaths of the sky and stare at the same objects night after night, sometimes for years; various teams are turning small telescopes into robots, creating networks that span the globe and devoting them to survey projects that big telescopes don't have a prayer of tackling. PMID:17832960

  12. Search for VHE gamma-ray emission from Geminga pulsar and nebula with the MAGIC telescopes

    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.; Berti, A.; 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.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Fallah Ramazani, V.; 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.; Overkemping, A.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Peresano, M.; Perri, L.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Reichardt, 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.; Surić, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Torres, D. F.; Toyama, T.; Treves, A.; Vanzo, G.; Verguilov, V.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.

    2016-06-01

    The Geminga pulsar, one of the brighest gamma-ray sources, is a promising candidate for emission of very-high-energy (VHE > 100 GeV) pulsed gamma rays. Also, detection of a large nebula has been claimed by water Cherenkov instruments. We performed deep observations of Geminga with the MAGIC telescopes, yielding 63 h of good-quality data, and searched for emission from the pulsar and pulsar wind nebula. We did not find any significant detection, and derived 95% confidence level upper limits. The resulting upper limits of 5.3 × 10-13 TeV cm-2 s-1 for the Geminga pulsar and 3.5 × 10-12 TeV cm-2 s-1 for the surrounding nebula at 50 GeV are the mostconstraining ones obtained so far at VHE. To complement the VHE observations, we also analyzed 5 yr of Fermi-LAT data from Geminga, finding that the sub-exponential cut-off is preferred over the exponential cut-off that has been typically used in the literature. We also find that, above 10 GeV, the gamma-ray spectra from Geminga can be described with a power law with index softer than 5. The extrapolation of the power-law Fermi-LAT pulsed spectra to VHE goes well below the MAGIC upper limits, indicating that the detection of pulsed emission from Geminga with the current generation of Cherenkov telescopes is very difficult.

  13. Exploring Galileo's Telescope

    ERIC Educational Resources Information Center

    Straulino, Samuele; Terzuoli, Alessandra

    2010-01-01

    In the first months of 2009, the International Year of Astronomy, the authors developed an educational project for middle-level students connected with the first astronomical discoveries that Galileo Galilei (1564-1642) made 400 years ago. The project included the construction of a basic telescope and the observation of the Moon. The project, if…

  14. The Falcon Telescope Network

    NASA Astrophysics Data System (ADS)

    Chun, F.; Tippets, R.; Dearborn, M.; Gresham, K.; Freckleton, R.; Douglas, M.

    2014-09-01

    The Falcon Telescope Network (FTN) is a global network of small aperture telescopes developed by the Center for Space Situational Awareness Research in the Department of Physics at the United States Air Force Academy (USAFA). Consisting of commercially available equipment, the FTN is a collaborative effort between USAFA and other educational institutions ranging from two- and four-year colleges to major research universities. USAFA provides the equipment (e.g. telescope, mount, camera, filter wheel, dome, weather station, computers and storage devices) while the educational partners provide the building and infrastructure to support an observatory. The user base includes USAFA along with K-12 and higher education faculty and students. Since the FTN has a general use purpose, objects of interest include satellites, astronomical research, and STEM support images. The raw imagery, all in the public domain, will be accessible to FTN partners and will be archived at USAFA in the Cadet Space Operations Center. FTN users will be able to submit observational requests via a web interface. The requests will then be prioritized based on the type of user, the object of interest, and a user-defined priority. A network wide schedule will be developed every 24 hours and each FTN site will autonomously execute its portion of the schedule. After an observational request is completed, the FTN user will receive notification of collection and a link to the data. The Falcon Telescope Network is an ambitious endeavor, but demonstrates the cooperation that can be achieved by multiple educational institutions.

  15. The Liverpool Telescope

    NASA Astrophysics Data System (ADS)

    Smith, Robert J.; Bates, S. D.; Clay, Neil R.; Fraser, Stephen N.; Marchant, J. M.; Mottram, C. J.; Steele, I. A.; Tomlinson, M. D.

