Support of research in X-ray astronomy

NASA Technical Reports Server (NTRS)

Garmire, G.

1983-01-01

Activities described include: (1) the evaluation of CCD detectors for X-ray astronomy applications; (2) contributions to the development of an imaging gas scintillation proportional counter; (3) the evaluation of certain metal oxide crystals as potential radiation detectors; (4) optical observations and searches for X-ray sources discovered by the HEAO-1 A2 experiment; and (5) theoretical modeling of nonequilibrium ionization structure of supernova remnants.

Fiber optically coupled radioluminescence detectors: A short review of key strengths and weaknesses of BCF-60 and Al2O3:C scintillating-material based systems in radiotherapy dosimetry applications

NASA Astrophysics Data System (ADS)

Buranurak, S.; Andersen, C. E.

2017-06-01

Radiotherapy technologies have improved for several decades aiming to effectively destroy cancerous tissues without overdosing surrounding healthy tissues. In order to fulfil this requirement, accurate and precise dosimetry systems play an important role. Throughout the years, ionization chambers have been used as a standard detector for basic linear accelerator calibrations and reference dosimetry in hospitals. However, they are not ideal for all treatment modalities: and limitations and difficulties have been reported in case of (i) small treatment fields, (ii) strong magnetic field used in the new hybrid MRI LINAC/cobalt systems, and (iii) in vivo measurements due to safety-issues related to the high operating voltage. Fiber optically coupled luminescence detectors provide a promising supplement to ionization chambers by offering the capability of real-time in vivo dose monitoring with high time resolution. In particular, the all-optical nature of these detectors is an advantage for in vivo measurements due to the absence of high voltage supply or electrical wire that could cause harm to the patient or disturb the treatment. Basically, fiber-coupled luminescence detector systems function by radiation-induced generation of radioluminescence from a sub-mm size organic/inorganic phosphor. A thin optical fiber cable is used for guiding the radioluminescence to a photomultiplier tube or similar sensitive light detection systems. The measured light intensity is proportional to dose rate. Throughout the years, developments and research of the fiber detector systems have undergone in several groups worldwide. In this article, the in-house developed fiber detector systems based on two luminescence phosphors of (i) BCF-60 polystyrene-based organic plastic scintillator and (ii) carbon-doped aluminum oxide crystal (Al2O3:C) are reviewed with comparison to the same material-based systems reported in the literature. The potential use of these detectors for reference-class dosimetry in radiotherapy will be discussed with a particular emphasis on uses in small and large MV photon fields.

Nuclear Science Symposium, 4th, and Nuclear Power Systems Symposium, 9th, San Francisco, Calif., October 19-21, 1977, Proceedings

NASA Technical Reports Server (NTRS)

1978-01-01

Consideration is given to the following types of high energy physics instrumentation: drift chambers, multiwire proportional chambers, calorimeters, optical detectors, ionization and scintillation detectors, solid state detectors, and electronic and digital subsystems. Attention is also paid to reactor instrumentation, nuclear medicine instrumentation, data acquisition systems for nuclear instrumentation, microprocessor applications in nuclear science, environmental instrumentation, control and instrumentation of nuclear power generating stations, and radiation monitoring. Papers are also presented on instrumentation for the High Energy Astronomy Observatory.

ScintSim1: A new Monte Carlo simulation code for transport of optical photons in 2D arrays of scintillation detectors

PubMed Central

Mosleh-Shirazi, Mohammad Amin; Zarrini-Monfared, Zinat; Karbasi, Sareh; Zamani, Ali

2014-01-01

Two-dimensional (2D) arrays of thick segmented scintillators are of interest as X-ray detectors for both 2D and 3D image-guided radiotherapy (IGRT). Their detection process involves ionizing radiation energy deposition followed by production and transport of optical photons. Only a very limited number of optical Monte Carlo simulation models exist, which has limited the number of modeling studies that have considered both stages of the detection process. We present ScintSim1, an in-house optical Monte Carlo simulation code for 2D arrays of scintillation crystals, developed in the MATLAB programming environment. The code was rewritten and revised based on an existing program for single-element detectors, with the additional capability to model 2D arrays of elements with configurable dimensions, material, etc., The code generates and follows each optical photon history through the detector element (and, in case of cross-talk, the surrounding ones) until it reaches a configurable receptor, or is attenuated. The new model was verified by testing against relevant theoretically known behaviors or quantities and the results of a validated single-element model. For both sets of comparisons, the discrepancies in the calculated quantities were all <1%. The results validate the accuracy of the new code, which is a useful tool in scintillation detector optimization. PMID:24600168

ScintSim1: A new Monte Carlo simulation code for transport of optical photons in 2D arrays of scintillation detectors.

PubMed

Mosleh-Shirazi, Mohammad Amin; Zarrini-Monfared, Zinat; Karbasi, Sareh; Zamani, Ali

2014-01-01

Two-dimensional (2D) arrays of thick segmented scintillators are of interest as X-ray detectors for both 2D and 3D image-guided radiotherapy (IGRT). Their detection process involves ionizing radiation energy deposition followed by production and transport of optical photons. Only a very limited number of optical Monte Carlo simulation models exist, which has limited the number of modeling studies that have considered both stages of the detection process. We present ScintSim1, an in-house optical Monte Carlo simulation code for 2D arrays of scintillation crystals, developed in the MATLAB programming environment. The code was rewritten and revised based on an existing program for single-element detectors, with the additional capability to model 2D arrays of elements with configurable dimensions, material, etc., The code generates and follows each optical photon history through the detector element (and, in case of cross-talk, the surrounding ones) until it reaches a configurable receptor, or is attenuated. The new model was verified by testing against relevant theoretically known behaviors or quantities and the results of a validated single-element model. For both sets of comparisons, the discrepancies in the calculated quantities were all <1%. The results validate the accuracy of the new code, which is a useful tool in scintillation detector optimization.

Radiation Effects on Optoelectronic Devices in Space Missions

NASA Technical Reports Server (NTRS)

Johnston, Allan H.

2006-01-01

Radiation degradation of optoelectronic devices is discussed, including effects on optical emitters, detectors and optocouplers. The importance of displacement damage is emphasized, including the limitations of non-ionizing energy loss (NIEL) in normalizing damage. Failures of optoelectronics in fielded space systems are discussed, along with testing and qualification methods.

Analysis of SOFCAL calibration data

NASA Technical Reports Server (NTRS)

Gregory, John C.

1993-01-01

Ionization calorimeters determine the total energy of a particle by absorbing, within the mass of the calorimeter, the entire energy of the particle or a significant (and determinable) fraction of it. The JACEE group has used passive ionization calorimetery, which employs photographic emulsions as the detector medium, to measure the charge composition and energy spectrum of cosmic rays up to, and exceeding, 10(exp 14)eV. The SOFIC approach depends similarly on the use of three-dimensional nuclear-electromagnetic shower theory to relate the ionization deposits obtained during a shower to the energy of the particle causing the shower. Bundles of thousands of scintillating optical fibers are read out using image-intensified CCD's. Such an event may be triggered by a fast shower detector placed under the instrument or if only heavy particles are of interest, from a fast primary Cerention detector placed above the calorimeter. In the first study, fast Hammatsu photomultiplier tubes were purchased and tested for possible application for a triggering purpose. In the second study, some refinements have been made to the theoretical treatment of hadronic interactions in the central collision region. These will be helpful in improving the simulations necessary for observations of high energy cosmic ray nuclei with a SOFIC.

Coincidence velocity map imaging using Tpx3Cam, a time stamping optical camera with 1.5 ns timing resolution

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

Zhao, Arthur; van Beuzekom, Martin; Bouwens, Bram

Here, we demonstrate a coincidence velocity map imaging apparatus equipped with a novel time-stamping fast optical camera, Tpx3Cam, whose high sensitivity and nanosecond timing resolution allow for simultaneous position and time-of-flight detection. This single detector design is simple, flexible, and capable of highly differential measurements. We show detailed characterization of the camera and its application in strong field ionization experiments.

Coincidence velocity map imaging using Tpx3Cam, a time stamping optical camera with 1.5 ns timing resolution

DOE PAGES

Zhao, Arthur; van Beuzekom, Martin; Bouwens, Bram; ...

2017-11-07

Here, we demonstrate a coincidence velocity map imaging apparatus equipped with a novel time-stamping fast optical camera, Tpx3Cam, whose high sensitivity and nanosecond timing resolution allow for simultaneous position and time-of-flight detection. This single detector design is simple, flexible, and capable of highly differential measurements. We show detailed characterization of the camera and its application in strong field ionization experiments.

Effects of sub-bandgap illumination on electrical properties and detector performances of CdZnTe:In

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

Xu, Lingyan; Jie, Wanqi, E-mail: jwq@nwpu.edu.cn; Zha, Gangqiang, E-mail: zha-gq@hotmail.com

2014-06-09

The effects of sub-bandgap illumination on electrical properties of CdZnTe:In crystals and spectroscopic performances of the fabricated detectors were discussed. The excitation process of charge carriers through thermal and optical transitions at the deep trap could be described by the modified Shockley-Read-Hall model. The ionization probability of the deep donor shows an increase under illumination, which should be responsible for the variation of electrical properties within CdZnTe bulk materials with infrared (IR) irradiation. By applying Ohm's law, diffusion model and interfacial layer-thermionic-diffusion theory, we obtain the decrease of bulk resistivity and the increase of space charge density in the illuminatedmore » crystals. Moreover, the illumination induced ionization will further contribute to improving carrier transport property and charge collection efficiency. Consequently, the application of IR irradiation in the standard working environment is of great significance to improve the spectroscopic characteristics of CdZnTe radiation detectors.« less

Electrical Versus Optical: Comparing Methods for Detecting Terahertz Radiation Using Neon Lamps

NASA Astrophysics Data System (ADS)

Slocombe, L. L.; Lewis, R. A.

2018-05-01

Terahertz radiation impinging on a lit neon tube causes additional ionization of the encapsulated gas. As a result, the electrical current flowing between the electrodes increases and the glow discharge in the tube brightens. These dual phenomena suggest two distinct modes of terahertz sensing. The electrical mode simply involves measuring the electrical current. The optical mode involves monitoring the brightness of the weakly ionized plasma glow discharge. Here, we directly compare the two detection modes under identical experimental conditions. We measure 0.1-THz radiation modulated at frequencies in the range 0.1-10 kHz, for lamp currents in the range 1-10 mA. We find that electrical detection provides a superior signal-to-noise ratio while optical detection has a faster response. Either method serves as the basis of a compact, robust, and inexpensive room-temperature detector of terahertz radiation.

Modelling the transport of optical photons in scintillation detectors for diagnostic and radiotherapy imaging

NASA Astrophysics Data System (ADS)

Roncali, Emilie; Mosleh-Shirazi, Mohammad Amin; Badano, Aldo

2017-10-01

Computational modelling of radiation transport can enhance the understanding of the relative importance of individual processes involved in imaging systems. Modelling is a powerful tool for improving detector designs in ways that are impractical or impossible to achieve through experimental measurements. Modelling of light transport in scintillation detectors used in radiology and radiotherapy imaging that rely on the detection of visible light plays an increasingly important role in detector design. Historically, researchers have invested heavily in modelling the transport of ionizing radiation while light transport is often ignored or coarsely modelled. Due to the complexity of existing light transport simulation tools and the breadth of custom codes developed by users, light transport studies are seldom fully exploited and have not reached their full potential. This topical review aims at providing an overview of the methods employed in freely available and other described optical Monte Carlo packages and analytical models and discussing their respective advantages and limitations. In particular, applications of optical transport modelling in nuclear medicine, diagnostic and radiotherapy imaging are described. A discussion on the evolution of these modelling tools into future developments and applications is presented. The authors declare equal leadership and contribution regarding this review.

Image simulation for electron energy loss spectroscopy

DOE PAGES

Oxley, Mark P.; Pennycook, Stephen J.

2007-10-22

In this paper, aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations.more » Finally, the affect of the channelling of the electron probe within the sample is also discussed.« less

Absolute measurement of the extreme UV solar flux

NASA Technical Reports Server (NTRS)

Carlson, R. W.; Ogawa, H. S.; Judge, D. L.; Phillips, E.

1984-01-01

A windowless rare-gas ionization chamber has been developed to measure the absolute value of the solar extreme UV flux in the 50-575-A region. Successful results were obtained on a solar-pointing sounding rocket. The ionization chamber, operated in total absorption, is an inherently stable absolute detector of ionizing UV radiation and was designed to be independent of effects from secondary ionization and gas effusion. The net error of the measurement is + or - 7.3 percent, which is primarily due to residual outgassing in the instrument, other errors such as multiple ionization, photoelectron collection, and extrapolation to the zero atmospheric optical depth being small in comparison. For the day of the flight, Aug. 10, 1982, the solar irradiance (50-575 A), normalized to unit solar distance, was found to be 5.71 + or - 0.42 x 10 to the 10th photons per sq cm sec.

InAlAs/InGaAs avalanche photodiode arrays for free space optical communication.

PubMed

Ferraro, Mike S; Clark, William R; Rabinovich, William S; Mahon, Rita; Murphy, James L; Goetz, Peter G; Thomas, Linda M; Burris, Harris R; Moore, Christopher I; Waters, William D; Vaccaro, Kenneth; Krejca, Brian D

2015-11-01

In free space optical communication, photodetectors serve not only as communications receivers but also as position sensitive detectors (PSDs) for pointing, tracking, and stabilization. Typically, two separate detectors are utilized to perform these tasks, but recent advances in the fabrication and development of large-area, low-noise avalanche photodiode (APD) arrays have enabled these devices to be used both as PSDs and as communications receivers. This combined functionality allows for more flexibility and simplicity in optical system design without sacrificing the sensitivity and bandwidth performance of smaller, single-element data receivers. This work presents the development of APD arrays rated for bandwidths beyond 1 GHz with measured carrier ionization ratios of approximately 0.2 at moderate APD gains. We discuss the fabrication and characterization of three types of APD arrays along with their performance as high-speed photodetectors.

Energy Calibration of the Scintillating Optical Fiber Calorimeter Chamber (SOFCAL)

NASA Technical Reports Server (NTRS)

Christl, M. C.; Fountain, W. F.; Parnell, T.; Roberts, F. E.; Gregory, J. C.; Johnson, J.; Takahashi, Y.

1997-01-01

The Scintillating Optical Fiber Calorimeter (SOFCAL) detector is designed to make direct measures of the primary cosmic ray spectrum from -200 GeV/amu - 20 TeV/amu. The primary particles are resolved into groups according to their charge (p, He, CNO, Medium Z, Heavy Z) using both active and passive components integrated into the detector. The principal part of SOFCAL is a thin ionization calorimeter that measures the electromagnetic cascades that result from these energetic particles interacting in the detector. The calorimeter is divided into two sections: a thin passive emulsion/x-ray film calorimeter, and a fiber calorimeter that uses crossing layers of small scintillating optical fibers to sample the energy deposition of the cascades. The energy determination is made by fitting the fiber data to transition curves generated by Monte Carlo simulations. The fiber data must first be calibrated using the electron counts from the emulsion plates in the calorimeter for a small number of events. The technique and results of this calibration will be presented together with samples of the data from a balloon flight.

Miniature triaxial metastable ionization detector for gas chromatographic trace analysis of extraterrestrial volatiles

NASA Technical Reports Server (NTRS)

Woeller, F. H.; Kojiro, D. R.; Carle, G. C.

1984-01-01

The present investigation is concerned with a miniature metastable ionization detector featuring an unconventional electrode configuration, whose performance characteristics parallel those of traditional design. The ionization detector is to be incorporated in a flight gas chromatograph (GC) for use in the Space Shuttle. The design of the detector is discussed, taking into account studies which verified the sensitivity of the detector. The triaxial design of the detector is compared with a flat-plate style. The obtained results show that the principal goal of developing a miniature, highly sensitive ionization detector for flight applications was achieved. Improved fabrication techniques will utilize glass-to-metal seals and brazing procedures.

New prototype scintillator detector for the Tibet ASγ experiment

NASA Astrophysics Data System (ADS)

Zhang, Y.; Gou, Q.-B.; Cai, H.; Chen, T.-L.; Danzengluobu; Feng, C.-F.; Feng, Y.-L.; Feng, Z.-Y.; Gao, Q.; Gao, X.-J.; Guo, Y.-Q.; Guo, Y.-Y.; Hou, Y.-Y.; Hu, H.-B.; Jin, C.; Li, H.-J.; Liu, C.; Liu, M.-Y.; Qian, X.-L.; Tian, Z.; Wang, Z.; Xue, L.; Zhang, X.-Y.; Zhang, Xi-Ying

2017-11-01

The hybrid Tibet AS array was successfully constructed in 2014. It has 4500 m2 underground water Cherenkov pools used as the muon detector (MD) and 789 scintillator detectors covering 36900 m2 as the surface array. At 100 TeV, cosmic-ray background events can be rejected by approximately 99.99%, according to the full Monte Carlo (MC) simulation for γ-ray observations. In order to use the muon detector efficiently, we propose to extend the surface array area to 72900 m2 by adding 120 scintillator detectors around the current array to increase the effective detection area. A new prototype scintillator detector is developed via optimizing the detector geometry and its optical surface, by selecting the reflective material and adopting dynode readout. {This detector can meet our physics requirements with a positional non-uniformity of the output charge within 10% (with reference to the center of the scintillator), time resolution FWHM of ~2.2 ns, and dynamic range from 1 to 500 minimum ionization particles}.

State of the art on nuclear heating in a mixed (n/γ) field in research reactors

NASA Astrophysics Data System (ADS)

Amharrak, H.; Salvo, J. Di; Lyoussi, A.; Carette, M.; Reynard-Carette, C.

2014-06-01

This article aims at inventorying the knowledge on nuclear heating measurements in a mixed (n,γ) field in low-power research reactors using ThermoLuminescent Detectors (TLDs), Optically Stimulated Luminescent Detectors (OSLDs) and Ionization Chambers. The difficulty in measuring a mixed (n,γ) field in a reactor configuration lies in quantifying the contribution of the gamma photons and neutrons to the full signal measured by these detectors. The algorithms and experimental protocols developed together with the calculation methods used to assess the contribution of the neutron dose to the total integrated dose as measured by these detectors will be described in this article. This 'inventory' will be used to summarize the best methods to be used in relation to the requirements.

Pulsed helium ionization detection system

DOEpatents

Ramsey, R.S.; Todd, R.A.

1985-04-09

A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

Pulsed helium ionization detection system

DOEpatents

Ramsey, Roswitha S.; Todd, Richard A.

1987-01-01

A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

Time-resolved imaging of the MALDI linear-TOF ion cloud: direct visualization and exploitation of ion optical phenomena using a position- and time-sensitive detector.

PubMed

Ellis, Shane R; Soltwisch, Jens; Heeren, Ron M A

2014-05-01

In this study, we describe the implementation of a position- and time-sensitive detection system (Timepix detector) to directly visualize the spatial distributions of the matrix-assisted laser desorption ionization ion cloud in a linear-time-of-flight (MALDI linear-ToF) as it is projected onto the detector surface. These time-resolved images allow direct visualization of m/z-dependent ion focusing effects that occur within the ion source of the instrument. The influence of key parameters, namely extraction voltage (E(V)), pulsed-ion extraction (PIE) delay, and even the matrix-dependent initial ion velocity was investigated and were found to alter the focusing properties of the ion-optical system. Under certain conditions where the spatial focal plane coincides with the detector plane, so-called x-y space focusing could be observed (i.e., the focusing of the ion cloud to a small, well-defined spot on the detector). Such conditions allow for the stigmatic ion imaging of intact proteins for the first time on a commercial linear ToF-MS system. In combination with the ion-optical magnification of the system (~100×), a spatial resolving power of 11–16 μm with a pixel size of 550 nm was recorded within a laser spot diameter of ~125 μm. This study demonstrates both the diagnostic and analytical advantages offered by the Timepix detector in ToF-MS.

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

Samedov, V. V., E-mail: v-samedov@yandex.ru

Fluctuations of charge induced by charge carriers on the detector electrodes make a significant contribution to the energy resolution of ionization detectors, namely, semiconductor detectors and gas and liquid ionization chambers. These fluctuations are determined by the capture of charge carriers, as they drift in the bulk of the detector under the action of an electric field, by traps. In this study, we give a correct mathematical description of charge induction on electrodes of an ionization detector for an arbitrary electric field distribution in the detector with consideration of charge carrier capture by traps. The characteristic function obtained in thismore » study yields the general expression for the distribution function of the charge induced on the detector electrodes. The formulas obtained in this study are useful for analysis of the influence of charge carrier transport on energy resolution of ionization detectors.« less

EVALUATION OF SMOKE AND GAS SENSOR RESPONSES FOR FIRES OF COMMON MINE COMBUSTIBLES

PubMed Central

Perera, Inoka Eranda; Litton, Charles D.

2015-01-01

Experiments were conducted to evaluate the response characteristics of commercially available gas, smoke, and flame sensors to fires of common combustible mine materials. The experiments were conducted in the large-scale Fire gallery located at the National Institute for Occupational Safety and Health (NIOSH) Lake Lynn Laboratory (LLL) in Fairchance, PA, using Ponderosa Pine, Red Oak, Douglas-fir, high and low volatile coals, PVC and SBR conveyor belt, No. 2 diesel fuel, and diesel exhaust. All the experiments (except those using No. 2 diesel fuel and the diesel exhaust tests) were conducted in a similar manner, with combustible materials heated rapidly by electrical strip heaters producing smoldering fires that quickly transitioned into flaming fires. The sensors included a diffusion-type carbon monoxide (CO) sensor, photoelectric- and ionization-type smoke sensors, a video smoke/flame detector, and an optical flame detector. Simultaneous measurements were obtained for average gas concentrations, smoke mass concentrations, and smoke optical densities in order to quantify the levels of combustion products at the alert and alarm times of the sensors. Because the required sensor alarm levels are 10 ppm and 0.044 m−1 optical density for CO and smoke sensors, respectively, the different sensor alarms are compared to the time at which the CO and smoke reached these alarm levels (1). In addition, the potential impact of using smoke sensors that have met the performance standards from accredited testing laboratories is also evaluated using the response of an Underwriters’ Laboratory (UL)-approved combination photoelectric/ionization smoke detector. The results are discussed relative to fire sensor needs that can have a positive impact on mine fire safety. PMID:26229418

EVALUATION OF SMOKE AND GAS SENSOR RESPONSES FOR FIRES OF COMMON MINE COMBUSTIBLES.

PubMed

Perera, Inoka Eranda; Litton, Charles D

Experiments were conducted to evaluate the response characteristics of commercially available gas, smoke, and flame sensors to fires of common combustible mine materials. The experiments were conducted in the large-scale Fire gallery located at the National Institute for Occupational Safety and Health (NIOSH) Lake Lynn Laboratory (LLL) in Fairchance, PA, using Ponderosa Pine, Red Oak, Douglas-fir, high and low volatile coals, PVC and SBR conveyor belt, No. 2 diesel fuel, and diesel exhaust. All the experiments (except those using No. 2 diesel fuel and the diesel exhaust tests) were conducted in a similar manner, with combustible materials heated rapidly by electrical strip heaters producing smoldering fires that quickly transitioned into flaming fires. The sensors included a diffusion-type carbon monoxide (CO) sensor, photoelectric- and ionization-type smoke sensors, a video smoke/flame detector, and an optical flame detector. Simultaneous measurements were obtained for average gas concentrations, smoke mass concentrations, and smoke optical densities in order to quantify the levels of combustion products at the alert and alarm times of the sensors. Because the required sensor alarm levels are 10 ppm and 0.044 m -1 optical density for CO and smoke sensors, respectively, the different sensor alarms are compared to the time at which the CO and smoke reached these alarm levels (1). In addition, the potential impact of using smoke sensors that have met the performance standards from accredited testing laboratories is also evaluated using the response of an Underwriters' Laboratory (UL)-approved combination photoelectric/ionization smoke detector. The results are discussed relative to fire sensor needs that can have a positive impact on mine fire safety.

Gas amplified ionization detector for gas chromatography

DOEpatents

Huston, Gregg C.

1992-01-01

A gas-amplified ionization detector for gas chromatrography which possesses increased sensitivity and a very fast response time. Solutes eluding from a gas chromatographic column are ionized by UV photoionization of matter eluting therefrom. The detector is capable of generating easily measured voltage signals by gas amplification/multiplication of electron products resulting from the UV photoionization of at least a portion of each solute passing through the detector.

Alkali metal ionization detector

DOEpatents

Bauerle, James E.; Reed, William H.; Berkey, Edgar

1978-01-01

Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

Setup for irradiation and characterization of materials and Si particle detectors at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Väyrynen, S.; Pusa, P.; Sane, P.; Tikkanen, P.; Räisänen, J.; Kuitunen, K.; Tuomisto, F.; Härkönen, J.; Kassamakov, I.; Tuominen, E.; Tuovinen, E.

2007-03-01

A novel facility for proton irradiation with sample cryocooling has been developed at the Accelerator Laboratory of Helsinki University (equipped with a 5 MV tandem accelerator). The setup enables unique experiments to be carried out within the temperature range of 10-300 K. The setup has been constructed for "on-line" studies of vacancies with positron annihilation spectroscopy (PAS) including the option for optical ionization of the vacancies, and for current-voltage ( IV) measurements of irradiated silicon particle detectors. The setup is described in detail and typical performance characteristics are provided. The facility functionality was tested by performing PAS experiments with high-resistivity silicon and by IV measurements for two types of irradiated silicon particle detectors.

Recent technological developments on LGAD and iLGAD detectors for tracking and timing applications

NASA Astrophysics Data System (ADS)

Pellegrini, G.; Baselga, M.; Carulla, M.; Fadeyev, V.; Fernández-Martínez, P.; García, M. Fernández; Flores, D.; Galloway, Z.; Gallrapp, C.; Hidalgo, S.; Liang, Z.; Merlos, A.; Moll, M.; Quirion, D.; Sadrozinski, H.; Stricker, M.; Vila, I.

2016-09-01

This paper reports the latest technological development on the Low Gain Avalanche Detector (LGAD) and introduces a new architecture of these detectors called inverse-LGAD (iLGAD). Both approaches are based on the standard Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray detection applications, including an internal multiplication of the charge generated by radiation. The multiplication is inherent to the basic n++-p+-p structure, where the doping profile of the p+ layer is optimized to achieve high field and high impact ionization at the junction. The LGAD structures are optimized for applications such as tracking or timing detectors for high energy physics experiments or medical applications where time resolution lower than 30 ps is required. Detailed TCAD device simulations together with the electrical and charge collection measurements are presented through this work.

40 CFR 91.304 - Test equipment overview.

Code of Federal Regulations, 2013 CFR

2013-07-01

... non-dispersive infrared detector (NDIR) absorption type for carbon monoxide and carbon dioxide analysis; paramagnetic detector (PMD), zirconia (ZRDO), or electrochemical type (ECS) for oxygen analysis; a flame ionization detector (FID) or heated flame ionization detector (HFID) type for hydrocarbon...

40 CFR 91.304 - Test equipment overview.

Code of Federal Regulations, 2012 CFR

2012-07-01

... non-dispersive infrared detector (NDIR) absorption type for carbon monoxide and carbon dioxide analysis; paramagnetic detector (PMD), zirconia (ZRDO), or electrochemical type (ECS) for oxygen analysis; a flame ionization detector (FID) or heated flame ionization detector (HFID) type for hydrocarbon...

40 CFR 91.304 - Test equipment overview.

Code of Federal Regulations, 2011 CFR

2011-07-01

... non-dispersive infrared detector (NDIR) absorption type for carbon monoxide and carbon dioxide analysis; paramagnetic detector (PMD), zirconia (ZRDO), or electrochemical type (ECS) for oxygen analysis; a flame ionization detector (FID) or heated flame ionization detector (HFID) type for hydrocarbon...

40 CFR 91.304 - Test equipment overview.

Code of Federal Regulations, 2010 CFR

2010-07-01

... non-dispersive infrared detector (NDIR) absorption type for carbon monoxide and carbon dioxide analysis; paramagnetic detector (PMD), zirconia (ZRDO), or electrochemical type (ECS) for oxygen analysis; a flame ionization detector (FID) or heated flame ionization detector (HFID) type for hydrocarbon...

High-resolution ionization detector and array of such detectors

DOEpatents

McGregor, Douglas S [Ypsilanti, MI; Rojeski, Ronald A [Pleasanton, CA

2001-01-16

A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

Dosimetry of heavy ions by use of CCD detectors

NASA Technical Reports Server (NTRS)

Schott, J. U.

1994-01-01

The design and the atomic composition of Charge Coupled Devices (CCD's) make them unique for investigations of single energetic particle events. As detector system for ionizing particles they detect single particles with local resolution and near real time particle tracking. In combination with its properties as optical sensor, particle transversals of single particles are to be correlated to any objects attached to the light sensitive surface of the sensor by simple imaging of their shadow and subsequent image analysis of both, optical image and particle effects, observed in affected pixels. With biological objects it is possible for the first time to investigate effects of single heavy ions in tissue or extinguished organs of metabolizing (i.e. moving) systems with a local resolution better than 15 microns. Calibration data for particle detection in CCD's are presented for low energetic protons and heavy ions.

Electrode configuration and signal subtraction technique for single polarity charge carrier sensing in ionization detectors

DOEpatents

Luke, Paul

1996-01-01

An ionization detector electrode and signal subtraction apparatus and method provides at least one first conductive trace formed onto the first surface of an ionization detector. The first surface opposes a second surface of the ionization detector. At least one second conductive trace is also formed on the first surface of the ionization detector in a substantially interlaced and symmetrical pattern with the at least one first conductive trace. Both of the traces are held at a voltage potential of a first polarity type. By forming the traces in a substantially interlaced and symmetric pattern, signals generated by a charge carrier are substantially of equal strength with respect to both of the traces. The only significant difference in measured signal strength occurs when the charge carrier moves to within close proximity of the traces and is received at the collecting trace. The measured signals are then subtracted and compared to quantitatively measure the magnitude of the charge and to determine the position at which the charge carrier originated within the ionization detector.

Electrode configuration and signal subtraction technique for single polarity charge carrier sensing in ionization detectors

DOEpatents

Luke, P.

1996-06-25

An ionization detector electrode and signal subtraction apparatus and method provide at least one first conductive trace formed onto the first surface of an ionization detector. The first surface opposes a second surface of the ionization detector. At least one second conductive trace is also formed on the first surface of the ionization detector in a substantially interlaced and symmetrical pattern with the at least one first conductive trace. Both of the traces are held at a voltage potential of a first polarity type. By forming the traces in a substantially interlaced and symmetric pattern, signals generated by a charge carrier are substantially of equal strength with respect to both of the traces. The only significant difference in measured signal strength occurs when the charge carrier moves to within close proximity of the traces and is received at the collecting trace. The measured signals are then subtracted and compared to quantitatively measure the magnitude of the charge and to determine the position at which the charge carrier originated within the ionization detector. 9 figs.

40 CFR 91.304 - Test equipment overview.

Code of Federal Regulations, 2014 CFR

2014-07-01

... infrared detector (NDIR) absorption type for carbon monoxide and carbon dioxide analysis; paramagnetic detector (PMD), zirconia (ZRDO), or electrochemical type (ECS) for oxygen analysis; a flame ionization detector (FID) or heated flame ionization detector (HFID) type for hydrocarbon analysis; and a...

Alkali ionization detector

DOEpatents

Hrizo, John; Bauerle, James E.; Witkowski, Robert E.

1982-01-01

A calibration filament containing a sodium-bearing compound is included in combination with the sensing filament and ion collector plate of a sodium ionization detector to permit periodic generation of sodium atoms for the in-situ calibration of the detector.

Performance of the improved larger acceptance spectrometer: VAMOS++

NASA Astrophysics Data System (ADS)

Rejmund, M.; Lecornu, B.; Navin, A.; Schmitt, C.; Damoy, S.; Delaune, O.; Enguerrand, J. M.; Fremont, G.; Gangnant, P.; Gaudefroy, L.; Jacquot, B.; Pancin, J.; Pullanhiotan, S.; Spitaels, C.

2011-08-01

Measurements and ion optic calculations showed that the large momentum acceptance of the VAMOS spectrometer at GANIL could be further increased from ˜11% to ˜30% by suitably enlarging the dimensions of the detectors used at the focal plane. Such a new detection system built for the focal plane of VAMOS is described. It consists of larger area detectors (1000 mm×150 mm) namely, a Multi-Wire Parallel Plate Avalanche Counter (MWPPAC), two drift chambers, a segmented ionization chamber and an array of Si detectors. Compared to the earlier existing system (VAMOS), we show that the new system (VAMOS++) has a dispersion-independent momentum acceptance. Additionally, a start detector (MWPPAC) has been introduced near the target to further improve the mass resolution to ˜1/220. The performance of the VAMOS++ spectrometer is demonstrated using measurements of residues formed in the collisions of 129Xe at 967 MeV on 197Au.

40 CFR 86.317-79 - Hydrocarbon analyzer specifications.

Code of Federal Regulations, 2012 CFR

2012-07-01

... flame ionization detector (HFID) analyzer. (b) Option. A non-heated flame ionization detector (FID) that... temperature oven housing the detector and sample-handling components. It shall maintain temperature with 2 °C of the set point. The detector, oven, and sample-handling components within the oven shall be...

40 CFR 86.317-79 - Hydrocarbon analyzer specifications.

Code of Federal Regulations, 2010 CFR

2010-07-01

... flame ionization detector (HFID) analyzer. (b) Option. A non-heated flame ionization detector (FID) that... temperature oven housing the detector and sample-handling components. It shall maintain temperature with 2 °C of the set point. The detector, oven, and sample-handling components within the oven shall be...

40 CFR 86.317-79 - Hydrocarbon analyzer specifications.

Code of Federal Regulations, 2011 CFR

2011-07-01

... flame ionization detector (HFID) analyzer. (b) Option. A non-heated flame ionization detector (FID) that... temperature oven housing the detector and sample-handling components. It shall maintain temperature with 2 °C of the set point. The detector, oven, and sample-handling components within the oven shall be...

40 CFR 86.317-79 - Hydrocarbon analyzer specifications.

Code of Federal Regulations, 2013 CFR

2013-07-01

... flame ionization detector (HFID) analyzer. (b) Option. A non-heated flame ionization detector (FID) that... temperature oven housing the detector and sample-handling components. It shall maintain temperature with 2 °C of the set point. The detector, oven, and sample-handling components within the oven shall be...

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

Phipps, Arran T.J.

Determining the composition of dark matter is at the forefront of modern scientific research. There is compelling evidence for the existence of vast quantities of dark matter throughout the universe, however it has so-far eluded all direct detection efforts and its identity remains a mystery. Weakly interacting massive particles (WIMPs) are a favored dark matter candidate and have been the primary focus of direct detection for several decades. The Cryogenic Dark Matter Search (CDMS) has developed the Z-dependent Ionization and Phonon (ZIP) detector to search for such particles. Typically made from germanium, these detectors are capable of distinguishing between electromagneticmore » background and a putative WIMP signal through the simultaneous measurement of ionization and phonons produced by scattering events. CDMS has operated several arrays of these detectors at the Soudan Underground Laboratory (Soudan, MN, USA) resulting in many competitive (often world-leading) WIMP exclusion limits. This dissertation focuses on ionization collection in these detectors under the sub-Kelvin, low electric field, and high crystal purity conditions unique to CDMS. The design and performance of a fully cryogenic HEMT-based amplifier capable of achieving the SuperCDMS SNOLAB ionization energy resolution goal of 100 eVee is presented. The experimental apparatus which has been used to record electron and hole properties under CDMS conditions is described. Measurements of charge transport, trapping, and impact ionization as a function of electric field in two CDMS detectors are shown, and the ionization collection efficiency is determined. The data is used to predict the error in the nuclear recoil energy scale under both CDMSlite and iZIP operating modes. A two species, two state model is developed to describe how ionization collection and space charge generation in CDMS detectors are controlled by the presence of “overcharged” D- donor and A+ acceptor impurity states. The thermal stability of these states is exclusive to sub-Kelvin operation, explaining why ionization collection in CDMS detectors differs from similar semiconductor detectors operating at higher temperature. This work represents a solid foundation for the understanding ionization collection in CDMS detectors.« less

Optical Diagnostics of Multi-Gap Gas Switches for Linear Transformer Drivers

NASA Astrophysics Data System (ADS)

Sheng, Liang; Li, Yang; Sun, Tieping; Cong, Peitian; Zhang, Mei; Peng, Bodong; Zhao, Jizhen; Yue, Zhiqin; Wei, Fuli; Yuan, Yuan

2014-07-01

The trigger characteristics of a multi-gap gas switch with double insulating layers, a square-groove electrode supporter and a UV pre-ionizing structure are investigated aided by a high sensitivity fiber-bundle array detector, a UV fiber detector, and a framing camera, in addition to standard electrical diagnostics. The fiber-bundle-array detector is used to track the turn-on sequence of each electrode gap at a timing precision of 0.6 ns. Each fiber bundle, including five fibers with different azimuth angles, aims at the whole emitting area of each electrode gap and is fed to a photomultiplier tube. The UV fiber detector with a spectrum response of 260-320 nm, including a fused-quartz fiber of 200 μm in diameter and a solar-blinded photomultiplier tube, is adopted to study the effect of UV pre-ionizing on trigger characteristics. The framing camera, with a capacity of 4 frames per shot and an exposure time of 5 ns, is employed to capture the evolution of channel arcs. Based on the turn-on light signal of each electrode gap, the breakdown delay is divided into statistical delay and formative delay. A decrease in both of them, a smaller switch jitter and more channel arcs are observed with lower gas pressure. An increase in trigger voltage can reduce the statistical delay and its jitter, while higher trigger voltage has a relatively small influence on the formative delay and the number of channel arcs. With the UV pre-ionizing structure at 0.24 MPa gas pressure and 60 kV trigger voltage, the statistical delay and its jitter can be reduced by 1.8 ns and 0.67 ns, while the formative delay and its jitter can only be reduced by 0.5 ns and 0.25 ns.

SuperCDMS Prototype Detector Design and Testing

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

Kennedy, Allison Blair

A substantial amount of astrophysical evidence indicates that approximately a quarter of all energy in the universe is composed of a nonluminous, and nonbaryonic \\dark" matter. Of the potential dark matter particle candidates, Weakly Interacting Massive Particles, or WIMPs, is particularly well motivated. As a means to directly detect WIMP interactions with baryonic matter, the Cryogenic Dark Matter Search (CDMS) project was established, operating at the Soudan Underground Laboratory from 2003 - 2015, under the CDMS II and SuperCDMS Soudan experiments. CDMS detectors simultaneously measure the ionization and phonon energies of recoil events in Si and Ge crystals kept atmore » cryogenic temperatures in a low-background environment. The ratio of ionization energy to recoil energy serves as a discrimination parameter to separate nuclear recoil events from the electron-recoil background. The next installation, SuperCDMS SNOLAB, is preparing for future operation, with an initial payload of eighteen Ge and six Si, 100 mm diameter, 33 mm thick detectors. Of this initial payload, eight Ge and four Si detectors will operate in a high-voltage ( 100 V) mode, which have an increased sensitivity to low-mass WIMPs due to decreased energy thresholds. The SuperCDMS test facility at University of Minnesota aids in the detector R&D and characterization of prototype detectors, as part of the scale-up eort for Super- CDMS SNOLAB. This thesis presents the rst full ionization and phonon characterization study of a 100 mm diameter, 33 mm thick prototype Ge detector with interleaved phonon and ionization channels. Measurements include ionization collection eciency, surface event rejection capabilities, and successful demonstration of nuclear recoil event discrimination. Results indicate that 100 mm diameter, interleaved Ge detectors show potential for use in SuperCDMS SNOLAB. As part of detector R&D, the Minnesota test facility also looks beyond the next stage of SuperCDMS, investigating larger individual detectors as a means to easily scale up the sensitive mass of future searches. This thesis presents the design and initial testing results of a prototype 150 mm diameter, 33 mm thick silicon ionization detector, which is 5.2 times larger than those used in SuperCDMS at Soudan and 2.25 times larger than those planned for use at SuperCDMS SNOLAB. In addition, the detector was operated with contact-free ionization electrodes to minimize bias leakage currents, which can limit operation at high bias voltages. The results show promise for the operation of both large volume silicon detectors and contact-free ionization electrodes for scaling up detector mass and bias.« less

Amorphous silicon ionizing particle detectors

DOEpatents

Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

1988-01-01

Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

Large-area field-ionization detector for the study of Rydberg atoms.

PubMed

Jones, A C L; Piñeiro, A M; Roeder, E E; Rutbeck-Goldman, H J; Tom, H W K; Mills, A P

2016-11-01

We describe here the development and characterization of a micro-channel plate (MCP) based detector designed for the efficient collection and detection of Rydberg positronium (Ps) atoms for use in a time-of-flight apparatus. The designed detector collects Rydberg atoms over a large area (∼4 times greater than the active area of the MCP), ionizing incident atoms and then collecting and focusing the freed positrons onto the MCP. Here we discuss the function, design, and optimization of the device. The detector has an efficiency for Rydberg Ps that is two times larger than that of the γ-ray scintillation detector based scheme it has been designed to replace, with half the background signal. In principle, detectors of the type described here could be readily employed for the detection of any Rydberg atom species, provided a sufficient field can be applied to achieve an ionization rate of ≥10 8 /s. In such cases, the best time resolution would be achieved by collecting ionized electrons rather than the positive ions.

Amorphous silicon ionizing particle detectors

DOEpatents

Street, R.A.; Mendez, V.P.; Kaplan, S.N.

1988-11-15

Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation. 15 figs.

A Centrality and Event Plane Detector for STAR to Complete the Phase Diagram of Quantum Chromodynamics

NASA Astrophysics Data System (ADS)

Halal, George; STAR Collaboration

2017-09-01

The properties of the nearly perfect liquid, Quark Gluon Plasma (QGP), which filled the universe a microsecond after the Big Bang are studied by colliding heavy-ions at relativistic energies. Our project focuses on building and testing an Event Plane Detector (EPD) for the STAR experiment and analyzing the data collected from collisions. When a minimum ionizing particle hits one of the optically-isolated tiles of this detector, which are made of scintillator plastic, it lights up. The light then travels through a wavelength-shifting fiber embedded in the tile to a clear optical fiber to be detected by silicon photo-multipliers. This detector is an improved version of the Beam-Beam Counter, which is currently at STAR. It will help us measure the centrality and event plane of collisions with more precision. Data collected will aid us in mapping out the transition phase between the QGP and hadronic matter, which evolved into the chemical elements we see today, and in searching for a unique critical point in the phase diagram of Quantum Chromodynamics matter. In 2017, a commissioning run has taken place at RHIC, colliding protons at 510 GeV and gold ions at 54.4 GeV. Some data analysis from one eighth of the EPD that is installed will also be discussed.

Closed-loop pulsed helium ionization detector

DOEpatents

Ramsey, Roswitha S.; Todd, Richard A.

1987-01-01

A helium ionization detector for gas chromatography is operated in a constant current, pulse-modulated mode by configuring the detector, electrometer and a high voltage pulser in a closed-loop control system. The detector current is maintained at a fixed level by varying the frequency of fixed-width, high-voltage bias pulses applied to the detector. An output signal proportional to the pulse frequency is produced which is indicative of the charge collected for a detected species.

Small field detector correction factors: effects of the flattening filter for Elekta and Varian linear accelerators

PubMed Central

Liu, Paul Z.Y.; Lee, Christopher; McKenzie, David R.; Suchowerska, Natalka

2016-01-01

Flattening filter‐free (FFF) beams are becoming the preferred beam type for stereotactic radiosurgery (SRS) and stereotactic ablative radiation therapy (SABR), as they enable an increase in dose rate and a decrease in treatment time. This work assesses the effects of the flattening filter on small field output factors for 6 MV beams generated by both Elekta and Varian linear accelerators, and determines differences between detector response in flattened (FF) and FFF beams. Relative output factors were measured with a range of detectors (diodes, ionization chambers, radiochromic film, and microDiamond) and referenced to the relative output factors measured with an air core fiber optic dosimeter (FOD), a scintillation dosimeter developed at Chris O'Brien Lifehouse, Sydney. Small field correction factors were generated for both FF and FFF beams. Diode measured detector response was compared with a recently published mathematical relation to predict diode response corrections in small fields. The effect of flattening filter removal on detector response was quantified using a ratio of relative detector responses in FFF and FF fields for the same field size. The removal of the flattening filter was found to have a small but measurable effect on ionization chamber response with maximum deviations of less than ±0.9% across all field sizes measured. Solid‐state detectors showed an increased dependence on the flattening filter of up to ±1.6%. Measured diode response was within ±1.1% of the published mathematical relation for all fields up to 30 mm, independent of linac type and presence or absence of a flattening filter. For 6 MV beams, detector correction factors between FFF and FF beams are interchangeable for a linac between FF and FFF modes, providing that an additional uncertainty of up to ±1.6% is accepted. PACS number(s): 87.55.km, 87.56.bd, 87.56.Da PMID:27167280

Development of the MICROMEGAS detector for measuring the energy spectrum of alpha particles by using a 241Am source

NASA Astrophysics Data System (ADS)

Kim, Do Yoon; Ham, Cheolmin; Shin, Jae Won; Park, Tae-Sun; Hong, Seung-Woo; Andriamonje, Samuel; Kadi, Yacine; Tenreiro, Claudio

2016-05-01

We have developed MICROMEGAS (MICRO MEsh GASeous) detectors for detecting a particles emitted from an 241Am standard source. The voltage applied to the ionization region of the detector is optimized for stable operation at room temperature and atmospheric pressure. The energy of a particles from the 241Am source can be varied by changing the flight path of the a particle from the 241Am source. The channel numbers of the experimentally-measured pulse peak positions for different energies of the a particles are associated with the energies deposited by the alpha particles in the ionization region of the detector as calculated by using GEANT4 simulations; thus, the energy calibration of the MICROMEGAS detector for a particles is done. For the energy calibration, the thickness of the ionization region is adjusted so that a particles may completely stop in the ionization region and their kinetic energies are fully deposited in the region. The efficiency of our MICROMEGAS detector for a particles under the present conditions is found to be ~97.3%.

Characterizing energy dependence and count rate performance of a dual scintillator fiber-optic detector for computed tomography

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

Hoerner, Matthew R., E-mail: mrh5038@ufl.edu; Stepusin, Elliott J.; Hyer, Daniel E.

Purpose: Kilovoltage (kV) x-rays pose a significant challenge for radiation dosimetry. In the kV energy range, even small differences in material composition can result in significant variations in the absorbed energy between soft tissue and the detector. In addition, the use of electronic systems in light detection has demonstrated measurement losses at high photon fluence rates incident to the detector. This study investigated the feasibility of using a novel dual scintillator detector and whether its response to changes in beam energy from scatter and hardening is readily quantified. The detector incorporates a tissue-equivalent plastic scintillator and a gadolinium oxysulfide scintillator,more » which has a higher sensitivity to scatter x-rays. Methods: The detector was constructed by coupling two scintillators: (1) small cylindrical plastic scintillator, 500 μm in diameter and 2 mm in length, and (2) 100 micron sheet of gadolinium oxysulfide 500 μm in diameter, each to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photomultiplier tube. Count rate linearity data were obtained from a wide range of exposure rates delivered from a radiological x-ray tube by adjusting the tube current. The data were fitted to a nonparalyzable dead time model to characterize the time response. The true counting rate was related to the reference free air dose air rate measured with a 0.6 cm{sup 3} Radcal{sup ®} thimble chamber as described in AAPM Report No. 111. Secondary electron and photon spectra were evaluated using Monte Carlo techniques to analyze ionization quenching and photon energy-absorption characteristics from free-in-air and in phantom measurements. The depth/energy dependence of the detector was characterized using a computed tomography dose index QA phantom consisting of nested adult head and body segments. The phantom provided up to 32 cm of acrylic with a compatible 0.6 cm{sup 3} calibrated ionization chamber to measure the reference air kerma. Results: Each detector exhibited counting losses of 5% when irradiated at a dose rate of 26.3 mGy/s (Gadolinium) and 324.3 mGy/s (plastic). The dead time of the gadolinium oxysulfide detector was determined to be 48 ns, while the dead time of the plastic scintillating detector was unable to accurately be calculated due to poor counting statistics from low detected count rates. Noticeable depth/energy dependence was observed for the plastic scintillator for depths greater than 16 cm of acrylic that was not present for measurements using the gadolinium oxysulfide scintillator, leading us to believe that quenching may play a larger role in the depth dependence of the plastic scintillator than the incident x-ray energy spectrum. When properly corrected for dead time effects, the energy response of the gadolinium oxysulfide scintillator is consistent with the plastic scintillator. Using the integrated dual detector method was superior to each detector individually as the depth-dependent measure of dose was correctable to less than 8% between 100 and 135 kV. Conclusions: The dual scintillator fiber-optic detector accommodates a methodology for energy dependent corrections of the plastic scintillator, improving the overall accuracy of the dosimeter across the range of diagnostic energies.« less

Characterizing energy dependence and count rate performance of a dual scintillator fiber-optic detector for computed tomography.

PubMed

Hoerner, Matthew R; Stepusin, Elliott J; Hyer, Daniel E; Hintenlang, David E

2015-03-01

Kilovoltage (kV) x-rays pose a significant challenge for radiation dosimetry. In the kV energy range, even small differences in material composition can result in significant variations in the absorbed energy between soft tissue and the detector. In addition, the use of electronic systems in light detection has demonstrated measurement losses at high photon fluence rates incident to the detector. This study investigated the feasibility of using a novel dual scintillator detector and whether its response to changes in beam energy from scatter and hardening is readily quantified. The detector incorporates a tissue-equivalent plastic scintillator and a gadolinium oxysulfide scintillator, which has a higher sensitivity to scatter x-rays. The detector was constructed by coupling two scintillators: (1) small cylindrical plastic scintillator, 500 μm in diameter and 2 mm in length, and (2) 100 micron sheet of gadolinium oxysulfide 500 μm in diameter, each to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photomultiplier tube. Count rate linearity data were obtained from a wide range of exposure rates delivered from a radiological x-ray tube by adjusting the tube current. The data were fitted to a nonparalyzable dead time model to characterize the time response. The true counting rate was related to the reference free air dose air rate measured with a 0.6 cm(3) Radcal(®) thimble chamber as described in AAPM Report No. 111. Secondary electron and photon spectra were evaluated using Monte Carlo techniques to analyze ionization quenching and photon energy-absorption characteristics from free-in-air and in phantom measurements. The depth/energy dependence of the detector was characterized using a computed tomography dose index QA phantom consisting of nested adult head and body segments. The phantom provided up to 32 cm of acrylic with a compatible 0.6 cm(3) calibrated ionization chamber to measure the reference air kerma. Each detector exhibited counting losses of 5% when irradiated at a dose rate of 26.3 mGy/s (Gadolinium) and 324.3 mGy/s (plastic). The dead time of the gadolinium oxysulfide detector was determined to be 48 ns, while the dead time of the plastic scintillating detector was unable to accurately be calculated due to poor counting statistics from low detected count rates. Noticeable depth/energy dependence was observed for the plastic scintillator for depths greater than 16 cm of acrylic that was not present for measurements using the gadolinium oxysulfide scintillator, leading us to believe that quenching may play a larger role in the depth dependence of the plastic scintillator than the incident x-ray energy spectrum. When properly corrected for dead time effects, the energy response of the gadolinium oxysulfide scintillator is consistent with the plastic scintillator. Using the integrated dual detector method was superior to each detector individually as the depth-dependent measure of dose was correctable to less than 8% between 100 and 135 kV. The dual scintillator fiber-optic detector accommodates a methodology for energy dependent corrections of the plastic scintillator, improving the overall accuracy of the dosimeter across the range of diagnostic energies.

Clinical prototype of a plastic water-equivalent scintillating fiber dosimeter array for QA applications.

PubMed

Lacroix, Fréderic; Archambault, Louis; Gingras, Luc; Guillot, Mathieu; Beddar, A Sam; Beaulieu, Luc

2008-08-01

A clinical prototype of a scintillating fiber dosimeter array for quality assurance applications is presented. The array consists of a linear array of 29 plastic scintillation detectors embedded in a water-equivalent plastic sheet coupled to optical fibers used to guide optical photons to a charge coupled device (CCD) camera. The CCD is packaged in a light-tight, radiation-shielded housing designed for convenient transport. A custom designed connector is used to ensure reproducible mechanical positioning of the optical fibers relative to the CCD. Profile and depth dose characterization measurements are presented and show that the prototype provides excellent dose measurement reproducibility (+/-0.8%) in-field and good accuracy (+/-1.6% maximum deviation) relative to the dose measured with an IC10 ionization chamber.

Semiconductor detector with smoothly tunable effective thickness for the study of ionization loss by moderately relativistic electrons

NASA Astrophysics Data System (ADS)

Shchagin, A. V.; Shul'ga, N. F.; Trofymenko, S. V.; Nazhmudinov, R. M.; Kubankin, A. S.

2016-11-01

The possibility of measurement of electrons ionization loss in Si layer of smoothly tunable thickness is shown in the proof-of-principle experiment. The Si surface-barrier detector with the depleted layer thickness controlled by the value of high voltage power supply has been used. Ionization loss spectra for electrons emitted by radioactive source 207Bi are presented and discussed. Experimental results for the most probable ionization loss in the Landau spectral peak are compared with theoretical calculations. The possibility of research of evolution of electromagnetic field of ultra-relativistic particles traversing media interface with the use of detectors with smoothly tunable thickness is proposed.

Unraveling nonadiabatic ionization and Coulomb potential effect in strong-field photoelectron holography.

PubMed

Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; Liu, Peng; Chen, Zhangjin; Yang, Weifeng; Hu, Shilin; Lin, C D; Chen, Jing

2016-06-22

Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. In addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. We showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules.

Unraveling nonadiabatic ionization and Coulomb potential effect in strong-field photoelectron holography

PubMed Central

Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; Liu, Peng; Chen, Zhangjin; Yang, Weifeng; Hu, Shilin; Lin, C. D.; Chen, Jing

2016-01-01

Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. In addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. We showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules. PMID:27329071

Unraveling nonadiabatic ionization and Coulomb potential effect in strong-field photoelectron holography

DOE PAGES

Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; ...

2016-06-22

Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. Inmore » addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. Here, we showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules.« less

Innovative mid-infrared detector concepts

NASA Astrophysics Data System (ADS)

Höfling, Sven; Pfenning, Andreas; Weih, Robert; Ratajczak, Albert; Hartmann, Fabian; Knebl, Georg; Kamp, Martin; Worschech, Lukas

2016-09-01

Gas sensing is a key technology with applications in various industrial, medical and environmental areas. Optical detection mechanisms allow for a highly selective, contactless and fast detection. For this purpose, rotational-vibrational absorption bands within the mid infrared (MIR) spectral region are exploited and probed with appropriate light sources. During the past years, the development of novel laser concepts such as interband cascade lasers (ICLs) and quantum cascade lasers (QCLs) has driven a continuous optimization of MIR laser sources. On the other hand side, there has been relatively little progress on detectors in this wavelength range. Here, we study two novel and promising GaSb-based detector concepts: Interband cascade detectors (ICD) and resonant tunneling diode (RTD) photodetectors. ICDs are a promising approach towards highly sensitive room temperature detection of MIR radiation. They make use of the cascading scheme that is enabled by the broken gap alignment of the two binaries GaSb and InAs. The interband transition in GaSb/InAs-superlattices (SL) allows for normal incidence detection. The cut-off wavelength, which determines the low energy detection limit, can be engineered via the SL period. RTD photodetectors act as low noise and high speed amplifiers of small optically generated electrical signals. In contrast to avalanche photodiodes, where the gain originates from multiplication due to impact ionization, in RTD photodetectors a large tunneling current is modulated via Coulomb interaction by the presence of photogenerated minority charge carriers. For both detector concepts, first devices operational at room temperature have been realized.

New radiological material detection technologies for nuclear forensics: Remote optical imaging and graphene-based sensors.

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

Harrison, Richard Karl; Martin, Jeffrey B.; Wiemann, Dora K.

We developed new detector technologies to identify the presence of radioactive materials for nuclear forensics applications. First, we investigated an optical radiation detection technique based on imaging nitrogen fluorescence excited by ionizing radiation. We demonstrated optical detection in air under indoor and outdoor conditions for alpha particles and gamma radiation at distances up to 75 meters. We also contributed to the development of next generation systems and concepts that could enable remote detection at distances greater than 1 km, and originated a concept that could enable daytime operation of the technique. A second area of research was the development ofmore » room-temperature graphene-based sensors for radiation detection and measurement. In this project, we observed tunable optical and charged particle detection, and developed improved devices. With further development, the advancements described in this report could enable new capabilities for nuclear forensics applications.« less

Single-crystalline oxide films of the Al2O3-Y2O3-R2O3 system as optical sensors of various types of ionizing radiation: significant advantages over volume analogs

NASA Astrophysics Data System (ADS)

Zorenko, Yuri V.; Batenchuk, M.; Gorbenco, V.; Pashkovsky, M.

1997-02-01

This investigation is dedicated to studying of peculiarities of luminescent properties of the single crystalline films (SCF) of Al2O3-Y2O3-R2O3 oxide system with alpha-Al2O3 and garnet structure, which are used as various types of ionizing radiation luminescent detectors. These peculiarities define the number of nontrivial advantages over their volume analogues. It is shown that SCF are characterized by the low concentrations of vacancy type defects and substituent defects, and the high concentration of Pb ion as dopant. This allows us to substantially increase the spatial resolution and selectivity of cathodoluminophores on the base of these compounds.

Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography

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

Kroll, Florian; Karsch, Leonhard; Pawelke, Jörg

2013-08-15

Purpose: Clinical QA in teletherapy as well as the characterization of experimental radiation sources for future medical applications requires effective methods for measuring three-dimensional (3D) dose distributions generated in a water-equivalent medium. Current dosimeters based on ionization chambers, diodes, thermoluminescence detectors, radiochromic films, or polymer gels exhibit various drawbacks: High quality 3D dose determination is either very sophisticated and expensive or requires high amounts of effort and time for the preparation or read out. New detectors based on scintillator blocks in combination with optical tomography are studied, since they have the potential to facilitate the desired cost-effective, transportable, and long-termmore » stable dosimetry system that is able to determine 3D dose distributions with high spatial resolution in a short time.Methods: A portable detector prototype was set up based on a plastic scintillator block and four digital cameras. During irradiation the scintillator emits light, which is detected by the fixed cameras. The light distribution is then reconstructed by optical tomography, using maximum-likelihood expectation maximization. The result of the reconstruction approximates the 3D dose distribution. First performance tests of the prototype using laser light were carried out. Irradiation experiments were performed with ionizing radiation, i.e., bremsstrahlung (6 to 21 MV), electrons (6 to 21 MeV), and protons (68 MeV), provided by clinical and research accelerators.Results: Laser experiments show that the current imaging properties differ from the design specifications: The imaging scale of the optical systems is position dependent, ranging from 0.185 mm/pixel to 0.225 mm/pixel. Nevertheless, the developed dosimetry method is proven to be functional for electron and proton beams. Induced radiation doses of 50 mGy or more made 3D dose reconstructions possible. Taking the imaging properties into account, determined dose profiles are in agreement with reference measurements. An inherent drawback of the scintillator is the nonlinear light output for high stopping-power radiation due to the quenching effect. It impacts the depth dose curves measured with the dosimeter. For single Bragg peak distributions this leads to a peak to plateau ratio of 2.8 instead of 4.5 for the reference ionization chamber measurement. Furthermore, the transmission of the clinical bremsstrahlung beams through the scintillator leads to the saturation of one camera, making dose reconstructions in that case presently not feasible.Conclusions: It is shown that distributions of scintillation light generated by proton or electron beams can be reconstructed by the dosimetry system within minutes. The quenching apparent for proton irradiation, and the yet not precisely determined position dependency of the imaging scale, require further investigation and corrections. Upgrading the prototype with larger or inorganic scintillators would increase the detectable proton and electron energy range. The presented results show that the determination of 3D dose distributions using scintillator blocks and optical tomography is a promising dosimetry method.« less

Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography.

PubMed

Kroll, Florian; Pawelke, Jörg; Karsch, Leonhard

2013-08-01

Clinical QA in teletherapy as well as the characterization of experimental radiation sources for future medical applications requires effective methods for measuring three-dimensional (3D) dose distributions generated in a water-equivalent medium. Current dosimeters based on ionization chambers, diodes, thermoluminescence detectors, radiochromic films, or polymer gels exhibit various drawbacks: High quality 3D dose determination is either very sophisticated and expensive or requires high amounts of effort and time for the preparation or read out. New detectors based on scintillator blocks in combination with optical tomography are studied, since they have the potential to facilitate the desired cost-effective, transportable, and long-term stable dosimetry system that is able to determine 3D dose distributions with high spatial resolution in a short time. A portable detector prototype was set up based on a plastic scintillator block and four digital cameras. During irradiation the scintillator emits light, which is detected by the fixed cameras. The light distribution is then reconstructed by optical tomography, using maximum-likelihood expectation maximization. The result of the reconstruction approximates the 3D dose distribution. First performance tests of the prototype using laser light were carried out. Irradiation experiments were performed with ionizing radiation, i.e., bremsstrahlung (6 to 21 MV), electrons (6 to 21 MeV), and protons (68 MeV), provided by clinical and research accelerators. Laser experiments show that the current imaging properties differ from the design specifications: The imaging scale of the optical systems is position dependent, ranging from 0.185 mm/pixel to 0.225 mm/pixel. Nevertheless, the developed dosimetry method is proven to be functional for electron and proton beams. Induced radiation doses of 50 mGy or more made 3D dose reconstructions possible. Taking the imaging properties into account, determined dose profiles are in agreement with reference measurements. An inherent drawback of the scintillator is the nonlinear light output for high stopping-power radiation due to the quenching effect. It impacts the depth dose curves measured with the dosimeter. For single Bragg peak distributions this leads to a peak to plateau ratio of 2.8 instead of 4.5 for the reference ionization chamber measurement. Furthermore, the transmission of the clinical bremsstrahlung beams through the scintillator leads to the saturation of one camera, making dose reconstructions in that case presently not feasible. It is shown that distributions of scintillation light generated by proton or electron beams can be reconstructed by the dosimetry system within minutes. The quenching apparent for proton irradiation, and the yet not precisely determined position dependency of the imaging scale, require further investigation and corrections. Upgrading the prototype with larger or inorganic scintillators would increase the detectable proton and electron energy range. The presented results show that the determination of 3D dose distributions using scintillator blocks and optical tomography is a promising dosimetry method.

Study of material properties important for an optical property modulation-based radiation detection method for positron emission tomography.

PubMed

Tao, Li; Daghighian, Henry M; Levin, Craig S

2017-01-01

We compare the performance of two detector materials, cadmium telluride (CdTe) and bismuth silicon oxide (BSO), for optical property modulation-based radiation detection method for positron emission tomography (PET), which is a potential new direction to dramatically improve the annihilation photon pair coincidence time resolution. We have shown that the induced current flow in the detector crystal resulting from ionizing radiation determines the strength of optical modulation signal. A larger resistivity is favorable for reducing the dark current (noise) in the detector crystal, and thus the higher resistivity BSO crystal has a lower (50% lower on average) noise level than CdTe. The CdTe and BSO crystals can achieve the same sensitivity under laser diode illumination at the same crystal bias voltage condition while the BSO crystal is not as sensitive to 511-keV photons as the CdTe crystal under the same crystal bias voltage. The amplitude of the modulation signal induced by 511-keV photons in BSO crystal is around 30% of that induced in CdTe crystal under the same bias condition. In addition, we have found that the optical modulation strength increases linearly with crystal bias voltage before saturation. The modulation signal with CdTe tends to saturate at bias voltages higher than 1500 V due to its lower resistivity (thus larger dark current) while the modulation signal strength with BSO still increases after 3500 V. Further increasing the bias voltage for BSO could potentially further enhance the modulation strength and thus, the sensitivity.

Characteristics of a p-Si detector in high energy electron fields.

PubMed

Rikner, G

1985-01-01

Comparison of depth ionization distributions from a silicon semiconductor detector and depth dose curves from a plane parallel ionization chamber show that a semiconductor detector of p-type is well suited for relative electron dosimetry in the energy range of 6 to 20 MeV in Ep,0. Maximum deviations of the order of 1.5 per cent and of 1 mm were obtained down to a phantom depth of about 1 mm. The directional dependence of the detector was about 4 per cent.

40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements...

40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements...

40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements...

The ArDM experiment

DOE PAGES

Harańczyk, M.; Amsler, C.; Badertscher, A.; ...

2010-08-24

The aim of the ArDM project is the development and operation of a one ton double-phase liquid argon detector for direct Dark Matter searches. The detector measures both the scintillation light and the ionization charge from ionizing radiation using two independent readout systems. This paper briefly describes the detector concept and presents preliminary results from the ArDM R & D program, including a 3 l prototype developed to test the charge readout system.

Cosmic ray experimental observations

NASA Technical Reports Server (NTRS)

Balasubrahmanyan, V. K.; Mcdonald, F. B.

1974-01-01

The current experimental situation in cosmic ray studies is discussed, with special emphasis on the development of new detector systems. Topics covered are the techniques for particle identification, energy measurements, gas Cerenkov counters, magnet spectrometers, ionization spectrometers, track detectors, nuclear emulsions, multiparameter analysis using arrays of detectors, the Goddard ionization spectrometer, charge spectra, relative abundances, isotope composition, antinuclei in cosmic rays, electrons, the measurement of cosmic ray arrival directions, and the prehistory of cosmic rays.

Method for detection of dental caries and periodontal disease using optical imaging

DOEpatents

Nathel, Howard; Kinney, John H.; Otis, Linda L.

1996-01-01

A method for detecting the presence of active and inactive caries in teeth and diagnosing periodontal disease uses non-ionizing radiation with techniques for reducing interference from scattered light. A beam of non-ionizing radiation is divided into sample and reference beams. The region to be examined is illuminated by the sample beam, and reflected or transmitted radiation from the sample is recombined with the reference beam to form an interference pattern on a detector. The length of the reference beam path is adjustable, allowing the operator to select the reflected or transmitted sample photons that recombine with the reference photons. Thus radiation scattered by the dental or periodontal tissue can be prevented from obscuring the interference pattern. A series of interference patterns may be generated and interpreted to locate dental caries and periodontal tissue interfaces.

Surface dose measurements with commonly used detectors: a consistent thickness correction method.

PubMed

Reynolds, Tatsiana A; Higgins, Patrick

2015-09-08

The purpose of this study was to review application of a consistent correction method for the solid state detectors, such as thermoluminescent dosimeters (chips (cTLD) and powder (pTLD)), optically stimulated detectors (both closed (OSL) and open (eOSL)), and radiochromic (EBT2) and radiographic (EDR2) films. In addition, to compare measured surface dose using an extrapolation ionization chamber (PTW 30-360) with other parallel plate chambers RMI-449 (Attix), Capintec PS-033, PTW 30-329 (Markus) and Memorial. Measurements of surface dose for 6MV photons with parallel plate chambers were used to establish a baseline. cTLD, OSLs, EDR2, and EBT2 measurements were corrected using a method which involved irradiation of three dosimeter stacks, followed by linear extrapolation of individual dosimeter measurements to zero thickness. We determined the magnitude of correction for each detector and compared our results against an alternative correction method based on effective thickness. All uncorrected surface dose measurements exhibited overresponse, compared with the extrapolation chamber data, except for the Attix chamber. The closest match was obtained with the Attix chamber (-0.1%), followed by pTLD (0.5%), Capintec (4.5%), Memorial (7.3%), Markus (10%), cTLD (11.8%), eOSL (12.8%), EBT2 (14%), EDR2 (14.8%), and OSL (26%). Application of published ionization chamber corrections brought all the parallel plate results to within 1% of the extrapolation chamber. The extrapolation method corrected all solid-state detector results to within 2% of baseline, except the OSLs. Extrapolation of dose using a simple three-detector stack has been demonstrated to provide thickness corrections for cTLD, eOSLs, EBT2, and EDR2 which can then be used for surface dose measurements. Standard OSLs are not recommended for surface dose measurement. The effective thickness method suffers from the subjectivity inherent in the inclusion of measured percentage depth-dose curves and is not recommended for these types of measurements.

development of a neutral mass spectrometer dedicated to the analysis of planetary envelopes (NIMEIS)

NASA Astrophysics Data System (ADS)

Becker, J.

2012-12-01

LATMOS worked for several years on a newly designed instrument suitable for measuring neutral environments as rarefied exosphere of Mars, Venus, Europa, asteroids or Titan for example. This instrument NIMEIS for Neutral and Ion Mass and Energy Imaging Spectrometer has as main features the ability to measure low densities of neutral but also conduct an analysis of mass and energy in an energy range covering the thermal and suprathermal between ~ 1 eV and 20 eV far unexplored. My thesis is divided into two independent parts. First, we optimize the ionization source, that is an innovative concept, and secondly we design the optics of the instrument based on an electrostatic optimization. The ionization source is based on the use of carbon nanotubes and to extract the electrons and ionize the neutral. Employing this technology we can significantly reduce the power, because previously we were using heated filaments. We develop this technology in close collaboration with a laboratory Ajou University (South Korea) that provides us with carbon nanotubes. I did a simulation study of the mode of extraction of electrons from initial tests, from an assembly developed by our laboratory in South Korea. The instrument has been optimized so that the impact on the detector gives us the one hand the energy of the particle and on the other hand the mass of the particle simultaneously and in continuous time. I developed the optics of the instrument using an electrostatic optical software. A comprehensive numerical model has been defined and a prototype is being manufactured.

Radiotherapy dosimetry using a commercial OSL system.

PubMed

Viamonte, A; da Rosa, L A R; Buckley, L A; Cherpak, A; Cygler, J E

2008-04-01

A commercial optically stimulated luminescence (OSL) system developed for radiation protection dosimetry by Landauer, Inc., the InLight microStar reader, was tested for dosimetry procedures in radiotherapy. The system uses carbon-doped aluminum oxide, Al2O3:C, as a radiation detector material. Using this OSL system, a percent depth dose curve for 60Co gamma radiation was measured in solid water. Field size and SSD dependences of the detector response were also evaluated. The dose response relationship was investigated between 25 and 400 cGy. The decay of the response with time following irradiation and the energy dependence of the Al2O3:C OSL detectors were also measured. The results obtained using OSL dosimeters show good agreement with ionization chamber and diode measurements carried out under the same conditions. Reproducibility studies show that the response of the OSL system to repeated exposures is 2.5% (1sd), indicating a real possibility of applying the Landauer OSL commercial system for radiotherapy dosimetric procedures.

SU-E-I-88: The Effect of System Dead Time On Real-Time Plastic and GOS Based Fiber-Optic Dosimetry Systems

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

Hoerner, M; Hintenlang, D

Purpose: A methodology is presented to correct for measurement inaccuracies at high detector count rates using a plastic and GOS scintillation fibers coupled to a photomultiplier tube with digital readout. This system allows temporal acquisition and manipulation of measured data. Methods: The detection system used was a plastic scintillator and a separate gadolinium scintillator, both (0.5 diameter) coupled to an optical fiber with a Hamamatsu photon counter with a built-in microcontroller and digital interface. Count rate performance of the system was evaluated using the nonparalzable detector model. Detector response was investigated across multiple radiation sources including: orthovoltage x-ray system, colbat-60more » gamma rays, proton therapy beam, and a diagnostic radiography x-ray tube. The dead time parameter was calculated by measuring the count rate of the system at different exposure rates using a reference detector. Results: The system dead time was evaluated for the following sources of radiation used clinically: diagnostic energy x-rays, cobalt-60 gamma rays, orthovoltage xrays, particle proton accelerator, and megavoltage x-rays. It was found that dead time increased significantly when exposing the detector to sources capable of generating Cerenkov radiation, all of the sources sans the diagnostic x-rays, with increasing prominence at higher photon energies. Percent depth dose curves generated by a dedicated ionization chamber and compared to the detection system demonstrated that correcting for dead time improves accuracy. On most sources, nonparalzable model fit provided an improved system response. Conclusion: Overall, the system dead time was variable across the investigated radiation particles and energies. It was demonstrated that the system response accuracy was greatly improved by correcting for dead time effects. Cerenkov radiation plays a significant role in the increase in the system dead time through transient absorption effects attributed to electron hole-pair creations within the optical waveguide.« less

Optical fiber sensor for low dose gamma irradiation monitoring

NASA Astrophysics Data System (ADS)

de Andrés, Ana I.; Esteban, Ã.`scar; Embid, Miguel

2016-05-01

An optical fiber gamma ray detector is presented in this work. It is based on a Terbium doped Gadolinium Oxysulfide (Gd2O2S:Tb) scintillating powder which cover a chemically etched polymer fiber tip. This etching improves the fluorescence gathering by the optical fiber. The final diameter has been selected to fulfill the trade-off between light gathering and mechanical strength. Powder has been encapsulated inside a microtube where the fiber tip is immersed. The sensor has been irradiated with different air Kerma doses up to 2 Gy/h with a 137Cs source, and the spectral distribution of the fluorescence intensity has been recorded in a commercial grade CCD spectrometer. The obtained signal-to-noise ratio is good enough even for low doses, which has allowed to reduce the integration time in the spectrometer. The presented results show the feasibility for using low cost equipment to detect/measure ionizing radiation as gamma rays are.

High efficiency photoionization detector

DOEpatents

Anderson, David F.

1984-01-01

A high efficiency photoionization detector using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36.+-.0.02 eV, and a vapor pressure of 0.35 torr at 20.degree. C.

Test results from a comparative evaluation of a condensation nuclei fire detector

NASA Technical Reports Server (NTRS)

Bricker, R. W.

1985-01-01

The fire/smoke alarm response of a condensation nuclei fire detector (CNFD) was compared with photoelectric and ionization detectors. Tests were conducted in a former control room 8.5 m by 8.9 with a 2.7 m ceiling. The room had air supplied from above the ceiling and under the floor with return air exiting from ceiling grills. The environment was varied from 278 to 305 K and relative humidities from 8 to 65%. Four detection zones were located in the room. Each zone contained a sampling head for the CNDF, a photodetector, and an ionization detector so that each detector system had four opportunities to alarm during tests. The particle level in the test room was also monitored during tests with a condensation nuclei particle counter. The CNFD responded to 90% of exposures to smoldering plastic and 84% of exposures to visible fire. The photoelectric response was 43 and 12.5% respectively for the same conditions. The ionization response was 9 and 48 respectively.

A magnetic-bottle multi-electron-ion coincidence spectrometer

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

Matsuda, Akitaka; Hishikawa, Akiyoshi; Department of Chemistry, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8602

2011-10-15

A novel multi-electron-ion coincidence spectrometer developed on the basis of a 1.5 m-long magnetic-bottle electron spectrometer is presented. Electrons are guided by an inhomogeneous magnetic field to a detector at the end of the flight tube, while a set of optics is used to extract counterpart ions to the same detector, by a pulsed inhomogeneous electric field. This setup allows ion detection with high mass resolution, without impairing the high collection efficiency for electrons. The performance of the coincidence spectrometer was tested with double ionization of carbon disulfide, CS{sub 2} {yields} CS{sub 2}{sup 2+} + e{sup -} + e{sup -},more » in ultrashort intense laser fields (2.8 x 10{sup 13} W/cm{sup 2}, 280 fs, 1030 nm) to clarify the electron correlation below the rescattering threshold.« less

Using Ionizing Radiation Detectors. Module 11. Vocational Education Training in Environmental Health Sciences.

ERIC Educational Resources Information Center

Consumer Dynamics Inc., Rockville, MD.

This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on using ionizing radiation detectors. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) naming and telling the function…

QUALITY ASSURANCE STUDY OF MARINE LIPID CLASS DETERMINATION USING CHROMAROD/IATROSCAN( REG. TRADEMARK) THIN-LAYER CHROMATOGRAPHY-FLAME IONIZATION DETECTOR

EPA Science Inventory

An Iatroscan thin-layer chromatorgraphy-flame ionization detector has been utilized to quantify lipid classes in marine samples. This method was evaluated relative to established quality assurance (QA) procedures used for the gas chromatographic analysis of PCBs. A method for ext...

X-ray radiation detectors of ``scintillator-photoreceiving device type'' for industrial digital radiography with improved spatial resolution

NASA Astrophysics Data System (ADS)

Ryzhykov, V. D.; Lysetska, O. K.; Opolonin, O. D.; Kozin, D. N.

2003-06-01

Main types of photoreceivers used in X-ray digital radiography systems are luminescent screens that transfer the optical image onto charge collection instruments, which require cooling, and semiconductor silicon detectors, which limit the contrast sensitivity. We have developed and produced X-ray radiation detectors of "scintillator-photoreceiving device" (S-PRD) type, which are integrally located on the inverse side of the photodiode (PD). The receiving-converting circuit (RCC) is designed for data conversion into digital form and their input into PC. Software is provided for RCC control and image visualization. Main advantages of these detectors are high industrial resolution (3-5 line pairs per mm), detecting activity up to 20 μm, controlled sensitivity, low weight and small size, imaging low (0.1-0.3 mrad) object dose in real time. In this work, main characteristics of 32-, 64- and 1024-channel detectors of S-PRD type were studied and compared for X-ray sensitivity with S-PD detectors. Images of the tested objects have been obtained. Recommendations are given on the use of different scintillation materials, depending upon the purpose of a digital radiographic system. The detectors operate in a broad energy range of ionizing radiation, hence the size of the controlled object is not limited. The system is sufficiently powerful to ensure frontal (through two walls) observation of pipelines with wall thickness up to 10 cm.

The "collimator monitoring fill factor" of a two-dimensional detector array, a measure of its ability to detect collimation errors.

PubMed

Stelljes, Tenzin Sonam; Looe, Hui Khee; Harder, Dietrich; Poppe, Björn

2017-03-01

Two-dimensional detector arrays are routinely used for constancy checks and treatment plan verification in photon-beam radiotherapy. In addition to the spatial resolution of the dose profiles, the "coverage" of the radiation field with respect to the detection of any beam collimation deficiency appears as the second characteristic feature of a detector array. The here proposed "collimator monitoring fill factor" (CM fill factor) has been conceived to serve as a quantitative characteristic of this "coverage". The CM fill factor is defined as the probability of a 2D array to detect any collimator position error. Therefore, it is represented by the ratio of the "sensitive area" of a single detector, in which collimator position errors are detectable, and the geometrical "cell area" associated with this detector within the array. Numerical values of the CM fill factor have been Monte Carlo simulated for 2D detector arrays equipped with air-vented ionization chambers, liquid-filled ionization chambers and diode detectors and were compared with the "FWHM fill factor" defined by Gago-Arias et al. (2012). For arrays with vented ionization chambers, the differences between the CM fill factor and the FWHM fill factor are moderate, but occasionally the latter exceeds unity. For narrower detectors such as liquid-filled ionization chambers and Si diodes and for small sampling distances, large differences between the FWHM fill factor and the CM fill factor have been observed. These differences can be explained by the shapes of the fluence response functions of these narrow detectors. A new parameter "collimator monitoring fill factor" (CM fill factor), applicable to quantitate the collimator position error detection probability of a 2D detector array, has been proposed. It is designed as a help in classifying the clinical performance of two-dimensional detector arrays in photon-beam radiotherapy. © 2017 American Association of Physicists in Medicine.

A single dopant atom in silicon sees the light

NASA Astrophysics Data System (ADS)

Rogge, Sven

2014-03-01

Optical access to a single qubit is very attractive since it allows for readout with unprecedented high spectral resolution and long distance coupling. Substantial progress has been demonstrated for nitrogen-vacancy centers in diamond (Bernien, Nature, 2013). Optical access to qubits in silicon been an important goal but has to date only been achieved in the ensemble limit (Steger, Science, 2012). Here, we present the photoionization of an individual erbium dopant in silicon (Yin, Nature, 2013). A single-electron transistor is used as a single-shot charge detector to observe the resonant ionization of a single atom as a function of photon energy. This allows for optical addressing and electrical detection of individual erbium dopants with exceptionally narrow line width. The hyperfine coupling is clearly resolved which paves the way to single shot readout of the nuclear spin. This hybrid approach is a first step towards an optical interface to dopants in silicon. in collaboration with Chunming Yin, Milos Rancic, Gabriele G. de Boo, Nikolas Stavrias, Jeffrey C. McCallum, Matthew J. Sellars.

Test study of boron nitride as a new detector material for dosimetry in high-energy photon beams.

PubMed

Poppinga, D; Halbur, J; Lemmer, S; Delfs, B; Harder, D; Looe, H K; Poppe, B

2017-09-05

The aim of this test study is to check whether boron nitride (BN) might be applied as a detector material in high-energy photon-beam dosimetry. Boron nitride exists in various crystalline forms. Hexagonal boron nitride (h-BN) possesses high mobility of the electrons and holes as well as a high volume resistivity, so that ionizing radiation in the clinical range of the dose rate can be expected to produce a measurable electrical current at low background current. Due to the low atomic numbers of its constituents, its density (2.0 g cm -3 ) similar to silicon and its commercial availability, h-BN appears as possibly suitable for the dosimetry of ionizing radiation. Five h-BN plates were contacted to triaxial cables, and the detector current was measured in a solid-state ionization chamber circuit at an applied voltage of 50 V. Basic dosimetric properties such as formation by pre-irradiation, sensitivity, reproducibility, linearity and temporal resolution were measured with 6 MV photon irradiation. Depth dose curves at quadratic field sizes of 10 cm and 40 cm were measured and compared to ionization chamber measurements. After a pre-irradiation with 6 Gy, the devices show a stable current signal at a given dose rate. The current-voltage characteristic up to 400 V shows an increase in the collection efficiency with the voltage. The time-resolved detector current behavior during beam interrupts is comparable to diamond material, and the background current is negligible. The measured percentage depth dose curves at 10 cm  ×  10 cm field size agreed with the results of ionization chamber measurements within  ±2%. This is a first study of boron nitride as a detector material for high-energy photon radiation. By current measurements on solid ionization chambers made from boron nitride chips we could demonstrate that boron nitride is in principle suitable as a detector material for high-energy photon-beam dosimetry.

Test study of boron nitride as a new detector material for dosimetry in high-energy photon beams

NASA Astrophysics Data System (ADS)

Poppinga, D.; Halbur, J.; Lemmer, S.; Delfs, B.; Harder, D.; Looe, H. K.; Poppe, B.

2017-09-01

The aim of this test study is to check whether boron nitride (BN) might be applied as a detector material in high-energy photon-beam dosimetry. Boron nitride exists in various crystalline forms. Hexagonal boron nitride (h-BN) possesses high mobility of the electrons and holes as well as a high volume resistivity, so that ionizing radiation in the clinical range of the dose rate can be expected to produce a measurable electrical current at low background current. Due to the low atomic numbers of its constituents, its density (2.0 g cm-3) similar to silicon and its commercial availability, h-BN appears as possibly suitable for the dosimetry of ionizing radiation. Five h-BN plates were contacted to triaxial cables, and the detector current was measured in a solid-state ionization chamber circuit at an applied voltage of 50 V. Basic dosimetric properties such as formation by pre-irradiation, sensitivity, reproducibility, linearity and temporal resolution were measured with 6 MV photon irradiation. Depth dose curves at quadratic field sizes of 10 cm and 40 cm were measured and compared to ionization chamber measurements. After a pre-irradiation with 6 Gy, the devices show a stable current signal at a given dose rate. The current-voltage characteristic up to 400 V shows an increase in the collection efficiency with the voltage. The time-resolved detector current behavior during beam interrupts is comparable to diamond material, and the background current is negligible. The measured percentage depth dose curves at 10 cm  ×  10 cm field size agreed with the results of ionization chamber measurements within  ±2%. This is a first study of boron nitride as a detector material for high-energy photon radiation. By current measurements on solid ionization chambers made from boron nitride chips we could demonstrate that boron nitride is in principle suitable as a detector material for high-energy photon-beam dosimetry.

Neutron and gamma detector using an ionization chamber with an integrated body and moderator

DOEpatents

Ianakiev, Kiril D.; Swinhoe, Martyn T.; Lestone, John Paul

2006-07-18

A detector for detecting neutrons and gamma radiation includes a cathode that defines an interior surface and an interior volume. A conductive neutron-capturing layer is disposed on the interior surface of the cathode and a plastic housing surrounds the cathode. A plastic lid is attached to the housing and encloses the interior volume of the cathode forming an ionization chamber, into the center of which an anode extends from the plastic lid. A working gas is disposed within the ionization chamber and a high biasing voltage is connected to the cathode. Processing electronics are coupled to the anode and process current pulses which are converted into Gaussian pulses, which are either counted as neutrons or integrated as gammas, in response to whether pulse amplitude crosses a neutron threshold. The detector according to the invention may be readily fabricated into single or multilayer detector arrays.

Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301.

PubMed

Mathur; Green; Arav; Brotherton; Crenshaw; deKool; Elvis; Goodrich; Hamann; Hines; Kashyap; Korista; Peterson; Shields; Shlosman; van Breugel W; Voit

2000-04-20

We present a deep ASCA observation of a broad absorption line quasar (BALQSO) PG 0946+301. The source was clearly detected in one of the gas imaging spectrometers, but not in any other detector. If BALQSOs have intrinsic X-ray spectra similar to normal radio-quiet quasars, our observations imply that there is Thomson thick X-ray absorption (NH greater, similar1024 cm-2) toward PG 0946+301. This is the largest column density estimated so far toward a BALQSO. The absorber must be at least partially ionized and may be responsible for attenuation in the optical and UV. If the Thomson optical depth toward BALQSOs is close to 1, as inferred here, then spectroscopy in hard X-rays with large telescopes like XMM would be feasible.

Surface Contamination by Radon Daughters Measured by Ionization-Heat NTD Germanium Detectors

NASA Astrophysics Data System (ADS)

Navick, X.-F.

2008-05-01

The discrimination power of the NTD ionization-heat detectors to distinguish nuclear recoils from electron recoils is affected by events interpreted as surface events. On the basis of the data from EDELWEISS I and first data taking of EDELWEISS-2, we present a coherent interpretation and direct evidence that surface events occur and are due to radon daughter deposition on detector surface and close-by surfaces. The estimation of the surface activities of contaminated surface are extracted from the new data taking.

High efficiency photoionization detector

DOEpatents

Anderson, D.F.

1984-01-31

A high efficiency photoionization detector is described using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36 [+-] 0.02 eV, and a vapor pressure of 0.35 torr at 20 C. 6 figs.

Method for detection of dental caries and periodontal disease using optical imaging

DOEpatents

Nathel, H.; Kinney, J.H.; Otis, L.L.

1996-10-29

A method is disclosed for detecting the presence of active and inactive caries in teeth and diagnosing periodontal disease uses non-ionizing radiation with techniques for reducing interference from scattered light. A beam of non-ionizing radiation is divided into sample and reference beams. The region to be examined is illuminated by the sample beam, and reflected or transmitted radiation from the sample is recombined with the reference beam to form an interference pattern on a detector. The length of the reference beam path is adjustable, allowing the operator to select the reflected or transmitted sample photons that recombine with the reference photons. Thus radiation scattered by the dental or periodontal tissue can be prevented from obscuring the interference pattern. A series of interference patterns may be generated and interpreted to locate dental caries and periodontal tissue interfaces. 7 figs.

Terrestrial gamma-ray flashes monitor demonstrator on CubeSat

NASA Astrophysics Data System (ADS)

Dániel, V.; Pína, L.; Inneman, A.; Zadražil, V.; Báča, T.; Platkevič, M.; Stehlíková, V.; Nentvich, O.; Urban, M.

2016-09-01

The CubeSat mission with the demonstrator of miniaturized X-ray telescope is presented. The paper presents one of the mission objectives of using the instrument for remote sensing of the Terrestrial Gamma-ray Flashes (TGFs). TGFs are intense sources of gamma-rays associated with lightning bolt activity and tropical thunderstorms. The measurement of TGFs exists and was measured by sounding rockets, high altitude balloons or several satellite missions. Past satellite missions were equipped with different detectors working from 10 keV up to 10 MeV. The RHESSI mission spectrum measurement of TGFs shows the maximum counts per second around 75 keV. The used detectors were in general big in volume and cannot be utilized by the CubeSat mission. The presented CubeSat is equipped with miniaturized X-ray telescope using the Timepix non-cooled pixel detector. The detector works between 3 and 60 keV in counting mode (dosimetry) or in spectrum mode with resolution 5 keV. The wide-field X-ray "Lobster-eye" optics/collimator (depending on energy) is used with a view angle of 3 degrees for the source location definition. The UV detectors with FOV 30 degrees and 1.5 degrees are added parallel with the optic as a part of the telescope. The telescope is equipped with software distinguishing between the photons and other particles. Using this software the TGF's detection is possible also in the field of South Atlantic anomaly. For the total ionization dose, the additional detector is used based on Silicone (12-60 keV) and CdTe (20 keV - 1 MeV). The presented instruments are the demonstrators suitable also for the astrophysical, sun and moon observation. The paper shows the details of TGF's observation modes, detectors details, data processing and handling system and mission. The CubeSat launch is planned to summer 2016.

Bone optical spectroscopy for the measurement of hemoglobin content

NASA Astrophysics Data System (ADS)

Hollmann, Joseph L.; Arambel, Paula; Piet, Judith; Shefelbine, Sandra; Markovic, Stacey; Niedre, Mark; DiMarzio, Charles A.

2014-05-01

Osteoporosis is a common side effect of spinal cord injuries. Blood perfusion in the bone provides an indication of bone health and may help to evaluate therapies addressing bone loss. Current methods for measuring blood perfusion of bone use dyes and ionizing radiation, and yield qualitative results. We present a device capable of measuring blood oxygenation in the tibia. The device illuminates the skin directly over the tibia with a white light source and measures the diffusely reflected light in the near infrared spectrum. Multiple source-detector distances are utilized so that the blood perfusion in skin and bone may be differentiated.

The Scintillating Optical Fiber Calorimeter Instrument Performance (SOFCAL)

NASA Technical Reports Server (NTRS)

Christl, M. J.; Benson, C. M.; Berry, F. A.; Fountain, W. F.; Gregory, J. C.; Johnson, J. S.; Munroe, R. B.; Parnell, T. A.; Takahashi, Y.; Watts, J. W.

1999-01-01

SOFCAL is a balloon-borne instrument designed to measure the P-He cosmic ray spectra from about 200 GeV/amu - 20 TeV/amu. SOFCAL uses a thin lead and scintillating-fiber ionization calorimeter to measure the cascades produced by cosmic rays interacting in the hybrid detector system. Above the fiber calorimeter is an emulsion chamber that provides the interaction target, primary particle identification and in-flight energy calibration for the scintillating fiber data. The energy measurement technique and its calibration are described, and the present results from the analysis of a 1 day balloon flight will be presented.

Ionizing radiation measurements using low cost instruments for teaching in college or high-school in Brazil

NASA Astrophysics Data System (ADS)

Silva, M. C.; Vilela, D. C.; Migoto, V. G.; Gomes, M. P.; Martin, I. M.; Germano, J. S. E.