    2011-03-01

    The Liverpool Telescope (LT) is a fully robotic 2m optical telescope at a world-class observatory site. It runs autonomously without direct human control either on site or remotely. It is not operated primarily for a single science project, but rather is a common-user facility, time allocated by an open, peer-review process and conducting a variety of optical and IR imaging, spectroscopic and polarimetric programs. This paper describes some of aspects of the site infrastructure and instrument suite designed specifically to support robust and reliable unsupervised operations. Aside from the telescope hardware, the other aspect of robotic operations is the mechanisms whereby users interact with the telescope and its automated scheduler. We describe how these have been implemented for the LT. Observing routinely since 2004, the LT has demonstrated it is possible to operate a large, common-user robotic observatory. Making the most of the flexibility afforded by fully robotic operations, development continues in collaboration with both observers and other observatories to develop observing modes to enable new science across the broad discipline of time-domain astrophysics.

  16. Wearable telescopic contact lens.

    PubMed

    Arianpour, Ashkan; Schuster, Glenn M; Tremblay, Eric J; Stamenov, Igor; Groisman, Alex; Legerton, Jerry; Meyers, William; Amigo, Goretty Alonso; Ford, Joseph E

    2015-08-20

    We describe the design, fabrication, and testing of a 1.6 mm thick scleral contact lens providing both 1× and 2.8× magnified vision paths, intended for use as a switchable eye-borne telescopic low-vision aid. The F/9.7 telescopic vision path uses an 8.2 mm diameter annular entrance pupil and 4 internal reflections in a polymethyl methacrylate precision optic. This gas-impermeable insert is contained inside a smooth outer casing of rigid gas-permeable polymer, which also provides achromatic correction for refraction at the curved lens face. The unmagnified F/4.1 vision path is through the central aperture of the lens, with additional transmission between the annular telescope rings to enable peripheral vision. We discuss potential solutions for providing oxygenation for an extended wear version of the lens. The prototype lenses were characterized using a scale-model human eye, and telescope functionality was confirmed in a small-scale clinical (nondispensed) demonstration. PMID:26368753

  17. The Large Millimeter Telescope

    NASA Astrophysics Data System (ADS)

    Hughes, D. H.; Schloerb, F. P.; LMT Project Team

    2009-05-01

    This paper, presented on behalf of the Large Millimeter Telescope (LMT) project team, describes the status and near-term plans for the telescope and its initial instrumentation. The LMT is a bi-national collaboration between México and the USA, led by the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE) and the University of Massachusetts at Amherst, to construct, commission and operate a 50 m diameter millimeter-wave radio telescope. Construction activities are nearly complete at the LMT site, at an altitude of ˜ 4600 m on the summit of Sierra Negra, an extinct volcano in the Mexican state of Puebla. Full movement of the telescope, under computer control in both azimuth and elevation, has been achieved. First-light at centimeter wavelengths on astronomical sources was obtained in November 2006. Installation of precision surface segments for millimeter-wave operation is underway, with the inner 32 m diameter of the surface now complete and ready to be used to obtain first-light at millimeter wavelengths in 2008. Installation of the remainder of the reflector will continue during the next year and be completed in 2009 for final commissioning of the antenna. The full LMT antenna, outfitted with its initial complement of scientific instruments, will be a world-leading scientific research facility for millimeter-wave astronomy.

  18. The Large Millimeter Telescope

    NASA Astrophysics Data System (ADS)

    Schloerb, F. Peter

    2008-07-01

    This paper, presented on behalf of the Large Millimeter Telescope (LMT) project team, describes the status and near-term plans for the telescope and its initial instrumentation. The LMT is a bi-national collaboration between Mexico and the USA, led by the Instituto Nacional de Astrofísica, Optica y Electronica (INAOE) and the University of Massachusetts at Amherst, to construct, commission and operate a 50m-diameter millimeter-wave radio telescope. Construction activities are nearly complete at the 4600m LMT site on the summit of Sierra Negra, an extinct volcano in the Mexican state of Puebla. Full movement of the telescope, under computer control in both azimuth and elevation, has been achieved. First-light at centimeter wavelengths on astronomical sources was obtained in November 2006. Installation of precision surface segments for millimeter-wave operation is underway, with the inner 32m-diameter of the surface now complete and ready to be used to obtain first light at millimeter wavelengths in 2008. Installation of the remainder of the reflector will continue during the next year and be completed in 2009 for final commissioning of the antenna. The full LMT antenna, outfitted with its initial complement of scientific instruments, will be a world-leading scientific research facility for millimeter-wave astronomy.

  19. A Simple "Tubeless" Telescope

    ERIC Educational Resources Information Center

    Straulino, S.; Bonechi, L.