2017-11-01

Ionizing radiation one of modern physics experimental teaching in colleges and high school can be easily implemented today due to low coasts of detectors and also electronic circuits and data acquisition interfaces. First it is interesting to show to young’s students what is ionizing radiation and from where they appears near ground level? How it is possible to measure these radiations and how to check intensities variation during day, night, dry and wet periods in the same school? For increasing interest and stimulation in others students how to proceed in making the graphics of the ionizing radiation and presenting him in real time using Web internet facilities? Many others facilities like calibration of the detector using low intensities radioactive ionizing radiation sources, make comparison of the measurements and discussions of the results should be possible between many groups of students from several schools in the region of Brazil. This paper presents the experimental procedures including detectors and associated electronic including data acquisition, graphics elaboration and Web internet procedures to discuss and exchanging data measurements from several schools.

Lipid analysis via HPLC with a charged aerosol detector

USDA-ARS?s Scientific Manuscript database

Most lipid extracts are a mixture of saturated and unsaturated molecules. Therefore, the most successful HPLC detectors for the quantitative analysis of lipids have involved the use of “universal” or “mass” detectors such as flame ionization detectors (FID) and evaporative light scattering detectors...

49 CFR 173.310 - Exceptions for radiation detectors.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 2 2012-10-01 2012-10-01 false Exceptions for radiation detectors. 173.310... for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are excepted...

49 CFR 173.310 - Exceptions for radiation detectors.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 2 2013-10-01 2013-10-01 false Exceptions for radiation detectors. 173.310... for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are excepted...

49 CFR 173.310 - Exceptions for radiation detectors.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 2 2014-10-01 2014-10-01 false Exceptions for radiation detectors. 173.310... for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are excepted...

A comparison of flame ionization and ozone chemiluminescence for the determination of atmospheric hydrocarbons.

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

Marley, N. A.; Gaffney, J. S.; Environmental Research

A reactive hydrocarbon analyzer has been constructed on the basis of chemiluminescence reaction with ozone. This detector is designed to operate at varying temperatures which take advantage of the different rates of reaction of the hydrocarbon classes with ozone to yield a measure of their atmospheric reactivity. When operated at high temperatures (170 C), all hydrocarbons will give a chemiluminescence signal. Reported here is a direct comparison of the ozone chemiluminescent detector (operated at a temperature of 170 C) with a flame ionization detector. This comparison was accomplished by connecting a capillary gas chromatograph to each of the two detectorsmore » by means of a switching valve. Twenty-seven compounds representing alkanes, alkenes, aromatics, and oxygenated hydrocarbons (aldehydes, ketones, alcohols, and ethers) were studied. For the compounds studied, analytical sensitivities were 10-1000 times better for the chemiluminescence detector. The results of this comparison indicate that the response of the chemiluminescent detector at 170 C correlates with a total carbon detector (flame ionization detection) and that total response is a measure of total carbon in the sample. The chemiluminescent system will be very useful for gas chromatographic detection of atmospheric hydrocarbons, particularly of oxygenates in complex mixtures.« less

CMOS sensor as charged particles and ionizing radiation detector

NASA Astrophysics Data System (ADS)

Cruz-Zaragoza, E.; Piña López, I.

2015-01-01

This paper reports results of CMOS sensor suitable for use as charged particles and ionizing radiation detector. The CMOS sensor with 640 × 480 pixels area has been integrated into an electronic circuit for detection of ionizing radiation and it was exposed to alpha particle (Am-241, Unat), beta (Sr-90), and gamma photons (Cs-137). Results show after long period of time (168 h) irradiation the sensor had not loss of functionality and also the energy of the charge particles and photons were very well obtained.

Detection of positive and negative ions from a flowing atmospheric pressure afterglow using a Mattauch-Herzog mass spectrograph equipped with a Faraday-strip array detector.

PubMed

Schilling, Gregory D; Shelley, Jacob T; Barnes, James H; Sperline, Roger P; Denton, M Bonner; Barinaga, Charles J; Koppenaal, David W; Hieftje, Gary M

2010-01-01

An ambient desorption/ionization (ADI) source, known as the flowing atmospheric pressure afterglow (FAPA), has been coupled to a Mattauch-Herzog mass spectrograph (MHMS) equipped with a focal plane camera (FPC) array detector. The FAPA ionization source enables direct mass spectral analysis of solids, liquids, and gases through either positive or negative ionization modes. In either case, spectra are generally simple with dominant peaks being the molecular ions or protonated molecular ions. Use of the FAPA source with the MHMS allows the FPC detector to be characterized for the determination of molecular species, whereas previously only atomic mass spectrometry (MS) has been demonstrated. Furthermore, the FPC is shown to be sensitive to negative ions without the need to change any detector parameters. The analysis of solid, liquid, and gaseous samples through positive and negative ionization is demonstrated with detection limits (1-25 fmol/s, approximately 0.3-10 pg of analyte per mL of helium) surpassing those obtained with the FAPA source coupled to a time-of-flight mass analyzer. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

Detector to detector corrections: a comprehensive experimental study of detector specific correction factors for beam output measurements for small radiotherapy beams.

PubMed

Azangwe, Godfrey; Grochowska, Paulina; Georg, Dietmar; Izewska, Joanna; Hopfgartner, Johannes; Lechner, Wolfgang; Andersen, Claus E; Beierholm, Anders R; Helt-Hansen, Jakob; Mizuno, Hideyuki; Fukumura, Akifumi; Yajima, Kaori; Gouldstone, Clare; Sharpe, Peter; Meghzifene, Ahmed; Palmans, Hugo

2014-07-01

The aim of the present study is to provide a comprehensive set of detector specific correction factors for beam output measurements for small beams, for a wide range of real time and passive detectors. The detector specific correction factors determined in this study may be potentially useful as a reference data set for small beam dosimetry measurements. Dose response of passive and real time detectors was investigated for small field sizes shaped with a micromultileaf collimator ranging from 0.6 × 0.6 cm(2) to 4.2 × 4.2 cm(2) and the measurements were extended to larger fields of up to 10 × 10 cm(2). Measurements were performed at 5 cm depth, in a 6 MV photon beam. Detectors used included alanine, thermoluminescent dosimeters (TLDs), stereotactic diode, electron diode, photon diode, radiophotoluminescent dosimeters (RPLDs), radioluminescence detector based on carbon-doped aluminium oxide (Al2O3:C), organic plastic scintillators, diamond detectors, liquid filled ion chamber, and a range of small volume air filled ionization chambers (volumes ranging from 0.002 cm(3) to 0.3 cm(3)). All detector measurements were corrected for volume averaging effect and compared with dose ratios determined from alanine to derive a detector correction factors that account for beam perturbation related to nonwater equivalence of the detector materials. For the detectors used in this study, volume averaging corrections ranged from unity for the smallest detectors such as the diodes, 1.148 for the 0.14 cm(3) air filled ionization chamber and were as high as 1.924 for the 0.3 cm(3) ionization chamber. After applying volume averaging corrections, the detector readings were consistent among themselves and with alanine measurements for several small detectors but they differed for larger detectors, in particular for some small ionization chambers with volumes larger than 0.1 cm(3). The results demonstrate how important it is for the appropriate corrections to be applied to give consistent and accurate measurements for a range of detectors in small beam geometry. The results further demonstrate that depending on the choice of detectors, there is a potential for large errors when effects such as volume averaging, perturbation and differences in material properties of detectors are not taken into account. As the commissioning of small fields for clinical treatment has to rely on accurate dose measurements, the authors recommend the use of detectors that require relatively little correction, such as unshielded diodes, diamond detectors or microchambers, and solid state detectors such as alanine, TLD, Al2O3:C, or scintillators.

Optical Imaging of Ionizing Radiation from Clinical Sources

PubMed Central

Shaffer, Travis M.; Drain, Charles Michael

2016-01-01

Nuclear medicine uses ionizing radiation for both in vivo diagnosis and therapy. Ionizing radiation comes from a variety of sources, including x-rays, beam therapy, brachytherapy, and various injected radionuclides. Although PET and SPECT remain clinical mainstays, optical readouts of ionizing radiation offer numerous benefits and complement these standard techniques. Furthermore, for ionizing radiation sources that cannot be imaged using these standard techniques, optical imaging offers a unique imaging alternative. This article reviews optical imaging of both radionuclide- and beam-based ionizing radiation from high-energy photons and charged particles through mechanisms including radioluminescence, Cerenkov luminescence, and scintillation. Therapeutically, these visible photons have been combined with photodynamic therapeutic agents preclinically for increasing therapeutic response at depths difficult to reach with external light sources. Last, new microscopy methods that allow single-cell optical imaging of radionuclides are reviewed. PMID:27688469

Gas electron multiplier (GEM) enhanced ionization chamber for fluorescence detector

NASA Astrophysics Data System (ADS)

Shaban, E. H.; Siddons, D. P.; Kuczewski, A.

2007-11-01

Detecting dilute elements in thin materials using extended X-ray absorption fluorescence spectroscopy (EXAFS) method requires a detector capable of high count rate and low noise. For detection of dilute elements, the fluorescence signal amplitude is often overcome by the presence of noise or background interference. In this paper we have used a gas ionization chamber enhanced by a gas electron multiplier (GEM) to amplify the primary ionized electrons due to the X-ray fluorescence of a dilute element. The GEM provides an essentially noise free electron amplification of the signal primary photoelectrons. It provides a larger output current prior to the electronic amplification, allowing a lower gain amplifier with lower electronic circuit noise contribution and hence improved S/ N ratio. In addition, since the signal is produced only by electrons, and not from ion motion, the detector is capable of recording rapidly changing signals. Iron in an arbitrary tree leaf was used as a test sample. This sample was measured using our detector SUBRSAB, and also with Lytle and passivated implanted planar silicon (PIPS) detectors. An improvement in the signal amplitude by a factor of 20 and a factor of 2 are recorded for the proposed detector with respect to the Lytle and PIPS detectors, respectively. Although the gain in signal over the PIPS detector is small for this detector, its lack of sensitivity to light and its low and temperature-independent dark current are further advantages.

40 CFR 91.4 - Acronyms and abbreviations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon monoxide CO2—Carbon...—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—Independent... OEM—Original engine manufacturer PMD—paramagnetic detector PWC—personal watercraft RPM—revolutions per...

40 CFR 91.4 - Acronyms and abbreviations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon monoxide CO2—Carbon...—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—Independent... OEM—Original engine manufacturer PMD—paramagnetic detector PWC—personal watercraft RPM—revolutions per...

40 CFR 91.4 - Acronyms and abbreviations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon monoxide CO2—Carbon...—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—Independent... OEM—Original engine manufacturer PMD—paramagnetic detector PWC—personal watercraft RPM—revolutions per...

40 CFR 91.4 - Acronyms and abbreviations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon monoxide CO2—Carbon...—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—Independent... OEM—Original engine manufacturer PMD—paramagnetic detector PWC—personal watercraft RPM—revolutions per...

40 CFR 91.4 - Acronyms and abbreviations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon monoxide CO2—Carbon...—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—Independent... OEM—Original engine manufacturer PMD—paramagnetic detector PWC—personal watercraft RPM—revolutions per...

Semiconductor radiation detector

DOEpatents

Bell, Zane W.; Burger, Arnold

2010-03-30

A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

High resolution mass spectrometry method and system for analysis of whole proteins and other large molecules

DOEpatents

Reilly, Peter T. A. [Knoxville, TN; Harris, William A [Naperville, IL

2010-03-02

A matrix assisted laser desorption/ionization (MALDI) method and related system for analyzing high molecular weight analytes includes the steps of providing at least one matrix-containing particle inside an ion trap, wherein at least one high molecular weight analyte molecule is provided within the matrix-containing particle, and MALDI on the high molecular weight particle while within the ion trap. A laser power used for ionization is sufficient to completely vaporize the particle and form at least one high molecular weight analyte ion, but is low enough to avoid fragmenting the high molecular weight analyte ion. The high molecular weight analyte ion is extracted out from the ion trap, and is then analyzed using a detector. The detector is preferably a pyrolyzing and ionizing detector.

49 CFR 173.310 - Exceptions for radiation detectors.

Code of Federal Regulations, 2010 CFR

2010-10-01

...-GENERAL REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are excepted...

49 CFR 173.310 - Exceptions for radiation detectors.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-GENERAL REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are excepted...

Optical Imaging of Ionizing Radiation from Clinical Sources.

PubMed

Shaffer, Travis M; Drain, Charles Michael; Grimm, Jan

2016-11-01

Nuclear medicine uses ionizing radiation for both in vivo diagnosis and therapy. Ionizing radiation comes from a variety of sources, including x-rays, beam therapy, brachytherapy, and various injected radionuclides. Although PET and SPECT remain clinical mainstays, optical readouts of ionizing radiation offer numerous benefits and complement these standard techniques. Furthermore, for ionizing radiation sources that cannot be imaged using these standard techniques, optical imaging offers a unique imaging alternative. This article reviews optical imaging of both radionuclide- and beam-based ionizing radiation from high-energy photons and charged particles through mechanisms including radioluminescence, Cerenkov luminescence, and scintillation. Therapeutically, these visible photons have been combined with photodynamic therapeutic agents preclinically for increasing therapeutic response at depths difficult to reach with external light sources. Last, new microscopy methods that allow single-cell optical imaging of radionuclides are reviewed. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

A Laboratory Experiment To Measure Henry's Law Constants of Volatile Organic Compounds with a Bubble Column and a Gas Chromatography Flame Ionization Detector (GC-FID)

ERIC Educational Resources Information Center

Lee, Shan-Hu; Mukherjee, Souptik; Brewer, Brittany; Ryan, Raphael; Yu, Huan; Gangoda, Mahinda

2013-01-01

An undergraduate laboratory experiment is described to measure Henry's law constants of organic compounds using a bubble column and gas chromatography flame ionization detector (GC-FID). This experiment is designed for upper-division undergraduate laboratory courses and can be implemented in conjunction with physical chemistry, analytical…

Surface dose measurements with commonly used detectors: a consistent thickness correction method

PubMed Central

Higgins, Patrick

2015-01-01

The purpose of this study was to review application of a consistent correction method for the solid state detectors, such as thermoluminescent dosimeters (chips (cTLD) and powder (pTLD)), optically stimulated detectors (both closed (OSL) and open (eOSL)), and radiochromic (EBT2) and radiographic (EDR2) films. In addition, to compare measured surface dose using an extrapolation ionization chamber (PTW 30‐360) with other parallel plate chambers RMI‐449 (Attix), Capintec PS‐033, PTW 30‐329 (Markus) and Memorial. Measurements of surface dose for 6 MV photons with parallel plate chambers were used to establish a baseline. cTLD, OSLs, EDR2, and EBT2 measurements were corrected using a method which involved irradiation of three dosimeter stacks, followed by linear extrapolation of individual dosimeter measurements to zero thickness. We determined the magnitude of correction for each detector and compared our results against an alternative correction method based on effective thickness. All uncorrected surface dose measurements exhibited overresponse, compared with the extrapolation chamber data, except for the Attix chamber. The closest match was obtained with the Attix chamber (−0.1%), followed by pTLD (0.5%), Capintec (4.5%), Memorial (7.3%), Markus (10%), cTLD (11.8%), eOSL (12.8%), EBT2 (14%), EDR2 (14.8%), and OSL (26%). Application of published ionization chamber corrections brought all the parallel plate results to within 1% of the extrapolation chamber. The extrapolation method corrected all solid‐state detector results to within 2% of baseline, except the OSLs. Extrapolation of dose using a simple three‐detector stack has been demonstrated to provide thickness corrections for cTLD, eOSLs, EBT2, and EDR2 which can then be used for surface dose measurements. Standard OSLs are not recommended for surface dose measurement. The effective thickness method suffers from the subjectivity inherent in the inclusion of measured percentage depth‐dose curves and is not recommended for these types of measurements. PACS number: 87.56.‐v PMID:26699319

Fast range measurement of spot scanning proton beams using a volumetric liquid scintillator detector.

PubMed

Hui, CheukKai; Robertson, Daniel; Alsanea, Fahed; Beddar, Sam

2015-08-01

Accurate confirmation and verification of the range of spot scanning proton beams is crucial for correct dose delivery. Current methods to measure proton beam range using ionization chambers are either time-consuming or result in measurements with poor spatial resolution. The large-volume liquid scintillator detector allows real-time measurements of the entire dose profile of a spot scanning proton beam. Thus, liquid scintillator detectors are an ideal tool for measuring the proton beam range for commissioning and quality assurance. However, optical artefacts may decrease the accuracy of measuring the proton beam range within the scintillator tank. The purpose of the current study was to 1) develop a geometric calibration system to accurately calculate physical distances within the liquid scintillator detector, taking into account optical artefacts; and 2) assess the accuracy, consistency, and robustness of proton beam range measurement using the liquid scintillator detector with our geometric calibration system. The range of the proton beam was measured with the calibrated liquid scintillator system and was compared to the nominal range. Measurements were made on three different days to evaluate the setup robustness from day to day, and three sets of measurements were made for each day to evaluate the consistency from delivery to delivery. All proton beam ranges measured using the liquid scintillator system were within half a millimeter of the nominal range. The delivery-to-delivery standard deviation of the range measurement was 0.04 mm, and the day-to-day standard deviation was 0.10 mm. In addition to the accuracy and robustness demonstrated by these results when our geometric calibration system was used, the liquid scintillator system allowed the range of all 94 proton beams to be measured in just two deliveries, making the liquid scintillator detector a perfect tool for range measurement of spot scanning proton beams.

Fast range measurement of spot scanning proton beams using a volumetric liquid scintillator detector

PubMed Central

Hui, CheukKai; Robertson, Daniel; Alsanea, Fahed; Beddar, Sam

2016-01-01

Accurate confirmation and verification of the range of spot scanning proton beams is crucial for correct dose delivery. Current methods to measure proton beam range using ionization chambers are either time-consuming or result in measurements with poor spatial resolution. The large-volume liquid scintillator detector allows real-time measurements of the entire dose profile of a spot scanning proton beam. Thus, liquid scintillator detectors are an ideal tool for measuring the proton beam range for commissioning and quality assurance. However, optical artefacts may decrease the accuracy of measuring the proton beam range within the scintillator tank. The purpose of the current study was to 1) develop a geometric calibration system to accurately calculate physical distances within the liquid scintillator detector, taking into account optical artefacts; and 2) assess the accuracy, consistency, and robustness of proton beam range measurement using the liquid scintillator detector with our geometric calibration system. The range of the proton beam was measured with the calibrated liquid scintillator system and was compared to the nominal range. Measurements were made on three different days to evaluate the setup robustness from day to day, and three sets of measurements were made for each day to evaluate the consistency from delivery to delivery. All proton beam ranges measured using the liquid scintillator system were within half a millimeter of the nominal range. The delivery-to-delivery standard deviation of the range measurement was 0.04 mm, and the day-to-day standard deviation was 0.10 mm. In addition to the accuracy and robustness demonstrated by these results when our geometric calibration system was used, the liquid scintillator system allowed the range of all 94 proton beams to be measured in just two deliveries, making the liquid scintillator detector a perfect tool for range measurement of spot scanning proton beams. PMID:27274863

Proton and Electron Threshold Energy Measurements for Extravehicular Activity Space Suits. Chapter 2

NASA Technical Reports Server (NTRS)

Moyers, M. F.; Nelson, G. D.; Saganti, P. B.

2003-01-01

Construction of ISS will require more than 1000 hours of EVA. Outside of ISS during EVA, astronauts and cosmonauts are likely to be exposed to a large fluence of electrons and protons. Development of radiation protection guidelines requires the determination of the minimum energy of electrons and protons that penetrate the suits at various locations. Measurements of the water-equivalent thickness of both US. and Russian EVA suits were obtained by performing CT scans. Specific regions of interest of the suits were further evaluated using a differential range shift technique. This technique involved measuring thickness ionization curves for 6-MeV electron and 155-MeV proton beams with ionization chambers using a constant source-to-detector distance. The thicknesses were obtained by stacking polystyrene slabs immediately upstream of the detector. The thicknesses of the 50% ionizations relative to the maximum ionizations were determined. The detectors were then placed within the suit and the stack thickness adjusted until the 50% ionization was reestablished. The difference in thickness between the 50% thicknesses was then used with standard range-energy tables to determine the threshold energy for penetration. This report provides a detailed description of the experimental arrangement and results.

Comparison of depth-dose distributions of proton therapeutic beams calculated by means of logical detectors and ionization chamber modeled in Monte Carlo codes

NASA Astrophysics Data System (ADS)

Pietrzak, Robert; Konefał, Adam; Sokół, Maria; Orlef, Andrzej

2016-08-01

The success of proton therapy depends strongly on the precision of treatment planning. Dose distribution in biological tissue may be obtained from Monte Carlo simulations using various scientific codes making it possible to perform very accurate calculations. However, there are many factors affecting the accuracy of modeling. One of them is a structure of objects called bins registering a dose. In this work the influence of bin structure on the dose distributions was examined. The MCNPX code calculations of Bragg curve for the 60 MeV proton beam were done in two ways: using simple logical detectors being the volumes determined in water, and using a precise model of ionization chamber used in clinical dosimetry. The results of the simulations were verified experimentally in the water phantom with Marcus ionization chamber. The average local dose difference between the measured relative doses in the water phantom and those calculated by means of the logical detectors was 1.4% at first 25 mm, whereas in the full depth range this difference was 1.6% for the maximum uncertainty in the calculations less than 2.4% and for the maximum measuring error of 1%. In case of the relative doses calculated with the use of the ionization chamber model this average difference was somewhat greater, being 2.3% at depths up to 25 mm and 2.4% in the full range of depths for the maximum uncertainty in the calculations of 3%. In the dose calculations the ionization chamber model does not offer any additional advantages over the logical detectors. The results provided by both models are similar and in good agreement with the measurements, however, the logical detector approach is a more time-effective method.

A review of advances in pixel detectors for experiments with high rate and radiation

NASA Astrophysics Data System (ADS)

Garcia-Sciveres, Maurice; Wermes, Norbert

2018-06-01

The large Hadron collider (LHC) experiments ATLAS and CMS have established hybrid pixel detectors as the instrument of choice for particle tracking and vertexing in high rate and radiation environments, as they operate close to the LHC interaction points. With the high luminosity-LHC upgrade now in sight, for which the tracking detectors will be completely replaced, new generations of pixel detectors are being devised. They have to address enormous challenges in terms of data throughput and radiation levels, ionizing and non-ionizing, that harm the sensing and readout parts of pixel detectors alike. Advances in microelectronics and microprocessing technologies now enable large scale detector designs with unprecedented performance in measurement precision (space and time), radiation hard sensors and readout chips, hybridization techniques, lightweight supports, and fully monolithic approaches to meet these challenges. This paper reviews the world-wide effort on these developments.

Fabrication and characterization of a 3D Positive ion detector and its applications

NASA Astrophysics Data System (ADS)

Venkatraman, Pitchaikannu; Sureka, Chandrasekaran Senbagavadivoo

2017-11-01

There is a growing interest to experimentally evaluate the track structure induced by ionizing particles in order to characterize the radiobiological quality of ionizing radiation for applications in radiotherapy and radiation protection. To do so, a novel positive ion detector based on the multilayer printed circuit board (PCB) technology has been proposed previously, which works under the principle of ion induced impact ionization. Based on this, an upgraded 3D positive ion detector was fabricated in order to improve its efficiency and use it for various applications. To improve the efficiency of the detector, cathodes with different insulators (Bakelite plate and Steatite Ceramics) and conducting layers (ITO, FTO, and Gold coated cathode) were studied under various gaseous media (methane, nitrogen, and air) using Am-241, Co-60, Co-57, Na-22, Cs-137, and Ba-133 sources. From this study, it is confirmed that the novel 3D positive ion detector that has been upgraded using gold as strip material, tungsten (87%) coated copper (13%) as the core wire, gold coated ceramic as cathode, and thickness of 3.483 mm showed 9.2% efficiency under methane medium at 0.9 Torr pressure using an Am-241 source. It is also confirmed that when the conductivity of the cathode and thickness of the detector is increased, the performance of the detector is improved significantly. Further, the scope of the detector to use in the field of radiation protection, radiation dosimetry, gamma spectrometry, radiation biology, and oncology are reported here.

Improved Apparatus to Study Matter-Wave Quantum Optics in a Sodium Spinor Bose-Einstein Condensate

NASA Astrophysics Data System (ADS)

Zhong, Shan; Bhagat, Anita; Zhang, Qimin; Schwettmann, Arne

2017-04-01

We present and characterize our recently improved experimental apparatus for studying matter-wave quantum optics in spin space in ultracold sodium gases. Improvements include our recent addition of a 3D-printed Helmholtz coil frame for field stabilization and a crossed optical dipole trap. Spin-exchange collisions in the F = 1 spinor Bose-Einstein condensate can be precisely controlled by microwave dressing, and generate pairs of entangled atoms with magnetic quantum numbers mF = + 1 and mF = - 1 from pairs of mF = 0 atoms. Spin squeezing generated by the collisions can reduce the noise of population measurements below the shot noise limit. Versatile microwave pulse sequences will be used to implement an interferometer, a phase-sensitive amplifier and other devices with sub-shot noise performance. With an added ion detector to detect Rydberg atoms via pulse-field ionization, we later plan to study the effect of Rydberg excitations on the spin evolution of the ultracold gas.

Amorphous and crystalline optical materials used as instruments for high gamma radiation doses estimations

NASA Astrophysics Data System (ADS)

Ioan, M.-R.

2016-06-01

Nuclear radiation induce some changes to the structure of exposed materials. The main effect of ionizing radiation when interacting with optical materials is the occurrence of color centers, which are quantitatively proportional to the up-taken doses. In this paper, a relation between browning effect magnitude and dose values was found. Using this relation, the estimation of a gamma radiation dose can be done. By using two types of laser wavelengths (532 nm and 633 nm), the optical powers transmitted thru glass samples irradiated to different doses between 0 and 59.1 kGy, were measured and the associated optical browning densities were determined. The use of laser light gives the opportunity of using its particularities: monochromaticity, directionality and coherence. Polarized light was also used for enhancing measurements quality. These preliminary results bring the opportunity of using glasses as detectors for the estimation of the dose in a certain point in space and for certain energy, especially in particles accelerators experiments, where the occurred nuclear reactions are involving the presence of high gamma rays fields.

Laser interlock system

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

Woodruff, Steven D; Mcintyre, Dustin L

2015-01-13

A method and device for providing a laser interlock having a first optical source, a first beam splitter, a second optical source, a detector, an interlock control system, and a means for producing dangerous optical energy. The first beam splitter is optically connected to the first optical source, the first detector and the second optical source. The detector is connected to the interlock control system. The interlock control system is connected to the means for producing dangerous optical energy and configured to terminate its optical energy production upon the detection of optical energy at the detector from the second opticalmore » source below a predetermined detector threshold. The second optical source produces an optical energy in response to optical energy from the first optical source. The optical energy from the second optical source has a different wavelength, polarization, modulation or combination thereof from the optical energy of the first optical source.« less

Multi-channel infrared thermometer

DOEpatents

Ulrickson, M.A.

A device for measuring the two-dimensional temperature profile of a surface comprises imaging optics for generating an image of the light radiating from the surface; an infrared detector array having a plurality of detectors; and optical means positioned between the imaging optics and the detector array for sampling, transmitting, and distributing the image over the detector surfaces. The optical means may be a light pipe array having one light pipe for each detector in the detector array.

Results from prototypes of environmental and health alarm devices based on gaseous detectors operating in air in counting mode

NASA Astrophysics Data System (ADS)

Charpak, G.; Benaben, P.; Breuil, P.; Martinengo, P.; Nappi, E.; Peskov, V.

2011-02-01

We have developed and successfully tested two prototypes of detectors of dangerous gases based on wire-type counters operating in air in avalanche mode: one is for radon (Rn) detection whereas the other one is for the detection of gases with an ionization potential less than the air components. Due to the operation in pulse counting mode these prototypes have sensitivities comparable to (in the case of the Rn detector) or much higher than (in the case of the detector for low ionization gases) the best commercial devices currently available on the market. We believe that due to their high sensitivity, simplicity and low cost such new detectors will find massive applications. One of them, discussed in this paper, could be the on-line monitoring of Rn for the prediction of earthquakes.

Development of 100 g Si and 250 g Ge detectors for a dark matter search

NASA Astrophysics Data System (ADS)

Brink, P. L.; Cabrera, B.; Chugg, B.; Clarke, R. M.; Davies, A.; Nam, S. W.; Young, B. A.

1996-05-01

Over the last two years we have proposed and implemented a new phonon sensing scheme for Cryogenic elementary particle detectors based upon Transition Edge Sensors (TES) operated in the (negative) Electrothermal-feedback (ETF) mode, and utilizing large Al collection pads for the initial phonon absorption. We have also implemented an ionization electrode, in addition to the phonon sensors, to allow the simultaneous measurement of ionization and phonon signals in Si and Ge absorbers. Our progress to date include successfully discriminating between electron and nuclear recoils down to a threshold of 4 keV recoil energy for a 4 g Si detector. Our first 100 g Si detectors have been fabricated, and initial work on Ge detectors indicates that our phonon sensing scheme will also work on large mass Ge absorbers.

Design for gas chromatography-corona discharge-ion mobility spectrometry.

PubMed

Jafari, Mohammad T; Saraji, Mohammad; Sherafatmand, Hossein

2012-11-20

A corona discharge ionization-ion mobility spectrometry (CD-IMS) with a novel sample inlet system was designed and constructed as a detector for capillary gas chromatography. In this design, a hollow needle was used instead of a solid needle which is commonly used for corona discharge creation, helping us to have direct axial interfacing for GC-IMS. The capillary column was passed through the needle, resulting in a reaction of effluents with reactant ions on the upstream side of the corona discharge ionization source. Using this sample introduction design, higher ionization efficiency was achieved relative to the entrance direction through the side of the drift tube. In addition, the volume of the ionization region was reduced to minimize the resistance time of compounds in the ionization source, increasing chromatographic resolution of the instrument. The effects of various parameters such as drift gas flow, makeup gas flow, and column tip position inside the needle were investigated. The designed instrument was exhaustively validated in terms of sensitivity, resolution, and reproducibility by analyzing the standard solutions of methyl isobutyl ketone, heptanone, nonanone, and acetophenone as the test compounds. The results obtained by CD-IMS detector were compared with those of the flame ionization detector, which revealed the capability of the proposed GC-IMS for two-dimensional separation (based on the retention time and drift time information) and identification of an analyte in complex matrixes.

Solid xenon radiation detectors

NASA Astrophysics Data System (ADS)

Dolinski, Michelle J.

2014-03-01

Cryogenic liquid xenon detectors have become a popular technology in the search for rare events, such as dark matter interactions and neutrinoless double beta decay. The power of the liquid xenon detector technology is in the combination of the ionization and scintillation signals, resulting in particle discrimination and improved energy resolution over the ionization-only signal. The improved energy resolution results from a unique anti-correlation phenomenon that has not been described from first principles. Solid xenon bolometers, under development at Drexel University, are expected to have excellent counting statistics in the phonon channel, with energy resolution of 0.1% or better. This additional energy channel may offer the final piece of the puzzle in understanding liquid xenon detector energy response. Supported by a grant from the Charles E. Kaufman Foundation.

Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry.

PubMed

Di Venanzio, C; Marinelli, Marco; Milani, E; Prestopino, G; Verona, C; Verona-Rinati, G; Falco, M D; Bagalà, P; Santoni, R; Pimpinella, M

2013-02-01

To investigate the dosimetric properties of synthetic single crystal diamond based Schottky diodes under irradiation with therapeutic electron beams from linear accelerators. A single crystal diamond detector was fabricated and tested under 6, 8, 10, 12, and 15 MeV electron beams. The detector performances were evaluated using three types of commercial detectors as reference dosimeters: an Advanced Markus plane parallel ionization chamber, a Semiflex cylindrical ionization chamber, and a p-type silicon detector. Preirradiation, linearity with dose, dose rate dependence, output factors, lateral field profiles, and percentage depth dose profiles were investigated and discussed. During preirradiation the diamond detector signal shows a weak decrease within 0.7% with respect to the plateau value and a final signal stability of 0.1% (1σ) is observed after about 5 Gy. A good linear behavior of the detector response as a function of the delivered dose is observed with deviations below ±0.3% in the dose range from 0.02 to 10 Gy. In addition, the detector response is dose rate independent, with deviations below 0.3% in the investigated dose rate range from 0.17 to 5.45 Gy∕min. Percentage depth dose curves obtained from the diamond detector are in good agreement with the ones from the reference dosimeters. Lateral beam profile measurements show an overall good agreement among detectors, taking into account their respective geometrical features. The spatial resolution of solid state detectors is confirmed to be better than that of ionization chambers, being the one from the diamond detector comparable to that of the silicon diode. A good agreement within experimental uncertainties was also found in terms of output factor measurements between the diamond detector and reference dosimeters. The observed dosimetric properties indicate that the tested diamond detector is a suitable candidate for clinical electron beam dosimetry.

Ionization-chamber smoke detector system

DOEpatents

Roe, Robert F.

1976-10-19

This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system is designed to reduce false alarms caused by fluctuations in ambient temperature. Means are provided for periodically firing the gas discharge triode and each time recording the triggering voltage required. A computer compares each triggering voltage with its predecessor. The computer is programmed to energize an alarm if the difference between the two compared voltages is a relatively large value indicative of particulates in the measuring chamber and to disregard smaller differences typically resulting from changes in ambient temperature.

133 Ba+: a new ion qubit

NASA Astrophysics Data System (ADS)

Christensen, Justin; Hucul, David; Campbell, Wesley; Hudson, Eric

2017-04-01

133 Ba+ combines many of the advantages of commonly used trapped ion qubits. 133Ba+ has a nuclear spin 1/2, allowing for a robust hyperfine qubit with simple state preparation and readout. The existence of long-lived metastable D-states and a lack of low-lying F-states simplifies shelving, which will allow high fidelity state detection. The visible wavelength optical transitions enable the use of high-power lasers, low-loss fibers, high quantum efficiency detectors, and other optical technologies developed for visible wavelength light. Furthermore, background-free qubit readout, where the readout is insensitive to laser scatter, is possible in 133Ba+, and simplifies its use in small ion traps and the study of ions near surfaces. We report progress on realizing this qubit. We load barium ions into an ion trap using thermal ionization from a platinum ribbon. We experimentally demonstrate the isotopic purification of large numbers of barium ions using laser heating and cooling along with mass filtering to produce isotopically pure chains of any naturally-occurring barium isotope. This purification process has allowed us to laser cool rare, naturally-occurring barium isotopes 132Ba+and130Ba+, and we report the isotope shifts from 138Ba+ of the P1/2 to D3/2 transitions near 650 nm for the first time. In addition, we have developed an ion gun to produce high luminosity ion beams with adjustable mean kinetic energy by combining a surface ionization source and ion optics.

First Limit on the Direct Detection of Lightly Ionizing Particles for Electric Charge as Low as e / 1000 with the Majorana Demonstrator

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

Alvis, S. I.; Arnquist, I. J.; Avignone, F. T.

The Majorana Demonstrator is an ultralow-background experiment searching for neutrinoless double-beta decay in 76Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. Free, relativistic, lightly ionizing particles with an electrical charge less than e are forbidden by the standard model but predicted by some of its extensions. If such particles exist, they might be detected in the Majorana Demonstrator by searching for multiple-detector events with individual-detector energy depositions down to 1 keV. This search is background-free, and no candidatemore » events have been found in 285 days of data taking. As a result, new direct-detection limits are set for the flux of lightly ionizing particles for charges as low as e/1000.« less

First Limit on the Direct Detection of Lightly Ionizing Particles for Electric Charge as Low as e /1000 with the Majorana Demonstrator

NASA Astrophysics Data System (ADS)

Alvis, S. I.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Barton, C. J.; Bertrand, F. E.; Brudanin, V.; Busch, M.; Buuck, M.; Caldwell, T. S.; Chan, Y.-D.; Christofferson, C. D.; Chu, P.-H.; Cuesta, C.; Detwiler, J. A.; Dunagan, C.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Gilliss, T.; Giovanetti, G. K.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Haufe, C. R.; Hehn, L.; Henning, R.; Hoppe, E. W.; Howe, M. A.; Konovalov, S. I.; Kouzes, R. T.; Lopez, A. M.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Myslik, J.; O'Shaughnessy, C.; Othman, G.; Pettus, W.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Reine, A. L.; Rielage, K.; Robertson, R. G. H.; Ruof, N. W.; Shanks, B.; Shirchenko, M.; Suriano, A. M.; Tedeschi, D.; Varner, R. L.; Vasilyev, S.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C.-H.; Yumatov, V.; Zhitnikov, I.; Zhu, B. X.; Majorana Collaboration

2018-05-01

The Majorana Demonstrator is an ultralow-background experiment searching for neutrinoless double-beta decay in 76Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. Free, relativistic, lightly ionizing particles with an electrical charge less than e are forbidden by the standard model but predicted by some of its extensions. If such particles exist, they might be detected in the Majorana Demonstrator by searching for multiple-detector events with individual-detector energy depositions down to 1 keV. This search is background-free, and no candidate events have been found in 285 days of data taking. New direct-detection limits are set for the flux of lightly ionizing particles for charges as low as e /1000 .

A Low-Noise Germanium Ionization Spectrometer for Low-Background Science

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

Aalseth, Craig E.; Colaresi, Jim; Collar, Juan I.

2016-12-01

Recent progress on the development of very low energy threshold high purity germanium ionization spectrometers has produced an instrument of 1.2 kg mass and excellent noise performance. The detector was installed in a low-background cryostat intended for use in a low mass, WIMP dark matter direct detection search. The integrated detector and low background cryostat achieved noise performance of 98 eV full-width half-maximum of an input electronic pulse generator peak and gamma-ray energy resolution of 1.9 keV full-width half-maximum at the 60Co gamma-ray energy of 1332 keV. This Transaction reports the thermal characterization of the low-background cryostat, specifications of themore » newly prepared 1.2 kg p-type point contact germanium detector, and the ionization spectroscopy – energy resolution and energy threshold – performance of the integrated system.« less

Pulse-Shape Discrimination of Alpha Particles of Different Specific Energy-Loss With Parallel-Plate Avalanche Counters

NASA Astrophysics Data System (ADS)

Nakhostin, M.; Baba, M.

2014-06-01

Parallel-plate avalanche counters have long been recognized as timing detectors for heavily ionizing particles. However, these detectors suffer from a poor pulse-height resolution which limits their capability to discriminate between different ionizing particles. In this paper, a new approach for discriminating between charged particles of different specific energy-loss with avalanche counters is demonstrated. We show that the effect of the self-induced space-charge in parallel-plate avalanche counters leads to a strong correlation between the shape of output current pulses and the amount of primary ionization created by the incident charged particles. The correlation is then exploited for the discrimination of charged particles with different energy-losses in the detector. The experimental results obtained with α-particles from an 241Am α-source demonstrate a discrimination capability far beyond that achievable with the standard pulse-height discrimination method.

Status of the evidence for a magnetic monopole

NASA Technical Reports Server (NTRS)

Price, P. B.

1975-01-01

The experimental evidence supporting the detection of a moving magnetic monopole, using a balloon-borne array of track detectors, was presented. Although the results cannot be proved to have been produced by a monopole, they do not seem to have been produced by any nucleus. The very high, roughly constant ionization rate inferred from track etch rate measurements in a stack of Lexan detectors implies passage of a minimum-ionizing particle more highly charged than any known nucleus, yet the Cerenkov film detectors indicated a velocity less than about 0.68 times the speed of light and the size of the track in the nuclear emulsion indicated a velocity approximately equal to 0.5 times the speed of light. At this velocity the ionization rate of a highly electrically charged particle would have changed dramatically with pathlength unless its mass to charge ratio were far greater than that of a nucleus.

First Limit on the Direct Detection of Lightly Ionizing Particles for Electric Charge as Low as e / 1000 with the Majorana Demonstrator

DOE PAGES

Alvis, S. I.; Arnquist, I. J.; Avignone, F. T.; ...

2018-05-25

The Majorana Demonstrator is an ultralow-background experiment searching for neutrinoless double-beta decay in 76Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. Free, relativistic, lightly ionizing particles with an electrical charge less than e are forbidden by the standard model but predicted by some of its extensions. If such particles exist, they might be detected in the Majorana Demonstrator by searching for multiple-detector events with individual-detector energy depositions down to 1 keV. This search is background-free, and no candidatemore » events have been found in 285 days of data taking. As a result, new direct-detection limits are set for the flux of lightly ionizing particles for charges as low as e/1000.« less

10 CFR 32.15 - Same: Quality assurance, prohibition of transfer, and labeling.

Code of Federal Regulations, 2014 CFR

2014-01-01

.... (2) For ionization chamber smoke detectors, label or mark each detector and its point-of-sale package so that: (i) Each detector has a durable, legible, readily visible label or marking on the external surface of the detector containing: (A) The following statement: “CONTAINS RADIOACTIVE MATERIAL”; (B) The...

10 CFR 32.15 - Same: Quality assurance, prohibition of transfer, and labeling.

Code of Federal Regulations, 2010 CFR

2010-01-01

... can be identified. (2) For ionization chamber smoke detectors, label or mark each detector and its point-of-sale package so that: (i) Each detector has a durable, legible, readily visible label or marking on the external surface of the detector containing: (A) The following statement: “CONTAINS...

10 CFR 32.15 - Same: Quality assurance, prohibition of transfer, and labeling.

Code of Federal Regulations, 2012 CFR

2012-01-01

... can be identified. (2) For ionization chamber smoke detectors, label or mark each detector and its point-of-sale package so that: (i) Each detector has a durable, legible, readily visible label or marking on the external surface of the detector containing: (A) The following statement: “CONTAINS...

10 CFR 32.15 - Same: Quality assurance, prohibition of transfer, and labeling.

Code of Federal Regulations, 2011 CFR

2011-01-01

... can be identified. (2) For ionization chamber smoke detectors, label or mark each detector and its point-of-sale package so that: (i) Each detector has a durable, legible, readily visible label or marking on the external surface of the detector containing: (A) The following statement: “CONTAINS...

10 CFR 32.15 - Same: Quality assurance, prohibition of transfer, and labeling.

Code of Federal Regulations, 2013 CFR

2013-01-01

.... (2) For ionization chamber smoke detectors, label or mark each detector and its point-of-sale package so that: (i) Each detector has a durable, legible, readily visible label or marking on the external surface of the detector containing: (A) The following statement: “CONTAINS RADIOACTIVE MATERIAL”; (B) The...

Liquid-purity monitor for the LUX-ZEPLIN dark matter search

NASA Astrophysics Data System (ADS)

Manalaysay, Aaron; Lux-Zeplin Collaboration

2016-03-01

The LUX-ZEPLIN (LZ) experiment will be the first liquid-xenon (LXe) dark matter search to feature a multi-tonne fiducial target. Drawing on the lessons learned in the LUX and ZEPLIN experiments, this next step will probe dark-matter candidates with unprecedented sensitivity. As these LXe detectors have grown larger, so too has the distance over which ionization electrons (from particle interactions) must be drifted through the liquid. Because of this, even minute levels of electronegative impurities can significantly attenuate the ionization signal, and must therefore be closely monitored. I will present the concept of a liquid-purity monitor which uses new and novel techniques, including state-of-the-art UV LEDs and low-work-function materials, and will measure levels of impurities in LZ's liquid circulation line in real time. This device will provide vital supplemental data to the roughly weekly in-situ purity measurements carried out within the detector's active volume, will greatly improve the resolution of the ionization channel in this detector, and will yield instant feedback in response to changing detector conditions.

40 CFR 90.5 - Acronyms and abbreviations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Materials CAA—Clean Air Act CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon... per kilowatt hour HC—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—independent Commercial Importer NDIR—non-dispersive infrared analyzer NIST—National Institute...

40 CFR 90.5 - Acronyms and abbreviations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Materials CAA—Clean Air Act CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon... per kilowatt hour HC—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—independent Commercial Importer NDIR—non-dispersive infrared analyzer NIST—National Institute...

40 CFR 90.5 - Acronyms and abbreviations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Materials CAA—Clean Air Act CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon... per kilowatt hour HC—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—independent Commercial Importer NDIR—non-dispersive infrared analyzer NIST—National Institute...

40 CFR 90.5 - Acronyms and abbreviations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Materials CAA—Clean Air Act CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon... per kilowatt hour HC—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—independent Commercial Importer NDIR—non-dispersive infrared analyzer NIST—National Institute...

40 CFR 90.5 - Acronyms and abbreviations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Materials CAA—Clean Air Act CAAA—Clean Air Act Amendments of 1990 CLD—chemiluminescent detector CO—Carbon... per kilowatt hour HC—hydrocarbons HCLD—heated chemiluminescent detector HFID—heated flame ionization detector ICI—independent Commercial Importer NDIR—non-dispersive infrared analyzer NIST—National Institute...

A diamond detector in the dosimetry of high-energy electron and photon beams.