    2010-01-01

    Two lenses make it possible to create a simple telescope with quite large magnification. The set-up is very simple and can be reproduced in schools, provided the laboratory has a range of lenses with different focal lengths. In this article, the authors adopt the Keplerian configuration, which is composed of two converging lenses. This instrument,…

  20. Nordic optical telescope

    NASA Astrophysics Data System (ADS)

    Ardeberg, Arne

    The Nordic Optical Telescope for the Roque de los Muchachos Observatory at La Palma is presented. It has been designed with highest emphasis on good resulting image quality. Within a tight budget frame a compact altazimuth mounted telescope has emerged. We have aimed at high-quality blind pointing and tracking. Optomechanically the telescope should be able to take advantage also of the observing periods with best seeing. The building has been designed with main emphasis on image quality. Partly guided by wind-tunnel tests, we have chosen a small dome with favourable air-flow performance. Data on micro-thermal activity has made us opt for a height above ground of the primary mirror being about eight metres. A relatively complete site-testing programme has confirmed the excellent quality of the observatory. The telescope will be operated with a Cassegrain focus only. Provisions are foreseen for rapid exchange of ancillary instrumentation. A set of standard ancillary instruments will be available at all times under the responsibility of on-site staff. It will include modern imaging devices, photometers, polarimeters and spectrographs for various tasks.

  1. Starburst galaxies as seen by gamma-ray telescopes

    NASA Astrophysics Data System (ADS)

    Ohm, Stefan

    2016-06-01

    Starburst galaxies have a highly increased star-formation rate compared to regular galaxies and inject huge amounts of kinetic power into the interstellar medium via supersonic stellar winds, and supernova explosions. Supernova remnants, which are considered to be the main source of cosmic rays (CRs), form an additional, significant energy and pressure component and might influence the star-formation process in a major way. Observations of starburst galaxies at γ-ray energies give us the unique opportunity to study non-thermal phenomena associated with hadronic CRs and their relation to the star-formation process. In this work, recent observations of starburst galaxies with space and ground-based γ-ray telescopes are being reviewed, and the current state of theoretical work on the γ-ray emission is discussed. A special emphasis is put on the prospects of the next-generation Cherenkov Telescope Array for the study of starburst galaxies in particular and star-forming galaxies in general. xml:lang="fr"

  2. Cherenkov and scintillation light separation on the TheiaR &D experiment

    NASA Astrophysics Data System (ADS)

    Caravaca, Javier; Land, Benjamin

    2016-03-01

    Identifying by separate the scintillation and Cherenkov light produced in a scintillation medium enables outstanding capabilities for future particle detectors, being the most relevant: allowing particle directionality information in a low energy threshold detector and improved particle identification. The TheiaR &D experiment uses an array of small and fast photomultipliers (PMTs) and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in a scintillation medium, based on the number of produced photoelectrons and the timing information. A charged particle ionizing a scintillation medium produces a prompt Cherenkov cone and late isotropic scintillation light, typically delayed by <1ns. 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) provides a medium with a tunable Cherenkov/Scintillation light yield ratio, enhancing the visibility of the dimer Cherenkov light in presence of the scintillation light. Description of the experiment, details of the analysis and preliminary results of the first months of running will be discussed.

  3. Allen Telescope Array

    NASA Astrophysics Data System (ADS)

    Bower, Geoffrey

    2007-05-01

    The Allen Telescope Array (ATA) is a pioneering centimeter-wavelength radio telescope that will produce science that cannot be done with any other instrument. The ATA is the first radio telescope designed for commensal observing; it will undertake the most comprehensive and sensitive SETI surveys ever done as well as the deepest and largest area continuum and spectroscopic surveys. Science operations will commence this year with a 42-element array. The ATA will ultimately comprise 350 6-meter dishes at Hat Creek in California, and will make possible large, deep radio surveys that were not previously feasible. The telescope incorporates many new design features including hydroformed antenna surfaces, a log-periodic feed covering the entire range of frequencies from 500 MHz to 11.2 GHz, low noise, wide-band amplifiers with a flat response over the entire band. The full array has the sensitivity of the Very Large Array but with a survey capability that is greater by an order of magnitude due to the wide field of view of the 6-meter dishes. Even with 42 elements, the ATA will be one of the most powerful radio survey telescopes. Science goals include the Five GHz sky survey (FiGSS) to match the 1.4-GHz NRAO VLA Sky Survey (NVSS) and the Sloan Digital Sky Survey within the first year of operation with the 42 element array, and a deep all-sky survey of extragalactic hydrogen to investigate galaxy evolution and intergalactic gas accretion. Transient and variable source surveys, pulsar science, spectroscopy of new molecular species in the galaxy, large-scale mapping of galactic magnetic filaments, and wide-field imaging of comets and other solar system objects are among the other key science objectives of the ATA. SETI surveys will reach sufficient sensitivity to detect an Arecibo planetary radar from 1,000,000 stars to distances of 300 pc.

  4. Neutral Buoyancy Test - NB23 - Space Telescope

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Once the United States' space program had progressed from Earth's orbit into outerspace, the prospect of building and maintaining a permanent presence in space was realized. To accomplish this feat, NASA launched a temporary workstation, Skylab, to discover the effects of low gravity and weightlessness on the human body, and also to develop tools and equipment that would be needed in the future to build and maintain a more permanent space station. The structures, techniques, and work schedules had to be carefully designed to fit this unique construction site. The components had to be lightweight for transport into orbit, yet durable. The station also had to be made with removable parts for easy servicing and repairs by astronauts. All of the tools necessary for service and repairs had to be designed for easy manipulation by a suited astronaut. And construction methods had to be efficient due to limited time the astronauts could remain outside their controlled environment. In lieu of all the specific needs for this project, an environment on Earth had to be developed that could simulate a low gravity atmosphere. A Neutral Buoyancy Simulator (NBS) was constructed by NASA Marshall Space Flight Center (MSFC) in 1968. Since then, NASA scientists have used this facility to understand how humans work best in low gravity and also provide information about the different kinds of structures that can be built. Included in the plans for the space station was a space telescope. This telescope would be attached to the space station and directed towards outerspace. Astronomers hoped that the space telescope would provide a look at space that is impossible to see from Earth because of Earth's atmosphere and other man made influences. In an effort to make replacement and repairs easier on astronauts the space telescope was designed to be modular. Practice makes perfect as demonstrated in this photo: an astronaut practices moving modular pieces of the space telescope in the Neutral

  5. Holographic Optical Elements as Scanning Lidar Telescopes

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Rallison, Richard D.; Wilkerson, Thomas D.; Guerra, David V.

    2005-01-01

    We have developed and investigated the use of holographic optical elements (HOEs) and holographic transmission gratings for scanning lidar telescopes. For example, rotating a flat HOE in its own plane with the focal spot on the rotation axis makes a very simple and compact conical scanning telescope. We developed and tested transmission and reflection HOEs for use at the first three harmonic wavelengths of Nd:YAG lasers. The diffraction efficiency, diffraction angle, focal length, focal spot size and optical losses were measured for several HOEs and holographic gratings, and found to be suitable for use as lidar receiver telescopes, and in many cases could also serve as the final collimating and beam steering optic for the laser transmitter. Two lidar systems based on this technology have been designed, built, and successfully tested in atmospheric science applications. This technology will enable future spaceborne lidar missions by significantly lowering the size, weight, power requirement and cost of a large aperture, narrow field of view scanning telescope.

  6. The directional dependence of apertures, limits and sensitivity of the lunar Cherenkov technique to a UHE neutrino flux

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    We use computer simulations to obtain the directional-dependence of the lunar Cherenkov technique for ultra-high energy (UHE) neutrino detection. We calculate the instantaneous effective area of past lunar Cherenkov experiments at Parkes, Goldstone (Goldstone Lunar Ultra-high energy neutrino Experiment, GLUE), and Kalyazin, as a function of neutrino arrival direction, finding that the potential sensitivity to a point source of UHE neutrinos for these experiments was as much as thirty times that to an isotropic flux, depending on the beam-pointing position and incident neutrino energy. Convolving our results with the known lunar positions during the Parkes and Goldstone experiments allows us to calculate an exposure map, and hence the directional-dependence of the combined limit imposed by these experiments. In the 10 21-10 23 eV range, we find parts of the sky where the GLUE limit likely still dominates, and areas where none of the limits from either Parkes, GLUE, or experiments such as the Antarctic Impulsive Transient Antenna (ANITA) balloon experiment or FORTE (Fast On-orbit Recording of Transient Events) satellite experiment are likely to be significant. Hence a large anisotropic flux of UHE neutrinos from these regions is not yet excluded. We also determine the directional dependence of the aperture of future planned experiments with the Australia Telescope Compact Array (ATCA), Australian SKA Pathfinder (ASKAP) and the Square Kilometre Array (SKA) to a UHE neutrino flux, and calculate the potential annual exposure to astronomical objects as a function of angular distance from the lunar trajectory through celestial coordinates. We find that the potential exposure of all experiments at 10 20 eV and below, integrated over a calendar year, is flat out to ˜25° from the lunar trajectory and then drops off rapidly. The region of greater sensitivity includes much of the Supergalactic Plane, including M87 and Cen A, as well as the Galactic Centre. At higher energies