PubMed

Laub, W U; Kaulich, T W; Nüsslin, F

1999-09-01

A diamond detector type 60003 (PTW Freiburg) was examined for the purpose of dosimetry with 4-20 MeV electron beams and 4-25 MV photon beams. Results were compared with those obtained by using a Markus chamber for electron beams and an ionization chamber for photon beams. Dose distributions were measured in a water phantom with the detector connected to a Unidos electrometer (PTW Freiburg). After a pre-irradiation of about 5 Gy the diamond detector shows a stability in response which is better than that of an ionization chamber. The current of the diamond detector was measured under variation of photon beam dose rate between 0.1 and 7 Gy min(-1). Different FSDs were chosen. Furthermore the pulse repetition frequency and the depth of the detector were changed. The electron beam dose rate was varied between 0.23 and 4.6 Gy min(-1) by changing the pulse-repetition frequency. The response shows no energy dependence within the covered photon-beam energy range. Between 4 MeV and 18 MeV electron beam energy it shows only a small energy dependence of about 2%, as expected from theory. For smaller electron energies the response increases significantly and an influence of the contact material used for the diamond detector can be surmised. A slight sublinearity of the current and dose rate was found. Detector current and dose rate are related by the expression i alpha Ddelta, where i is the detector current, D is the dose rate and delta is a correction factor of approximately 0.963. Depth-dose curves of photon beams, measured with the diamond detector, show a slight overestimation compared with measurements with the ionization chamber. This overestimation is compensated for by the above correction term. The superior spatial resolution of the diamond detector leads to minor deviations between depth-dose curves of electron beams measured with a Markus chamber and a diamond detector.

Space Solar Patrol data and changes in weather and climate, including global warming

NASA Astrophysics Data System (ADS)

Avakyan, S. V.; Baranova, L. A.; Leonov, N. B.; Savinov, E. P.; Voronin, N. A.

2010-08-01

In this paper, the results obtained during the execution of several ISTC projects are presented. The general aim of these projects has been the study of global changes in the environment, connected with solar activity. A brief description of the optical apparatus of the Space Solar Patrol (SSP) developed and built in the framework of the ISTC projects 385, 385.2, 1523 and 2500 is given. The SSP is intended for permanent monitoring of spectra and absolute fluxes of soft x-ray and extreme ultraviolet (x-ray/EUV) radiation from the full disk of the Sun which ionizes the upper atmosphere of the Earth. Permanent solar monitoring in the main part of the ionizing radiation spectra 0.8-115 (119) nm does not exist. The apparatus of the SSP was developed in the years 1996-2005 with multiyear experience of developing such apparatus in S I Vavilov State Optical Institute. The basis of this apparatus is the use of unique detectors of ionizing radiation—open secondary electron multipliers, which are 'solar blind' to near UV, visible and IR radiation from the Sun, and new methodology of these solar spectroradiometric absolute measurements. The prospects are discussed of using the SSP data for the investigation and forecast of the influence of solar variability on the weather and climate including global warming and also on the biosphere including human beings (proposal 3878). This article was originally submitted for inclusion with the papers from the 9th International Symposium on Measurement Science and Intelligent Instruments (ISMTII-2009), published in the May 2010 issue.

Gas chromatography with simultaneous detection: Ultraviolet spectroscopy, flame ionization, and mass spectrometry.

PubMed

Gras, Ronda; Luong, Jim; Haddad, Paul R; Shellie, Robert A

2018-05-08

An effective analytical strategy was developed and implemented to exploit the synergy derived from three different detector classes for gas chromatography, namely ultraviolet spectroscopy, flame ionization, and mass spectrometry for volatile compound analysis. This strategy was achieved by successfully hyphenating a user-selectable multi-wavelength diode array detector featuring a positive temperature coefficient thermistor as an isothermal heater to a gas chromatograph. By exploiting the non-destructive nature of the diode array detector, the effluent from the detector was split to two parallel detectors; namely a quadrupole mass spectrometer and a flame ionization detector. This multi-hyphenated configuration with the use of three detectors is a powerful approach not only for selective detection enhancement but also for improvement in structural elucidation of volatile compounds where fewer fragments can be obtained or for isomeric compound analysis. With the diode array detector capable of generating high resolution gas phase spectra, the information collected provides useful confirmatory information without a total dependence on the chromatographic separation process which is based on retention time. This information-rich approach to chromatography is achieved without incurring extra analytical time, resulting in improvements in compound identification accuracy, analytical productivity, and cost. Chromatographic performance obtained from model compounds was found to be acceptable with a relative standard deviation of the retention times of less than 0.01% RSD, and a repeatability at two levels of concentration of 100 and 1000 ppm (v/v) of less than 5% (n = 10). With this configuration, correlation of data between the three detectors was simplified by having near identical retention times for the analytes studied. Copyright © 2018 Elsevier B.V. All rights reserved.

A sensitive gas chromatography detector based on atmospheric pressure chemical ionization by a dielectric barrier discharge.

PubMed

Kirk, Ansgar T; Last, Torben; Zimmermann, Stefan

2017-02-03

In this work, we present a novel concept for a gas chromatography detector utilizing an atmospheric pressure chemical ionization which is initialized by a dielectric barrier discharge. In general, such a detector can be simple and low-cost, while achieving extremely good limits of detection. However, it is non-selective apart from the use of chemical dopants. Here, a demonstrator manufactured entirely from fused silica capillaries and printed circuit boards is shown. It has a size of 75×60×25mm 3 and utilizes only 2W of power in total. Unlike other known discharge detectors, which require high-purity helium, this detector can theoretically be operated using any gas able to form stable ion species. Here, purified air is used. With this setup, limits of detection in the low parts-per-billion range have been obtained for acetone. Copyright © 2017 Elsevier B.V. All rights reserved.

Device for calibrating a radiation detector system

DOEpatents

McFee, M.C.; Kirkham, T.J.; Johnson, T.H.

1994-12-27

A device is disclosed for testing a radiation detector system that includes at least two arrays of radiation detectors that are movable with respect to each other. The device includes a ''shield plate'' or shell, and an opposing ''source plate'' containing a source of ionizing radiation. Guides are attached to the outer surface of the shell for engaging the forward ends of the detectors, thereby reproducibly positioning the detectors with respect to the source and with respect to each other, thereby ensuring that a predetermined portion of the radiation emitted by the source passes through the shell and reaches the detectors. The shell is made of an hydrogenous material having approximately the same radiological attenuation characteristics as composite human tissue. The source represents a human organ such as the lungs, heart, kidneys, liver, spleen, pancreas, thyroid, testes, prostate, or ovaries. The source includes a source of ionizing radiation having a long half-life and an activity that is within the range typically searched for in human subjects. 3 figures.

Development of 10B-Based 3He Replacement Neutron Detectors

NASA Astrophysics Data System (ADS)

King, Michael J.; Gozani, Tsahi; Hilliard, Donald B.

2011-12-01

Radiation portal monitors (RPM) are currently deployed at United States border crossings to passively inspect vehicles and persons for any emission of neutrons and/or gamma rays, which may indicate the presence of unshielded nuclear materials. The RPM module contains an organic scintillator with 3He proportional counters to detect gamma rays and thermalized neutrons, respectively. The supply of 3He is rapidly dwindling, requiring alternative detectors to provide the same function and performance. Our alternative approach is one consisting of a thinly-coated 10B flat-panel ionization chamber neutron detector that can be deployed as a direct drop-in replacement for current RPM 3He detectors. The uniqueness of our approach in providing a large-area detector is in the simplicity of construction, scalability of the unit cell detector, ease of adaptability to a variety of applications and low cost. Currently, Rapiscan Laboratories and Helicon Thin Film Systems have designed and developed an operational 100 cm2 multi-layer prototype 10BB-based ionization chamber.

Device for calibrating a radiation detector system

DOEpatents

Mc Fee, Matthew C.; Kirkham, Tim J.; Johnson, Tippi H.

1994-01-01

A device for testing a radiation detector system that includes at least two arrays of radiation detectors that are movable with respect to each other. The device includes a "shield plate" or shell, and an opposing "source plate" containing a source of ionizing radiation. Guides are attached to the outer surface of the shell for engaging the forward ends of the detectors, thereby reproducibly positioning the detectors with respect to the source and with respect to each other, thereby ensuring that a predetermined portion of the radiation emitted by the source passes through the shell and reaches the detectors. The shell is made of an hydrogenous material having approximately the same radiological attenuation characteristics as composite human tissue. The source represents a human organ such as the lungs, heart, kidneys, heart, liver, spleen, pancreas, thyroid, testes, prostate, or ovaries. The source includes a source of ionizing radiation having a long half-life and an activity that is within the range typically searched for in human subjects.

40 CFR 86.1326-90 - Calibration of other equipment.

Code of Federal Regulations, 2012 CFR

2012-07-01

... equipment requiring calibration is the gas chromatograph and flame ionization detector used in measuring methanol and the high pressure liquid chromatograph (HPLC) and ultraviolet detector for measuring...

40 CFR 86.1326-90 - Calibration of other equipment.

Code of Federal Regulations, 2011 CFR

2011-07-01

... equipment requiring calibration is the gas chromatograph and flame ionization detector used in measuring methanol and the high pressure liquid chromatograph (HPLC) and ultraviolet detector for measuring...

40 CFR 86.1326-90 - Calibration of other equipment.

Code of Federal Regulations, 2013 CFR

2013-07-01

... equipment requiring calibration is the gas chromatograph and flame ionization detector used in measuring methanol and the high pressure liquid chromatograph (HPLC) and ultraviolet detector for measuring...

40 CFR 86.1326-90 - Calibration of other equipment.

Code of Federal Regulations, 2010 CFR

2010-07-01

... equipment requiring calibration is the gas chromatograph and flame ionization detector used in measuring methanol and the high pressure liquid chromatograph (HPLC) and ultraviolet detector for measuring...

Nuclear-Recoil Energy Scale in CDMS II Silicon Dark-Matter Detectors

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

Agnese, R.; et al.

The Cryogenic Dark Matter Search (CDMS II) experiment aims to detect dark matter particles that elastically scatter from nuclei in semiconductor detectors. The resulting nuclear-recoil energy depositions are detected by ionization and phonon sensors. Neutrons produce a similar spectrum of low-energy nuclear recoils in such detectors, while most other backgrounds produce electron recoils. The absolute energy scale for nuclear recoils is necessary to interpret results correctly. The energy scale can be determined in CDMS II silicon detectors using neutrons incident from a broad-spectrummore » $$^{252}$$Cf source, taking advantage of a prominent resonance in the neutron elastic scattering cross section of silicon at a recoil (neutron) energy near 20 (182) keV. Results indicate that the phonon collection efficiency for nuclear recoils is $$4.8^{+0.7}_{-0.9}$$% lower than for electron recoils of the same energy. Comparisons of the ionization signals for nuclear recoils to those measured previously by other groups at higher electric fields indicate that the ionization collection efficiency for CDMS II silicon detectors operated at $$\\sim$$4 V/cm is consistent with 100% for nuclear recoils below 20 keV and gradually decreases for larger energies to $$\\sim$$75% at 100 keV. The impact of these measurements on previously published CDMS II silicon results is small.« less

Characterization of Advanced Avalanche Photodiodes for Water Vapor Lidar Receivers

NASA Technical Reports Server (NTRS)

Refaat, Tamer F.; Halama, Gary E.; DeYoung, Russell J.

2000-01-01

Development of advanced differential absorption lidar (DIAL) receivers is very important to increase the accuracy of atmospheric water vapor measurements. A major component of such receivers is the optical detector. In the near-infrared wavelength range avalanche photodiodes (APD's) are the best choice for higher signal-to-noise ratio, where there are many water vapor absorption lines. In this study, characterization experiments were performed to evaluate a group of silicon-based APD's. The APD's have different structures representative of different manufacturers. The experiments include setups to calibrate these devices, as well as characterization of the effects of voltage bias and temperature on the responsivity, surface scans, noise measurements, and frequency response measurements. For each experiment, the setup, procedure, data analysis, and results are given and discussed. This research was done to choose a suitable APD detector for the development of an advanced atmospheric water vapor differential absorption lidar detection system operating either at 720, 820, or 940 nm. The results point out the benefits of using the super low ionization ratio (SLIK) structure APD for its lower noise-equivalent power, which was found to be on the order of 2 to 4 fW/Hz(sup (1/2)), with an appropriate optical system and electronics. The water vapor detection systems signal-to-noise ratio will increase by a factor of 10.

Pulsed, high-current, in-line reversal electron attachment detector

NASA Technical Reports Server (NTRS)

Bernius, Mark T.; Chutjian, Ara

1989-01-01

A new, pulsed, high-current, in-line reversal electron attachment ionizer/detector is described. The ionizer is capable of delivering a beam of electrons into an electrostatic mirror field to form a planar wall of electrons having zero kinetic energy. Electron attachment to a molecular target at the reversal point produces either parent or fragment negative ions through a zero-energy (s-wave) state. The atomic or molecular ion is pulsed out of the attachment region approximately 2 microsec after the electrons are pulsed off, and focused onto the entrance plane of a quadrupole mass analyzer. The sensitivity of the apparatus is preliminarily assessed, and its higher-energy behavior with regard to molecular attachment and ionization is described.

Cosmic Radiation Detection and Observations

NASA Astrophysics Data System (ADS)

Ramirez Chavez, Juan; Troncoso, Maria

Cosmic rays consist of high-energy particles accelerated from remote supernova remnant explosions and travel vast distances throughout the universe. Upon arriving at earth, the majority of these particles ionize gases in the upper atmosphere, while others interact with gas molecules in the troposphere and producing secondary cosmic rays, which are the main focus of this research. To observe these secondary cosmic rays, a detector telescope was designed and equipped with two silicon photomultipliers (SiPMs). Each SiPM is coupled to a bundle of 4 wavelength shifting optical fibers that are embedded inside a plastic scintillator sheet. The SiPM signals were amplified using a fast preamplifier with coincidence between detectors established using a binary logic gate. The coincidence events were recorded with two devices; a digital counter and an Arduino micro-controller. For detailed analysis of the SiPM waveforms, a DRS4 sensory digitizer captured the waveforms for offline analysis with the CERN software package Physics Analysis Workstation in a Linux environment. Results from our experiments would be presented. Hartnell College STEM Internship Program.

Dosimetric audit in brachytherapy

PubMed Central

Bradley, D A; Nisbet, A

2014-01-01

Dosimetric audit is required for the improvement of patient safety in radiotherapy and to aid optimization of treatment. The reassurance that treatment is being delivered in line with accepted standards, that delivered doses are as prescribed and that quality improvement is enabled is as essential for brachytherapy as it is for the more commonly audited external beam radiotherapy. Dose measurement in brachytherapy is challenging owing to steep dose gradients and small scales, especially in the context of an audit. Several different approaches have been taken for audit measurement to date: thimble and well-type ionization chambers, thermoluminescent detectors, optically stimulated luminescence detectors, radiochromic film and alanine. In this work, we review all of the dosimetric brachytherapy audits that have been conducted in recent years, look at current audits in progress and propose required directions for brachytherapy dosimetric audit in the future. The concern over accurate source strength measurement may be essentially resolved with modern equipment and calibration methods, but brachytherapy is a rapidly developing field and dosimetric audit must keep pace. PMID:24807068

Measurements of output factors with different detector types and Monte Carlo calculations of stopping-power ratios for degraded electron beams.

PubMed

Björk, Peter; Knöös, Tommy; Nilsson, Per

2004-10-07

The aim of the present study was to investigate three different detector types (a parallel-plate ionization chamber, a p-type silicon diode and a diamond detector) with regard to output factor measurements in degraded electron beams, such as those encountered in small-electron-field radiotherapy and intraoperative radiation therapy (IORT). The Monte Carlo method was used to calculate mass collision stopping-power ratios between water and the different detector materials for these complex electron beams (nominal energies of 6, 12 and 20 MeV). The diamond detector was shown to exhibit excellent properties for output factor measurements in degraded beams and was therefore used as a reference. The diode detector was found to be well suited for practical measurements of output factors, although the water-to-silicon stopping-power ratio was shown to vary slightly with treatment set-up and irradiation depth (especially for lower electron energies). Application of ionization-chamber-based dosimetry, according to international dosimetry protocols, will introduce uncertainties smaller than 0.3% into the output factor determination for conventional IORT beams if the variation of the water-to-air stopping-power ratio is not taken into account. The IORT system at our department includes a 0.3 cm thin plastic scatterer inside the therapeutic beam, which furthermore increases the energy degradation of the electrons. By ignoring the change in the water-to-air stopping-power ratio due to this scatterer, the output factor could be underestimated by up to 1.3%. This was verified by the measurements. In small-electron-beam dosimetry, the water-to-air stopping-power ratio variation with field size could mostly be ignored. For fields with flat lateral dose profiles (>3 x 3 cm2), output factors determined with the ionization chamber were found to be in close agreement with the results of the diamond detector. For smaller field sizes the lateral extension of the ionization chamber hampers its use. We therefore recommend that the readily available silicon diode detector should be used for output factor measurements in complex electron fields.

Improved ion detector

DOEpatents

Tullis, A.M.

1986-01-30

An improved ion detector device of the ionization detection device chamber type comprises an ionization chamber having a central electrode therein surrounded by a cylindrical electrode member within the chamber with a collar frictionally fitted around at least one of the electrodes. The collar has electrical contact means carried in an annular groove in an inner bore of the collar to contact the outer surface of the electrode to provide electrical contact between an external terminal and the electrode without the need to solder leads to the electrode.

Dark matter candidates and methods for detecting them

NASA Technical Reports Server (NTRS)

Raffelt, G. G.

1992-01-01

A number of experiments employing Ge and Si ionization detectors have excluded large regions in the plane of masses and scattering cross-sections for weakly-interacting dark matter (DM) candidates. It is judged that, before a realistic detection experiment for supersymmetric DM candidates can be conducted, significant development efforts will have to be completed for suitable cryogenic or ionization detectors. Pilot experiments have demonstrated the feasibility of axion searches with microwave cavities, but these are at least two orders of magnitude too low in sensitivity.

Parallel Study of HEND, RAD, and DAN Instrument Response to Martian Radiation and Surface Conditions

NASA Technical Reports Server (NTRS)

Martiniez Sierra, Luz Maria; Jun, Insoo; Litvak, Maxim; Sanin, Anton; Mitrofanov, Igor; Zeitlin, Cary

2015-01-01

Nuclear detection methods are being used to understand the radiation environment at Mars. JPL (Jet Propulsion Laboratory) assets on Mars include: Orbiter -2001 Mars Odyssey [High Energy Neutron Detector (HEND)]; Mars Science Laboratory Rover -Curiosity [(Radiation Assessment Detector (RAD); Dynamic Albedo Neutron (DAN))]. Spacecraft have instruments able to detect ionizing and non-ionizing radiation. Instrument response on orbit and on the surface of Mars to space weather and local conditions [is discussed] - Data available at NASA-PDS (Planetary Data System).

Conceptual study of a heavy-ion-ERDA spectrometer for energies below 6 MeV

NASA Astrophysics Data System (ADS)

Julin, Jaakko; Sajavaara, Timo

2017-09-01

Elastic recoil detection analysis (ERDA) is a well established technique and it offers unique capabilities in thin film analysis. Simultaneous detection and depth profiling of all elements, including hydrogen, is possible only with time-of-flight ERDA. Bragg ionization chambers or ΔE - E detectors can also be used to identify the recoiling element if sufficiently high energies are used. The chief limitations of time-of-flight ERDA are the beam induced sample damage and the requirement of a relatively large accelerator. In this paper we propose a detector setup, which could be used with 3 MeV to 6 MeV medium heavy beams from either a single ended accelerator (40Ar) or from a tandem accelerator (39K). The detector setup consists of two timing detectors and a gas ionization chamber energy detector. Compared to use of very heavy low energy ions the hydrogen recoils with this beam have sufficient energy to be detected with current gas ionization chamber energy detector. To reduce the beam induced damage the proposed detector setup covers a solid angle larger than 1 msr, roughly an order of magnitude improvement over most time-of-flight ERDA setups. The setup could be used together with a small accelerator to be used for light element analysis of approximately 50 nm films. The concept is tested with 39K beam from a 1.7 MV Pelletron tandem accelerator with the Jyväskylä ToF-ERDA setup. In addition to the measurements effects related to low energies and increase in the solid angle are simulated with Monte Carlo methods.

Simultaneous ESI-APCI+ ionization and fragmentation pathways for nine benzodiazepines and zolpidem using single quadrupole LC-MS.

PubMed

Galaon, Toma; Vacaresteanu, Catalina; Anghel, Dan-Florin; David, Victor

2014-05-01

Nine important 1,4-benzodiazepines and zolpidem were characterized by liquid chromatography-mass spectrometry using a multimode ionization source able to generate ions using both electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), and a single quadrupole mass analyzer. An optimum chromatographic separation was applied for all target compounds in less than 8 minutes using a Zorbax Eclipse Plus column (100 × 4.6 mm, 3.5 µm) kept at 35°C and a 0.3% HCOOH/ACN/IPA (61:34:5) mobile phase pumped at 1 ml/min. Optimization of LC-MS method generated low limit of quantitation (LOQ) values situated in the range 0.3-20.5 ng/ml. Comparison between differences in method sensitivity, under specified chromatographic conditions, when using ESI-only, APCI-only, and simultaneous ESI-APCI ionization with such a multimode source was discussed. Mixed ESI-APCI(+) mode proved to be the most sensitive ionization generating an average 35% detector response increase compared to ESI-only ionization and 350% detector response increase with respect to APCI-only ionization. Characterization of the nine benzodiazepines and zolpidem concerning their MS fragmentation pathway following 'in-source' collision-induced dissociation is discussed in detail and some general trends regarding these fragmentations are set. Copyright © 2013 John Wiley & Sons, Ltd.

Assessment of the setup dependence of detector response functions for mega-voltage linear accelerators

PubMed Central

Fox, Christopher; Simon, Tom; Simon, Bill; Dempsey, James F.; Kahler, Darren; Palta, Jatinder R.; Liu, Chihray; Yan, Guanghua

2010-01-01

Purpose: Accurate modeling of beam profiles is important for precise treatment planning dosimetry. Calculated beam profiles need to precisely replicate profiles measured during machine commissioning. Finite detector size introduces perturbations into the measured profiles, which, in turn, impact the resulting modeled profiles. The authors investigate a method for extracting the unperturbed beam profiles from those measured during linear accelerator commissioning. Methods: In-plane and cross-plane data were collected for an Elekta Synergy linac at 6 MV using ionization chambers of volume 0.01, 0.04, 0.13, and 0.65 cm3 and a diode of surface area 0.64 mm2. The detectors were orientated with the stem perpendicular to the beam and pointing away from the gantry. Profiles were measured for a 10×10 cm2 field at depths ranging from 0.8 to 25.0 cm and SSDs from 90 to 110 cm. Shaping parameters of a Gaussian response function were obtained relative to the Edge detector. The Gaussian function was deconvolved from the measured ionization chamber data. The Edge detector profile was taken as an approximation to the true profile, to which deconvolved data were compared. Data were also collected with CC13 and Edge detectors for additional fields and energies on an Elekta Synergy, Varian Trilogy, and Siemens Oncor linear accelerator and response functions obtained. Response functions were compared as a function of depth, SSD, and detector scan direction. Variations in the shaping parameter were introduced and the effect on the resulting deconvolution profiles assessed. Results: Up to 10% setup dependence in the Gaussian shaping parameter occurred, for each detector for a particular plane. This translated to less than a ±0.7 mm variation in the 80%–20% penumbral width. For large volume ionization chambers such as the FC65 Farmer type, where the cavity length to diameter ratio is far from 1, the scan direction produced up to a 40% difference in the shaping parameter between in-plane and cross-plane measurements. This is primarily due to the directional difference in penumbral width measured by the FC65 chamber, which can more than double in profiles obtained with the detector stem parallel compared to perpendicular to the scan direction. For the more symmetric CC13 chamber the variation was only 3% between in-plane and cross-plane measurements. Conclusions: The authors have shown that the detector response varies with detector type, depth, SSD, and detector scan direction. In-plane vs cross-plane scanning can require calculation of a direction dependent response function. The effect of a 10% overall variation in the response function, for an ionization chamber, translates to a small deviation in the penumbra from that of the Edge detector measured profile when deconvolved. Due to the uncertainties introduced by deconvolution the Edge detector would be preferable in obtaining an approximation of the true profile, particularly for field sizes where the energy dependence of the diode can be neglected. However, an averaged response function could be utilized to provide a good approximation of the true profile for large ionization chambers and for larger fields for which diode detectors are not recommended. PMID:20229856

Crossed beam roof target for motion tracking

NASA Technical Reports Server (NTRS)

Olczak, Eugene (Inventor)

2009-01-01

A system for detecting motion between a first body and a second body includes first and second detector-emitter pairs, disposed on the first body, and configured to transmit and receive first and second optical beams, respectively. At least a first optical rotator is disposed on the second body and configured to receive and reflect at least one of the first and second optical beams. First and second detectors of the detector-emitter pairs are configured to detect the first and second optical beams, respectively. Each of the first and second detectors is configured to detect motion between the first and second bodies in multiple degrees of freedom (DOFs). The first optical rotator includes a V-notch oriented to form an apex of an isosceles triangle with respect to a base of the isosceles triangle formed by the first and second detector-emitter pairs. The V-notch is configured to receive the first optical beam and reflect the first optical beam to both the first and second detectors. The V-notch is also configured to receive the second optical beam and reflect the second optical beam to both the first and second detectors.

Apparatus and method for the simultaneous detection of neutrons and ionizing electromagnetic radiation

DOEpatents

Bell, Zane W.

2000-01-01

A sensor for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising: a sensor for the detection of gamma radiation, the sensor defining a sensing head; the sensor further defining an output end in communication with the sensing head; and an exterior neutron-sensitive material configured to form around the sensing head; wherein the neutron-sensitive material, subsequent to the capture of the neutron, fissions into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the first excited state decaying via the emission of a single gamma ray at 478 keV which can in turn be detected by the sensing head; and wherein the sensing head can also detect the ionizing electromagnetic radiation from an incident radiation field without significant interference from the neutron-sensitive material. A method for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising the steps of: providing a gamma ray sensitive detector comprising a sensing head and an output end; conforming an exterior neutron-sensitive material configured to form around the sensing head of the detector; capturing neutrons by the sensing head causing the neutron-sensitive material to fission into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the state decaying via the emission of a single gamma ray at 478 keV; sensing gamma rays entering the detector through the neutron-sensitive material; and producing an output through a readout device coupled to the output end; wherein the detector provides an output which is proportional to the energy of the absorbed ionizing electromagnetic radiation.

VUV photodynamics of free tholins nanoparticles investigated by imaging Angle-Resolved Photoemission with the Synchrotron Radiation

NASA Astrophysics Data System (ADS)

Tigrine, Sarah; Nahon, Laurent; Carrasco, Nathalie; Garcia-Macias, Gustavo

2016-06-01

Thanks to the Cassini Huygens mission, it is now established that the aerosols appear from an altitude of 1,000 km in Titan's atmosphere. Once they are formed and through their descent towards the surface, those grains will still interact with persistent UV/VUV radiations, at different energies, that can reach lower atmospheric layers. This interaction has some impact, for example on the radiative transfer or on the ionization yield of the atmospheric compounds. Models are a good way to study those processes, but the lack of data on the refractive index or the absolute absorption/ionization cross subsections of the aerosols can be an obstacle. In order to shed some light and quantify those processes, we ionize analogs of aerosols produced with the PAMPRE experiment (LATMOS) on the SAPHIRS platform from the DESIRS VUV beamline at the synchrotron SOLEIL, equipped with an aerodynamic lens. The aerosols are injected directly under vacuum as isolated free nanoparticles and do not need to take the form of a film deposited on a substrate. The generated photoelectrons are then collected with a Velocity Map Imaging detector and their energetic and angular signatures are analyzed using the ARPES method (Angle-Resolved PhotoElectron Spectroscopy). Both the nanoparticles size distribution and the incident wavelength determine the parameters governing the photoemission process (intra-particles electron mean free path, photon penetration depth) as revealed by the angular distribution of the photoelectron showing in same cases a marked forward/backward asymmetry with respect to the photon axis. Those parameters may provide us with information on the optical behavior of the aerosols. In addition we can extract the ionization potential in direct connection with the absorption cross subsections of the aerosol, from which altitude dependent photodynamics can be unraveled. We will present here the experiments performed, at different VUV energies, on Titan's aerosol analogs with the ARPES method and show how the first results can have implications regarding Titan's atmosphere overall optical characteristics.

A combined segmented anode gas ionization chamber and time-of-flight detector for heavy ion elastic recoil detection analysis

NASA Astrophysics Data System (ADS)

Ström, Petter; Petersson, Per; Rubel, Marek; Possnert, Göran

2016-10-01

A dedicated detector system for heavy ion elastic recoil detection analysis at the Tandem Laboratory of Uppsala University is presented. Benefits of combining a time-of-flight measurement with a segmented anode gas ionization chamber are demonstrated. The capability of ion species identification is improved with the present system, compared to that obtained when using a single solid state silicon detector for the full ion energy signal. The system enables separation of light elements, up to Neon, based on atomic number while signals from heavy elements such as molybdenum and tungsten are separated based on mass, to a sample depth on the order of 1 μm. The performance of the system is discussed and a selection of material analysis applications is given. Plasma-facing materials from fusion experiments, in particular metal mirrors, are used as a main example for the discussion. Marker experiments using nitrogen-15 or oxygen-18 are specific cases for which the described improved species separation and sensitivity are required. Resilience to radiation damage and significantly improved energy resolution for heavy elements at low energies are additional benefits of the gas ionization chamber over a solid state detector based system.

Strip Ionization Chamber as Beam Monitor in the Proton Therapy Eye Treatment

NASA Astrophysics Data System (ADS)

Marchetto, F.; Cirio, R.; Garella, M. A.; Giordanengo, S.; Boriano, A.; Givehchi, N.; La Rosa, A.; Peroni, C.; Donetti, M.; Bourhaleb, F.; Pitta', G.; Cirrone, G. A. P.; Cuttone, G.; Raffaele, L.; Sabini, M. G.; Valastro, L.

2006-04-01

Since spring 2002, ocular pathologies have been treated in Catania at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) within a collaboration between INFN Laboratori Nazionali del Sud (LNS), Physics Department, Ophthalmology Institute, Radiology Institute of the Catania University and CSFNSM Catania. A beam line from a 62 MeV Superconducting Cyclotron is used to treat shallow tumors. The beam is conformed to the tumor shape with a passive delivery system. A detector system has been developed in collaboration with INFN-Torino to be used as real time beam monitor. The detector, placed upstream of the patient collimator, consists of two parallel plate ionization chambers with the anode segmented in strips. Each anode is made of 0.5 mm-wide 256 strips corresponding to (12.8 × 12.8) cm2 sensitive area. With the two strip ionization chambers one can measure the relevant beam parameters during treatment to probe both asymmetry and flatness. In the test carried out at CATANA the detector has been used under different and extreme beam conditions. Preliminary results are given for profiles and skewness, together with a comparison with reference detectors.

Application of gas chromatography/flame ionization detector-based metabolite fingerprinting for authentication of Asian palm civet coffee (Kopi Luwak).

PubMed

Jumhawan, Udi; Putri, Sastia Prama; Yusianto; Bamba, Takeshi; Fukusaki, Eiichiro

2015-11-01

Development of authenticity screening for Asian palm civet coffee, the world-renowned priciest coffee, was previously reported using metabolite profiling through gas chromatography/mass spectrometry (GC/MS). However, a major drawback of this approach is the high cost of the instrument and maintenance. Therefore, an alternative method is needed for quality and authenticity evaluation of civet coffee. A rapid, reliable and cost-effective analysis employing a universal detector, GC coupled with flame ionization detector (FID), and metabolite fingerprinting has been established for discrimination analysis of 37 commercial and non-commercial coffee beans extracts. gas chromatography/flame ionization detector (GC/FID) provided higher sensitivity over a similar range of detected compounds than GC/MS. In combination with multivariate analysis, GC/FID could successfully reproduce quality prediction from GC/MS for differentiation of commercial civet coffee, regular coffee and coffee blend with 50 wt % civet coffee content without prior metabolite details. Our study demonstrated that GC/FID-based metabolite fingerprinting can be effectively actualized as an alternative method for coffee authenticity screening in industries. Copyright © 2015. Published by Elsevier B.V.

Efficient photoconductive terahertz detector with all-dielectric optical metasurface

NASA Astrophysics Data System (ADS)

Mitrofanov, Oleg; Siday, Thomas; Thompson, Robert J.; Luk, Ting Shan; Brener, Igal; Reno, John L.

2018-05-01

We designed an optically thin photoconductive channel as an all-dielectric metasurface comprising an array of low-temperature grown GaAs nanobeams and a sub-surface distributed Bragg reflector. The metasurface exhibited enhanced optical absorption, and it was integrated into a photoconductive THz detector, which showed high efficiency and sensitivity as a result. The detector produced photocurrents over one order of magnitude higher compared to a similar detector with an unstructured surface with only 0.5 mW of optical excitation while exhibiting high dark resistance required for low-noise detection in THz time-domain spectroscopy and imaging. At that level of optical excitation, the metasurface detector showed a high signal to noise ratio of 106. The detector showed saturation above that level.

Spectroscopic quantification of extremely rare molecular species in the presence of interfering optical absorption

DOEpatents

Ognibene, Ted; Bench, Graham; McCartt, Alan Daniel; Turteltaub, Kenneth; Rella, Chris W.; Tan, Sze; Hoffnagle, John A.; Crosson, Eric

2017-05-09

Optical spectrometer apparatus, systems, and methods for analysis of carbon-14 including a resonant optical cavity configured to accept a sample gas including carbon-14, an optical source configured to deliver optical radiation to the resonant optical cavity, an optical detector configured to detect optical radiation emitted from the resonant cavity and to provide a detector signal; and a processor configured to compute a carbon-14 concentration from the detector signal, wherein computing the carbon-14 concentration from the detector signal includes fitting a spectroscopic model to a measured spectrogram, wherein the spectroscopic model accounts for contributions from one or more interfering species that spectroscopically interfere with carbon-14.

Evaluation of a novel helium ionization detector within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography.

PubMed

Franchina, Flavio A; Maimone, Mariarosa; Sciarrone, Danilo; Purcaro, Giorgia; Tranchida, Peter Q; Mondello, Luigi

2015-07-10

The present research is focused on the use and evaluation of a novel helium ionization detector, defined as barrier discharge ionization detector (BID), within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography (FM GC×GC). The performance of the BID device was compared to that of a flame ionization detector (FID), under similar FM GC×GC conditions. Following development and optimization of the FM GC×GC method, the BID was subjected to fine tuning in relation to acquisition frequency and discharge flow. Moreover, the BID performance was measured and compared to that of the FID, in terms of extra-column band broadening, sensitivity and dynamic range. The comparative study was carried out by using standard compounds belonging to different chemical classes, along with a sample of diesel fuel. Advantages and disadvantages of the BID system, also within the context of FM GC×GC, are critically discussed. In general, the BID system was characterized by a more limited dynamic range and increased sensitivity, compared to the FID. Additionally, BID and FID contribution to band broadening was found to be similar under the operational conditions applied. Particular attention was devoted to the behaviour of the FM GC×GC-BID system toward saturated and aromatic hydrocarbons, for a possible future use in the field of mineral-oil food contamination research. Copyright © 2015 Elsevier B.V. All rights reserved.

Test Port for Fiber-Optic-Coupled Laser Altimeter

NASA Technical Reports Server (NTRS)

Ramos Izquierdo, Luis; Scott, V. Stanley; Rinis, Haris; Cavanaugh, John

2011-01-01

A test port designed as part of a fiber optic coupled laser altimeter receiver optical system allows for the back-illumination of the optical system for alignment verification, as well as illumination of the detector(s) for testing the receiver electronics and signal-processing algorithms. Measuring the optical alignment of a laser altimeter instrument is difficult after the instrument is fully assembled. The addition of a test port in the receiver aft-optics allows for the back-illumination of the receiver system such that its focal setting and boresight alignment can be easily verified. For a multiple-detector receiver system, the addition of the aft-optics test port offers the added advantage of being able to simultaneously test all the detectors with different signals that simulate the expected operational conditions. On a laser altimeter instrument (see figure), the aft-optics couple the light from the receiver telescope to the receiver detector(s). Incorporating a beam splitter in the aft-optics design allows for the addition of a test port to back-illuminate the receiver telescope and/or detectors. The aft-optics layout resembles a T with the detector on one leg, the receiver telescope input port on the second leg, and the test port on the third leg. The use of a custom beam splitter with 99-percent reflection, 1-percent transmission, and a mirrored roof can send the test port light to the receiver telescope leg as well as the detector leg, without unduly sacrificing the signal from the receiver telescope to the detector. The ability to test the receiver system alignment, as well as multiple detectors with different signals without the need to disassemble the instrument or connect and reconnect components, is a great advantage to the aft-optics test port. Another benefit is that the receiver telescope aperture is fully back-illuminated by the test port so the receiver telescope focal setting vs. pressure and or temperature can be accurately measured (as compared to schemes where the aperture is only partially illuminated). Fiber-optic coupling the test port also allows for the modularity of testing the receiver detectors with a variety of background and signal laser sources without the need of using complex optical set-ups to optimize the efficiency of each source.

A study of the effect of gamma and laser irradiation on the thermal, optical and structural properties of CR-39 nuclear track detector

NASA Astrophysics Data System (ADS)

Nouh, S. A.; Atta, M. R.; El-Melleegy, W. M.

2004-08-01

A comparative study of the effect of gamma and laser irradiation on the thermal, optical and structural properties of the CR-39 diglycol carbonate solid state nuclear track detector has been carried out. Samples from CR-39 polymer were classified into two main groups: the first group was irradiated by gamma rays with doses at levels between 20 and 300 kGy, whereas the second group was exposed to infrared laser radiation with energy fluences at levels between 0.71 and 8.53 J/cm(2). Non-isothermal studies were carried out using thermogravimetry, differential thermogravimetry and differential thermal analysis to obtain activation energy of decomposition and transition temperatures for the non-irradiated and all irradiated CR-39 samples. In addition, optical and structural property studies were performed on non-irradiated and irradiated CR-39 samples using refractive index and X-ray diffraction measurements. Variation in the onset temperature of decomposition T-o, activation energy of decomposition E-a, melting temperature T-m, refractive index n and the mass fraction of the amorphous phase after gamma and laser irradiation were studied. It was found that many changes in the thermal, optical and structural properties of the CR-39 polymer could be produced by gamma irradiation via degradation and cross-linking mechanisms. Also, the gamma dose has an advantage of increasing the correlation between thermal stability of the CR-39 polymer and bond formation created by the ionizing effect of gamma radiation. On the other hand, higher laser-energy fluences in the range 4.27-8.53 J/cm(2) decrease the melting temperature of the CR-39 polymer and this is most suitable for applications requiring molding of the polymer at lower temperatures.

Development and tests of x-ray multifoil optical system for 1D imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Pína, Ladislav; Hudec, René; Inneman, Adolf J.; Baca, Tomas; Blazek, M.; Platkevic, M.; Sieger, Ladislav; Doubravova, Daniela; McEntaffer, Randall L.; Schultz, Ted B.; Dániel, Vladimír.

2016-09-01

The proposed wide-field optical system has not been used yet. Described novel approach is based on the use of 1D "Lobster eye" optics in combination with Timepix X-ray detector in the energy range 3 - 40 keV. The proposed project includes theoretical study and a functional sample of the Timepix X-ray detector with multifoil wide-field X-ray "Lobster eye" optics. Using optics to focus X-rays on a detector is necessary in cases where the intensity of impinging X-ray radiation is below the sensitivity of the detector without optic. Generally this is the case of very low light phenomena, or e.g. monitoring astrophysical objects in space. Namely, such optical system could find applications in laboratory spectroscopy systems or in a rocket space experiment. Designed wide-field optical system combined with Timepix X-ray detector is described together with experimental results obtained during laboratory tests.

Quantification of Optical and Physical Properties of Combustion-Generated Carbonaceous Aerosols (

PubMed Central

Perera, Inoka Eranda; Litton, Charles D.

2016-01-01

A series of experiments were conducted to quantify and characterize the optical and physical properties of combustion-generated aerosols during both flaming and smoldering combustion of three materials common to underground mines—Pittsburgh Seam coal, Styrene Butadiene Rubber (a common mine conveyor belt material), and Douglas-fir wood—using a combination of analytical and gravimetric measurements. Laser photometers were utilized in the experiments for continuous measurement of aerosol mass concentrations and for comparison to measurements made using gravimetric filter samples. The aerosols of interest lie in the size range of tens to a few hundred nanometers, out of range of the standard photometer calibration. To correct for these uncertainties, the photometer mass concentrations were compared to gravimetric samples to determine if consistent correlations existed. The response of a calibrated and modified combination ionization/photoelectric smoke detector was also used. In addition, the responses of this sensor and a similar, prototype ionization/photoelectric sensor, along with discrete angular scattering, total scattering, and total extinction measurements, were used to define in real time the size, morphology, and radiative transfer properties of these differing aerosols that are generally in the form of fractal aggregates. SEM/TEM images were also obtained in order to compare qualitatively the real-time, continuous experimental measurements with the visual microscopic measurements. These data clearly show that significant differences exist between aerosols from flaming and from smoldering combustion and that these differences produce very different scattering and absorption signatures. The data also indicate that ionization/photoelectric sensors can be utilized to measure continuously and in real time aerosol properties over a broad spectrum of applications related to adverse environmental and health effects. PMID:27546898

Quantification of Optical and Physical Properties of Combustion-Generated Carbonaceous Aerosols (

PubMed

Perera, Inoka Eranda; Litton, Charles D

2015-03-01

A series of experiments were conducted to quantify and characterize the optical and physical properties of combustion-generated aerosols during both flaming and smoldering combustion of three materials common to underground mines-Pittsburgh Seam coal, Styrene Butadiene Rubber (a common mine conveyor belt material), and Douglas-fir wood-using a combination of analytical and gravimetric measurements. Laser photometers were utilized in the experiments for continuous measurement of aerosol mass concentrations and for comparison to measurements made using gravimetric filter samples. The aerosols of interest lie in the size range of tens to a few hundred nanometers, out of range of the standard photometer calibration. To correct for these uncertainties, the photometer mass concentrations were compared to gravimetric samples to determine if consistent correlations existed. The response of a calibrated and modified combination ionization/photoelectric smoke detector was also used. In addition, the responses of this sensor and a similar, prototype ionization/photoelectric sensor, along with discrete angular scattering, total scattering, and total extinction measurements, were used to define in real time the size, morphology, and radiative transfer properties of these differing aerosols that are generally in the form of fractal aggregates. SEM/TEM images were also obtained in order to compare qualitatively the real-time, continuous experimental measurements with the visual microscopic measurements. These data clearly show that significant differences exist between aerosols from flaming and from smoldering combustion and that these differences produce very different scattering and absorption signatures. The data also indicate that ionization/photoelectric sensors can be utilized to measure continuously and in real time aerosol properties over a broad spectrum of applications related to adverse environmental and health effects.

Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

DOEpatents

Woodruff, Steven D.; Mcintyre, Dustin L.

2016-03-29

A device for Laser based Analysis using a Passively Q-Switched Laser comprising an optical pumping source optically connected to a laser media. The laser media and a Q-switch are positioned between and optically connected to a high reflectivity mirror (HR) and an output coupler (OC) along an optical axis. The output coupler (OC) is optically connected to the output lens along the optical axis. A means for detecting atomic optical emission comprises a filter and a light detector. The optical filter is optically connected to the laser media and the optical detector. A control system is connected to the optical detector and the analysis electronics. The analysis electronics are optically connected to the output lens. The detection of the large scale laser output production triggers the control system to initiate the precise timing and data collection from the detector and analysis.

Measurements of speed of response of high-speed visible and IR optical detectors

NASA Technical Reports Server (NTRS)

Rowe, H. E.; Osmundson, J. S.

1972-01-01

A technique for measuring speed of response of high speed visible and IR optical detectors to mode-locked Nd:YAG laser pulses is described. Results of measurements of response times of four detectors are presented. Three detectors that can be used as receivers in a 500-MHz optical communication system are tested.

Detectors for optical communications: A review

NASA Technical Reports Server (NTRS)

Katz, J.

1983-01-01

Detectors for optical communications in the visible and near infrared regions of the spectrum are reviewed. The three generic types of detectors described are: photomultipliers, photodiodes and avalanche photodiodes. Most of the information is applicable to other optical communications systems.

Ionizing Radiation Measurements Using Low Cost Instruments for Teaching in College or High-School in Brazil

ERIC Educational Resources Information Center

Silva, M. C.; Vilela, D. C.; Migoto, V. G.; Gomes, M. P.; Martin, I. M.; Germano, J. S. E.

2017-01-01

Ionizing radiation one of modern physics experimental teaching in colleges and high school can be easily implemented today due to low coasts of detectors and also electronic circuits and data acquisition interfaces. First it is interesting to show to young's students what is ionizing radiation and from where they appears near ground level? How it…

Multiplexed electronically programmable multimode ionization detector for chromatography

DOEpatents

Wise, M.B.; Buchanan, M.V.

1988-05-19

Method and apparatus for detecting and differentiating organic compounds based on their electron affinity. An electron capture detector cell (ECD) is operated in a plurality of multiplexed electronically programmable operating modes to alter the detector response during a single sampling cycle to acquire multiple simultaneous chromatograms corresponding to each of the different operating modes. The cell is held at a constant subatmospheric pressure while the electron collection bias voltage applied to the cell is modulated electronically to allow acquisition of multiple chromatograms for a single sample elution from a chromatograph representing three distinctly different response modes. A system is provided which automatically controls the programmed application of bias pulses at different intervals and/or amplitudes to switch the detector from an ionization mode to the electron capture mode and various degrees therebetween to provide an improved means of tuning an ECD for multimode detection and improved specificity. 6 figs.

Multiplexed electronically programmable multimode ionization detector for chromatography

DOEpatents

Wise, Marcus B.; Buchanan, Michelle V.

1989-01-01

Method and apparatus for detecting and differentiating organic compounds based on their electron affinity. An electron capture detector cell (ECD) is operated in a plurality of multiplexed electroncially programmable operating modes to alter the detector response during a single sampling cycle to acquire multiple simultaneous chromatograms corresponding to each of the different operating modes. The cell is held at a constant subatmospheric pressure while the electron collection bias voltage applied to the cell is modulated electronically to allow acquisition of multiple chromatograms for a single sample elution from a chromatograph representing three distinctly different response modes. A system is provided which automatically controls the programmed application of bias pulses at different intervals and/or amplitudes to switch the detector from an ionization mode to the electron capture mode and various degrees therebetween to provide an improved means of tuning an ECD for multimode detection and improved specificity.

Utilizing two detectors in the measurement of trichloroacetic acid in human urine by reaction headspace gas chromatography.

PubMed

Xie, Wei-Qi; Gong, Yi-Xian; Yu, Kong-Xian

2018-05-16

A reaction headspace gas chromatography (HS-GC) technique was investigated for quantitatively analyzing trichloroacetic acid in human urine. This method is based on the decomposition reaction of trichloroacetic acid under high-temperature conditions. The carbon dioxide and chloroform formed from the decomposition reaction can be respectively detected by the thermal conductivity detection HS-GC and flame ionization detection HS-GC. The reaction can be completed in 60 min at 90°C. This method was used to quantify 25 different human urine samples, which had a range of trichloroacetic acid from 0.52 to 3.47 mg/L. It also utilized two different detectors, the thermal conductivity detector and the flame ionization detector. The present reaction HS-GC method is accurate, reliable and well suitable for batch detection of trichloroacetic acid in human urine. Copyright © 2018 John Wiley & Sons, Ltd.

Measurement and analysis of the conversion gain degradation of the CIS detectors in harsh radiation environments

NASA Astrophysics Data System (ADS)

Wang, Zujun; Xue, Yuanyuan; Guo, Xiaoqiang; Bian, Jingying; Yao, Zhibin; He, Baoping; Ma, Wuying; Sheng, Jiangkun; Dong, Guantao; Liu, Yan

2018-07-01

The conversion gain of the CMOS image sensor (CIS) is one of the most important key parameters to the CIS detector. The conversion gain degradation induced by radiation damage will seriously affect the performances of the CIS detector. The experiments of the CISs irradiated by protons, neutrons, and gamma rays are presented. The CISs have 4 Megapixels and pinned photodiode (PPD) pixel architecture with a standard 0.18 μm CMOS technology. The conversion gains versus the proton fluence (including the proton ionizing dose), neutron fluence and gamma total ionizing dose are presented, respectively. The mechanisms of the conversion gain degradation induced by radiation damage are analyzed in details. The investigations will help to improve the PPD CIS detector design, reliability and applicability for applications in the harsh radiation environments such as space and nuclear environments.

Microscale mass spectrometry systems, devices and related methods

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

Ramsey, John Michael

Mass spectrometry systems or assemblies therefore include an ionizer that includes at least one planar conductor, a mass analyzer with a planar electrode assembly, and a detector comprising at least one planar conductor. The ionizer, the mass analyzer and the detector are attached together in a compact stack assembly. The stack assembly has a perimeter that bounds an area that is between about 0.01 mm.sup.2 to about 25 cm.sup.2 and the stack assembly has a thickness that is between about 0.1 mm to about 25 mm.

Microscale mass spectrometry systems, devices and related methods

DOEpatents

Ramsey, John Michael

2016-06-21

Mass spectrometry systems or assemblies therefore include an ionizer that includes at least one planar conductor, a mass analyzer with a planar electrode assembly, and a detector comprising at least one planar conductor. The ionizer, the mass analyzer and the detector are attached together in a compact stack assembly. The stack assembly has a perimeter that bounds an area that is between about 0.01 mm.sup.2 to about 25 cm.sup.2 and the stack assembly has a thickness that is between about 0.1 mm to about 25 mm.

Mini-lidar sensor for the remote stand-off sensing of chemical/biological substances and method for sensing same

DOEpatents

Ray, Mark D.; Sedlacek, Arthur J.

2003-08-19

A method and apparatus for remote, stand-off, and high efficiency spectroscopic detection of biological and chemical substances. The apparatus including an optical beam transmitter which transmits a beam having an axis of transmission to a target, the beam comprising at least a laser emission. An optical detector having an optical detection path to the target is provided for gathering optical information. The optical detection path has an axis of optical detection. A beam alignment device fixes the transmitter proximal to the detector and directs the beam to the target along the optical detection path such that the axis of transmission is within the optical detection path. Optical information gathered by the optical detector is analyzed by an analyzer which is operatively connected to the detector.

Development and investigation of a magnetic resonance imaging-compatible microlens-based optical detector

NASA Astrophysics Data System (ADS)

Paar, Steffen; Umathum, Reiner; Jiang, Xiaoming; Majer, Charles L.; Peter, Jörg

2015-09-01

A noncontact optical detector for in vivo imaging has been developed that is compatible with magnetic resonance imaging (MRI). The optical detector employs microlens arrays and might be classified as a plenoptic camera. As a resulting of its design, the detector possesses a slim thickness and is self-shielding against radio frequency (RF) pulses. For experimental investigation, a total of six optical detectors were arranged in a cylindrical fashion, with the imaged object positioned in the center of this assembly. A purposely designed RF volume resonator coil has been developed and is incorporated within the optical imaging system. The whole assembly was placed into the bore of a 1.5 T patient-sized MRI scanner. Simple-geometry phantom studies were performed to assess compatibility and performance characteristics regarding both optical and MR imaging systems. A bimodal ex vivo nude mouse measurement was conducted. From the MRI data, the subject surface was extracted. Optical images were projected on this surface by means of an inverse mapping algorithm. Simultaneous measurements did not reveal influences from the magnetic field and RF pulses onto optical detector performance (spatial resolution, sensitivity). No significant influence of the optical imaging system onto MRI performance was detectable.

Development and investigation of a magnetic resonance imaging-compatible microlens-based optical detector.

PubMed

Paar, Steffen; Umathum, Reiner; Jiang, Xiaoming; Majer, Charles L; Peter, Jörg

2015-09-01

A noncontact optical detector for in vivo imaging has been developed that is compatible with magnetic resonance imaging (MRI). The optical detector employs microlens arrays and might be classified as a plenoptic camera. As a resulting of its design, the detector possesses a slim thickness and is self-shielding against radio frequency (RF) pulses. For experimental investigation, a total of six optical detectors were arranged in a cylindrical fashion, with the imaged object positioned in the center of this assembly. A purposely designed RF volume resonator coil has been developed and is incorporated within the optical imaging system. The whole assembly was placed into the bore of a 1.5 T patient-sized MRI scanner. Simple-geometry phantom studies were performed to assess compatibility and performance characteristics regarding both optical and MR imaging systems. A bimodal ex vivo nude mouse measurement was conducted. From the MRI data, the subject surface was extracted. Optical images were projected on this surface by means of an inverse mapping algorithm. Simultaneous measurements did not reveal influences from the magnetic field and RF pulses onto optical detector performance (spatial resolution, sensitivity). No significant influence of the optical imaging system onto MRI performance was detectable.

Evaluating analytical ionization quenching correction models for 3D liquid organic scintillator detector

NASA Astrophysics Data System (ADS)

Alsanea, F.; Beddar, S.

2017-05-01

Proton therapy offers dosimetric advantage over conventional photon therapy due to the finite range of the proton beam, which improves dose conformity. However, one of the main challenges of proton beam therapy is verification of the complex treatment plans delivered to a patient. Thus, 3D measurements are needed to verify the complex dose distribution. A 3D organic scintillator detector is capable of such measurements. However, organic scintillators exhibit a non-linear relation to the ionization density called ionization quenching. The ionization quenching phenomenon in organic scintillators must be accounted for to obtain accurate dose measurements. We investigated the energy deposition by secondary electrons (EDSE) model to explain ionization quenching in 3D liquid organic scintillator when exposed to proton beams. The EDSE model was applied to volumetric scintillation measurement of proton pencil beam with energies of 85.6, 100.9, 144.9 and 161.9 MeV. The quenching parameter in EDSE model ρq was determined by plotting the total light output vs the initial energy of the ion. The results were compared to the Birks semi-empirical formula of scintillation light emission.

40 CFR 63.321 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... volatilize and recover perchloroethylene from contaminated perchloroethylene. Temperature sensor means a thermometer or thermocouple used to measure temperature. Transfer machine system means a multiple-machine dry... December 9, 1991. PCE gas analyzer means a flame ionization detector, photoionization detector, or infrared...

40 CFR 63.321 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... volatilize and recover perchloroethylene from contaminated perchloroethylene. Temperature sensor means a thermometer or thermocouple used to measure temperature. Transfer machine system means a multiple-machine dry... December 9, 1991. PCE gas analyzer means a flame ionization detector, photoionization detector, or infrared...

40 CFR 63.321 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... volatilize and recover perchloroethylene from contaminated perchloroethylene. Temperature sensor means a thermometer or thermocouple used to measure temperature. Transfer machine system means a multiple-machine dry... December 9, 1991. PCE gas analyzer means a flame ionization detector, photoionization detector, or infrared...

40 CFR 63.321 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... volatilize and recover perchloroethylene from contaminated perchloroethylene. Temperature sensor means a thermometer or thermocouple used to measure temperature. Transfer machine system means a multiple-machine dry... December 9, 1991. PCE gas analyzer means a flame ionization detector, photoionization detector, or infrared...

40 CFR 63.321 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... volatilize and recover perchloroethylene from contaminated perchloroethylene. Temperature sensor means a thermometer or thermocouple used to measure temperature. Transfer machine system means a multiple-machine dry... December 9, 1991. PCE gas analyzer means a flame ionization detector, photoionization detector, or infrared...

First application of combined isochronous and Schottky mass spectrometry: Half-lives of fully ionized Cr 24 + 49 and Fe 26 + 53 atoms

NASA Astrophysics Data System (ADS)

Tu, X. L.; Chen, X. C.; Zhang, J. T.; Shuai, P.; Yue, K.; Xu, X.; Fu, C. Y.; Zeng, Q.; Zhou, X.; Xing, Y. M.; Wu, J. X.; Mao, R. S.; Mao, L. J.; Fang, K. H.; Sun, Z. Y.; Wang, M.; Yang, J. C.; Litvinov, Yu. A.; Blaum, K.; Zhang, Y. H.; Yuan, Y. J.; Ma, X. W.; Zhou, X. H.; Xu, H. S.

2018-01-01

Lifetime measurements of β -decaying highly charged ions have been performed in the experimental storage ring (CSRe) by applying the isochronous Schottky mass spectrometry. The fully ionized 49Cr and 53Fe ions were produced in projectile fragmentation of 58Ni primary beam and were stored in the CSRe tuned into the isochronous ion-optical mode. The new resonant Schottky detector was applied to monitor the intensities of stored uncooled Cr 24 + 49 and Fe 26 + 53 ions. The extracted half-lives T1 /2(Cr 24 + 49 ) =44.0 (27 ) min and T1 /2(Fe 26 + 53 ) =8.47 (19 ) min are in excellent agreement with the literature half-life values corrected for the disabled electron capture branchings. This is an important proof-of-principle step towards realizing the simultaneous mass and lifetime measurements on exotic nuclei at the future storage ring facilities.

Radiation imaging with optically read out GEM-based detectors

NASA Astrophysics Data System (ADS)

Brunbauer, F. M.; Lupberger, M.; Oliveri, E.; Resnati, F.; Ropelewski, L.; Streli, C.; Thuiner, P.; van Stenis, M.

2018-02-01

Modern imaging sensors allow for high granularity optical readout of radiation detectors such as MicroPattern Gaseous Detectors (MPGDs). Taking advantage of the high signal amplification factors achievable by MPGD technologies such as Gaseous Electron Multipliers (GEMs), highly sensitive detectors can be realised and employing gas mixtures with strong scintillation yield in the visible wavelength regime, optical readout of such detectors can provide high-resolution event representations. Applications from X-ray imaging to fluoroscopy and tomography profit from the good spatial resolution of optical readout and the possibility to obtain images without the need for extensive reconstruction. Sensitivity to low-energy X-rays and energy resolution permit energy resolved imaging and material distinction in X-ray fluorescence measurements. Additionally, the low material budget of gaseous detectors and the possibility to couple scintillation light to imaging sensors via fibres or mirrors makes optically read out GEMs an ideal candidate for beam monitoring detectors in high energy physics as well as radiotherapy. We present applications and achievements of optically read out GEM-based detectors including high spatial resolution imaging and X-ray fluorescence measurements as an alternative readout approach for MPGDs. A detector concept for low intensity applications such as X-ray crystallography, which maximises detection efficiency with a thick conversion region but mitigates parallax-induced broadening is presented and beam monitoring capabilities of optical readout are explored. Augmenting high resolution 2D projections of particle tracks obtained with optical readout with timing information from fast photon detectors or transparent anodes for charge readout, 3D reconstruction of particle trajectories can be performed and permits the realisation of optically read out time projection chambers. Combining readily available high performance imaging sensors with compatible scintillating gases and the strong signal amplification factors achieved by MPGDs makes optical readout an attractive alternative to the common concept of electronic readout of radiation detectors. Outstanding signal-to-noise ratios and robustness against electronic noise allow unprecedented imaging capabilities for various applications in fields ranging from high energy physics to medical instrumentation.

Prototyping of MWIR MEMS-based optical filter combined with HgCdTe detector

NASA Astrophysics Data System (ADS)

Kozak, Dmitry A.; Fernandez, Bautista; Velicu, Silviu; Kubby, Joel

2010-02-01

In the past decades, there have been several attempts to create a tunable optical detector with operation in the infrared. The drive for creating such a filter is its wide range of applications, from passive night vision to biological and chemical sensors. Such a device would combine a tunable optical filter with a wide-range detector. In this work, we propose using a Fabry-Perot interferometer centered in the mid-wave infrared (MWIR) spectrum with an HgCdTe detector. Using a MEMS-based interferometer with an integrated Bragg stack will allow in-plane operation over a wide range. Because such devices have a tendency to warp, creating less-than-perfect optical surfaces, the Fabry-Perot interferometer is prototyped using the SOI-MUMPS process to ensure desirable operation. The mechanical design is aimed at optimal optical flatness of the moving membranes and a low operating voltage. The prototype is tested for these requirements. An HgCdTe detector provides greater performance than a pyroelectic detector used in some previous work, allowing for lower noise, greater detection speed and higher sensitivity. Both a custom HgCdTe detector and commercially available pyroelectric detector are tested with commercial optical filter. In previous work, monolithic integration of HgCdTe detectors with optical filters proved to be problematic. Part of this work investigates the best approach to combining these two components, either monolithically in HgCdTe or using a hybrid packaging approach where a silicon MEMS Fabry-Perot filter is bonded at low temperature to a HgCdTe detector.

On the possibilities of large-scale radio and fiber optics detectors in cosmic rays

NASA Technical Reports Server (NTRS)

Gusev, G. A.; Markov, M. A.; Zheleznykh, I. M.

1985-01-01

Different variants of radio and fiber optics detectors for registration of super high energy cascades in the atmosphere and in dense media are discussed. Particularly the possibilities for investigation of quasi horizontal cosmic ray showers (CRS) and simulated muons from these CRS with the help of radio detectors and fiber optics detectors located on the ice surface are considered.

Throughput of Coded Optical CDMA Systems with AND Detectors

NASA Astrophysics Data System (ADS)

Memon, Kehkashan A.; Umrani, Fahim A.; Umrani, A. W.; Umrani, Naveed A.

2012-09-01

Conventional detection techniques used in optical code-division multiple access (OCDMA) systems are not optimal and result in poor bit error rate performance. This paper analyzes the coded performance of optical CDMA systems with AND detectors for enhanced throughput efficiencies and improved error rate performance. The results show that the use of AND detectors significantly improve the performance of an optical channel.

Diamond Pixel Detectors

NASA Astrophysics Data System (ADS)

Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Doroshenko, J.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foster, J.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Gobbi, B.; Grim, G. P.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Lander, R.; Logiudice, A.; Lu, R.; mac Lynne, L.; Manfredotti, C.; Meier, D.; Mishina, M.; Moroni, L.; Oh, A.; Pan, L. S.; Pernicka, M.; Perera, L.; Pirollo, S.; Plano, R.; Procario, M.; Riester, J. L.; Roe, S.; Rott, C.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Wedenig, R.; Weilhammer, P.; White, C.; Zeuner, W.; Zoeller, M.

2001-06-01

Diamond based pixel detectors are a promising radiation-hard technology for use at the LHC. We present first results on a CMS diamond pixel sensor. With a threshold setting of 2000 electrons, an average pixel efficiency of 78% was obtained for normally incident minimum ionizing particles.

Multi-purpose two- and three-dimensional momentum imaging of charged particles for attosecond experiments at 1 kHz repetition rate

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

Månsson, Erik P., E-mail: erik.mansson@sljus.lu.se; Sorensen, Stacey L.; Gisselbrecht, Mathieu

2014-12-15

We report on the versatile design and operation of a two-sided spectrometer for the imaging of charged-particle momenta in two dimensions (2D) and three dimensions (3D). The benefits of 3D detection are to discern particles of different mass and to study correlations between fragments from multi-ionization processes, while 2D detectors are more efficient for single-ionization applications. Combining these detector types in one instrument allows us to detect positive and negative particles simultaneously and to reduce acquisition times by using the 2D detector at a higher ionization rate when the third dimension is not required. The combined access to electronic andmore » nuclear dynamics available when both sides are used together is important for studying photoreactions in samples of increasing complexity. The possibilities and limitations of 3D momentum imaging of electrons or ions in the same spectrometer geometry are investigated analytically and three different modes of operation demonstrated experimentally, with infrared or extreme ultraviolet light and an atomic/molecular beam.« less

Real-time monitoring of BTEX in air via ambient-pressure MPI

NASA Astrophysics Data System (ADS)

Swenson, Orven F.; Carriere, Josef P.; Isensee, Harlan; Gillispie, Gregory D.; Cooper, William F.; Dvorak, Michael A.

1998-05-01

We have developed and begun to field test a very sensitive method for real-time measurements of single-ring aromatic hydrocarbons in ambient air. In this study, we focus on the efficient 1 + 1 resonance enhanced multiphoton ionization (REMPI) of the BTEX species in the narrow region between 266 and 267 nm. We particularly emphasize 266.7 nm, a wavelength at which both benzene and toluene exhibit a sharp absorbance feature and benzene and its alkylated derivatives all absorb. An optical parametric oscillator system generating 266.7 nm, a REMPI cell, and digital oscilloscope detector are mounted on a breadboard attached to a small cart. In the first field test, the cart was wheeled through the various rooms of a chemistry research complex. Leakage of fuel through the gas caps of cars and light trucks in a parking lot was the subject of the second field test. The same apparatus was also used for a study in which the performance of the REMPI detector and a conventional photoionization detector were compared as a BTEX mixture was eluted by gas chromatography. Among the potential applications of the methodology are on-site analysis of combustion and manufacturing processes, soil gas and water headspace monitoring, space cabin and building air quality, and fuel leak detection.

Ionizing radiation detector

DOEpatents

Thacker, Louis H.

1990-01-01

An ionizing radiation detector is provided which is based on the principle of analog electronic integration of radiation sensor currents in the sub-pico to nano ampere range between fixed voltage switching thresholds with automatic voltage reversal each time the appropriate threshold is reached. The thresholds are provided by a first NAND gate Schmitt trigger which is coupled with a second NAND gate Schmitt trigger operating in an alternate switching state from the first gate to turn either a visible or audible indicating device on and off in response to the gate switching rate which is indicative of the level of radiation being sensed. The detector can be configured as a small, personal radiation dosimeter which is simple to operate and responsive over a dynamic range of at least 0.01 to 1000 R/hr.

Ultra High Mass Range Mass Spectrometer System

DOEpatents

Reilly, Peter T. A. [Knoxville, TN

2005-12-06

Applicant's present invention comprises mass spectrometer systems that operate in a mass range from 1 to 10.sup.16 DA. The mass spectrometer system comprising an inlet system comprising an aerodynamic lens system, a reverse jet being a gas flux generated in an annulus moving in a reverse direction and a multipole ion guide; a digital ion trap; and a thermal vaporization/ionization detector system. Applicant's present invention further comprises a quadrupole mass spectrometer system comprising an inlet system having a quadrupole mass filter and a thermal vaporization/ionization detector system. Applicant's present invention further comprises an inlet system for use with a mass spectrometer system, a method for slowing energetic particles using an inlet system. Applicant's present invention also comprises a detector device and a method for detecting high mass charged particles.

Improved detection limits for electrospray ionization on a magnetic sector mass spectrometer by using an array detector.

PubMed

Cody, R B; Tamura, J; Finch, J W; Musselman, B D

1994-03-01

Array detection was compared with point detection for solutions of hen egg-white lysozyme, equine myoglobin, and ubiquitin analyzed by electrospray ionization with a magnetic sector mass spectrometer. The detection limits for samples analyzed by using the array detector system were at least 10 times lower than could be achieved by using a point detector on the same mass spectrometer. The minimum detectable quantity of protein corresponded to a signal-to-background ratio of approximately 2∶1 for a 500 amol/μL solution of hen egg-white lysozyme. However, the ultimate practical sample concentrations appeared to be in the 10-100 fmol/μL range for the analysis of dilute solutions of relatively pure proteins or simple mixtures.

Focal Plane Alignment Utilizing Optical CMM

NASA Technical Reports Server (NTRS)

Liebe, Carl Christian; Meras, Patrick L.; Clark, Gerald J.; Sedaka, Jack J.; Kaluzny, Joel V.; Hirsch, Brian; Decker, Todd A.; Scholtz, Christopher R.

2012-01-01

In many applications, an optical detector has to be located relative to mechanical reference points. One solution is to specify stringent requirements on (1) mounting the optical detector relative to the chip carrier, (2) soldering the chip carrier onto the printed circuit board (PCB), and (3) installing the PCB to the mechanical structure of the subsystem. Figure 1 shows a sketch of an optical detector mounted relative to mechanical reference with high positional accuracy. The optical detector is typically a fragile wafer that cannot be physically touched by any measurement tool. An optical coordinate measuring machine (CMM) can be used to position optical detectors relative to mechanical reference points. This approach will eliminate all requirements on positional tolerances. The only requirement is that the PCB is manufactured with oversized holes. An exaggerated sketch of this situation is shown in Figure 2. The sketch shows very loose tolerances on mounting the optical detector in the chip carrier, loose tolerance on soldering the chip carrier to the PCB, and finally large tolerance on where the mounting screws are located. The PCB is held with large screws and oversized holes. The PCB is mounted loosely so it can move freely around. The optical CMM measures the mechanical reference points. Based on these measurements, the required positions of the optical detector corners can be calculated. The optical CMM is commanded to go to the position where one detector corner is supposed to be. This is indicated with the cross-hairs in Figure 2(a). This figure is representative of the image of the optical CMM monitor. Using a suitable tapping tool, the PCB is manually tapped around until the corner of the optical detector is at the crosshairs of the optical CMM. The CMM is commanded to another corner, and the process is repeated a number of times until all corners of the optical detector are within a distance of 10 to 30 microns of the required position. The situation is sketched in Figure 2(b) (the figure also shows the tapping tool and where to tap). At this point the fasteners for the PCB are torqued slightly so the PCB can still move. The PCB location is adjusted again with the tapping tool. This process is repeated 3 to 4 times until the final torque is achieved. The oversized mounting holes are then filled with a liquid bonding agent to secure the board in position (not shown in the sketch). A 10- to 30-micron mounting accuracy has been achieved utilizing this method..

Rare Earth Optical Temperature Sensor

NASA Technical Reports Server (NTRS)

Chubb, Donald L. (Inventor); Jenkins, Phillip (Inventor)

2004-01-01

A rare earth optical temperature sensor is disclosed for measuring high temperatures. Optical temperature sensors exist that channel emissions from a sensor to a detector using a light pipe. The invention uses a rare earth emitter to transform the sensed thermal energy into a narrow band width optical signal that travels to a detector using a light pipe. An optical bandpass filter at the detector removes any noise signal outside of the band width of the signal from the emitter.

System and Method for Measuring the Transfer Function of a Guided Wave Device

NASA Technical Reports Server (NTRS)

Froggatt, Mark E. (Inventor); Erdogan, Turan (Inventor)

2002-01-01

A method/system are provided for measuring the NxN scalar transfer function elements for an N-port guided wave device. Optical energy of a selected wavelength is generated at a source and directed along N reference optical paths having N reference path lengths. Each reference optical path terminates in one of N detectors such that N reference signals are produced at the N detectors. The reference signals are indicative of amplitude, phase and frequency of the optical energy carried along the N reference optical paths. The optical energy from the source is also directed to the N-ports of the guided wave device and then on to each of the N detectors such that N measurement optical paths are defined between the source and each of the N detectors. A portion of the optical energy is modified in terms of at least one of the amplitude and phase to produce N modified signals at each of the N detectors. At each of the N detectors, each of the N modified signals is combined with a corresponding one of the N reference signals to produce corresponding N combined signals at each of the N detectors. A total of N(sup 2) measurement signals are generated by the N detectors. Each of the N(sup 2) measurement signals is sampled at a wave number increment (Delta)k so that N(sup 2) sampled signals are produced. The NxN transfer function elements are generated using the N(sup 2) sampled signals. Reference and measurement path length constraints are defined such that the N combined signals at each of the N detectors are spatially separated from one another in the time domain.

Radiation response issues for infrared detectors

NASA Technical Reports Server (NTRS)

Kalma, Arne H.

1990-01-01

Researchers describe the most important radiation response issues for infrared detectors. In general, the two key degradation mechanisms in infrared detectors are the noise produced by exposure to a flux of ionizing particles (e.g.; trapped electronics and protons, debris gammas and electrons, radioactive decay of neutron-activated materials) and permanent damage produced by exposure to total dose. Total-dose-induced damage is most often the result of charge trapping in insulators or at interfaces. Exposure to short pulses of ionization (e.g.; prompt x rays or gammas, delayed gammas) will cause detector upset. However, this upset is not important to a sensor unless the recovery time is too long. A few detector technologies are vulnerable to neutron-induced displacement damage, but fortunately most are not. Researchers compare the responses of the new technologies with those of the mainstream technologies of PV HgCdTe and IBC Si:As. One important reason for this comparison is to note where some of the newer technologies have the potential to provide significantly improved radiation hardness compared with that of the mainstream technologies, and thus to provide greater motivation for the pursuit of these technologies.

Measuring ionizing radiation in the atmosphere with a new balloon-borne detector

NASA Astrophysics Data System (ADS)

Aplin, K. L.; Briggs, A. A.; Harrison, R. G.; Marlton, G. J.

2017-05-01

Increasing interest in energetic particle effects on weather and climate has motivated development of a miniature scintillator-based detector intended for deployment on meteorological radiosondes or unmanned airborne vehicles. The detector was calibrated with laboratory gamma sources up to 1.3 MeV and known gamma peaks from natural radioactivity of up to 2.6 MeV. The specifications of our device in combination with the performance of similar devices suggest that it will respond to up to 17 MeV gamma rays. Laboratory tests show that the detector can measure muons at the surface, and it is also expected to respond to other ionizing radiation including, for example, protons, electrons (>100 keV), and energetic helium nuclei from cosmic rays or during space weather events. Its estimated counting error is ±10%. Recent tests, when the detector was integrated with a meteorological radiosonde system and carried on a balloon to 25 km altitude, identified the transition region between energetic particles near the surface, which are dominated by terrestrial gamma emissions, to higher-energy particles in the free troposphere.

Current developments and tests of small x-ray optical systems for space applications

NASA Astrophysics Data System (ADS)

Pina, L.; Hudec, R.; Inneman, A.; Doubravová, D.; Marsikova, V.

2017-05-01

The paper addresses the X-ray monitoring for astrophysical applications. A novel approach based on the use of 1D and 2D "Lobster eye" optics in combination with Timepix X-ray detector in the energy range 3 - 40 keV was further studied. Wide-field optical system of this type has not been used in space yet. Designed wide-field optical system combined with Timepix X-ray detector is described together with latest experimental results obtained during laboratory tests. Proposed project includes theoretical study and a functional sample of the Timepix X-ray detector with multifoil wide-field X-ray "Lobster eye" optics. Using optics to focus X-rays on a detector is the only solution in cases where intensity of impinging X-ray radiation is below the sensitivity of the detector, e.g. while monitoring astrophysical objects in space, or phenomena in the Earth's atmosphere. The optical system is considered to be used in a student rocket experiment.

Making MUSIC: A multiple sampling ionization chamber

NASA Astrophysics Data System (ADS)

Shumard, B.; Henderson, D. J.; Rehm, K. E.; Tang, X. D.

2007-08-01

A multiple sampling ionization chamber (MUSIC) was developed for use in conjunction with the Atlas scattering chamber (ATSCAT). This chamber was developed to study the (α, p) reaction in stable and radioactive beams. The gas filled ionization chamber is used as a target and detector for both particles in the outgoing channel (p + beam particles for elastic scattering or p + residual nucleus for (α, p) reactions). The MUSIC detector is followed by a Si array to provide a trigger for anode events. The anode events are gated by a gating grid so that only (α, p) reactions where the proton reaches the Si detector result in an anode event. The MUSIC detector is a segmented ionization chamber. The active length of the chamber is 11.95 in. and is divided into 16 equal anode segments (3.5 in. × 0.70 in. with 0.3 in. spacing between pads). The dead area of the chamber was reduced by the addition of a Delrin snout that extends 0.875 in. into the chamber from the front face, to which a mylar window is affixed. 0.5 in. above the anode is a Frisch grid that is held at ground potential. 0.5 in. above the Frisch grid is a gating grid. The gating grid functions as a drift electron barrier, effectively halting the gathering of signals. Setting two sets of alternating wires at differing potentials creates a lateral electric field which traps the drift electrons, stopping the collection of anode signals. The chamber also has a reinforced mylar exit window separating the Si array from the target gas. This allows protons from the (α, p) reaction to be detected. The detection of these protons opens the gating grid to allow the drift electrons released from the ionizing gas during the (α, p) reaction to reach the anode segment below the reaction.

Development of CDMS-II Surface Event Rejection Techniques and Their Extensions to Lower Energy Thresholds

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

Hofer, Thomas James

2014-12-01

The CDMS-II phase of the Cryogenic Dark Matter Search, a dark matter direct-detection experiment, was operated at the Soudan Underground Laboratory from 2003 to 2008. The full payload consisted of 30 ZIP detectors, totaling approximately 1.1 kg of Si and 4.8 kg of Ge, operated at temperatures of 50 mK. The ZIP detectors read out both ionization and phonon pulses from scatters within the crystals; channel segmentation and analysis of pulse timing parameters allowed e ective ducialization of the crystal volumes and background rejection su cient to set world-leading limits at the times of their publications. A full re-analysis ofmore » the CDMS-II data was motivated by an improvement in the event reconstruction algorithms which improved the resolution of ionization energy and timing information. The Ge data were re-analyzed using three distinct background-rejection techniques; the Si data from runs 125 - 128 were analyzed for the rst time using the most successful of the techniques from the Ge re-analysis. The results of these analyses prompted a novel \\mid-threshold" analysis, wherein energy thresholds were lowered but background rejection using phonon timing information was still maintained. This technique proved to have signi cant discrimination power, maintaining adequate signal acceptance and minimizing background leakage. The primary background for CDMS-II analyses comes from surface events, whose poor ionization collection make them di cult to distinguish from true nuclear recoil events. The novel detector technology of SuperCDMS, the successor to CDMS-II, uses interleaved electrodes to achieve full ionization collection for events occurring at the top and bottom detector surfaces. This, along with dual-sided ionization and phonon instrumentation, allows for excellent ducialization and relegates the surface-event rejection techniques of CDMS-II to a secondary level of background discrimination. Current and future SuperCDMS results hold great promise for mid- to low-mass WIMP-search results.« less

FIELD ANALYTICAL SCREENING PROGRAM: PCP METHOD - INNOVATIVE TECHNOLOGY EVALUATION REPORT

EPA Science Inventory

The Field Analytical Screening Program (FASP) pentachlorophenol (PCP) method uses a gas chromatograph (GC) equipped with a megabore capillary column and flame ionization detector (FID) and electron capture detector (ECD) to identify and quantify PCP. The FASP PCP method is design...

Search for lightly ionizing particles with the MACRO detector

NASA Astrophysics Data System (ADS)

Ambrosio, M.; Antolini, R.; Auriemma, G.; Bakari, D.; Baldini, A.; Barbarino, G. C.; Barish, B. C.; Battistoni, G.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bisi, V.; Bloise, C.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Cecchini, S.; Cei, F.; Chiarella, V.; Choudhary, B. C.; Coutu, S.; de Cataldo, G.; Dekhissi, H.; de Marzo, C.; de Mitri, I.; Derkaoui, J.; de Vincenzi, M.; di Credico, A.; Erriquez, O.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Gray, L.; Grillo, A.; Guarino, F.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Iarocci, E.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D. S.; Lipari, P.; Longley, N. P.; Longo, M. J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M. N.; Michael, D. G.; Mikheyev, S.; Miller, L.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolò, D.; Nolty, R.; Orth, C.; Okada, C.; Osteria, G.; Ouchrif, M.; Palamara, O.; Patera, V.; Patrizii, L.; Pazzi, R.; Peck, C. W.; Perrone, L.; Petrera, S.; Pistilli, P.; Popa, V.; Rainò, A.; Reynoldson, J.; Ronga, F.; Satriano, C.; Satta, L.; Scapparone, E.; Scholberg, K.; Sciubba, A.; Serra, P.; Sioli, M.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J. L.; Sulak, L. R.; Surdo, A.; Tarlè, G.; Togo, V.; Vakili, M.; Vilela, E.; Walter, C. W.; Webb, R.

2000-09-01

A search for lightly ionizing particles has been performed with the MACRO detector. This search was sensitive to particles with charges between 15 e and close to the charge of an electron, with β between approximately 0.25 and 1.0. Unlike previous searches both single track events and tracks buried within high multiplicity muon showers were examined. In a period of approximately one year no candidates were observed. Assuming an isotropic flux, for the single track sample this corresponds to a 90% C.L. upper flux limit Φ<=9.2×10-15 cm-2 s-1 sr-1.

Characterization of Novel Operation Modes for Secondary Emission Ionization Calorimetry

NASA Astrophysics Data System (ADS)

Tiras, Emrah; Dilsiz, Kamuran; Ogul, Hasan; Snyder, Christina; Bilki, Burak; Onel, Yasar; Winn, David

2017-01-01

Secondary Emission (SE) Ionization Calorimetry is a novel technique to measure electromagnetic showers in high radiation environments. We have developed new operation modes by modifying the bias of the conventional PMT circuits. Hamamatsu single anode R7761 and multi-anode R5900-00-M16 Photomultiplier Tubes (PMTs) with modified bases are used as SE detector modules in our SE calorimetry prototype. In this detector module, the first dynode is used as the active media as opposed to photocathode. Here, we report the technical design of new modes and characterization measurements for both SE and PMT modes.

Recent developments in cyanide detection: A review

PubMed Central

Ma, Jian; Dasgupta, Purnendu K.

2010-01-01

The extreme toxicity of cyanide and environmental concerns from its continued industrial use continue to generate interest in facile and sensitive methods for cyanide detection. In recent years there is also additional recognition of HCN toxicity from smoke inhalation and potential use of cyanide as a weapon of terrorism. This review summarizes the literature since 2005 on cyanide measurement in different matrices ranging from drinking water and wastewater, to cigarette smoke and exhaled breath to biological fluids like blood, urine and saliva. The dramatic increase in the number of publications on cyanide measurement is indicative of the great interest in this field not only from analytical chemists, but also researchers from diverse environmental, medical, forensic and clinical arena. The recent methods cover both established and emerging analytical disciplines and include naked eye visual detection, spectrophotometry/colorimetry, capillary electrophoresis with optical absorbance detection, fluorometry, chemiluminescence, near-infrared cavity ring down spectroscopy, atomic absorption spectrometry, electrochemical methods (potentiometry/amperometry/ion chromatography-pulsed amperometry), mass spectrometry (selected ion flow tube mass spectrometry, electrospray ionization mass spectrometry, gas chromatography-mass spectrometry), gas chromatography (nitrogen phosphorus detector, electron capture detector) and quartz crystal mass monitors. PMID:20599024

Geometry Survey of the Time-of-Flight Neutron-Elastic Scattering (Antonella) Experiment

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

Oshinowo, Babatunde O.; Izraelevitch, Federico

The Antonella experiment is a measurement of the ionization efficiency of nuclear recoils in silicon at low energies [1]. It is a neutron elastic scattering experiment motivated by the search for dark matter particles. In this experiment, a proton beam hits a lithium target and neutrons are produced. The neutron shower passes through a collimator that produces a neutron beam. The beam illuminates a silicon detector. With a certain probability, a neutron interacts with a silicon nucleus of the detector producing elastic scattering. After the interaction, a fraction of the neutron energy is transferred to the silicon nucleus which acquiresmore » kinetic energy and recoils. This kinetic energy is then dissipated in the detector producing ionization and thermal energy. The ionization produced is measured with the silicon detector electronics. On the other hand, the neutron is scattered out of the beam. A neutron-detector array (made of scintillator bars) registers the neutron arrival time and the scattering angle to reconstruct the kinematics of the neutron-nucleus interaction with the time-of-flight technique [2]. In the reconstruction equations, the energy of the nuclear recoil is a function of the scattering angle with respect to the beam direction, the time-of-flight of the neutron and the geometric distances between components of the setup (neutron-production target, silicon detector, scintillator bars). This paper summarizes the survey of the different components of the experiment that made possible the off-line analysis of the collected data. Measurements were made with the API Radian Laser Tracker and I-360 Probe Wireless. The survey was completed at the University of Notre Dame, Indiana, USA in February 2015.« less

Wide-range radioactive-gas-concentration detector

DOEpatents

Anderson, D.F.

1981-11-16

A wide-range radioactive-gas-concentration detector and monitor capable of measuring radioactive-gas concentrations over a range of eight orders of magnitude is described. The device is designed to have an ionization chamber sufficiently small to give a fast response time for measuring radioactive gases but sufficiently large to provide accurate readings at low concentration levels. Closely spaced parallel-plate grids provide a uniform electric field in the active region to improve the accuracy of measurements and reduce ion migration time so as to virtually eliminate errors due to ion recombination. The parallel-plate grids are fabricated with a minimal surface area to reduce the effects of contamination resulting from absorption of contaminating materials on the surface of the grids. Additionally, the ionization-chamber wall is spaced a sufficient distance from the active region of the ionization chamber to minimize contamination effects.

Interactive display system having a matrix optical detector

DOEpatents

Veligdan, James T.; DeSanto, Leonard

2007-01-23

A display system includes a waveguide optical panel having an inlet face and an opposite outlet face. An image beam is projected across the inlet face laterally and transversely for display on the outlet face. An optical detector including a matrix of detector elements is optically aligned with the inlet face for detecting a corresponding lateral and transverse position of an inbound light spot on the outlet face.

Analyzing the Formation, Physicochemical, and Optical Properties of Aging Biomass Burning Aerosol Using an Indoor Smog Chamber

NASA Astrophysics Data System (ADS)

Smith, D. M.; Fiddler, M. N.; Bililign, S.; Spann, M.

2017-12-01

Biomass burning (BB) is recognized as one of the largest sources of absorbing aerosols in the atmosphere and significantly influences the radiative properties of the atmosphere. The chemical composition and physical properties of particles evolve during their atmospheric lifetime due to condensation, oxidation reactions, etc., which alters their optical properties. To this end, an indoor smog chamber was constructed to study aging BB aerosol in a laboratory setting. Injections to the chamber, including NOx, O3, and various biogenic and anthropogenic VOCs, can simulate a variety of atmospheric conditions. These components and some of their oxidation products are monitored during the aging process. A tube furnace is used for combustion of biomass to be introduced to the chamber, while size distributions are taken as the aerosol ages. Online measurements of optical properties are determined using a Cavity Ring-down Spectrometry and Integrating Nephelometry system. Chemical properties are measured from samples captured on filters and analyzed using Ultra-Performance Liquid Chromatography coupled in-line to both a Diode Array Detector and High-Resolution Time-of-Flight Mass Spectrometer equipped with electrospray ionization. The measured changes in the optical properties as a function of particle size, aging, and chemical properties are presented for fuel sources used in Africa.

Optical Characterization of the SPT-3G Camera

NASA Astrophysics Data System (ADS)

Pan, Z.; Ade, P. A. R.; Ahmed, Z.; Anderson, A. J.; Austermann, J. E.; Avva, J. S.; Thakur, R. Basu; Bender, A. N.; Benson, B. A.; Carlstrom, J. E.; Carter, F. W.; Cecil, T.; Chang, C. L.; Cliche, J. F.; Cukierman, A.; Denison, E. V.; de Haan, T.; Ding, J.; Dobbs, M. A.; Dutcher, D.; Everett, W.; Foster, A.; Gannon, R. N.; Gilbert, A.; Groh, J. C.; Halverson, N. W.; Harke-Hosemann, A. H.; Harrington, N. L.; Henning, J. W.; Hilton, G. C.; Holzapfel, W. L.; Huang, N.; Irwin, K. D.; Jeong, O. B.; Jonas, M.; Khaire, T.; Kofman, A. M.; Korman, M.; Kubik, D.; Kuhlmann, S.; Kuo, C. L.; Lee, A. T.; Lowitz, A. E.; Meyer, S. S.; Michalik, D.; Montgomery, J.; Nadolski, A.; Natoli, T.; Nguyen, H.; Noble, G. I.; Novosad, V.; Padin, S.; Pearson, J.; Posada, C. M.; Rahlin, A.; Ruhl, J. E.; Saunders, L. J.; Sayre, J. T.; Shirley, I.; Shirokoff, E.; Smecher, G.; Sobrin, J. A.; Stark, A. A.; Story, K. T.; Suzuki, A.; Tang, Q. Y.; Thompson, K. L.; Tucker, C.; Vale, L. R.; Vanderlinde, K.; Vieira, J. D.; Wang, G.; Whitehorn, N.; Yefremenko, V.; Yoon, K. W.; Young, M. R.

2018-05-01

The third-generation South Pole Telescope camera is designed to measure the cosmic microwave background across three frequency bands (centered at 95, 150 and 220 GHz) with ˜ 16,000 transition-edge sensor (TES) bolometers. Each multichroic array element on a detector wafer has a broadband sinuous antenna that couples power to six TESs, one for each of the three observing bands and both polarizations, via lumped element filters. Ten detector wafers populate the detector array, which is coupled to the sky via a large-aperture optical system. Here we present the frequency band characterization with Fourier transform spectroscopy, measurements of optical time constants, beam properties, and optical and polarization efficiencies of the detector array. The detectors have frequency bands consistent with our simulations and have high average optical efficiency which is 86, 77 and 66% for the 95, 150 and 220 GHz detectors. The time constants of the detectors are mostly between 0.5 and 5 ms. The beam is round with the correct size, and the polarization efficiency is more than 90% for most of the bolometers.

Characterization of a multilayer ionization chamber prototype for fast verification of relative depth ionization curves and spread-out-Bragg-peaks in light ion beam therapy.

PubMed

Mirandola, Alfredo; Magro, Giuseppe; Lavagno, Marco; Mairani, Andrea; Molinelli, Silvia; Russo, Stefania; Mastella, Edoardo; Vai, Alessandro; Maestri, Davide; La Rosa, Vanessa; Ciocca, Mario

2018-05-01

To dosimetrically characterize a multilayer ionization chamber (MLIC) prototype for quality assurance (QA) of pristine integral ionization curves (ICs) and spread-out-Bragg-peaks (SOBPs) for scanning light ion beams. QUBE (De.Tec.Tor., Torino, Italy) is a modular detector designed for QA in particle therapy (PT). Its main module is a MLIC detector, able to evaluate particle beam relative depth ionization distributions at different beam energies and modulations. The charge collecting electrodes are made of aluminum, for a nominal water equivalent thickness (WET) of ~75 mm. The detector prototype was calibrated by acquiring the signals in the initial plateau region of a pristine BP and in terms of WET. Successively, it was characterized in terms of repeatability response, linearity, short-term stability and dose rate dependence. Beam-induced measurements of activation in terms of ambient dose equivalent rate were also performed. To increase the detector coarse native spatial resolution (~2.3 mm), several consecutive acquisitions with a set of certified 0.175-mm-thick PMMA sheets (Goodfellow, Cambridge Limited, UK), placed in front of the QUBE mylar entrance window, were performed. The ICs/SOBPs were achieved as the result of the sum of the set of measurements, made up of a one-by-one PMMA layer acquisition. The newly obtained detector spatial resolution allowed the experimental measurements to be properly comparable against the reference curves acquired in water with the PTW Peakfinder. Furthermore, QUBE detector was modeled in the FLUKA Monte Carlo (MC) code following the technical design details and ICs/SOBPs were calculated. Measurements showed a high repeatability: mean relative standard deviation within ±0.5% for all channels and both particle types. Moreover, the detector response was linear with dose (R 2  > 0.998) and independent on the dose rate. The mean deviation over the channel-by-channel readout respect to the reference beam flux (100%) was equal to 0.7% (1.9%) for the 50% (20%) beam flux level. The short-term stability of the gain calibration was very satisfying for both particle types: the channel mean relative standard deviation was within ±1% for all the acquisitions performed at different times. The ICs obtained with the MLIC QUBE at improved resolution satisfactorily matched both the MC simulations and the reference curves acquired with Peakfinder. Deviations from the reference values in terms of BP position, peak width and distal fall-off were submillimetric for both particle types in the whole investigated energy range. For modulated SOBPs, a submillimetric deviation was found when comparing both experimental MLIC QUBE data against the reference values and MC calculations. The relative dose deviations for the experimental MLIC QUBE acquisitions, with respect to Peakfinder data, ranged from ~1% to ~3.5%. Maximum value of 14.1 μSv/h was measured in contact with QUBE entrance window soon after a long irradiation with carbon ions. MLIC QUBE appears to be a promising detector for accurately measuring pristine ICs and SOBPs. A simple procedure to improve the intrinsic spatial resolution of the detector is proposed. Being the detector very accurate, precise, fast responding, and easy to handle, it is therefore well suited for daily checks in PT. © 2018 American Association of Physicists in Medicine.