  7. Wavefront Analysis of Adaptive Telescope

    NASA Technical Reports Server (NTRS)

    Hadaway, James B.; Hillman, Lloyd

    1997-01-01

    The motivation for this work came from a NASA Headquarters interest in investigating design concepts for a large space telescope employing active optics technology. The development of telescope optical requirements and potential optical design configurations is reported.

  8. SNM Detection with an Optimized Water Cherenkov Neutron Detector

    SciTech Connect

    Dazeley, S.; Sweany, M.; Bernstein, A.

    2012-07-23

    Special Nuclear Material (SNM) can either spontaneously fission or be induced to do so: either case results in neutron emission. For this reason, neutron detection performs a crucial role in the functionality of Radiation Portal Monitoring (RPM) devices. Since neutrons are highly penetrating and difficult to shield, they could potentially be detected escaping even a well-shielded cargo container. If the shielding were sophisticated, detecting escaping neutrons would require a highly efficient detector with close to full solid angle coverage. In 2008, we reported the successful detection of neutrons with a 250 liter (l) gadolinium doped water Cherenkov prototype—a technology that could potentially be employed cost effectively with full solid angle coverage. More recently we have built and tested both 1-kl and 3.5-kl versions, demonstrating that very large, cost effective, non-flammable and environmentally benign neutron detectors can be operated efficiently without being overwhelmed by background. In our paper, we present a new design for a modular system of water-based neutron detectors that could be deployed as a real RPM. The modules contain a number of optimizations that have not previously been combined within a single system. We present simulations of the new system, based on the performance of our previous detectors. These simulations indicate that an optimized system such as is presented here could achieve SNM sensitivity competitive with a large 3He-based system. Moreover, the realization of large, cost effective neutron detectors could, for the first time, enable the detection of multiple neutrons per fission from within a large object such as a cargo container. Such a signal would provide a robust indication of the presence of fissioning material, reducing the frequency of false alarms while increasing sensitivity.

  9. SNM Detection with an Optimized Water Cherenkov Neutron Detector

    DOE PAGESBeta

    Dazeley, S.; Sweany, M.; Bernstein, A.

    2012-07-23

    Special Nuclear Material (SNM) can either spontaneously fission or be induced to do so: either case results in neutron emission. For this reason, neutron detection performs a crucial role in the functionality of Radiation Portal Monitoring (RPM) devices. Since neutrons are highly penetrating and difficult to shield, they could potentially be detected escaping even a well-shielded cargo container. If the shielding were sophisticated, detecting escaping neutrons would require a highly efficient detector with close to full solid angle coverage. In 2008, we reported the successful detection of neutrons with a 250 liter (l) gadolinium doped water Cherenkov prototype—a technology thatmore » could potentially be employed cost effectively with full solid angle coverage. More recently we have built and tested both 1-kl and 3.5-kl versions, demonstrating that very large, cost effective, non-flammable and environmentally benign neutron detectors can be operated efficiently without being overwhelmed by background. In our paper, we present a new design for a modular system of water-based neutron detectors that could be deployed as a real RPM. The modules contain a number of optimizations that have not previously been combined within a single system. We present simulations of the new system, based on the performance of our previous detectors. These simulations indicate that an optimized system such as is presented here could achieve SNM sensitivity competitive with a large 3He-based system. Moreover, the realization of large, cost effective neutron detectors could, for the first time, enable the detection of multiple neutrons per fission from within a large object such as a cargo container. Such a signal would provide a robust indication of the presence of fissioning material, reducing the frequency of false alarms while increasing sensitivity.« less

  10. 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.