Design of a fiber-optic interrogator module for telecommunication satellites

NASA Astrophysics Data System (ADS)

Putzer, Philipp; Koch, Alexander W.; Plattner, Markus; Hurni, Andreas; Manhart, Markus

2017-11-01

In this paper we present the results of the radiation tests performed on the optical components of the fiber-optic interrogator module as a part of the Hybrid Sensor Bus (HSB) system. The HSB-system is developed in the frame of an ESAARTES program and will be verified as flight demonstrator onboard the German Heinrich Hertz satellite in 2016. The HSB system is based on a modular concept which includes sensor interrogation modules based on I2C electrical and fiber Bragg grating (FBG) fiber-optical sensor elements. Onboard fiber-optic sensing allows the implementation of novel control and monitoring methods. For read-out of multiple FBG sensors, a design based on a tunable laser diode as well as a design based on a spectrometer is considered. The expected and tested total ionizing dose (TID) applicable to the HSB system is in the range between 100 krad and 300 krad inside the satellite in the geostationary orbit over a life time of 15 years. We present radiation test results carried out on critical optical components to be used in the fiber-optic interrogation module. These components are a modulated grating Y-branch (MGY) tunable laser diode acting as light source for the tuning laser approach, the line detector of a spectrometer, photodetectors and the FBG sensors acting as sensor elements. A detailed literature inquiry of radiation effects on optical fibers and FBG sensors, is also included in the paper. The fiber-optic interrogator module implemented in the HSB system is based on the most suitable technology, which sustains the harsh environment in the geostationary orbit.

Camera System MTF: combining optic with detector

NASA Astrophysics Data System (ADS)

Andersen, Torben B.; Granger, Zachary A.

2017-08-01

MTF is one of the most common metrics used to quantify the resolving power of an optical component. Extensive literature is dedicated to describing methods to calculate the Modulation Transfer Function (MTF) for stand-alone optical components such as a camera lens or telescope, and some literature addresses approaches to determine an MTF for combination of an optic with a detector. The formulations pertaining to a combined electro-optical system MTF are mostly based on theory, and assumptions that detector MTF is described only by the pixel pitch which does not account for wavelength dependencies. When working with real hardware, detectors are often characterized by testing MTF at discrete wavelengths. This paper presents a method to simplify the calculation of a polychromatic system MTF when it is permissible to consider the detector MTF to be independent of wavelength.

Direct detection of MeV-scale dark matter utilizing germanium internal amplification for the charge created by the ionization of impurities

NASA Astrophysics Data System (ADS)

Mei, D.-M.; Wang, G.-J.; Mei, H.; Yang, G.; Liu, J.; Wagner, M.; Panth, R.; Kooi, K.; Yang, Y.-Y.; Wei, W.-Z.

2018-03-01

Light, MeV-scale dark matter (DM) is an exciting DM candidate that is undetectable by current experiments. A germanium (Ge) detector utilizing internal charge amplification for the charge carriers created by the ionization of impurities is a promising new technology with experimental sensitivity for detecting MeV-scale DM. We analyze the physics mechanisms of the signal formation, charge creation, charge internal amplification, and the projected sensitivity for directly detecting MeV-scale DM particles. We present a design for a novel Ge detector at helium temperature (˜ 4 K) enabling ionization of impurities from DM impacts. With large localized E-fields, the ionized excitations can be accelerated to kinetic energies larger than the Ge bandgap at which point they can create additional electron-hole pairs, producing intrinsic amplification to achieve an ultra-low energy threshold of ˜ 0.1 eV for detecting low-mass DM particles in the MeV scale. Correspondingly, such a Ge detector with 1 kg-year exposure will have high sensitivity to a DM-nucleon cross section of ˜ 5 × 10^{-45} cm2 at a DM mass of ˜ 10 MeV/c2 and a DM-electron cross section of ˜ 5 × 10^{-46} cm2 at a DM mass of ˜ 1 MeV/c^2.

A systematic characterization of the low-energy photon response of plastic scintillation detectors.

PubMed

Boivin, Jonathan; Beddar, Sam; Bonde, Chris; Schmidt, Daniel; Culberson, Wesley; Guillemette, Maxime; Beaulieu, Luc

2016-08-07

To characterize the low energy behavior of scintillating materials used in plastic scintillation detectors (PSDs), 3 PSDs were developed using polystyrene-based scintillating materials emitting in different wavelengths. These detectors were exposed to National Institute of Standards and Technology (NIST)-matched low-energy beams ranging from 20 kVp to 250 kVp, and to (137)Cs and (60)Co beams. The dose in polystyrene was compared to the dose in air measured by NIST-calibrated ionization chambers at the same location. Analysis of every beam quality spectrum was used to extract the beam parameters and the effective mass energy-absorption coefficient. Monte Carlo simulations were also performed to calculate the energy absorbed in the scintillators' volume. The scintillators' expected response was then compared to the experimental measurements and an energy-dependent correction factor was identified to account for low-energy quenching in the scintillators. The empirical Birks model was then compared to these values to verify its validity for low-energy electrons. The clear optical fiber response was below 0.2% of the scintillator's light for x-ray beams, indicating that a negligible amount of fluorescence contamination was produced. However, for higher-energy beams ((137)Cs and (60)Co), the scintillators' response was corrected for the Cerenkov stem effect. The scintillators' response increased by a factor of approximately 4 from a 20 kVp to a (60)Co beam. The decrease in sensitivity from ionization quenching reached a local minimum of about [Formula: see text] between 40 keV and 60 keV x-ray beam mean energy, but dropped by 20% for very low-energy (13 keV) beams. The Birks model may be used to fit the experimental data, but it must take into account the energy dependence of the kB quenching parameter. A detailed comprehension of intrinsic scintillator response is essential for proper calibration of PSD dosimeters for radiology.

A systematic characterization of the low-energy photon response of plastic scintillation detectors

NASA Astrophysics Data System (ADS)

Boivin, Jonathan; Beddar, Sam; Bonde, Chris; Schmidt, Daniel; Culberson, Wesley; Guillemette, Maxime; Beaulieu, Luc

2016-08-01

To characterize the low energy behavior of scintillating materials used in plastic scintillation detectors (PSDs), 3 PSDs were developed using polystyrene-based scintillating materials emitting in different wavelengths. These detectors were exposed to National Institute of Standards and Technology (NIST)-matched low-energy beams ranging from 20 kVp to 250 kVp, and to 137Cs and 60Co beams. The dose in polystyrene was compared to the dose in air measured by NIST-calibrated ionization chambers at the same location. Analysis of every beam quality spectrum was used to extract the beam parameters and the effective mass energy-absorption coefficient. Monte Carlo simulations were also performed to calculate the energy absorbed in the scintillators’ volume. The scintillators’ expected response was then compared to the experimental measurements and an energy-dependent correction factor was identified to account for low-energy quenching in the scintillators. The empirical Birks model was then compared to these values to verify its validity for low-energy electrons. The clear optical fiber response was below 0.2% of the scintillator’s light for x-ray beams, indicating that a negligible amount of fluorescence contamination was produced. However, for higher-energy beams (137Cs and 60Co), the scintillators’ response was corrected for the Cerenkov stem effect. The scintillators’ response increased by a factor of approximately 4 from a 20 kVp to a 60Co beam. The decrease in sensitivity from ionization quenching reached a local minimum of about 11%+/- 1% between 40 keV and 60 keV x-ray beam mean energy, but dropped by 20% for very low-energy (13 keV) beams. The Birks model may be used to fit the experimental data, but it must take into account the energy dependence of the kB quenching parameter. A detailed comprehension of intrinsic scintillator response is essential for proper calibration of PSD dosimeters for radiology.

Radiation Response of Emerging High Gain, Low Noise Detectors

NASA Technical Reports Server (NTRS)

Becker, Heidi N.; Farr, William H; Zhu, David Q.

2007-01-01

Data illustrating the radiation response of emerging high gain, low noise detectors are presented. Ionizing dose testing of silicon internal discrete avalanche photodiodes, and 51-MeV proton testing of InGaAs/InAlAs avalanche photodiodes operated in Geiger mode are discussed.

Ionizing radiation measurements on LDEF: A0015 Free flyer biostack experiment

NASA Technical Reports Server (NTRS)

Benton, E. V.; Frank, A. L.; Benton, E. R.; Csige, I.; Frigo, L. A.

1995-01-01

This report covers the analysis of passive radiation detectors flown as part of the A0015 Free Flyer Biostack on LDEF (Long Duration Exposure Facility). LET (linear energy transfer) spectra and track density measurements were made with CR-39 and Polycarbonate plastic nuclear track detectors. Measurements of total absorbed dose were carried out using Thermoluminescent Detectors. Thermal and resonance neutron dose equivalents were measured with LiF/CR-39 detectors. High energy neutron and proton dose equivalents were measured with fission foil/CR-39 detectors.

Charge distribution and response time for a modulation-doped extrinsic infrared detector

NASA Technical Reports Server (NTRS)

Hadek, Victor

1987-01-01

The electric charge distribution and response time of a modulation-doped extrinsic infrared detector are determined. First, it is demonstrated theoretically that the photoconductive layer is effectively depleted of ionized majority-impurity charges so that scattering is small and mobility is high for photogenerated carriers. Then, using parameters appropriate to an actual detector, the predicted response time is 10 to the -8th to about 10 to the -9th s, which is much faster than comparable conventional detectors. Thus, the modulation-doped detector design would be valuable for heterodyne applications.

Multi-channel infrared thermometer

DOEpatents

Ulrickson, Michael A.

1986-01-01

A device for measuring the two-dimensional temperature profile of a surface comprises imaging optics for generating an image of the light radiating from the surface; an infrared detector array having a plurality of detectors; and a light pipe array positioned between the imaging optics and the detector array for sampling, transmitting, and distributing the image over the detector surfaces. The light pipe array includes one light pipe for each detector in the detector array.

Lead foil wrapping of the plastic scintillators for the gamma ray detection: optical reflector or spectrum intensifier?

NASA Astrophysics Data System (ADS)

Taheri, A.; Askari, M.; Taghan Sasanpour, M.

2017-08-01

This paper studies the effect of lead wrapping on the response of the plastic scintillators as gamma detectors. Experimental tests and Geant4 simulations showed that lead wrapping cannot increase the gamma absorption efficiency of the detector but, as a reflector, it can improve the optical properties of the detector. The reflectivity of the lead foil as an optical reflector was determined equal to 66% using an experimental-simulation combined method. Based on the obtained results, the optical collection efficiency of the detector was also increased about 4% after employing the lead reflector.

Energy response corrections for profile measurements using a combination of different detector types.

PubMed

Wegener, Sonja; Sauer, Otto A

2018-02-01

Different detector properties will heavily affect the results of off-axis measurements outside of radiation fields, where a different energy spectrum is encountered. While a diode detector would show a high spatial resolution, it contains high atomic number elements, which lead to perturbations and energy-dependent response. An ionization chamber, on the other hand, has a much smaller energy dependence, but shows dose averaging over its larger active volume. We suggest a way to obtain spatial energy response corrections of a detector independent of its volume effect for profiles of arbitrary fields by using a combination of two detectors. Measurements were performed at an Elekta Versa HD accelerator equipped with an Agility MLC. Dose profiles of fields between 10 × 4 cm² and 0.6 × 0.6 cm² were recorded several times, first with different small-field detectors (unshielded diode 60012 and stereotactic field detector SFD, microDiamond, EDGE, and PinPoint 31006) and then with a larger volume ionization chamber Semiflex 31010 for different photon beam qualities of 6, 10, and 18 MV. Correction factors for the small-field detectors were obtained from the readings of the respective detector and the ionization chamber using a convolution method. Selected profiles were also recorded on film to enable a comparison. After applying the correction factors to the profiles measured with different detectors, agreement between the detectors and with profiles measured on EBT3 film was improved considerably. Differences in the full width half maximum obtained with the detectors and the film typically decreased by a factor of two. Off-axis correction factors outside of a 10 × 1 cm² field ranged from about 1.3 for the EDGE diode about 10 mm from the field edge to 0.7 for the PinPoint 31006 25 mm from the field edge. The microDiamond required corrections comparable in size to the Si-diodes and even exceeded the values in the tail region of the field. The SFD was found to require the smallest correction. The corrections typically became larger for higher energies and for smaller field sizes. With a combination of two detectors, experimentally derived correction factors can be obtained. Application of those factors leads to improved agreement between the measured profiles and those recorded on EBT3 film. The results also complement so far only Monte Carlo-simulated values for the off-axis response of different detectors. © 2017 American Association of Physicists in Medicine.

Optical sectioning in wide-field microscopy obtained by dynamic structured light illumination and detection based on a smart pixel detector array.

PubMed

Mitić, Jelena; Anhut, Tiemo; Meier, Matthias; Ducros, Mathieu; Serov, Alexander; Lasser, Theo

2003-05-01

Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing.

Compact cosmic ray detector for unattended atmospheric ionization monitoring

NASA Astrophysics Data System (ADS)

Aplin, K. L.; Harrison, R. G.

2010-12-01

Two vertical cosmic ray telescopes for atmospheric cosmic ray ionization event detection are compared. Counter A, designed for low power remote use, was deployed in the Welsh mountains; its event rate increased with altitude as expected from atmospheric cosmic ray absorption. Independently, Counter B's event rate was found to vary with incoming particle acceptance angle. Simultaneous co-located comparison of both telescopes exposed to atmospheric ionization showed a linear relationship between their event rates.

Medical gamma ray imaging

DOEpatents

Osborne, Louis S.; Lanza, Richard C.

1984-01-01

A method and apparatus for determining the distribution of a position-emitting radioisotope into an object, the apparatus consisting of a wire mesh radiation converter, an ionizable gas for propagating ionization events caused by electrodes released by the converter, a drift field, a spatial position detector and signal processing circuitry for correlating near-simultaneous ionization events and determining their time differences, whereby the position sources of back-to-back collinear radiation can be located and a distribution image constructed.

The MoEDAL experiment at the LHC. Searching beyond the standard model

NASA Astrophysics Data System (ADS)

Pinfold, James L.

2016-11-01

MoEDAL is a pioneering experiment designed to search for highly ionizing avatars of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles. Its groundbreaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; what is the mechanism for the generation of mass; does magnetic charge exist; what is the nature of dark matter; and, how did the big-bang develop. MoEDAL's purpose is to meet such far-reaching challenges at the frontier of the field. The innovative MoEDAL detector employs unconventional methodologies tuned to the prospect of discovery physics. The largely passive MoEDAL detector, deployed at Point 8 on the LHC ring, has a dual nature. First, it acts like a giant camera, comprised of nuclear track detectors - analyzed offline by ultra fast scanning microscopes - sensitive only to new physics. Second, it is uniquely able to trap the particle messengers of physics beyond the Standard Model for further study. MoEDAL's radiation environment is monitored by a state-of-the-art real-time TimePix pixel detector array. A new MoEDAL sub-detector to extend MoEDAL's reach to millicharged, minimally ionizing, particles (MMIPs) is under study Finally we shall describe the next step for MoEDAL called Cosmic MoEDAL, where we define a very large high altitude array to take the search for highly ionizing avatars of new physics to higher masses that are available from the cosmos.

Scintillating fibres coupled to silicon photomultiplier prototypes for fast beam monitoring and thin timing detectors

NASA Astrophysics Data System (ADS)

Papa, A.; Kettle, P.-R.; Ripiccini, E.; Rutar, G.

2016-07-01

Several scintillating fibre prototypes (single- and double-layers) made of 250 μm multi-clad square fibres coupled to silicon photomultiplier have been studied using electrons, positrons and muons at different energies. Current measurements show promising results: already for a single fibre layer and minimum ionizing particles we obtain a detection efficiency ≥ 95 % (mean collected light/fibre ≈ 8 phe), a timing resolution of 550 ps/fibre and a foreseen spatial resolution < 100 μm, based on the achieved negligible optical cross-talk between fibres (< 1 %). We will also discuss the performances of a double-layer staggered prototype configuration, for which a full detection efficiency (≥ 99 %) has been measured together with a timing resolution of ≈ 400 ps for double hit events.

A complex Lyman limit system at z=1.9 towards HS 1103+6416

NASA Astrophysics Data System (ADS)

Köhler, S.; Reimers, D.; Tytler, D.; Hagen, H.-J.; Barlow, T.; Burles, S.

1999-02-01

We analyse absorption lines in optical and ultraviolet spectra of the bright (V=15.8, z=2.19) QSO HS 1103+6416. High-resolution (FWHM =8 km s(-1) ) optical spectra have been obtained with the Keck 10 m telescope in the range from 3180 to 5780 Angstroms. Ultraviolet observations in the range from 1150 to 3280 Angstroms were performed with the FOS and the GHRS onboard the Hubble Space Telescope (HST). In this paper we concentrate our discussion on a complex Lyman limit system (LLS) at z=1.89. Absorption lines by carbon, silicon and aluminum in the optical spectra reveal a complex velocity structure with at least 11 components spanning a velocity range of 200 km s(-1) . From the Lyman limit in the ultraviolet spectra we derive a total neutral hydrogen column density of log N(H i) =17.46 cm(-2) . Column densities of heavy elements in the individual components were derived by Voigt profile fitting. The eleven components can be subdivided roughly into three groups: Components 2, 3 and 6 with radial velocities v = -129... -95 km s(-1) with low ionization (L), components 4, 5, 7, 8 (v = -75... +2) with intermediate ionization (I), and components 1, 9, 10, 11 (v = -129, +34... +57) with high ionization (H). In order to study the ionization and abundances in these systems we compare the observed column densities with photoionization models. The observed absorption in the optical data can be explained by individual clouds with slightly varying metal abundances photoionized by slightly different radiation fields. Highly ionized components favour the extragalactic radiation field as calculated by Haardt & Madau (\\cite{Haardt96}) while the components of low and intermediate ionization are better reproduced with a harder ionizing radiation field. Obviously local sources like stars can therefore be excluded as the main ionizing sources. Observational parameters for HST spectra of HS 1103+6416. <~bel{obs} Detector/Grating Exposure time Resolution Observed range Date Offset S/N_{subs{max}} [s] FWHM [Angstroms] [Angstroms] [Angstroms] AMBER/G270H 5336 2 2223-3277 Oct 31 1995 0.5 46 AMBER/G190H 8628 1.44 1572-2311 Oct 31 1995 1.24 21 DET1/G140L 17408 0.77 1415-1700 Jul 9 1996 0.66 8 DET1/G140L 22739 0.77 1150-1436 Jul 9 1996 0.66 12 Abundances in components L and I appear to be slightly different from those in the high ionization component H. In L and I we find roughly [C/H] = -0.9 while H has [C/H] = -1.2, consistent with the expectation that in a galaxy or groups of galaxies the abundances in the higher ionized `Halo' component are lower. The relative element abundances are also different. While in components L and I [Si/C] ~ 0.2, barely significant, and [S/C] and [O/C] ~ 0 within the uncertainties, component H shows [Si/C] = 0.5 and in addition [O/C] and [S/C] = 0.4 (both from HST spectra). [Al/C] measurable only in L and I is always ~ 0. The tendency of enhanced alpha element (O, Si, S) abundances at low C abundance is consistent with what is known from nucleosynthesis theory (SNII dominant at the beginning of galactic evolution), from metal deficient stars in our galaxy and from QSO absorption line systems. If all components were ionized by the same radiation field the relative overabundances of O and S in the highly ionized components would be even larger. We show that HS 1103+6416 will offer in the future for the first time the possibility to measure the cosmic He abundance at high redshift. Detailed calculations of He i absorption using the multicomponent model which explains the metal lines shows consistency with the observed first seven series members of the He i 584, 537, 522 Angstroms ... series for a helium abundance Y=0.24, the expected cosmic He abundance from Big Bang nucleosynthesis modified by stellar nucleosynthesis at ~ 1/10 solar metallicity. The presence of O i and possibly O vi absorption cannot be explained by our photoionization models and might hint at the existence of additional mainly neutral components with relatively low H i column density and further ionization mechanisms like, e.g., collisional ionization. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by Aura, Inc., under NASA contract NAS 5--26\\,555. Optical data presented herein were obtained at the W.M.\\ Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M.\\ Keck Foundation.

Centroid measurement error of CMOS detector in the presence of detector noise for inter-satellite optical communications

NASA Astrophysics Data System (ADS)

Li, Xin; Zhou, Shihong; Ma, Jing; Tan, Liying; Shen, Tao

2013-08-01

CMOS is a good candidate tracking detector for satellite optical communications systems with outstanding feature of sub-window for the development of APS (Active Pixel Sensor) technology. For inter-satellite optical communications it is critical to estimate the direction of incident laser beam precisely by measuring the centroid position of incident beam spot. The presence of detector noise results in measurement error, which degrades the tracking performance of systems. In this research, the measurement error of CMOS is derived taking consideration of detector noise. It is shown that the measurement error depends on pixel noise, size of the tracking sub-window (pixels number), intensity of incident laser beam, relative size of beam spot. The influences of these factors are analyzed by numerical simulation. We hope the results obtained in this research will be helpful in the design of CMOS detector satellite optical communications systems.

Characterization of AlMn TES Impedance, Noise, and Optical Efficiency in the First 150 mm Multichroic Array for Advanced ACTPol

NASA Technical Reports Server (NTRS)

Crowley, Kevin T.; Choi, Steve K.; Kuan, Jeffrey; Austermann, Jason E.; Beall, James A.; Datta, Rahul; Duff, Shannon M.; Gallardo, Patricia A.; Hasselfield, Matthew; Henderson, Shawn W.;

Accuracy of parameter estimates for closely spaced optical targets using multiple detectors

NASA Astrophysics Data System (ADS)

Dunn, K. P.

1981-10-01

In order to obtain the cross-scan position of an optical target, more than one scanning detector is used. As expected, the cross-scan position estimation performance degrades when two nearby optical targets interfere with each other. Theoretical bounds on the two-dimensional parameter estimation performance for two closely spaced optical targets are found. Two particular classes of scanning detector arrays, namely, the crow's foot and the brickwall (or mosaic) patterns, are considered.

Analytical validation applied to simultaneous determination of solvents dichloromethane (DCM), methyl isobutyl ketone (MIBK), tetrahydrofuran (THF) and toluene (TOL) in urine by headspace extraction and injection on chromatographic system with a flame ionization detector

NASA Astrophysics Data System (ADS)

Muna, E. D. M.; Pereira, R. P.

2016-07-01

The determination of the volatile organic solvents dichloromethane (DCM), methyl isobutyl ketone (MIBK), tetrahydrofuran (THF) and toluene (TOL) is applied on toxicological monitoring of employees in various industrial activities. The gas chromatography technique with flame ionization detector and headspace injection system has been applied. The analytical procedure developed allows the simultaneous determination of the above-mentioned solvents and the accuracy of the method was tested following the INMETRO guidelines through the DOQ-CGRE 008 Rev.04-July/2011.

Detecting a heavy neutrino electric dipole moment at the LHC

NASA Astrophysics Data System (ADS)

Sher, Marc; Stevens, Justin R.

2018-02-01

The milliQan Collaboration has proposed to search for millicharged particles by looking for very weakly ionizing tracks in a detector installed in a cavern near the CMS experiment at the LHC. We note that another form of exotica can also yield weakly ionizing tracks. If a heavy neutrino has an electric dipole moment (EDM), then the milliQan experiment may be sensitive to it as well. In particular, writing the general dimension-5 operator for an EDM with a scale of a TeV and a one-loop factor, one finds a potential EDM as high as a few times 10-17 e-cm, and models exist where it is an order of magnitude higher. Redoing the Bethe calculation of ionization energy loss for an EDM, it is found that the milliQan detector is sensitive to EDMs as small as 10-17 e-cm. Using the production cross-section and analyzing the acceptance of the milliQan detector, we find the expected 95% exclusion and 3σ sensitivity over the range of neutrino masses from 5-1000 GeV for integrated luminosities of 300 and 3000 fb-1 at the LHC.

Organic materials and devices for detecting ionizing radiation

DOEpatents

Doty, F Patrick [Livermore, CA; Chinn, Douglas A [Livermore, CA

2007-03-06

A .pi.-conjugated organic material for detecting ionizing radiation, and particularly for detecting low energy fission neutrons. The .pi.-conjugated materials comprise a class of organic materials whose members are intrinsic semiconducting materials. Included in this class are .pi.-conjugated polymers, polyaromatic hydrocarbon molecules, and quinolates. Because of their high resistivities (.gtoreq.10.sup.9 ohmcm), these .pi.-conjugated organic materials exhibit very low leakage currents. A device for detecting and measuring ionizing radiation can be made by applying an electric field to a layer of the .pi.-conjugated polymer material to measure electron/hole pair formation. A layer of the .pi.-conjugated polymer material can be made by conventional polymer fabrication methods and can be cast into sheets capable of covering large areas. These sheets of polymer radiation detector material can be deposited between flexible electrodes and rolled up to form a radiation detector occupying a small volume but having a large surface area. The semiconducting polymer material can be easily fabricated in layers about 10 .mu.m to 100 .mu.m thick. These thin polymer layers and their associated electrodes can be stacked to form unique multi-layer detector arrangements that occupy small volume.

A Practical Guide to Experimental Geometrical Optics

NASA Astrophysics Data System (ADS)

Garbovskiy, Yuriy A.; Glushchenko, Anatoliy V.

2017-12-01

Preface; 1. Markets of optical materials, components, accessories, light sources and detectors; 2. Introduction to optical experiments: light producing, light managing, light detection and measuring; 3. Light detectors based on semiconductors: photoresistors, photodiodes in a photo-galvanic regime. Principles of operation and measurements; 4. Linear light detectors based on photodiodes; 5. Basic laws of geometrical optics: experimental verification; 6. Converging and diverging thin lenses; 7. Thick lenses; 8. Lens systems; 9. Simple optical instruments I: the eye and the magnifier, eyepieces and telescopes; 10. Simple optical instruments II: light illuminators and microscope; 11. Spherical mirrors; 12. Introduction to optical aberrations; 13. Elements of optical radiometry; 14. Cylindrical lenses and vials; 15. Methods of geometrical optics to measure refractive index; 16. Dispersion of light and prism spectroscope; 17. Elements of computer aided optical design; Index.

Wide range radioactive gas concentration detector

DOEpatents

Anderson, David F.

1984-01-01

A wide range radioactive gas concentration detector and monitor which is capable of measuring radioactive gas concentrations over a range of eight orders of magnitude. The device of the present invention is designed to have an ionization chamber which is sufficiently small to give a fast response time for measuring radioactive gases but sufficiently large to provide accurate readings at low concentration levels. Closely spaced parallel plate grids provide a uniform electric field in the active region to improve the accuracy of measurements and reduce ion migration time so as to virtually eliminate errors due to ion recombination. The parallel plate grids are fabricated with a minimal surface area to reduce the effects of contamination resulting from absorption of contaminating materials on the surface of the grids. Additionally, the ionization chamber wall is spaced a sufficient distance from the active region of the ionization chamber to minimize contamination effects.

Hard disk drive based microsecond X-ray chopper for characterization of ionization chambers and photodiodes.

PubMed

Müller, O; Lützenkirchen-Hecht, D; Frahm, R

2015-03-01

A fast X-ray chopper capable of producing ms long X-ray pulses with a typical rise time of few μs was realized. It is ideally suited to investigate the temporal response of X-ray detectors with response times of the order of μs to ms, in particular, any kind of ionization chambers and large area photo diodes. The drive mechanism consists of a brushless DC motor and driver electronics from a common hard disk drive, keeping the cost at an absolute minimum. Due to its simple construction and small dimensions, this chopper operates at home lab based X-ray tubes and synchrotron radiation sources as well. The dynamics of the most important detectors used in time resolved X-ray absorption spectroscopy, namely, ionization chambers and Passivated Implanted Planar Silicon photodiodes, were investigated in detail. The results emphasize the applicability of this X-ray chopper.

Effects of Ionization-Induced Smog on Air Chemistry.

DTIC Science & Technology

1987-01-30

After leaving the monochromater, the beam was incident on the window of a HgCdTe Detector ( Infrared Assoc., Inc.), hereafter referred to as the...regulated power supply (Model 68735). The intensity of infrared light produced was measured by a thermopile detector (ORIEL Model 7102), hereafter...process measurements from the bolometer and detector and to control the stepper motor were located outside of the exposure room so as to reduce noise

Improved gaseous leak detector

DOEpatents

Juravic, F.E. Jr.

1983-10-06

In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the nonlinear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

Gaseous leak detector

DOEpatents

Juravic, Jr., Frank E.

1988-01-01

In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the non linear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, EXPLOSIVES DETECTION TECHNOLOGY, SRI INSTRUMENTS, MODEL 8610C, GAS CHROMATOGRAPH/THERMIONIC IONIZATION DETECTION

EPA Science Inventory

The SRI Model 86 1 OC gas chromatograph (GC) is a transportable instrument that can provide on-site analysis of soils for explosives. Coupling this transportable gas chromatograph with a thermionic ionization detector (TID) allows for the determination of explosives in soil matri...

Photoacoustic projection imaging using an all-optical detector array

NASA Astrophysics Data System (ADS)

Bauer-Marschallinger, J.; Felbermayer, K.; Berer, T.

2018-02-01

We present a prototype for all-optical photoacoustic projection imaging. By generating projection images, photoacoustic information of large volumes can be retrieved with less effort compared to common photoacoustic computed tomography where many detectors and/or multiple measurements are required. In our approach, an array of 60 integrating line detectors is used to acquire photoacoustic waves. The line detector array consists of fiber-optic MachZehnder interferometers, distributed on a cylindrical surface. From the measured variation of the optical path lengths of the interferometers, induced by photoacoustic waves, a photoacoustic projection image can be reconstructed. The resulting images represent the projection of the three-dimensional spatial light absorbance within the imaged object onto a two-dimensional plane, perpendicular to the line detector array. The fiber-optic detectors achieve a noise-equivalent pressure of 24 Pascal at a 10 MHz bandwidth. We present the operational principle, the structure of the array, and resulting images. The system can acquire high-resolution projection images of large volumes within a short period of time. Imaging large volumes at high frame rates facilitates monitoring of dynamic processes.

Performance parameters of a liquid filled ionization chamber array

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

Poppe, B.; Stelljes, T. S.; Looe, H. K.

2013-08-15

Purpose: In this work, the properties of the two-dimensional liquid filled ionization chamber array Octavius 1000SRS (PTW-Freiburg, Germany) for use in clinical photon-beam dosimetry are investigated.Methods: Measurements were carried out at an Elekta Synergy and Siemens Primus accelerator. For measurements of stability, linearity, and saturation effects of the 1000SRS array a Semiflex 31013 ionization chamber (PTW-Freiburg, Germany) was used as a reference. The effective point of measurement was determined by TPR measurements of the array in comparison with a Roos chamber (type 31004, PTW-Freiburg, Germany). The response of the array with varying field size and depth of measurement was evaluatedmore » using a Semiflex 31010 ionization chamber as a reference. Output factor measurements were carried out with a Semiflex 31010 ionization chamber, a diode (type 60012, PTW-Freiburg, Germany), and the detector array under investigation. The dose response function for a single detector of the array was determined by measuring 1 cm wide slit-beam dose profiles and comparing them against diode-measured profiles. Theoretical aspects of the low pass properties and of the sampling frequency of the detector array were evaluated. Dose profiles measured with the array and the diode detector were compared, and an intensity modulated radiation therapy (IMRT) field was verified using the Gamma-Index method and the visualization of line dose profiles.Results: The array showed a short and long term stability better than 0.1% and 0.2%, respectively. Fluctuations in linearity were found to be within ±0.2% for the vendor specified dose range. Saturation effects were found to be similar to those reported in other studies for liquid-filled ionization chambers. The detector's relative response varied with field size and depth of measurement, showing a small energy dependence accounting for maximum signal deviations of ±2.6% from the reference condition for the setup used. The σ-values of the Gaussian dose response function for a single detector of the array were found to be (0.72 ± 0.25) mm at 6 MV and (0.74 ± 0.25) mm at 15 MV and the corresponding low pass cutoff frequencies are 0.22 and 0.21 mm{sup −1}, respectively. For the inner 5 × 5 cm{sup 2} region and the outer 11 × 11 cm{sup 2} region of the array the Nyquist theorem is fulfilled for maximum sampling frequencies of 0.2 and 0.1 mm{sup −1}, respectively. An IMRT field verification with a Gamma-Index analysis yielded a passing rate of 95.2% for a 3 mm/3% criterion with a TPS calculation as reference.Conclusions: This study shows the applicability of the Octavius 1000SRS in modern dosimetry. Output factor and dose profile measurements illustrated the applicability of the array in small field and stereotactic dosimetry. The high spatial resolution ensures adequate measurements of dose profiles in regular and intensity modulated photon-beam fields.« less

LCOGT Imaging Lab

NASA Astrophysics Data System (ADS)

Tufts, Joseph R.; Lobdill, Rich; Haldeman, Benjamin J.; Haynes, Rachel; Hawkins, Eric; Burleson, Ben; Jahng, David

2008-07-01

The Las Cumbres Observatory Global Telescope Network (LCOGT) is an ambitious project to build and operate, within 5 years, a worldwide robotic network of 50 0.4, 1, and 2 m telescopes sharing identical instrumentation and optimized for precision photometry of time-varying sources. The telescopes, instrumentation, and software are all developed in house with two 2 m telescopes already installed. The LCOGT Imaging Lab is responsible for assembly and characterization of the network's cameras and instrumentation. In addition to a fully equipped CNC machine shop, two electronics labs, and a future optics lab, the Imaging Lab is designed from the ground up to be a superb environment for bare detectors, precision filters, and assembled instruments. At the heart of the lab is an ISO class 5 cleanroom with full ionization. Surrounding this, the class 7 main lab houses equipment for detector characterization including QE and CTE, and equipment for measuring transmission and reflection of optics. Although the first science cameras installed, two TEC cooled e2v 42-40 deep depletion based units and two CryoTiger cooled Fairchild Imaging CCD486-BI based units, are from outside manufacturers, their 18 position filter wheels and the remainder of the network's science cameras, controllers, and instrumentation will be built in house. Currently being designed, the first generation LCOGT cameras for the network's 1 m telescopes use existing CCD486-BI devices and an in-house controller. Additionally, the controller uses digital signal processing to optimize readout noise vs. speed, and all instrumentation uses embedded microprocessors for communication over ethernet.

Fiber optic detector

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

Partin, J.K.; Ward, T.E.; Grey, A.E.

1990-12-31

This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

Gated high speed optical detector

NASA Technical Reports Server (NTRS)

Green, S. I.; Carson, L. M.; Neal, G. W.

1973-01-01

The design, fabrication, and test of two gated, high speed optical detectors for use in high speed digital laser communication links are discussed. The optical detectors used a dynamic crossed field photomultiplier and electronics including dc bias and RF drive circuits, automatic remote synchronization circuits, automatic gain control circuits, and threshold detection circuits. The equipment is used to detect binary encoded signals from a mode locked neodynium laser.

Fiber optic detector for immuno-testing

DOEpatents

Partin, Judy K.; Ward, Thomas E.; Grey, Alan E.

1992-01-01

A portable fiber optic detector that senses the presence of specific target chemicals in air or a gas by exchanging the target chemical for a fluoroescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

Fiber optic detector

NASA Astrophysics Data System (ADS)

Partin, Judy K.; Ward, Thomas E.; Grey, Alan E.

1990-04-01

This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

Photon statistics in scintillation crystals

NASA Astrophysics Data System (ADS)

Bora, Vaibhav Joga Singh

Scintillation based gamma-ray detectors are widely used in medical imaging, high-energy physics, astronomy and national security. Scintillation gamma-ray detectors are eld-tested, relatively inexpensive, and have good detection eciency. Semi-conductor detectors are gaining popularity because of their superior capability to resolve gamma-ray energies. However, they are relatively hard to manufacture and therefore, at this time, not available in as large formats and much more expensive than scintillation gamma-ray detectors. Scintillation gamma-ray detectors consist of: a scintillator, a material that emits optical (scintillation) photons when it interacts with ionization radiation, and an optical detector that detects the emitted scintillation photons and converts them into an electrical signal. Compared to semiconductor gamma-ray detectors, scintillation gamma-ray detectors have relatively poor capability to resolve gamma-ray energies. This is in large part attributed to the "statistical limit" on the number of scintillation photons. The origin of this statistical limit is the assumption that scintillation photons are either Poisson distributed or super-Poisson distributed. This statistical limit is often dened by the Fano factor. The Fano factor of an integer-valued random process is dened as the ratio of its variance to its mean. Therefore, a Poisson process has a Fano factor of one. The classical theory of light limits the Fano factor of the number of photons to a value greater than or equal to one (Poisson case). However, the quantum theory of light allows for Fano factors to be less than one. We used two methods to look at the correlations between two detectors looking at same scintillation pulse to estimate the Fano factor of the scintillation photons. The relationship between the Fano factor and the correlation between the integral of the two signals detected was analytically derived, and the Fano factor was estimated using the measurements for SrI2:Eu, YAP:Ce and CsI:Na. We also found an empirical relationship between the Fano factor and the covariance as a function of time between two detectors looking at the same scintillation pulse. This empirical model was used to estimate the Fano factor of LaBr3:Ce and YAP:Ce using the experimentally measured timing-covariance. The estimates of the Fano factor from the time-covariance results were consistent with the estimates of the correlation between the integral signals. We found scintillation light from some scintillators to be sub-Poisson. For the same mean number of total scintillation photons, sub-Poisson light has lower noise. We then conducted a simulation study to investigate whether this low-noise sub-Poisson light can be used to improve spatial resolution. We calculated the Cramer-Rao bound for dierent detector geometries, position of interactions and Fano factors. The Cramer-Rao calculations were veried by generating simulated data and estimating the variance of the maximum likelihood estimator. We found that the Fano factor has no impact on the spatial resolution in gamma-ray imaging systems.

Limits on monopole fluxes from KFG experiment

NASA Technical Reports Server (NTRS)

Krishnaswamy, M. R.; Menon, M. G. K.; Mondal, N. K.; Hayashi, Y.; Ito, N.; Kawakami, S.; Miyake, S.

1985-01-01

The nucleon decay experiment at KGF at a depth of 2.3 Km is eminently suited for the search of Grand Unified theory (GUT) monopoles, whose velocities at the present epoch are predicted to be around 0.001C. At this depth the cosmic ray background is at a level 2/day in the detector of size 4m x 6m x 3.7m and one can look for monopoles traversing the detector in all directions, using three methods, i.e., (1) dE/dx (ionization); (2) time of flight and (3) catalysis of nucleon decay. The detector is composed of 34 layers of proportional counters arranged in horizontal planes one above the other in an orthogonal maxtrix. Each of the 1594 counters are instrumented to measure ionization in the gas (90% Argon + 10% Methane) as well as the time of arrival of particles.

Development of Solid Xenon Bolometers

NASA Astrophysics Data System (ADS)

Dolinski, Michelle; Hansen, Erin

2016-09-01

Cryogenic liquid xenon detectors have become a popular technology in the search for rare events, such as dark matter interactions and neutrinoless double beta decay. The power of liquid xenon detector technology is in the combination of ionization and scintillation signals, resulting in particle discrimination and improved energy resolution over the ionization-only signal. The improved energy resolution results from a microscopic anti-correlation phenomenon that has not been described from first principles. Solid xenon bolometers operated at 10 mK are expected to have excellent counting statistics in the phonon channel, with energy resolution of 0.1% or better. This additional energy channel may offer the final piece of the puzzle in understanding liquid xenon detector energy response. We present work toward the development and characterization of solid xenon bolometers at Drexel University. Funding for this project was provided by the Charles E. Kaufman Foundation of The Pittsburgh Foundation.

Pulse-Shape Analysis of Ionization Signals in Cryogenic Ge Detectors for Dark Matter

NASA Astrophysics Data System (ADS)

Foerster, N.; Broniatowski, A.; Eitel, K.; Marnieros, S.; Paul, B.; Piro, M.-C.; Siebenborn, B.

2016-08-01

The detectors of the direct dark matter search experiment EDELWEISS consist of high-purity germanium crystals operated at cryogenic temperatures (mathrm {{<}20 mK}) and low electric fields (mathrm {{<}1 V/cm}). The surface discrimination is based on the simultaneous measurement of the charge amplitudes on different sets of electrodes. As the rise time of a charge signal strongly depends on the location of an interaction in the crystal, a time-resolved measurement can also be used to identify surface interactions. This contribution presents the results of a study of the discrimination power of the rise time parameter from a hot carrier transport simulation in combination with time-resolved measurements using an EDELWEISS-type detector in a test cryostat at ground level. We show the setup for the time-resolved ionization signal read-out in the EDELWEISS-III experiment and first results from data taking in the underground laboratory of Modane.

The prototype of the Micro Vertex Detector of the CBM Experiment

NASA Astrophysics Data System (ADS)

Koziel, Michal; Amar-Youcef, Samir; Bialas, Norbert; Deveaux, Michael; Fröhlich, Ingo; Li, Qiyan; Michel, Jan; Milanović, Borislav; Müntz, Christian; Neumann, Bertram; Schrader, Christoph; Stroth, Joachim; Tischler, Tobias; Weirich, Roland; Wiebusch, Michael

2013-12-01

The Compressed Baryonic Matter (CBM) Experiment is one of the core experiments of the future FAIR facility at Darmstadt, Germany. This fixed-target experiment will explore the phase diagram of strongly interacting matter in the regime of highest net baryon densities with numerous probes, among them open charm. Reconstructing those short lived particles requires a vacuum compatible Micro Vertex Detector (MVD) with unprecedented properties. Its sensor technology has to feature a spatial resolution of <5 μm, a non-ionizing radiation tolerance of >1013 neq/cm2, an ionizing radiation tolerance of >3 Mrad and a time resolution of a few 10 μs. The MVD-prototype project aimed to study the integration the CMOS Monolithic Active Pixel Sensors foreseen for the MVD into an ultra light (0.3% X0) and a vacuum compatible detector system based on a cooling support made of CVD-diamond.

Miniature Ion-Mobility Spectrometer

NASA Technical Reports Server (NTRS)

Hartley, Frank T.

2006-01-01

The figure depicts a proposed miniature ion-mobility spectrometer that would be fabricated by micromachining. Unlike prior ion-mobility spectrometers, the proposed instrument would not be based on a time-of-flight principle and, consequently, would not have some of the disadvantageous characteristics of prior time-of-flight ion-mobility spectrometers. For example, one of these characteristics is the need for a bulky carrier-gas-feeding subsystem that includes a shutter gate to provide short pulses of gas in order to generate short pulses of ions. For another example, there is need for a complex device to generate pulses of ions from the pulses of gas and the device is capable of ionizing only a fraction of the incoming gas molecules; these characteristics preclude miniaturization. In contrast, the proposed instrument would not require a carrier-gas-feeding subsystem and would include a simple, highly compact device that would ionize all the molecules passing through it. The ionization device in the proposed instrument would be a 0.1-micron-thick dielectric membrane with metal electrodes on both sides. Small conical holes would be micromachined through the membrane and electrodes. An electric potential of the order of a volt applied between the membrane electrodes would give rise to an electric field of the order of several megavolts per meter in the submicron gap between the electrodes. An electric field of this magnitude would be sufficient to ionize all the molecules that enter the holes. Ionization (but not avalanche arcing) would occur because the distance between the ionizing electrodes would be less than the mean free path of gas molecules at the operating pressure of instrument. An accelerating grid would be located inside the instrument, downstream from the ionizing membrane. The electric potential applied to this grid would be negative relative to the potential on the inside electrode of the ionizing membrane and would be of a magnitude sufficient to generate a moderate electric field. Positive ions leaving the membrane holes would be accelerated in this electric field. The resulting flux of ions away from the ionization membrane would create a partial vacuum that would draw more of the gas medium through the membrane. The figure depicts a filter electrode and detector electrodes located along the sides of a drift tube downstream from the accelerator electrode. These electrodes would apply a transverse AC electric field superimposed on a ramped DC electric field. The AC field would effect differential transverse dispersal of ions. At a given instant of time, the trajectories of most of the ions would be bent toward the electrodes, causing most of the ions to collide with the electrodes and thereby become neutralized. The DC field would partly counteract the dispersive effect of the AC field, straightening the trajectories of a selected species of ions; the selection would vary with the magnitude of the applied DC field. The straightening of the trajectories of the selected ions would enable them to pass into the region between the detector electrodes. Depending on the polarity of the voltage applied to the detector electrodes, the electric field between the detector electrodes would draw the selected ions to one of these electrodes. Hence, the current collected by one of the detector electrodes would be a measure of the abundance of ions of the selected species. The ramping of the filter- electrode DC voltage would sweep the selection of ions through the spectrum of ionic species.

Optical properties of Argonne/KICP TES bolometers for CMB polarimetry.

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

Crites, A. T.; Bleem, L. E.; Carlstrom, J. E.