  11. Controlled steering of Cherenkov surface plasmon wakes with a one-dimensional metamaterial.

    PubMed

    Genevet, Patrice; Wintz, Daniel; Ambrosio, Antonio; She, Alan; Blanchard, Romain; Capasso, Federico

    2015-09-01

    In the Cherenkov effect a charged particle moving with a velocity faster than the phase velocity of light in the medium radiates light that forms a cone with a half angle determined by the ratio of the two speeds. Here, we show that by creating a running wave of polarization along a one-dimensional metallic nanostructure consisting of subwavelength-spaced rotated apertures that propagates faster than the surface plasmon polariton phase velocity, we can generate surface plasmon wakes, a two-dimensional analogue of Cherenkov radiation. The running wave of polarization travels with a speed determined by the angle of incidence and the photon spin angular momentum of the incident radiation. By changing either one of these properties we demonstrate controlled steering of the Cherenkov surface plasmon wakes. PMID:26149237

  12. Reversed Cherenkov-Transition Radiation by a Charge Crossing a Left-Handed Medium Boundary

    SciTech Connect

    Galyamin, Sergey N.; Tyukhtin, Andrey V.; Kanareykin, Alexey; Schoessow, Paul

    2009-11-06

    We analyze the radiation from a charged particle crossing the boundary between an ordinary medium and a 'left-handed' metamaterial. We obtain exact and approximate expressions for the field components and develop algorithms for their computation. The spatial radiation in this system can be separated into three distinct components, corresponding to ordinary transition radiation having a relatively large magnitude, Cherenkov radiation, and reversed Cherenkov-transition radiation (RCTR). The last one is explained by reflection and refraction of reversed Cherenkov radiation at the interface. Conditions for generating of RCTR are obtained. We note properties of this radiation that have potential applications in the detection of charged particles and accelerator beams and for the characterization of metamaterial macroscopic parameters (epsilon, mu).

  13. SYNCHROTRON EMISSION DRIVEN BY THE CHERENKOV-DRIFT INSTABILITY IN ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Osmanov, Z.; Chkheidze, N.

    2013-02-10

    In the present paper, we study the generation of synchrotron emission by means of the feedback of Cherenkov-drift waves on the particle distribution through the diffusion process. Despite the efficient synchrotron losses, it is demonstrated that the excited Cherenkov-drift instability leads to the quasi-linear diffusion (QLD), the effect of which is balanced by dissipation factors and, as a result, the pitch angles are prevented from damping, thus maintaining the corresponding synchrotron emission. We analyze the model for a wide range of physical parameters and determine that the mechanism of QLD guarantees the generation of electromagnetic radiation from soft X-rays up to soft {gamma}-rays, which is strongly correlated with Cherenkov-drift emission ranging from IR up to UV energy domains.

  14. Use of Cherenkov-type detectors for measurements of runaway electrons in the ISTTOK tokamak

    SciTech Connect

    Plyusnin, V. V.; Fernandes, H.; Silva, C.; Duarte, P.

    2008-10-15

    Gas, fluid, or solid Cherenkov-type detectors have been widely used in high-energy physics for determination of parameters of charged particles, which are moving with relativistic velocities. This paper presents experimental results on the detection of runaway electrons using Cherenkov-type detectors in the ISTTOK tokamak discharges. Such detectors have been specially designed for measurements of energetic electrons in tokamak plasma. The technique based on the use of the Cherenkov-type detectors has enabled the detection of energetic electrons (energies higher than 80 keV) and determination of their spatial and temporal parameters in the ISTTOK discharges. Obtained experimental data were found in adequate agreement to the results of numerical modeling of the runaway electron generation in ISTTOK.

  15. Distributed beam loss monitor based on the Cherenkov effect in an optical fiber

    NASA Astrophysics Data System (ADS)

    Maltseva, Yu; Emanov, F. A.; Petrenko, A. V.; Prisekin, V. G.

    2015-05-01

    This review discusses a distributed beam loss monitor which is based on the Cherenkov effect in an optical fiber and which has been installed at the VEPP-5 Injection Complex at the Budker Institute of Nuclear Physics. The principle of the device operation consists in detecting the Cherenkov radiation generated in an optical fiber by relativistic charged particles that are produced in an electromagnetic shower when highly relativistic beam particles (electrons or positrons) hit the accelerator vacuum chamber wall. Our experiments used a photomultiplier tube (PMT) to detect the Cherenkov light. Knowing when the PMT signal arrives tells us where the beam loss occurs. Using a 20-m-long optical fiber allowed a detector spatial resolution of 3 m. The way to improve the resolution is to optimize the monitor working conditions and optical fiber and PMT parameters, potentially leading to a resolution of as fine as 0.5 m according to our estimates.