2009-01-01

We present optical data on prototype polarization sensitive Argonne/KICP detectors fabricated at Argonne National Labs which are designed to be installed on the South Pole Telescope and used to measure the polarization of the Cosmic Microwave Background radiation. The detectors are Mo/Au transition edge sensors (TES) suspended on silicon nitride, with radiation coupled to the TES using a gold bar absorber. Two stacked detectors with bars in orthogonal directions will be used to measure both polarizations. We discuss measurements of the optical bandpass, time constants and cross-polarization of the detectors.

Optical Properties of Argonne/KICP TES Bolometers for CMB Polarimetry

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

Crites, A. T.; Bleem, L. E.; Carlstrom, J. E.

2009-12-16

We present optical data on prototype polarization sensitive Argonne/KICP detectors fabricated at Argonne National Labs which are designed to be installed on the South Pole Telescope and used to measure the polarization of the Cosmic Microwave Background radiation. The detectors are Mo/Au transition edge sensors (TES) suspended on silicon nitride, with radiation coupled to the TES using a gold bar absorber. Two stacked detectors with bars in orthogonal directions will be used to measure both polarizations. We discuss measurements of the optical bandpass, time constants and cross-polarization of the detectors.

Application of Al2O3:C+fibre dosimeters for 290 MeV/n carbon therapeustic beam dosimetry.

NASA Astrophysics Data System (ADS)

Nascimento, L. F.; Vanhavere, F.; Kodaira, S.; Kitamura, H.; Verellen, D.; De Deene, Y.

2015-10-01

The capability of radioluminescence (RL) dosimeters composed of carbon-doped aluminium oxide (Al2O3:C) detectors+optical fibre has been verified for absorbed dose-rate measurements during carbon radiotherapy. The RL signals from two separate Al2O3:C detectors (single crystal 'CG' and droplet 'P1') have been systematically measured and compared along the Bragg-curve and Spread-Out Bragg-Peak of 290 MeV/n carbon beams in the water. The absorbed dose response was assessed for the range of 0.5-10 Gy. For doses up to 6 Gy, we observed a linear response for both types of detectors, while for higher doses CG presented a more prominent supraliearity than P1. The RL response for low-LET protons in the entrance from the curve was found to closely resemble that observed for a clinical 6 MV X-ray beam, while it was found that P1 has a better agreement with the reference data from standard ionization chamber than CG. We observed a significant decrease in luminescence efficiency with LET in the Bragg peak region. The Al2O3:C RL luminescence efficiency differs from Al2O3:C OSL results, which implies that the signal can be corrected for LET dependency to match the correct SOBP and Bragg Peak.

Long range alpha particle detector

DOEpatents

MacArthur, Duncan W.; Wolf, Michael A.; McAtee, James L.; Unruh, Wesley P.; Cucchiara, Alfred L.; Huchton, Roger L.

1993-01-01

An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

Long range alpha particle detector

DOEpatents

MacArthur, D.W.; Wolf, M.A.; McAtee, J.L.; Unruh, W.P.; Cucchiara, A.L.; Huchton, R.L.

1993-02-02

An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

Roles of Tunneling, Multiphoton Ionization, and Cascade Ionization for Femtosecond Optical Breakdown in Aqueous Media

DTIC Science & Technology

2009-09-01

observed in the wavelength dependence of femtosecond breakdown would indicate a significant role of multiphoton ionization compared to tunneling ...relevant for femtosecond breakdown, and tunnel ionization featuring no Ith() dependence becomes ever more with decreasing pulse duration. However, it...c) Figure 4.22 Wavelength dependence of ionization probabilities by a) avalanche, b) multiphoton, and c) tunneling ionization. 1

Development of a liquid xenon time projection chamber for the XENON dark matter search

NASA Astrophysics Data System (ADS)

Ni, Kaixuan

This thesis describes the research conducted for the XENON dark matter direct detection experiment. The tiny energy and small cross-section, from the interaction of dark matter particle on the target, requires a low threshold and sufficient background rejection capability of the detector. The XENON experiment uses dual phase technology to detect scintillation and ionization simultaneously from an event in liquid xenon (LXe). The distinct ratio, between scintillation and ionization, for nuclear recoil and electron recoil events provides excellent background rejection potential. The XENON detector is designed to have 3D position sensitivity down to mm scale, which provides additional event information for background rejection. Started in 2002, the XENON project made steady progress in the R&D phase during the past few years. Those include developing sensitive photon detectors in LXe, improving the energy resolution and LXe purity for detecting very low energy events. Two major quantities related to the dark matter detection, the scintillation efficiency and ionization yield of nuclear recoils in LXe, have been established. A prototype dual phase detector (XENON3) has been built and tested extensively in above ground laboratory. The 3D position sensitivity, as well as the background discrimination potential demonstrated from the XENON3 prototype, allows the construction of a 10 kg scale detector (XENON10), to be deployed underground in early 2006. With 99.5% electron recoil rejection efficiency and 16 keVr nuclear recoil energy threshold, XENON10 will be able to probe the WIMP-nucleon cross-section down to 2 x 10-44 cm2 in the supersymmetry parameter space, after one month operation in the Gran Sasso underground laboratory.

Directional Sensitivity in Light-Mass Dark Matter Searches with Single-Electron-Resolution Ionization Detectors

NASA Astrophysics Data System (ADS)

Kadribasic, Fedja; Mirabolfathi, Nader; Nordlund, Kai; Sand, Andrea E.; Holmström, Eero; Djurabekova, Flyura

2018-03-01

We propose a method using solid state detectors with directional sensitivity to dark matter interactions to detect low-mass weakly interacting massive particles (WIMPs) originating from galactic sources. In spite of a large body of literature for high-mass WIMP detectors with directional sensitivity, no available technique exists to cover WIMPs in the mass range <1 GeV /c2 . We argue that single-electron-resolution semiconductor detectors allow for directional sensitivity once properly calibrated. We examine the commonly used semiconductor material response to these low-mass WIMP interactions.

An Avalanche Diode Electron Detector for Observing NEET

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

Kishimoto, Shunji

2004-05-12

Nuclear excitation by electron transition (NEET) occurs in atomic inner-shell ionization if the nuclear excitation and the electron transition have nearly the same energy and a common multipolarity. We successfully observed the NEET on 197Au and on 193Ir using a silicon avalanche diode electron detector. The detector was used to find internal conversion electrons emitted from excited nuclei in time spectroscopy with a time gate method. Some nuclear resonant levels, including 8.410 keV on 169Tm and 80.577 keV on 166Er, were also observed with the detector.

Construction of the TH-GEM detector components for metrology of low energy ionizing radiation

NASA Astrophysics Data System (ADS)

Silva, N. F.; Silva, T. F.; Castro, M. C.; Natal da Luz, H.; Caldas, L. V. E.

2018-03-01

The Gas Electron Multiplier (GEM) detector was originally proposed as a position sensitive detector to determine trajectories of particles prevenient from high-energy collisions. In order to study the potential of TH-GEM type detectors in dosimetric applications for low energy X-rays, specifically for the mammography standard qualities, it was proposed to construct a prototype with characteristics suitable for such use. In this work the general, structural and material parameters applicable to the necessary conditions were defined, establishing the process of construction of the components of a prototype.

Error detection capability of a novel transmission detector: a validation study for online VMAT monitoring.

PubMed

Pasler, Marlies; Michel, Kilian; Marrazzo, Livia; Obenland, Michael; Pallotta, Stefania; Björnsgard, Mari; Lutterbach, Johannes

2017-09-01

The purpose of this study was to characterize a new single large-area ionization chamber, the integral quality monitor system (iRT, Germany), for online and real-time beam monitoring. Signal stability, monitor unit (MU) linearity and dose rate dependence were investigated for static and arc deliveries and compared to independent ionization chamber measurements. The dose verification capability of the transmission detector system was evaluated by comparing calculated and measured detector signals for 15 volumetric modulated arc therapy plans. The error detection sensitivity was tested by introducing MLC position and linac output errors. Deviations in dose distributions between the original and error-induced plans were compared in terms of detector signal deviation, dose-volume histogram (DVH) metrics and 2D γ-evaluation (2%/2 mm and 3%/3 mm). The detector signal is linearly dependent on linac output and shows negligible (<0.4%) dose rate dependence up to 460 MU min -1 . Signal stability is within 1% for cumulative detector output; substantial variations were observed for the segment-by-segment signal. Calculated versus measured cumulative signal deviations ranged from  -0.16%-2.25%. DVH, mean 2D γ-value and detector signal evaluations showed increasing deviations with regard to the respective reference with growing MLC and dose output errors; good correlation between DVH metrics and detector signal deviation was found (e.g. PTV D mean : R 2   =  0.97). Positional MLC errors of 1 mm and errors in linac output of 2% were identified with the transmission detector system. The extensive tests performed in this investigation show that the new transmission detector provides a stable and sensitive cumulative signal output and is suitable for beam monitoring during patient treatment.

Error detection capability of a novel transmission detector: a validation study for online VMAT monitoring

NASA Astrophysics Data System (ADS)

Pasler, Marlies; Michel, Kilian; Marrazzo, Livia; Obenland, Michael; Pallotta, Stefania; Björnsgard, Mari; Lutterbach, Johannes

2017-09-01

The purpose of this study was to characterize a new single large-area ionization chamber, the integral quality monitor system (iRT, Germany), for online and real-time beam monitoring. Signal stability, monitor unit (MU) linearity and dose rate dependence were investigated for static and arc deliveries and compared to independent ionization chamber measurements. The dose verification capability of the transmission detector system was evaluated by comparing calculated and measured detector signals for 15 volumetric modulated arc therapy plans. The error detection sensitivity was tested by introducing MLC position and linac output errors. Deviations in dose distributions between the original and error-induced plans were compared in terms of detector signal deviation, dose-volume histogram (DVH) metrics and 2D γ-evaluation (2%/2 mm and 3%/3 mm). The detector signal is linearly dependent on linac output and shows negligible (<0.4%) dose rate dependence up to 460 MU min-1. Signal stability is within 1% for cumulative detector output; substantial variations were observed for the segment-by-segment signal. Calculated versus measured cumulative signal deviations ranged from  -0.16%-2.25%. DVH, mean 2D γ-value and detector signal evaluations showed increasing deviations with regard to the respective reference with growing MLC and dose output errors; good correlation between DVH metrics and detector signal deviation was found (e.g. PTV D mean: R 2  =  0.97). Positional MLC errors of 1 mm and errors in linac output of 2% were identified with the transmission detector system. The extensive tests performed in this investigation show that the new transmission detector provides a stable and sensitive cumulative signal output and is suitable for beam monitoring during patient treatment.

Ferroelectric Thin-Film Capacitors As Ultraviolet Detectors

NASA Technical Reports Server (NTRS)

Thakoor, Sarita

1995-01-01

Advantages include rapid response, solar blindness, and relative invulnerability to ionizing radiation. Ferroelectric capacitor made to function as photovoltaic detector of ultraviolet photons by making one of its electrodes semitransparent. Photovoltaic effect exploited more fully by making Schottky barrier at illuminated semitransparent-electrode/ferroelectric interface taller than Schottky barrier at other electrode/ferroelectric interface.

Quadruple parallel mass Spectrometry for analysis of vitamin D and triacylglycerols in a dietary supplement

USDA-ARS?s Scientific Manuscript database

A ‘dilute-and-shoot’ method for vitamin D and triacylglycerols is demonstrated that employed four mass spectrometers, operating in different ionization modes, for a ‘quadruple parallel mass spectrometry’ analysis, plus three other detectors, for seven detectors overall. Sets of five samples of diet...

Ion-ion coincidence imaging at high event rate using an in-vacuum pixel detector.

PubMed

Long, Jingming; Furch, Federico J; Durá, Judith; Tremsin, Anton S; Vallerga, John; Schulz, Claus Peter; Rouzée, Arnaud; Vrakking, Marc J J

2017-07-07

A new ion-ion coincidence imaging spectrometer based on a pixelated complementary metal-oxide-semiconductor detector has been developed for the investigation of molecular ionization and fragmentation processes in strong laser fields. Used as a part of a velocity map imaging spectrometer, the detection system is comprised of a set of microchannel plates and a Timepix detector. A fast time-to-digital converter (TDC) is used to enhance the ion time-of-flight resolution by correlating timestamps registered separately by the Timepix detector and the TDC. In addition, sub-pixel spatial resolution (<6 μm) is achieved by the use of a center-of-mass centroiding algorithm. This performance is achieved while retaining a high event rate (10 4 per s). The spectrometer was characterized and used in a proof-of-principle experiment on strong field dissociative double ionization of carbon dioxide molecules (CO 2 ), using a 400 kHz repetition rate laser system. The experimental results demonstrate that the spectrometer can detect multiple ions in coincidence, making it a valuable tool for studying the fragmentation dynamics of molecules in strong laser fields.

Ion-ion coincidence imaging at high event rate using an in-vacuum pixel detector

NASA Astrophysics Data System (ADS)

Long, Jingming; Furch, Federico J.; Durá, Judith; Tremsin, Anton S.; Vallerga, John; Schulz, Claus Peter; Rouzée, Arnaud; Vrakking, Marc J. J.

2017-07-01

A new ion-ion coincidence imaging spectrometer based on a pixelated complementary metal-oxide-semiconductor detector has been developed for the investigation of molecular ionization and fragmentation processes in strong laser fields. Used as a part of a velocity map imaging spectrometer, the detection system is comprised of a set of microchannel plates and a Timepix detector. A fast time-to-digital converter (TDC) is used to enhance the ion time-of-flight resolution by correlating timestamps registered separately by the Timepix detector and the TDC. In addition, sub-pixel spatial resolution (<6 μm) is achieved by the use of a center-of-mass centroiding algorithm. This performance is achieved while retaining a high event rate (104 per s). The spectrometer was characterized and used in a proof-of-principle experiment on strong field dissociative double ionization of carbon dioxide molecules (CO2), using a 400 kHz repetition rate laser system. The experimental results demonstrate that the spectrometer can detect multiple ions in coincidence, making it a valuable tool for studying the fragmentation dynamics of molecules in strong laser fields.

Simulations of a Thin Sampling Calorimeter with GEANT/FLUKA

NASA Technical Reports Server (NTRS)

Lee, Jeongin; Watts, John; Howell, Leonard; Rose, M. Franklin (Technical Monitor)

2000-01-01

The Advanced Cosmic-ray Composition Experiment for the Space Station (ACCESS) will investigate the origin, composition and acceleration mechanism of cosmic rays by measuring the elemental composition of the cosmic rays up to 10(exp 15) eV. These measurements will be made with a thin ionization calorimeter and a transition radiation detector. This paper reports studies of a thin sampling calorimeter concept for the ACCESS thin ionization calorimeter. For the past year, a Monte Carlo simulation study of a Thin Sampling Calorimeter (TSC) design has been conducted to predict the detector performance and to design the system for achieving the ACCESS scientific objectives. Simulation results show that the detector energy resolution function resembles a Gaussian distribution and the energy resolution of TSC is about 40%. In addition, simulations of the detector's response to an assumed broken power law cosmic ray spectra in the region where the 'knee' of the cosmic ray spectrum occurs have been conducted and clearly show that a thin sampling calorimeter can provide sufficiently accurate estimates of the spectral parameters to meet the science requirements of ACCESS. n

Large-Area Plasma-Panel Radiation Detectors for Nuclear Medicine Imaging to Homeland Security and the Super Large Hadron Collider

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

Friedman, Dr. Peter S.; Ball, Robert; Chapman, J. Wehrley

2010-01-01

A new radiation sensor derived from plasma panel display technology is introduced. It has the capability to detect ionizing and non-ionizing radiation over a wide energy range and the potential for use in many applications. The principle of operation is described and some early results presented.

Quality assurance and quality control for thermal/optical analysis of aerosol samples for organic and elemental carbon.

PubMed

Chow, Judith C; Watson, John G; Robles, Jerome; Wang, Xiaoliang; Chen, L-W Antony; Trimble, Dana L; Kohl, Steven D; Tropp, Richard J; Fung, Kochy K

2011-12-01

Accurate, precise, and valid organic and elemental carbon (OC and EC, respectively) measurements require more effort than the routine analysis of ambient aerosol and source samples. This paper documents the quality assurance (QA) and quality control (QC) procedures that should be implemented to ensure consistency of OC and EC measurements. Prior to field sampling, the appropriate filter substrate must be selected and tested for sampling effectiveness. Unexposed filters are pre-fired to remove contaminants and acceptance tested. After sampling, filters must be stored in the laboratory in clean, labeled containers under refrigeration (<4 °C) to minimize loss of semi-volatile OC. QA activities include participation in laboratory accreditation programs, external system audits, and interlaboratory comparisons. For thermal/optical carbon analyses, periodic QC tests include calibration of the flame ionization detector with different types of carbon standards, thermogram inspection, replicate analyses, quantification of trace oxygen concentrations (<100 ppmv) in the helium atmosphere, and calibration of the sample temperature sensor. These established QA/QC procedures are applicable to aerosol sampling and analysis for carbon and other chemical components.

Optical field ionization of atoms and ions using ultrashort laser pulses

NASA Astrophysics Data System (ADS)

Fittinghoff, D. N.

1993-12-01

This dissertation research is an investigation of the strong optical field ionization of atoms and ions by 120-fs, 614-run laser pulses and 130-fs, 800-nm laser pulses. The experiments have shown ionization that is enhanced above the predictions of sequential tunneling models for He(+2), Ne(+2), and Ar(+2). The ion yields for He(+1), Ne(sup +1) and Ar(sup +1) agree well with the theoretical predictions of optical tunneling models. Investigation of the polarization dependence of the ionization indicates that the enhancements are consistent with a nonsequential ionization mechanism in which the linearly polarized field drives the electron wavefunction back toward the ion core and causes double ionization through inelastic e-2e scattering. These investigations have initiated a number of other studies by other groups and are of current scientific interest in the fields of high-irradiance laser-matter interactions and production of high-density plasmas. This work involved the following: (1) Understanding the characteristic nature of the ion yields produced by tunneling ionization through investigation of analytic solutions for tunneling at optical frequencies. (2) Extensive characterization of the pulses produced by 614-nm and 800-ran ultrashort pulse lasers. Absolute calibration of the irradiance scale produced shows the practicality of the inverse problem--measuring peak laser irradiance using ion yields. (3) Measuring the ion yields for three noble gases using linear, circular and elliptical polarizations of laser pulses at 614-nm and 800-nm. The measurements are some of the first measurements for pulse widths as low as 120-fs.

SU-F-T-73: Experimental Determination of the Effective Point of Measurement in Electron Beams Using a Commercial Scintillation Detector

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

Simiele, E; Smith, B; Culberson, W

2016-06-15

Purpose: The aim of this work was to determine experimentally the effective point of measurement (EPOM) in clinical electron beams for three cylindrical ionization chambers using a commercial scintillation detector as a reference detector. Methods: Percent depth dose (PDD) curves were measured using an Exradin W1 scintillation detector and were used as a representative PDD to water. Depth dose curves were measured with the Exradin A18, A1SL, and A28 ionization chambers. The raw ionization chamber curve data were corrected by the chamber fluence perturbation correction factor and restricted mass collisional stopping power ratio at each depth to obtain a percentmore » depth dose curve to the gas volume (PDDGV) of the detector. Ratios of the W1 PDD to the ion chamber PDDGV were calculated for each measurement depth. The W1 PDD curve was shifted by small depth increments, Δz, until the ratio of the W1 PDD to the ion chamber PDDGV was depth-independent (optimal Δz). A MATLAB routine was developed to determine the optimal Δz value. Results: The optimal Δz shift was used as an estimate of the EPOM for each chamber. The average calculated EPOM shifts (expressed as a fraction of the chamber cavity radius) for the A18, A1SL, and A28 ionization chambers were 0.21 ± 0.04, 0.10 ± 0.05, and 0.22 ± 0.03, respectively. Conclusion: The experimentally determined EPOM values for the A18 and A1SL in this work agreed with the simulated values of Muir and Rogers (MedPhys 2014). The results also indicate that the Exradin W1 scintillator is water equivalent for electron energies of 6 MeV, 9 MeV, 12 MeV, and 16 MeV. In addition, we confirmed that the AAPM TG51 recommended EPOM shift of 0.5 times the cavity radius is not accurate for the A18 and A1SL chambers.« less

Passive cooler

NASA Technical Reports Server (NTRS)

Aronson, Albert Irving (Inventor)

1977-01-01

A three stage passive cooler for use in a spacecraft for cooling an infra-red detector includes a detector mounting cold plate for mounting the detector directly to the telescope optics. The telescope optics collect and direct the infra-red radiation from the earth, for example, to the infra-red detector, and are mounted directly to the spacecraft. The remaining stages of the cooler are mounted with thermal insulators to each other and to the spacecraft at separate locations from the detector mounting cold plate.

Note: A 102 dB dynamic-range charge-sampling readout for ionizing particle/radiation detectors based on an application-specific integrated circuit (ASIC)

NASA Astrophysics Data System (ADS)

Pullia, A.; Zocca, F.; Capra, S.

2018-02-01

An original technique for the measurement of charge signals from ionizing particle/radiation detectors has been implemented in an application-specific integrated circuit form. The device performs linear measurements of the charge both within and beyond its output voltage swing. The device features an unprecedented spectroscopic dynamic range of 102 dB and is suitable for high-resolution ion and X-γ ray spectroscopy. We believe that this approach may change a widespread paradigm according to which no high-resolution spectroscopy is possible when working close to or beyond the limit of the preamplifier's output voltage swing.

Note: A 102 dB dynamic-range charge-sampling readout for ionizing particle/radiation detectors based on an application-specific integrated circuit (ASIC).

PubMed

Pullia, A; Zocca, F; Capra, S

2018-02-01

An original technique for the measurement of charge signals from ionizing particle/radiation detectors has been implemented in an application-specific integrated circuit form. The device performs linear measurements of the charge both within and beyond its output voltage swing. The device features an unprecedented spectroscopic dynamic range of 102 dB and is suitable for high-resolution ion and X-γ ray spectroscopy. We believe that this approach may change a widespread paradigm according to which no high-resolution spectroscopy is possible when working close to or beyond the limit of the preamplifier's output voltage swing.

Analysis of bacterial fatty acids by flow modulated comprehensive two-dimensional gas chromatography with parallel flame ionization detector/mass spectrometry.

PubMed

Gu, Qun; David, Frank; Lynen, Frédéric; Rumpel, Klaus; Xu, Guowang; De Vos, Paul; Sandra, Pat

2010-06-25

Comprehensive two-dimensional gas chromatography (GCxGC) offers an interesting tool for profiling bacterial fatty acids. Flow modulated GCxGC using a commercially available system was evaluated, different parameters such as column flows and modulation time were optimized. The method was tested on bacterial fatty acid methyl esters (BAMEs) from Stenotrophomonas maltophilia LMG 958T by using parallel flame ionization detector (FID)/mass spectrometry (MS). The results are compared to data obtained using a thermal modulated GCxGC system. The data show that flow modulated GCxGC-FID/MS method can be applied in a routine environment and offers interesting perspectives for chemotaxonomy of bacteria.

Virtual detector theory for strong-field atomic ionization

NASA Astrophysics Data System (ADS)

Wang, Xu; Tian, Justin; Eberly, J. H.

2018-04-01

A virtual detector (VD) is an imaginary device located at a fixed position in space that extracts information from the wave packet passing through it. By recording the particle momentum and the corresponding probability current at each time, the VDs can accumulate and build the differential momentum distribution of the particle, in a way that resembles real experiments. A mathematical proof is given for the equivalence of the differential momentum distribution obtained by the VD method and by Fourier transforming the wave function. In addition to being a tool for reducing the computational load, VDs have also been found useful in interpreting the ultrafast strong-field ionization process, especially the controversial quantum tunneling process.

The design and construction of the MICE Electron-Muon Ranger

NASA Astrophysics Data System (ADS)

Asfandiyarov, R.; Bene, P.; Blondel, A.; Bolognini, D.; Cadoux, F.; Debieux, S.; Drielsma, F.; Giannini, G.; Graulich, J. S.; Husi, C.; Karadzhov, Y.; Lietti, D.; Masciocchi, F.; Nicola, L.; Noah Messomo, E.; Prest, M.; Rothenfusser, K.; Sandstrom, R.; Vallazza, E.; Verguilov, V.; Wisting, H.

2016-10-01

The Electron-Muon Ranger (EMR) is a fully-active tracking-calorimeter installed in the beam line of the Muon Ionization Cooling Experiment (MICE). The experiment will demonstrate ionization cooling, an essential technology needed for the realization of a Neutrino Factory and/or a Muon Collider. The EMR is designed to measure the properties of low energy beams composed of muons, electrons and pions, and perform the identification particle-by-particle. The detector consists of 48 orthogonal layers of 59 triangular scintillator bars. The readout is implemented using FPGA custom made electronics and commercially available modules. This article describes the construction of the detector from its design up to its commissioning with cosmic data.

High signal-to-noise-ratio electro-optical terahertz imaging system based on an optical demodulating detector array.

PubMed

Spickermann, Gunnar; Friederich, Fabian; Roskos, Hartmut G; Bolívar, Peter Haring

2009-11-01

We present a 64x48 pixel 2D electro-optical terahertz (THz) imaging system using a photonic mixing device time-of-flight camera as an optical demodulating detector array. The combination of electro-optic detection with a time-of-flight camera increases sensitivity drastically, enabling the use of a nonamplified laser source for high-resolution real-time THz electro-optic imaging.

Rapid Optical Shutter, Chopper, Modulator and Deflector

NASA Technical Reports Server (NTRS)

Danehy, Paul M. (Inventor)

2017-01-01

An optical device with a light source and a detector is provided. A digital micromirror device positioned between the detector and the light source may deflect light beams projected from the light source. An aperture in front of the detector may block an incoming light beam from the detector when the incoming light beam is incident on the detector outside of a passable incident range and including an aperture opening configured to pass the incoming light beam to the detector when the incoming light beam is incident on the detector within a passable incident range. The digital micromirror device may rotate between a first position causing the light beam to pass through the aperture opening and a second position causing the light beam to be blocked by the aperture. The optical device may be configured to operate as a shutter, chopper, modulator and/or deflector.

A laser-based FAIMS detector for detection of ultra-low concentrations of explosives

NASA Astrophysics Data System (ADS)

Akmalov, Artem E.; Chistyakov, Alexander A.; Kotkovskii, Gennadii E.; Sychev, Alexey V.; Tugaenko, Anton V.; Bogdanov, Artem S.; Perederiy, Anatoly N.; Spitsyn, Eugene M.

2014-06-01

A non-contact method for analyzing of explosives traces from surfaces was developed. The method is based on the laser desorption of analyzed molecules from the surveyed surfaces followed by the laser ionization of air sample combined with the field asymmetric ion mobility spectrometry (FAIMS). The pulsed radiation of the fourth harmonic of a portable GSGG: Cr3+ :Nd3+ laser (λ = 266 nm) is used. The laser desorption FAIMS analyzer have been developed. The detection limit of the analyzer equals 40 pg for TNT. The results of detection of trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX) and cyclotetramethylenetetranitramine (HMX) are presented. It is shown that laser desorption of nitro-compounds from metals is accompanied by their surface decomposition. A method for detecting and analyzing of small concentrations of explosives in air based on the laser ionization and the FAIMS was developed. The method includes a highly efficient multipass optical scheme of the intracavity fourthharmonic generation of pulsed laser radiation (λ = 266 nm) and the field asymmetric ion mobility (FAIM) spectrometer disposed within a resonator. The ions formation and detection proceed inside a resonant cavity. The laser ion source based on the multi-passage of radiation at λ = 266 nm through the ionization region was elaborated. On the basis of the method the laser FAIMS analyzer has been created. The analyzer provides efficient detection of low concentrations of nitro-compounds in air and shows a detection limit of 10-14 - 10-15 g/cm3 both for RDX and TNT.

Optical Measurements of Air Plasma

DTIC Science & Technology

2008-05-05

beam impact ionization of air was studied in the context of optical diagnostics . The electron beam originates in a pulsed 100 keV 20-mA source and...range of 636 Torr to 1 mTorr with pulse durations from 1 ms to 10 ms. Microwave diagnostics were used to quantify electron density and power; and an...optical diagnostic was used to quantify ozone production. An additional effort to quantify byproducts of electron impact ionization, that are

Measurement of quasi-isentropic compressibility of helium and deuterium at pressures of 1500-2000 GPa

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

Mochalov, M. A., E-mail: postmaster@ifv.vniief.ru; Il'kaev, R. I.; Fortov, V. E.

2012-10-15

The quasi-isentropic compressibility of helium and deuterium plasmas at pressures of up to 1500-2000 GPa has been measured using devices with spherical geometry and an X-ray diagnostic complex comprising three betatrons and a multichannel imaging system with electro-optic gamma detectors. A deuterium density of 4.5 g/cm{sup 3} and a helium density of 3.8 g/cm{sup 3} have been obtained at pressures of 2210 and 1580 GPa, respectively. The internal energy of a deuterium plasma at the indicated pressure is about 1 MJ/cm{sup 3}, which is about 100 times greater than the specific energy of condensed chemical explosives. Analysis of the obtainedmore » data shows that the degree of helium ionization under the achieved plasma compression parameters is about 0.9.« less

The Joint Astrophysical Plasmadynamic Experiment (J-PEX): a high-resolution rocket spectrometer

NASA Astrophysics Data System (ADS)

Barstow, Martin A.; Bannister, Nigel P.; Cruddace, Raymond G.; Kowalski, Michael P.; Wood, Kent S.; Yentis, Daryl J.; Gursky, Herbert; Barbee, Troy W., Jr.; Goldstein, William H.; Kordas, Joseph F.; Fritz, Gilbert G.; Culhane, J. Leonard; Lapington, Jonathan S.

2003-02-01

We report on the successful sounding rocket flight of the high resolution (R=3000-4000) J-PEX EUV spectrometer. J-PEX is a novel normal incidence instrument, which combines the focusing and dispersive elements of the spectrometer into a single optical element, a multilayer-coated grating. The high spectral resolution achieved has had to be matched by unprecedented high spatial resolution in the imaging microchannel plate detector used to record the data. We illustrate the performance of the complete instrument through an analysis of the 220-245Å spectrum of the white dwarf G191-B2B obtained with a 300 second exposure. The high resolution allows us to detect a low-density ionized helium component along the line of sight to the star and individual absorption lines from heavier elements in the photosphere.

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

Patel, Piyush, E-mail: piyush-patel130@yahoo.com; Vyas, S. M., E-mail: s-m-vyas-gu@hotmail.com; Patel, Vimal

The III-VI compound semiconductors is important for the fabrication of ionizing radiation detectors, solid-state electrodes, and photosensitive heterostructures, solar cell and ionic batteries. In this paper, In{sub 2}Se{sub 2.7} Sb{sub 0.3} single crystals were grown by the Bridgman method with temperature gradient of 60 °C/cm and the growth velocity 0.5cm/hr. The as-grown crystals were examined under the optical microscope for surface study, a various growth features observed on top free surface of the single crystal which is predominant of layers growth mechanism. The lattice parameters of as-grown crystal was determined by the XRD analysis. A Vickers’ projection microscope were usedmore » for the study of microhardness on the as-cleaved, cold-worked and annealed samples of the crystals, the results were discussed, and reported in detail.« less

Radiochromic film sensitivity calibrations using ion beams from a Pelletron accelerator

NASA Astrophysics Data System (ADS)

Filkins, T. M.; Steidle, Jessica; Ward, R. J.; Freeman, C. G.; Padalino, S. J.; Regan, S. P.; Sangster, T. C.

2015-11-01

Radiochromic film (RCF) is a transparent detector film that permanently changes color following exposure to ionizing radiation. The optical density of the film increases with increasing absorbed dose. RCF is convenient to use because it requires no chemical processing and can be scanned using commercially available document scanners. RCF is used frequently in medical applications, but is also used in a variety of diagnostics in high energy density physics. The film consists of a single or double layer of radiation-sensitive organic microcrystal monomers placed onto a polyester backing. GafchromicTM manufactures a large number of different types of RCF, and new types of film frequently replace older products. In this study, the sensitivity of several types of RCF to ion beams of different energies was measured. Ion beams produced by the SUNY Geneseo 1.7 MV Pelletron accelerator were directed into a target chamber where they scattered off of a gold foil. A sample of RCF was exposed to the scattered ions. The fluence of incident particles on the film was measured using a surface barrier detector. Results of these calibrations will be presented. This work was funded in part by a grant from the DOE through the Laboratory for Laser Energetics.

Carrier-envelope phase-dependent ionization of Xe in intense, ultrafast (two-cycle) laser fields

NASA Astrophysics Data System (ADS)

Vasa, Parinda; Dharmadhikari, Aditya K.; Mathur, Deepak

2018-01-01

We report an experimental study that shows the dependence of the tunnel ionization of Xe by two-cycle, intense, near infrared light on the carrier-envelope-phase (CEP) of incident laser pulses. At low values of the optical field (E), the ionization yield is found to be maximum for cos-like pulses; the CEP dependence of the ion yield becomes stronger for higher charge states. At higher E-values, the CEP dependence either washes out or flips. A simple phenomenological model is used to confirm that our results fall within the ambit of the current understanding of ionization dynamics in strong, ultrashort optical fields. In the observed tunnel ionization of Xe, CEP effects appear to persist for longer, eight-cycle, pulses. Electron rescattering is observed to play a relatively unimportant role in the observed CEP dependence. These results provide fresh perspectives in the ionization mechanisms of multielectron systems in the few-cycle regime.

Tandem sulfur chemiluminescence and flame ionization detection with planar microfluidic devices for the characterization of sulfur compounds in hydrocarbon matrices.

PubMed

Luong, J; Gras, R; Shellie, R A; Cortes, H J

2013-07-05

The detection of sulfur compounds in different hydrocarbon matrices, from light hydrocarbon feedstocks to medium synthetic crude oil feeds provides meaningful information for optimization of refining processes as well as demonstration of compliance with petroleum product specifications. With the incorporation of planar microfluidic devices in a novel chromatographic configuration, sulfur compounds from hydrogen sulfide to alkyl dibenzothiophenes and heavier distributions of sulfur compounds over a wide range of matrices spanning across a boiling point range of more than 650°C can be characterized, using one single analytical configuration in less than 25min. In tandem with a sulfur chemiluminescence detector for sulfur analysis is a flame ionization detector. The flame ionization detector can be used to establish the boiling point range of the sulfur compounds in various hydrocarbon fractions for elemental specific simulated distillation analysis as well as profiling the hydrocarbon matrices for process optimization. Repeatability of less than 3% RSD (n=20) over a range of 0.5-1000 parts per million (v/v) was obtained with a limit of detection of 50 parts per billion and a linear range of 0.5-1000 parts per million with a correlation co-efficient of 0.998. Copyright © 2013 Elsevier B.V. All rights reserved.

Film Vetoes for Alpha Background Rejection in Bolometer Detectors

NASA Astrophysics Data System (ADS)

Deporzio, Nicholas; Bucci, Carlo; Canonica, Lucia; Divacri, Marialaura; Cuore Collaboration; Absurd Team

2015-04-01

This study characterizes the effectiveness of encasing bolometer detectors in scintillator, metal ionization, and more exotic films to veto alpha radiation background. Bolometers are highly susceptible to alpha background and a successful veto should boost the statistical strength, speed, and signal-background ratio of bolometer particle searches. Plastic scintillator films are cooled to bolometer temperatures and bombarded with 1.4 MeV to 6.0 MeV alpha particles representative of detector conditions. Photomultipliers detect the keV range scintillation light and produce a veto signal. Also, layered films of a primary metal, dielectric, and secondary metal, such as gold-polyethylene-gold films, are cooled to milli-kelvin temperatures and biased with 0.1V to 100V to produce a current signal when incident 1.4 MeV to 6.0 MeV alpha particles ionize conduction paths through the film. Veto signals are characterized by their affect on bolometer detection of 865 keV target signals. Similar methods are applied to more exotic films. Early results show scintillator films raise target signal count rate and suppress counts above target energy by at least a factor of 10. This indicates scintillation vetoes are effective and that metal ionization and other films under study will also be effective.

Measurements of the optical performance of bolometers for SPICA/SAFARI

NASA Astrophysics Data System (ADS)

Audley, Michael D.; de Lange, Gert; Gao, Jian-Rong; Khosropanah, Pourya; Ridder, Marcel; Ferrari, Lorenza; Laauwen, Wouter M.; Ranjan, Manisha; Mauskopf, Philip D.; Morozov, Dmitry; Trappe, Neil A.

2012-09-01

We have measured the optical response of detectors designed for SAFARI, the far-infrared imaging spectrometer for the SPICA satellite. To take advantage of SPICA's cooled optics, SAFARI’s three bolometer arrays are populated with extremely sensitive (NEP~2×10-19 W/√Hz) transition edge sensors with a transition temperature close to 100 mK. The extreme sensitivity and low saturation power (~4 fW) of SAFARI’s detectors present challenges to characterizing them. We have therefore built up an ultra-low background test facility with a cryogen-free high-capacity dilution refrigerator, paying careful attention to stray-light exclusion. Our use of a pulse-tube cooler to pre-cool the dilution refrigerator required that the SAFARI Detector System Test Facility provide a high degree electrical, magnetic, and mechanical isolation for the detectors. We have carefully characterized the performance of the test facility in terms of background power loading. The test facility has been designed to be flexible and easily reconfigurable with internal illuminators that allow us to characterize the optical response of the detectors. We describe the test facility and some of the steps we took to create an ultra-low background test environment. We have measured the optical response of two detectors designed for SAFARI’s short-wave wavelength band in combination with a spherical backshort and conical feedhorn. We find an overall optical efficiency of 40% for both, compared with an ideal-case predicted optical efficiency of 66%.

Optical based tactile shear and normal load sensor

DOEpatents

Salisbury, Curt Michael

2015-06-09

Various technologies described herein pertain to a tactile sensor that senses normal load and/or shear load. The tactile sensor includes a first layer and an optically transparent layer bonded together. At least a portion of the first layer is made of optically reflective material. The optically transparent layer is made of resilient material (e.g., clear silicone rubber). The tactile sensor includes light emitter/light detector pair(s), which respectively detect either normal load or shear load. Light emitter(s) emit light that traverses through the optically transparent layer and reflects off optically reflective material of the first layer, and light detector(s) detect and measure intensity of reflected light. When a normal load is applied, the optically transparent layer compresses, causing a change in reflected light intensity. When shear load is applied, a boundary between optically reflective material and optically absorptive material is laterally displaced, causing a change in reflected light intensity.

Study of the optical properties and the carbonaceous clusters in DAM-ADC solid state nuclear track detectors

NASA Astrophysics Data System (ADS)

Rammah, Y. S.; Abdalla, A. M.

2017-12-01

The optical properties of DAM-ADC solid state nuclear track detectors (SSNTDs) were investigated. Samples of DAM-ADC detector were irradiated at room temperature with gamma doses in the range of 100-500 kGy using 1.25 MeV 60Co source of dose rate 4 kGy/h. The optical characterization of these detectors have been studied through the measurements of UV-visible absorption spectra of blank and γ- irradiated samples. The optical energy band gaps, Eg for the detectors were obtained from the direct and the indirect allowed transitions in K-space using two methods (Tauc's model and absorption spectrum fitting (ASF) method). The absorbance of DAM-ADC detector was found to increase with increasing of the gamma absorbed dose. The width of the tail of localized states in the band gap, Eu was evaluated with the Urbach's method. The number of carbon atoms per conjugated length (N), the number of carbon atoms per cluster (M), and refractive index (n) for the present samples were determined. Both of the direct and the indirect band gaps of DAM-ADC detector decrease with increasing of the gamma absorbed dose. Urbach's energy decreased significantly for the detector. An increase in N, M, and n with increasing of the gamma absorbed dose was noticed. Results shed light on the effect of gamma irradiations of DAM-ADC SSNTDs to suitable industrial applications and to modify the optical properties through gamma-induced modifications of the polymer structure.

Externally-Modulated Electro-Optically Coupled Detector Architecture for Nuclear Physics Instrumentation

NASA Astrophysics Data System (ADS)

Xi, Wenze; McKisson, J. E.; Weisenberger, Andrew G.; Zhang, Shukui; Zorn, Carl

2014-06-01

A new laser-based externally-modulated electro-optically coupled detector (EOCD) architecture is being developed to enable high-density readout for radiation detectors with accurate analog radiation pulse shape and timing preservation. Unlike digital conversion before electro-optical modulation, the EOCD implements complete analog optical signal modulation and multiplexing in its detector front-end. The result is a compact, high performance detector readout that can be both radiation tolerant and immune to magnetic fields. In this work, the feasibility of EOCD was explored by constructing a two-wavelength laser-based externally-modulated EOCD, and testing analog pulse shape preservation and wavelength-division multiplexing (WDM) crosstalk. Comparisons were first made between the corresponding initial pulses and the electro-optically coupled analog pulses. This confirmed an excellent analog pulse preservation over 29% of the modulator's switching voltage range. Optical spectrum analysis revealed less than -14 dB crosstalk with 1.2 nm WDM wavelength bandgap, and provided insight on experimental conditions that could lead to increased inter-wavelength crosstalk. Further discussions and previous research on the radiation tolerance and magnetic field immunity of the candidate materials were also given, and quantitative device testing is proposed in the future.

Compact Efficient Lidar Receiver for Measuring Atmospheric Aerosols

NASA Technical Reports Server (NTRS)

Gili, Christopher; De Young, Russell

2006-01-01

A small, light weight, and efficient aerosol lidar receiver was constructed and tested. Weight and space savings were realized by using rigid optic tubes and mounting cubes to package the steering optics and detectors in a compact assembly. The receiver had a 1064nm channel using an APD detector. The 532nm channel was split (90/10) into an analog channel (90%) and a photon counting channel (10%). The efficiency of the 1064nm channel with optical filter was 44.0%. The efficiency of the analog 532nm channel was 61.4% with the optical filter, and the efficiency of the 532nm photon counting channel was 7.6% with the optical filter. The results of the atmospheric tests show that the detectors were able to consistently return accurate results. The lidar receiver was able to detect distinct cloud layers, and the lidar returns also agreed across the different detectors. The use of a light weight fiber-coupled telescope reduced weight and allowed great latitude in detector assembly positioning due to the flexibility enabled by the use of fiber optics. The receiver is now ready to be deployed for aircraft or ground based aerosol lidar measurements.

Coherent Optical Adaptive Techniques (COAT)

DTIC Science & Technology

1975-01-01

8217 neceeemry and Identity by block number) Laser Phased Array Adaptive Optics Atmospheric-Turbulence and Thermal Blooming Compensation 20...characteristics of an experimental, visible wavelength, eighteen-element, self-adaptive optical phased array. Measurements on a well-characterized...V LOCAL PHASING ■ LOOP OPTICAL DETECTOR’ LOCAL LOCK / ROOF TOP "^/PROPAGATION’ ^ GLINT ■lm FOCAL LENGTH LENS DETECTOR DMWI rh

Characterization of a new commercial single crystal diamond detector for photon- and proton-beam dosimetry.

PubMed

Akino, Yuichi; Gautam, Archana; Coutinho, Len; Würfel, Jan; Das, Indra J

2015-11-01

A synthetic single crystal diamond detector (SCDD) is commercially available and is characterized for radiation dosimetry in various radiation beams in this study. The characteristics of the commercial SCDD model 60019 (PTW) with 6- and 15-MV photon beams, and 208-MeV proton beams, were investigated and compared with the pre-characterized detectors: Semiflex (model 31010) and PinPoint (model 31006) ionization chambers (PTW), the EDGE diode detector (Sun Nuclear Corp) and the SFD Stereotactic Dosimetry Diode Detector (IBA). To evaluate the effects of the pre-irradiation, the diamond detector, which had not been irradiated on the day, was set up in the water tank, and the response to 100 MU was measured every 20 s. The depth-dose and profiles data were collected for various field sizes and depths. For all radiation types and field sizes, the depth-dose data of the diamond chamber showed identical curves to those of the ionization chambers. The profile of the diamond detector was very similar to those of the EDGE and SFD detectors, although the Semiflex and PinPoint chambers showed volume-averaging effects in the penumbrae region. The temperature dependency was within 0.7% in the range of 4-41°C. A dose of 900 cGy and 1200 cGy was needed to stabilize the chamber to the level within 0.5% and 0.2%, respectively. The PTW type 60019 SCDD detector showed suitable characteristics for radiation dosimetry, for relative dose, depth-dose and profile measurements for a wide range of field sizes. However, at least 1000 cGy of pre-irradiation will be needed for accurate measurements. © The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Modular optical detector system

DOEpatents

Horn, Brent A [Livermore, CA; Renzi, Ronald F [Tracy, CA

2006-02-14

A modular optical detector system. The detector system is designed to detect the presence of molecules or molecular species by inducing fluorescence with exciting radiation and detecting the emitted fluorescence. Because the system is capable of accurately detecting and measuring picomolar concentrations it is ideally suited for use with microchemical analysis systems generally and capillary chromatographic systems in particular. By employing a modular design, the detector system provides both the ability to replace various elements of the detector system without requiring extensive realignment or recalibration of the components as well as minimal user interaction with the system. In addition, the modular concept provides for the use and addition of a wide variety of components, including optical elements (lenses and filters), light sources, and detection means, to fit particular needs.

Experimental Determination of the Ionization Energy in TlBr

NASA Astrophysics Data System (ADS)

Hitomi, Keitaro; Onodera, Toshiyuki; Kim, Seong-Yun; Shoji, Tadayoshi; Ishii, Keizo

2015-06-01

The average ionization energy required to excite an electron-hole pair in TlBr was estimated to be 5.50 ± 0.05 eV by comparing the peak position of 59.5-keV gamma rays obtained from four pixels of a pixelated TlBr detector to the peak position obtained from a Si PIN photodiode at room temperature.