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

    SciTech Connect

    Amenomori, M.; Nanjo, H.; Bi, X. J.; Ding, L. K.; Feng, Zhaoyang; He, H. H.; Hu, H. B.; Lu, H.; Lu, S. L.; Ren, J. R.; Tan, Y. H.; Wang, B.; Wang, H.; Wang, Y.; Wu, H. R.; Zhang, H. M.; Zhang, J. L.; Zhang, Y.; Chen, D.; Kawata, K.

    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 underground water Cherenkov muon detector.

  17. Quantum calculation of the Vavilov-Cherenkov radiation by twisted electrons

    NASA Astrophysics Data System (ADS)

    Ivanov, I. P.; Serbo, V. G.; Zaytsev, V. A.

    2016-05-01

    We present a detailed quantum electrodynamical description of Vavilov-Cherenkov radiation emitted by a relativistic twisted electron in the transparent medium. Simple expressions for the spectral and spectral-angular distributions as well as for the polarization properties of the emitted radiation are obtained. Unlike the plane-wave case, the twisted electron produces radiation within the annular angular region, with enhancement towards its boundaries. Additionally, the emitted photons can have linear polarization not only in the scattering plane but also in the orthogonal direction. We find that the Vavilov-Cherenkov radiation emitted by an electron in a superposition of two vortex states exhibits a strong azimuthal asymmetry. Thus, the Vavilov-Cherenkov radiation offers itself as a convenient diagnostic tool of such electrons and complements the traditional microscopic imaging.

  18. Science operations with Space Telescope

    NASA Technical Reports Server (NTRS)

    Giacconi, R.

    1982-01-01

    The operation, instrumentation, and expected contributions of the Space Telescope are discussed. Space Telescope capabilities are described. The organization and nature of the Space Telescope Science Institute are outlined, including the allocation of observing time and the data rights and data access policies of the institute.

  19. Lunar transit telescope lander design

    NASA Technical Reports Server (NTRS)

    Omar, Husam A.

    1992-01-01

    The Program Development group at NASA's Marshall Space Flight Center has been involved in studying the feasibility of placing a 16 meter telescope on the lunar surface to scan the skies using visible/ Ultraviolet/ Infrared light frequencies. The precursor telescope is now called the TRANSIT LUNAR TELESCOPE (LTT). The Program Development Group at Marshall Space Flight Center has been given the task of developing the basic concepts and providing a feasibility study on building such a telescope. The telescope should be simple with minimum weight and volume to fit into one of the available launch vehicles. The preliminary launch date is set for 2005. A study was done to determine the launch vehicle to be used to deliver the telescope to the lunar surface. The TITAN IV/Centaur system was chosen. The engineering challenge was to design the largest possible telescope to fit into the TITAN IV/Centaur launch system. The telescope will be comprised of the primary, secondary and tertiary mirrors and their supporting system in addition to the lander that will land the telescope on the lunar surface and will also serve as the telescope's base. The lunar lander should be designed integrally with the telescope in order to minimize its weight, thus allowing more weight for the telescope and its support components. The objective of this study were to design a lander that meets all the constraints of the launching system. The basic constraints of the TITAN IV/Centaur system are given.

  20. Lunar transit telescope lander design

    NASA Technical Reports Server (NTRS)

    Omar, Husam A.

    1991-01-01

    The Program Development group at NASA's Marshall Space Flight Center has been involved in studying the feasibility of placing a 16 meter telescope on the lunar surface to scan the skies using visible/ Ultraviolet/ Infrared light frequencies. The precursor telescope is now called the TRANSIT LUNAR TELESCOPE (LTT). The Program Development Group at Marshall Space Flight Center has been given the task of developing the basic concepts and providing a feasibility study on building such a telescope. The telescope should be simple with minimum weight and volume to fit into one of the available launch vehicles. The preliminary launch date is set for 2005. A study was done to determine the launch vehicle to be used to deliver the telescope to the lunar surface. The TITAN IV/Centaur system was chosen. The engineering challenge was to design the largest possible telescope to fit into the TITAN IV/Centaur launch system. The telescope will be comprised of the primary, secondary and tertiary mirrors and their supporting system in addition to the lander that will land the telescope on the lunar surface and will also serve as the telescope's base. The lunar lander should be designed integrally with the telescope in order to minimize its weight, thus allowing more weight for the telescope and its support components. The objective of this study were to design a lander that meets all the constraints of the launching system. The basic constraints of the TITAN IV/Centaur system are given.