The MoEDAL Experiment at the LHC - a New Light on the Terascale Frontier

NASA Astrophysics Data System (ADS)

Pinfold, J. L.

2015-07-01

MoEDAL is a pioneering experiment designed to search for highly ionizing avatars of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles. Its groundbreaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; what is the mechanism for the generation of mass; does magnetic charge exist; what is the nature of dark matter; and, how did the big-bang develop. MoEDAL's purpose is to meet such far-reaching challenges at the frontier of the field. The innovative MoEDAL detector employs unconventional methodologies tuned to the prospect of discovery physics. The largely passive MoEDAL detector, deployed at Point 8 on the LHC ring, has a dual nature. First, it acts like a giant camera, comprised of nuclear track detectors - analyzed offline by ultra fast scanning microscopes - sensitive only to new physics. Second, it is uniquely able to trap the particle messengers of physics beyond the Standard Model for further study. MoEDAL's radiation environment is monitored by a state-of-the-art real-time TimePix pixel detector array. A new MoEDAL sub-detector to extend MoEDAL's reach to millicharged, minimally ionizing, particles (MMIPs) is under study.

Measurements of charge distributions of the fragments in the low energy fission reaction

NASA Astrophysics Data System (ADS)

Wang, Taofeng; Han, Hongyin; Meng, Qinghua; Wang, Liming; Zhu, Liping; Xia, Haihong

2013-01-01

The measurement for charge distributions of fragments in spontaneous fission 252Cf has been performed by using a unique style of detector setup consisting of a typical grid ionization chamber and a ΔΕ-Ε particle telescope, in which a thin grid ionization chamber served as the ΔΕ-section and the E-section was an Au-Si surface barrier detector. The typical physical quantities of fragments, such as mass number and kinetic energies as well as the deposition in the gas ΔΕ detector and E detector were derived from the coincident measurement data. The charge distributions of the light fragments for the fixed mass number A2* and total kinetic energy (TKE) were obtained by the least-squares fits for the response functions of the ΔΕ detector with multi-Gaussian functions representing the different elements. The results of the charge distributions for some typical fragments are shown in this article which indicates that this detection setup has the charge distribution capability of Ζ:ΔΖ>40:1. The experimental method developed in this work for determining the charge distributions of fragments is expected to be employed in the neutron induced fissions of 232Th and 238U or other low energy fission reactions.

Ionization nebulae surrounding supersoft X-ray sources

NASA Technical Reports Server (NTRS)

Rappaport, S.; Chiang, E.; Kallman, T.; Malina, R.

1994-01-01

In this work we carry out a theoretical investigation of a new type of astrophysical gaseous nebula, viz., ionized regions surrounding supersoft X-ray sources. Supersoft X-ray sources, many of which have characteristic luminosities of approximately 10(exp 37)-(10(exp 38) ergs/s and effective temperatures of approximately 4 x 10(exp 5) K, were first discovered with the Einstein Observatory. These sources have now been shown to constitute a distinct class of X-ray source and are being found in substantial numbers with ROSAT. We predict that these sources should be surrounded by regions of ionized hydrogen and helium with properties that are distinct from other astrophysical gaseous nebulae. We present caluations of the ionization and temperature structure of these ionization nebulae, as well as the expected optical line fluxes. The ionization profiles for both hydrogen and helium exhibit substantially more gradual transitions from the ionized to the unionized state than is the case for conventional H II regions. The calculated optical line intensitites are presented as absolute fluxes from sources in the Large Magellanic Cloud and as fractions of the central source luminosity. We find, in particular, that (O III) lambda 5008 and He II lambda 4686 are especially prominent in these ionization nebulae as compared to other astrophysical nebulae. We propose that searches for supersoft X-rays via their characteristic optical lines may reveal sources in regions where the soft X-rays are nearly completely absorbed by the interstellar medium.

Proton Nonionizing Energy Loss (NIEL) for Device Applications

NASA Technical Reports Server (NTRS)

Jun, Insoo; Xapsos, Michael A.; Messenger, Scott R.; Burke, Edward A.; Walters, Robert J.; Summers, Geoff; Jordan, Thomas

2003-01-01

Nonionizing energy loss (NIEL) is a quantity that describes the rate of energy loss due to atomic displacements as a particle traverses a material. The product of the NIEL and the particle fluence (time integrated flux) gives the displacement damage energy deposition per unit mass of material. NIEL plays the same role to the displacement damage energy deposition as the stopping power to the total ionizing dose (TID). The concept of NIEL has been very useful for correlating particle induced displacement damage effects in semiconductor and optical devices. Many studies have successfully demonstrated that the degradation of semiconductor devices or optical sensors in a radiation field can be linearly correlated to the displacement damage energy, and subsequently to the NIEL deposited in the semiconductor devices or optical sensors. In addition, the NIEL concept was also useful in the study of both Si and GaAs solar cells and of high temperature superconductors, and at predicting the survivability of detectors used at the LHC at CERN. On the other hand, there are some instances where discrepancies are observed in the application of NIEL, most notably in GaAs semiconductor devices. However, NIEL is still a valuable tool, and can be used to scale damages produced by different particles and in different environments, even though this is not understood at the microscopic level.

Polysiloxane scintillator composition

DOEpatents

Walker, J.K.

1992-05-05

A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

Polysiloxane scintillator composition

DOEpatents

Walker, James K.

1992-01-01

A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

Results on nucleon life-time from the Kolar gold field experiment

NASA Technical Reports Server (NTRS)

Krishnaswamy, M. R.; Menon, M. G. K.; Mondal, N. K.; Narasimham, V. S.; Sreekantan, B. V.; Hayashi, Y.; Ito, N.; Kawakami, S.; Miyake, S.

1985-01-01

The KGF nucleon decay experiment has been in operation since October 1980 with a 140 ton calorimetric detector at a depth of 2.3 Km underground. The detector comprises 34 layers of proportional counters arranged in an orthogonal geometry with 12 mm thick iron plates in between successive layers. The proportional counters are made up of square (10 x 10 square centimeters) iron plates of wall thickness 2.3 mm. Each of the 1600 counters is instrumented to provide data on ionization, DE/dx and arrival time. The visible energy of a particle is determined to an accuracy of approximately 20% from the ionization and range of its track. The end point ionization of a stopping track provides the direction of motion as well as the nature of the particle (mu/pi,k,p). Decay of mu is recorded with an overall efficiency of only 20% in view of the thickness of 13 g/square centimeters between successive layers.

Optical Characterization of the SPT-3G Focal Plane

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

Pan, Z.; et al.

The third-generation South Pole Telescope camera is designed to measure the cosmic microwave background across three frequency bands (95, 150 and 220 GHz) with ~16,000 transition-edge sensor (TES) bolometers. Each multichroic pixel on a detector wafer has a broadband sinuous antenna that couples power to six TESs, one for each of the three observing bands and both polarization directions, via lumped element filters. Ten detector wafers populate the focal plane, which is coupled to the sky via a large-aperture optical system. Here we present the frequency band characterization with Fourier transform spectroscopy, measurements of optical time constants, beam properties, andmore » optical and polarization efficiencies of the focal plane. The detectors have frequency bands consistent with our simulations, and have high average optical efficiency which is 86%, 77% and 66% for the 95, 150 and 220 GHz detectors. The time constants of the detectors are mostly between 0.5 ms and 5 ms. The beam is round with the correct size, and the polarization efficiency is more than 90% for most of the bolometers« less

Realization of 10 GHz minus 30dB on-chip micro-optical links with Si-Ge RF bi-polar technology

NASA Astrophysics Data System (ADS)

Ogudo, Kingsley A.; Snyman, Lukas W.; Polleux, Jean-Luc; Viana, Carlos; Tegegne, Zerihun

2014-06-01

Si Avalanche based LEDs technology has been developed in the 650 -850nm wavelength regime [1, 2]. Correspondingly, small micro-dimensioned detectors with pW/μm2 sensitivity have been developed for the same wavelength range utilizing Si-Ge detector technology with detection efficiencies of up to 0.85, and with a transition frequencies of up to 80 GHz [3] A series of on-chip optical links of 50 micron length, utilizing 650 - 850 nm propagation wavelength have been designed and realized, utilizing a Si Ge radio frequency bipolar process. Micron dimensioned optical sources, waveguides and detectors were all integrated on the same chip to form a complete optical link on-chip. Avalanche based Si LEDs (Si Av LEDs), Schottky contacting, TEOS densification strategies, silicon nitride based waveguides, and state of the art Si-Ge bipolar detector technologies were used as key design strategies. Best performances show optical coupling from source to detector of up to 10GHz and - 40dBm total optical link budget loss with a potential transition frequency coupling of up to 40GHz utilizing Si Ge based LEDs. The technology is particularly suitable for application as on-chip optical links, optical MEMS and MOEMS, as well as for optical interconnects utilizing low loss, side surface, waveguide- to-optical fiber coupling. Most particularly is one of our designed waveguide which have a good core axis alignment with the optical source and yield 10GHz -30dB on-chip micro-optical links as shown in Fig 9 (c). The technology as developed has been appropriately IP protected.

Recent developments in materials and detectors for the infrared; Proceedings of the Meeting, Cannes, France, November 25, 26, 1985

NASA Technical Reports Server (NTRS)

Morten, F. D. (Editor); Seeley, John S. (Editor)

1986-01-01

The present conference on advancements in IR-sensitive materials and detector technologies employing them gives attention to thermal detectors, focal plane array processing detectors, novel detector designs, general properties of IR optics materials, and preparation methods for such materials. Specific topics encompass the fabrication of InSb MIS structures prepared by photochemical vapor deposition, IR heterodyne detectors employing cadmium mercury telluride, low microphony pyroelectric arrays, IR detection based on minority carrier extrusion, longwave reststrahl in IR crystals, and molecular beam techniques for optical thin film fabrication.

Properties of a commercial PTW-60019 synthetic diamond detector for the dosimetry of small radiotherapy beams.

PubMed

Lárraga-Gutiérrez, José Manuel; Ballesteros-Zebadúa, Paola; Rodríguez-Ponce, Miguel; García-Garduño, Olivia Amanda; de la Cruz, Olga Olinca Galván

2015-01-21

A CVD based radiation detector has recently become commercially available from the manufacturer PTW-Freiburg (Germany). This detector has a sensitive volume of 0.004 mm(3), a nominal sensitivity of 1 nC Gy(-1) and operates at 0 V. Unlike natural diamond based detectors, the CVD diamond detector reports a low dose rate dependence. The dosimetric properties investigated in this work were dose rate, angular dependence and detector sensitivity and linearity. Also, percentage depth dose, off-axis dose profiles and total scatter ratios were measured and compared against equivalent measurements performed with a stereotactic diode. A Monte Carlo simulation was carried out to estimate the CVD small beam correction factors for a 6 MV photon beam. The small beam correction factors were compared with those obtained from stereotactic diode and ionization chambers in the same irradiation conditions The experimental measurements were performed in 6 and 15 MV photon beams with the following square field sizes: 10 × 10, 5 × 5, 4 × 4, 3 × 3, 2 × 2, 1.5 × 1.5, 1 × 1 and 0.5 × 0.5 cm. The CVD detector showed an excellent signal stability (<0.2%) and linearity, negligible dose rate dependence (<0.2%) and lower response angular dependence. The percentage depth dose and off-axis dose profiles measurements were comparable (within 1%) to the measurements performed with ionization chamber and diode in both conventional and small radiotherapy beams. For the 0.5 × 0.5 cm, the measurements performed with the CVD detector showed a partial volume effect for all the dosimetric quantities measured. The Monte Carlo simulation showed that the small beam correction factors were close to unity (within 1.0%) for field sizes ≥1 cm. The synthetic diamond detector had high linearity, low angular and negligible dose rate dependence, and its response was energy independent within 1% for field sizes from 1.0 to 5.0 cm. This work provides new data showing the performance of the CVD detector compared against a high spatial resolution diode. It also presents a comparison of the CVD small beam correction factors with those of diode and ionization chamber for a 6 MV photon beam.

A study on the suitability of the PTW microDiamond detector for kilovoltage x-ray beam dosimetry.

PubMed

Damodar, Joshita; Odgers, David; Pope, Dane; Hill, Robin

2018-05-01

Kilovoltage x-ray beams are widely used in treating skin cancers and in biological irradiators. In this work, we have evaluated four dosimeters (ionization chambers and solid state detectors) in their suitability for relative dosimetry of kilovoltage x-ray beams in the energy range of 50 - 280kVp. The solid state detectors, which have not been investigated with low energy x-rays, were the PTW 60019 microDiamond synthetic diamond detector and the PTW 60012 diode. The two ionization chambers used were the PTW Advanced Markus parallel plate chamber and the PTW PinPoint small volume chamber. For each of the dosimeters, percentage depth doses were measured in water over the full range of x-ray beams and for field sizes ranging from 2cm diameter to 12 × 12cm. In addition, depth doses were measured for a narrow aperture (7mm diameter) using the PTW microDiamond detector. For comparison, the measured data was compared with Monte Carlo calculated doses using the EGSnrc Monte Carlo package. The depth dose results indicate that the Advanced Markus parallel plate and PinPoint ionization chambers were suitable for depth dose measurements in the beam quality range with an uncertainty of less than 3%, including in the regions closer to the surface of the water as compared with Monte Carlo depth dose data for all six energy beams. The response of the PTW Diode E detector was accurate to within 4% for all field sizes in the energy range of 50-125kVp but showed larger variations for higher energies of up to 12% with the 12 × 12cm field size. In comparison, the microDiamond detector had good agreement over all energies for both smaller and larger field sizes generally within 1% as compared to the Advanced Markus chamber field and Monte Carlo calculations. The only exceptions were in measuring the dose at the surface of the water phantom where larger differences were found. For the 7mm diameter field, the agreement between the microDiamond detector and Monte Carlo calculations was good being better than 1% except at the surface. Based on these results, the PTW microDiamond detector has shown to be a suitable detector for relative dosimetry of low energy x-ray beams over a wide range of x-ray beam energies. Copyright © 2018 Elsevier Ltd. All rights reserved.

A superconducting focal plane array for ultraviolet, optical, and near-infrared astrophysics.

PubMed

Mazin, Benjamin A; Bumble, Bruce; Meeker, Seth R; O'Brien, Kieran; McHugh, Sean; Langman, Eric

2012-01-16

Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology due to their sensitivity and the ease with which they can be multiplexed into large arrays. A MKID is an energy sensor based on a photon-variable superconducting inductance in a lithographed microresonator, and is capable of functioning as a photon detector across the electromagnetic spectrum as well as a particle detector. Here we describe the first successful effort to create a photon-counting, energy-resolving ultraviolet, optical, and near infrared MKID focal plane array. These new Optical Lumped Element (OLE) MKID arrays have significant advantages over semiconductor detectors like charge coupled devices (CCDs). They can count individual photons with essentially no false counts and determine the energy and arrival time of every photon with good quantum efficiency. Their physical pixel size and maximum count rate is well matched with large telescopes. These capabilities enable powerful new astrophysical instruments usable from the ground and space. MKIDs could eventually supplant semiconductor detectors for most astronomical instrumentation, and will be useful for other disciplines such as quantum optics and biological imaging.

Development of real-time thermal neutron monitor using boron-loaded plastic scintillator with optical fiber for boron neutron capture therapy.

PubMed

Ishikawa, M; Ono, K; Sakurai, Y; Unesaki, H; Uritani, A; Bengua, G; Kobayashi, T; Tanaka, K; Kosako, T

2004-11-01

A new thermal neutron monitor for boron neutron capture therapy was developed in this study. We called this monitor equipped boron-loaded plastic scintillator that uses optical fiber for signal transmission as an [scintillator with optical fiber] SOF detector. A water phantom experiment was performed to verify how the SOF detector compared with conventional method of measuring thermal neutron fluence. Measurements with a single SOF detector yielded indistinguishable signals for thermal neutrons and gamma rays. To account for the gamma ray contribution in the signal recorded by the SOF detector, a paired SOF detector system was employed. This was composed of an SOF detector with boron-loaded scintillator and an SOF detector with a boron-free scintillator. The difference between the recorded counts of these paired SOF detectors was used as the measure of the gamma ray contribution in the measured neutron fluence. The paired SOF detectors were ascertained to be effective in measuring thermal neutron flux in the range above 10(6)(n/cm(2)/s). Clinical trials using paired SOF to measure thermal neutron flux during therapy confirmed that paired SOF detectors were effective as a real-time thermal neutron flux monitor.

Xenon gamma-ray detector for ecological applications

NASA Astrophysics Data System (ADS)

Novikov, Alexander S.; Ulin, Sergey E.; Chernysheva, Irina V.; Dmitrenko, Valery V.; Grachev, Victor M.; Petrenko, Denis V.; Shustov, Alexander E.; Uteshev, Ziyaetdin M.; Vlasik, Konstantin F.

2015-01-01

A description of the xenon detector (XD) for ecological applications is presented. The detector provides high energy resolution and is able to operate under extreme environmental conditions (wide temperature range and unfavorable acoustic action). Resistance to acoustic noise as well as improvement in energy resolution has been achieved by means of real-time digital pulse processing. Another important XD feature is the ionization chamber's thin wall with composite housing, which significantly decreases the mass of the device and expands its energy range, especially at low energies.

Enhancement of concentration range of chromatographically detectable components with array detector mass spectrometry

DOEpatents

Enke, Christie

2013-02-19

Methods and instruments for high dynamic range analysis of sample components are described. A sample is subjected to time-dependent separation, ionized, and the ions dispersed with a constant integration time across an array of detectors according to the ions m/z values. Each of the detectors in the array has a dynamically adjustable gain or a logarithmic response function, producing an instrument capable of detecting a ratio of responses or 4 or more orders of magnitude.

Small area silicon diffused junction X-ray detectors

NASA Technical Reports Server (NTRS)

Walton, J. T.; Pehl, R. H.; Larsh, A. E.

1982-01-01

The low-temperature performance of silicon diffused junction detectors in the measurement of low energy X-rays is reported. The detectors have an area of 0.04 sq cm and a thickness of 100 microns. The spectral resolutions of these detectors were found to be in close agreement with expected values, indicating that the defects introduced by the high-temperature processing required in the device fabrication were not deleteriously affecting the detection of low-energy X-rays. Device performance over a temperature range of 77 K to 150 K is given. These detectors were designed to detect low-energy X-rays in the presence of minimum ionizing electrons. The successful application of silicon-diffused junction technology to X-ray detector fabrication may facilitate the development of other novel silicon X-ray detector designs.

Optical aurora detectors: using natural optics to motivate education and outreach

NASA Astrophysics Data System (ADS)

Shaw, Joseph A.; Way, Jesse M.; Pust, Nathan J.; Nugent, Paul W.; Coate, Hans; Balster, Daniel

2009-06-01

Natural optical phenomena enjoy a level of interest sufficiently high among a wide array of people to provide ideal education and outreach opportunities. The aurora promotes particularly high interest, perhaps because of its relative rarity in the areas of the world where most people live. A project is being conducted at Montana State University to use common interest and curiosity about auroras to motivate learning and outreach through the design and deployment of optical sensor systems that detect the presence of an auroral display and send cell phone messages to alert interested people. Project participants learn about the physics and optics of the aurora, basic principles of optical system design, radiometric calculations and calibrations, electro-optical detectors, electronics, embedded computer systems, and computer software. The project is moving into a stage where it will provide greatly expanded outreach and education opportunities as optical aurora detector kits are created and disbursed to colleges around our region.

Spectral method for the correction of the Cerenkov light effect in plastic scintillation detectors: A comparison study of calibration procedures and validation in Cerenkov light-dominated situations

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

Guillot, Mathieu; Gingras, Luc; Archambault, Louis

2011-04-15

Purpose: The purposes of this work were: (1) To determine if a spectral method can accurately correct the Cerenkov light effect in plastic scintillation detectors (PSDs) for situations where the Cerenkov light is dominant over the scintillation light and (2) to develop a procedural guideline for accurately determining the calibration factors of PSDs. Methods: The authors demonstrate, by using the equations of the spectral method, that the condition for accurately correcting the effect of Cerenkov light is that the ratio of the two calibration factors must be equal to the ratio of the Cerenkov light measured within the two differentmore » spectral regions used for analysis. Based on this proof, the authors propose two new procedures to determine the calibration factors of PSDs, which were designed to respect this condition. A PSD that consists of a cylindrical polystyrene scintillating fiber (1.6 mm{sup 3}) coupled to a plastic optical fiber was calibrated by using these new procedures and the two reference procedures described in the literature. To validate the extracted calibration factors, relative dose profiles and output factors for a 6 MV photon beam from a medical linac were measured with the PSD and an ionization chamber. Emphasis was placed on situations where the Cerenkov light is dominant over the scintillation light and on situations dissimilar to the calibration conditions. Results: The authors found that the accuracy of the spectral method depends on the procedure used to determine the calibration factors of the PSD and on the attenuation properties of the optical fiber used. The results from the relative dose profile measurements showed that the spectral method can correct the Cerenkov light effect with an accuracy level of 1%. The results obtained also indicate that PSDs measure output factors that are lower than those measured with ionization chambers for square field sizes larger than 25x25 cm{sup 2}, in general agreement with previously published Monte Carlo results. Conclusions: The authors conclude that the spectral method can be used to accurately correct the Cerenkov light effect in PSDs. The authors confirmed the importance of maximizing the difference of Cerenkov light production between calibration measurements. The authors also found that the attenuation of the optical fiber, which is assumed to be constant in the original formulation of the spectral method, may cause a variation of the calibration factors in some experimental setups.« less

A gas ionisation detector in the axial (Bragg) geometry used for the time-of-flight elastic recoil detection analysis

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

Siketić, Zdravko; Skukan, Natko; Bogdanović Radović, Iva

2015-08-15

In this paper, time-of-flight elastic recoil detection analysis spectrometer with a newly constructed gas ionization detector for energy detection is presented. The detector is designed in the axial (Bragg) geometry with a 3 × 3 array of 50 nm thick Si{sub 3}N{sub 4} membranes as an entrance window. 40 mbar isobutane gas was sufficient to stop a 30 MeV primary iodine beam as well as all recoils in the detector volume. Spectrometer and detector performances were determined showing significant improvement in the mass and energy resolution, respectively, comparing to the spectrometer with a standard silicon particle detector for an energymore » measurement.« less

System for testing optical fibers

DOEpatents

Golob, John E. [Olathe, KS; Looney, Larry D. [Los Alamos, NM; Lyons, Peter B. [Los Alamos, NM; Nelson, Melvin A. [Santa Barbara, CA; Davies, Terence J. [Santa Barbara, CA

1980-07-15

A system for measuring a combination of optical transmission properties of fiber optic waveguides. A polarized light pulse probe is injected into one end of the optical fiber. Reflections from discontinuities within the fiber are unpolarized whereas reflections of the probe pulse incident to its injection remain polarized. The polarized reflections are prevented from reaching a light detector whereas reflections from the discontinuities reaches the detector.

Investigations into the chemical structure based selectivity of the microfabricated nitrogen-phosphorus detector

DOE PAGES

Brocato, Terisse A.; Hess, Ryan F.; Moorman, Matthew; ...

2015-10-28

The nitrogen and phosphorus atoms are constituents of some of the most toxic chemical vapors. Nitrogen-phosphorus gas chromatograph detectors (NPDs) rely on selective ionization of such compounds using ionization temperatures typically greater than 600 °C. NPDs have previously been reported to be 7*10 4× and 10 5× more sensitive for nitrogen and phosphorus, respectively, than for carbon. Presented here is an investigation of the structure-based selectivity of a microfabricated nitrogen-phosphorus detector (μNPD). The μNPD presented here is smaller than a dime and can be placed in a system that is 1/100th the size of a commercial NPD. Comparison of responsesmore » of such devices to homologous anilines (p-methoxyaniline, p-fluoroaniline, and aniline) revealed that detection selectivity, determined by the ratio of μNPD to nonselective flame ionization detector (FID) peak areas, is correlated with acid disassociation pK a values for the respective analine. Selectivity was determined to be greatest for p-methoxyaniline, followed by p-fluoroaniline, with aniline having the smallest response. The limit of detection for a nitrogen containing chemical, p-methoxyaniline, using the μNPD was determined to be 0.29 ng compared to 59 ng for a carbon chemical containing no nitrogen or phosphorus, 1,3,5-trimethybenzene. The μNPD presented here has increased detection for nitrogen and phosphorus compared to the FID and with a slight increase in detection of carbon compounds compared to commercial NPD's sensitivity to nitrogen and carbon.« less

Quantification of biogenic volatile organic compounds with a flame ionization detector using the effective carbon number concept

DOE PAGES

Faiola, C. L.; Erickson, M. H.; Fricaud, V. L.; ...

2012-08-10

Biogenic volatile organic compounds (BVOCs) are emitted into the atmosphere by plants and include isoprene, monoterpenes, sesquiterpenes, and their oxygenated derivatives. These BVOCs are among the principal factors influencing the oxidative capacity of the atmosphere in forested regions. BVOC emission rates are often measured by collecting samples onto adsorptive cartridges in the field and then transporting these samples to the laboratory for chromatographic analysis. One of the most commonly used detectors in chromatographic analysis is the flame ionization detector (FID). For quantitative analysis with an FID, relative response factors may be estimated using the effective carbon number (ECN) concept. Themore » purpose of this study was to determine the ECN for a variety of terpenoid compounds to enable improved quantification of BVOC measurements. A dynamic dilution system was developed to make quantitative gas standards of VOCs with mixing ratios from 20–55 ppb. For each experiment using this system, one terpene standard was co-injected with an internal reference, n-octane, and analyzed via an automated cryofocusing system interfaced to a gas chromatograph flame ionization detector and mass spectrometer (GC/MS/FID). The ECNs of 16 compounds (14 BVOCs) were evaluated with this approach, with each test compound analyzed at least three times. The difference between the actual carbon number and measured ECN ranged from -24% to -2%. Furthermore, the difference between theoretical ECN and measured ECN ranged from -22% to 9%. Measured ECN values were within 10% of theoretical ECN values for most terpenoid compounds.« less

A novel optical detector concept for dedicated and multi-modality in vivo small animal imaging

NASA Astrophysics Data System (ADS)

Peter, Jörg; Schulz, Ralf B.; Unholtz, Daniel; Semmler, Wolfhard

2007-07-01

An optical detector suitable for inclusion in tomographic arrangements for non-contact in vivo bioluminescence and fluorescence imaging applications is proposed. It consists of a microlens array (MLA) intended for field-of-view definition, a large-field complementary metal-oxide-semiconductor (CMOS) chip for light detection, a septum mask for cross-talk suppression, and an exchangeable filter to block excitation light. Prototype detector units with sensitive areas of 2.5 cm x 5 cm each were assembled. The CMOS sensor constitutes a 512 x 1024 photodiode matrix at 48 μm pixel pitch. Refractive MLAs with plano-convex lenses of 480 μm in diameter and pitch were selected resulting in a 55 x 105 lens matrix. The CMOS sensor is aligned on the focal plane of the MLA at 2.15mm distance. To separate individual microlens images an opaque multi-bore septum mask of 2.1mm in thickness and bore diameters of 400 μm at 480 μm pitch, aligned with the lens pattern, is placed between MLA and CMOS. Intrinsic spatial detector resolution and sensitivity was evaluated experimentally as a function of detector-object distance. Due to its small overall dimensions such detectors can be favorably packed for tomographic imaging (optical diffusion tomography, ODT) yielding complete 2 π field-of-view coverage. We also present a design study of a device intended to simultaneously image positron labeled substrates (positron emission tomography, PET) and optical molecular probes in small animals such as mice and rats. It consists of a cylindrical allocation of optical detector units which form an inner detector ring while PET detector blocks are mounted in radial extension, those gaining complementary information in a single, intrinsically coregistered experimental data acquisition study. Finally, in a second design study we propose a method for integrated optical and magnetic resonance imaging (MRI) which yields in vivo functional/molecular information that is intrinsically registered with the anatomy of the image object.

Effect of Intense Optical Excitation on Internal Electric Field Evolution in CdTe Gamma-Ray Detectors

NASA Astrophysics Data System (ADS)

Suzuki, K.; Ichinohe, Y.; Seto, S.

2018-03-01

The time-of-flight (TOF) transient currents in radiation detectors made of CdTe and Cd0.9Zn0.1Te (CZT) have been measured at several optical excitation intensities to investigate the effect of drifting carriers on the internal field. Both detectors show so-called space-charge-perturbed (SCP) current under intense optical excitation. A Monte Carlo (MC) simulation combined with an iterative solution of Poisson's equation is used to reproduce the observed currents under several bias voltages and excitation intensities. The SCP theory describes well the transient current in the CZT detector, whereas injection of holes from the anode and a corresponding reduction of the electron lifetime are further required to describe that in the CdTe detector. We visualize the temporal changes in the charge distribution and internal electric field profiles of both detectors.

Development of an advanced antineutrino detector for reactor monitoring

DOE PAGES

Classen, T.; Bernstein, A.; Bowden, N. S.; ...

2014-11-05

We present the development of a compact antineutrino detector for the purpose of nuclear reactor monitoring, improving upon a previously successful design. Our paper will describe the design improvements of the detector which increases the antineutrino detection efficiency threefold over the previous effort. There are two main design improvements over previous generations of detectors for nuclear reactor monitoring: dual-ended optical readout and single volume detection mass. The dual-ended optical readout eliminates the need for fiducialization and increases the uniformity of the detector's optical response. The containment of the detection mass in a single active volume provides more target mass permore » detector footprint, a key design criteria for operating within a nuclear power plant. This technology could allow for real-time monitoring of the evolution of a nuclear reactor core, independent of reactor operator declarations of fuel inventories, and may be of interest to the safeguards community.« less

The laser and optical system for the RIBF-PALIS experiment

NASA Astrophysics Data System (ADS)

Sonoda, T.; Iimura, H.; Reponen, M.; Wada, M.; Katayama, I.; Sonnenschein, V.; Takamatsu, T.; Tomita, H.; Kojima, T. M.

2018-01-01

This paper describes the laser and optical system for the Parasitic radioactive isotope (RI) beam production by Laser Ion-Source (PALIS) in the RIKEN fragment separator facility. This system requires an optical path length of 70 m for transporting the laser beam from the laser light source to the place for resonance ionization. To accomplish this, we designed and implemented a simple optical system consisting of several mirrors equipped with compact stepping motor actuators, lenses, beam spot screens and network cameras. The system enables multi-step laser resonance ionization in the gas cell and gas jet via overlap with a diameter of a few millimeters, between the laser photons and atomic beam. Despite such a long transport distance, we achieved a transport efficiency for the UV laser beam of about 50%. We also confirmed that the position stability of the laser beam stays within a permissible range for dedicated resonance ionization experiments.

FOXSI: Properties of optics and detectors for hard-X rays

NASA Astrophysics Data System (ADS)

Buitrago-Casas, Juan Camilo; Glesener, Lindsay; Christe, Steven; Krucker, Sam; Ishikawa, Shin-nosuke; Foster, Natalie

2015-04-01

The Focusing Optics X-ray Solar Imager (FOXSI) is a state-of-the-art direct focusing X-ray telescope designed to observe the Sun. This experiment completed its second flight onboard a sounding rocket last December 11, 2014 from the White Sands Missile Range in New Mexico. The optics use a set of iridium-coated nickel/cobalt mirrors made using a replication technique based on an electroformed perfect polished surface. Since this technique creates full shells that no need to be co-aligned with other segments, an angular resolution of up to ~5 arcsec is gotten. The FOXSI focal plane consists of seven double-sided strip detectors. Five Silicon and 2 CdTe detectors were used during the second flight.We present on various properties of Wolter-I optics that are applicable to solar HXR observation, including ray-tracing simulations of the single-bounce (“ghost ray”) patterns from sources outside the field of view and angular resolution for different source angles and effective area measurements of the FOXSI optics. We also present the detectors calibration results, paying attention to energy resolution (~0.5 keV), energy thresholds (~4-15 keV for Silicon and ~4-20 keV for CdTe detectors), and spatial coherence of these values over the entire detector.

New generation of Cherenkov counters

NASA Astrophysics Data System (ADS)

Giomataris, Y.; Charpak, G.; Peskov, V.; Sauli, F.

1992-12-01

Experimental results with a parallel plate avalanche chamber (PPAC) having a CsI photocathode and pad array readout are reported. High gains in excess of 10 5 have been obtained with He gas at atmospheric pressure and traces of CH 4 or CF 4 quencher. Such light gas mixtures extend the transparency for the Cherenkov light to the extreme UV region and allow detector operation with very low sensitivity to the ionization produced by minimum ionizing particles. A hadron blind detector (HBD) is discussed which exploits the broad photon energy bandwidth (≈ 10 eV) and the high Cherenkov threshold ( pπ = 15 GeV). This fast detector, since it has a good spatial resolution, can be used at the future Large Hadron Collider (LHC) or the Superconductivity Super Collider (SSC) either as an efficient electron tagger, rejecting hadrons faking electrons in the calorimeter, or as a pretracker giving fast electron and high-energy muon signature and momentum estimation. Other potential applications in the domain of Cherenkov light detection are also discussed.

Search for space charge effects in the ICARUS T600 LAr-TPC

NASA Astrophysics Data System (ADS)

Torti, Marta

2016-11-01

Space charge in Liquid Argon Time Projection Chamber is due to the accumu- lation of positive ions, produced by ionizing tracks crossing the detector, which slowly flow toward the cathode. As a consequence, electric field distortions may arise, thus hindering the possibility to produce faithful 3D images of the ionizing events. The presence of space charge becomes relevant for large TPCs operating at surface or at shallow depths, where cosmic ray flux is high. These effects could interest the next phase of the ICARUS T600 detector, which will be deployed at shallow depths as a Far Detector for Short Baseline Neutrino experiment at FNAL dedicated to sterile neutrino searches. In 2001, the first ICARUS T600 module (T300) operated at surface in Pavia (Italy), recording cosmic ray data. In this work, a sample of cosmic muon tracks from the 2001 run was analyzed and results on space charge effects in LAr-TPCs are shown.

A multilayer ΔE-E R telescope for breakup reactions at energies around the Coulomb barrier

NASA Astrophysics Data System (ADS)

Ma, Nan-Ru; Lin, Cheng-Jian; Wang, Jian-Song; Yang, Lei; Wang, Dong-Xi; Zheng, Lei; Xu, Shi-Wei; Sun, Li-Jie; Jia, Hui-Ming; Ma, Jun-Bing; Ma, Peng; Jin, Shi-Lun; Bai, Zhen; Yang, Yan-Yun; Xu, Xin-Xing; Zhang, Gao-Long; Yang, Feng; He, Jian-Jun; Zhang, Huan-Qiao; Liu, Zu-Hua

2016-11-01

The breakup reactions of weakly-bound nuclei at energies around the Coulomb barrier and the corresponding coupling effect on the other reaction channels are hot topics nowadays. To overcome the difficulty in identifying both heavier and lighter fragments simultaneously, a new kind of ionization-chamber based detector telescope has been designed and manufactured. It consists of a PCB ionization chamber and three different thickness silicon detectors installed inside the chamber, which form a multilayer ΔE-E R telescope. The working conditions were surveyed by using an α source. An in-beam test experiment shows that the detector has good particle identification for heavy particles like 17F and 16O as well as light particles like protons and alpha particles. The measured quasi-elastic scattering angular distribution and the related discussions for 17F+208Pb are presented. Supported by National Key Basic Research Development Program of China (2013CB834404) and National Natural Science Foundation of China (11375268, 11475263, U1432127, U1432246).

Detection of X-ray spectra and images by Timepix

NASA Astrophysics Data System (ADS)

Urban, M.; Nentvich, O.; Stehlikova, V.; Sieger, L.

2017-07-01

X-ray monitoring for astrophysical applications mainly consists of two parts - optics and detector. The article describes an approach based on a combination of Lobster Eye (LE) optics with Timepix detector. Timepix is a semiconductor detector with 256 × 256 pixels on one electrode and a second electrode is common. Usage of the back-side-pulse from an common electrode of pixelated detector brings the possibility of an additional spectroscopic or trigger signal. In this article are described effects of the thermal stabilisation, and the cooling effect of the detector working as single pixel.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Design and manufacture of imaging time-of-propagation optics

NASA Astrophysics Data System (ADS)

Albrecht, Mike; Fast, James; Schwartz, Alan

2016-09-01

There are several challenges associated with the design and manufacture of the optics required for the imaging time-of- propagation detector constructed for the Belle II particle physics experiment. This detector uses Cherenkov light radiated in quartz bars to identify subatomic particles: pions, kaons, and protons. The optics are physically large (125 cm x 45 cm x 2 cm bars and 45 cm x 10 cm x 5 cm prisms), all surfaces are optically polished, and there is very little allowance for chamfers or surface defects. In addition to the optical challenges, there are several logistical and handling challenges associated with measuring, assembling, cleaning, packaging, and shipping these delicate precision optics. This paper describes a collaborative effort between Pacific Northwest National Laboratory, the University of Cincinnati, and ZYGO Corporation for the design and manufacture of 48 fused silica optics (30 bars and 18 prisms) for the iTOP Detector. Details of the iTOP detector design that drove the challenging optical requirements are provided, along with material selection considerations. Since the optics are so large, precise, and delicate, special care had to be given to the selection of a manufacturing process capable of achieving the challenging optical and surface defect requirements on such large and high-aspect-ratio (66:1) components. A brief update on the current status and performance of these optics is also provided.

Development of a novel polymeric fiber-optic magnetostrictive metal detector.

PubMed

Hua, Wei-Shu; Hooks, Joshua Rosenberg; Wu, Wen-Jong; Wang, Wei-Chih

2010-01-01

The purpose this paper is the development a novel polymeric fiber-optic magnetostrictive metal detector, using a fiber-optic Mach-Zehnder interferometer and polymeric magnetostrictive material. Metal detection is based on the strain-induced optical path length change steming from the ferromagnetic material introduced in the magnetic field. Varied optical phase shifts resulted largely from different metal objects. In this paper, the preliminary results on the different metal material detection will be discussed.

Interaction with the Lower Ionosphere of Electromagnetic Pulses from Lightning: Heating, Attachment, Ionization, and Optical Emissions

DTIC Science & Technology

1993-09-25

using Opal et al. [1971] data on the secondary electron spectra and the ionization potential approximation used by Richards and Torr [1990]. The...N£ most easily detectable in the natural aurora [ Vallance Jones, 1974]. 4? 44 OPTICAL EMISSIONS To study optical emissions from the D region...here) are considered to be weak based on observed auroral spectra [ Vallance Jones, 1974; p. 90]. The intensity of t’-th line is given by [Chamberlain

The Future of Single- to Multi-band Detector Technologies: Review

NASA Technical Reports Server (NTRS)

Abedin, M. Nurul; Bhat, Ishwara; Gunapala, Sarath D.; Bandara, Sumith V.; Refaat, Tamer F.; Sandford, Stephen P.; Singh, Upendra N.

2006-01-01

Using classical optical components such as filters, prisms and gratings to separate the desired wavelengths before they reach the detectors results in complex optical systems composed of heavy components. A simpler system will result by utilizing a single optical system and a detector that responds separately to each wavelength band. Therefore, a continuous endeavors to develop the capability to reliably fabricate detector arrays that respond to multiple wavelength regions. In this article, we will review the state-of-the-art single and multicolor detector technologies over a wide spectral-range, for use in space-based and airborne remote sensing applications. Discussions will be focused on current and the most recently developed focal plane arrays (FPA) in addition to emphasizing future development in UV-to-Far infrared multicolor FPA detectors for next generation space-based instruments to measure water vapor and greenhouse gases. This novel detector component will make instruments designed for these critical measurements more efficient while reducing complexity and associated electronics and weight. Finally, we will discuss the ongoing multicolor detector technology efforts at NASA Langley Research Center, Jet Propulsion Laboratory, Rensselaer Polytechnic Institute, and others.

Photosensitive dopants for liquid noble gases

DOEpatents

Anderson, David F.

1988-01-01

In an ionization type detector for high energy radiation wherein the energy of incident radiation is absorbed through the ionization of a liquid noble gas and resulting free charge is collected to form a signal indicative of the energy of the incident radiation, an improvement comprising doping the liquid noble gas with photosensitive molecules to convert scintillation light due to recombination of ions, to additional free charge.

Development of a Hampton University Program for Novel Breast Cancer Imaging and Therapy Research

DTIC Science & Technology

2013-04-01

intracavitary brachytherapy procedures during laboratory pre-clinical imaging and dosimetry equipment testing, calibration and data processing, in collaboration... electronics and detector instrumentation development; 4) breast phantom construction and implantation; 5) laboratory pre-clinical device testing...such as the ionization chamber, diode, radiographic verification 6 films and thermoluminescent dosimeters ( TLD ) but the scintillator fiber detectors

Plastic scintillation detectors for dose monitoring in digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Antunes, J.; Machado, J.; Peralta, L.; Matela, N.

2018-01-01

Plastic scintillators detectors (PSDs) have been studied as dosimeters, since they provide a cost-effective alternative to conventional ionization chambers. Measurement and analysis of energy dependency were performed on a Siemens Mammomat tomograph for two different peak kilovoltages: 26 kV and 35 kV. Both PSD displayed good linearity for each energy considered and almost no energy dependence.

Radiometric and Radiation Response of Visible FPAs

NASA Technical Reports Server (NTRS)

Hubbs, John

2007-01-01

The readout integrated circuit (ROIC) used in these devices was originally developed for use in space based infrared systems operating at deep cryogenic temperatures and was selected because of its proven tolerance to total ionizing radiation? The detectors are a 128 x 128 array of 60 pm x 60 pm pixel elements that have been anti-reflection (AR) coated to improve the response at very short wavelengths. These visible focal plane arrays were operated at -40 C (233 K). Two focal planes were characterized using cobalt-60 radiation to produce ionizing total dose damage in the VFPAs. Both operational and performance data were obtained as functions of total dose. The first device tested showed no appreciable change in responsivity or noise up to 300 krad(Si). However, at the next dose level of 600 krad(Si), the readout was non-operational due to failure in the digital circuitry. The second device was characterized to a total dose of 750 krad(Si) with no observed change in responsivity. An increase dark current was observed in both devices, and in the second device, the dark current caused an increase in noise at low irradiance at 400 krad(Si) and above. The increase in dark current was somewhat un-expected for visible PIN detectors. The median dark current increased more than two orders of magnitude at 300 krad(Si) for the first device and a factor of 350 at 750 krad(Si) for pixels near the edge for the second device. The dark current was found to be a strong function of detector bias, with pixels near the edge of the array showing a greater increase in dark current with bias than those near the center. Since the optical response was not a function of bias, it is hypothesized that the dark current is a surface effect and that the variation in dark current with location is due to a variation in pixel bias, caused by a voltage drop across the pixel common lead. As the total dose increased, the dark current and the voltage drop increased

Entwicklungsarbeit am Spurendetektor fur das CDF Experiment am Tevatron (in German/English)

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

Hartmann, Frank

2000-02-01

Silicon, the element, which revolutionized the development of electronics, is known as an important and multiusable material, dominating todays electronic technology. It's properties are well investigated and today well known. Silicon is used in solar cells, computers and telecommunications. Since the Sixties semiconductors have been used as particle detectors. Initially they were operated in fixed- target experiments as calorimeters and as detectors with a high precision track reconstruction. Since the Eighties they are widely used in collider experiments as silicon microstrip or silicon pixel detectors near the primary vertex. Silicon sensors have a very good intrinsic energy resolution: for everymore » 3.6 eV released by a particle crossing the medium, one electron-hole pair is produced. Compared to 30 eV required to ionize a gas molecule in a gaseous detector, one gets 10 times the number of particles. The average energy loss and high ionized particle number with 390 e V / μm ~ 108 (electron - hole pairs)/ μm is effectively high due to the high density of silicon. These detectors allow a high precision reconstruction of tracks, primary and secondary vertices, which are especially important for b flavour tagging. The Tevatron and its detectors are being upgraded for the next data taking run starting in 2001 (RUN II). The Collider Detector at Fermilab (CDF) [2] for the upcoming Run II and its upgraded components are described in chapter 2. The main upgrade project is the design and construction of a completely new inner tracking system.« less

Fiber optic sensors

NASA Technical Reports Server (NTRS)

Hesse, J.; Sohler, W.

1984-01-01

A survey of the developments in the field of fiber optics sensor technology is presented along with a discussion of the advantages of optical measuring instruments as compared with electronic sensors. The two primary types of fiber optics sensors, specifically those with multiwave fibers and those with monowave fibers, are described. Examples of each major sensor type are presented and discussed. Multiwave detectors include external and internal fiber optics sensors. Among the monowave detectors are Mach-Zender interferometers, Michelson interferometers, Sagnac interferometers (optical gyroscopes), waveguide resonators, and polarimeter sensors. Integrated optical sensors and their application in spectroscopy are briefly discussed.

System for testing optical fibers

DOEpatents

Golob, J.E.; Looney, L.D.; Lyons, P.B.; Nelson, M.A.; Davies, T.J.

1980-07-15

A system for measuring a combination of optical transmission properties of fiber optic waveguides. A polarized light pulse probe is injected into one end of the optical fiber. Reflections from discontinuities within the fiber are unpolarized whereas reflections of the probe pulse incident to its injection remain polarized. The polarized reflections are prevented from reaching a light detector whereas reflections from the discontinuities reaches the detector. 2 figs.

Variable Sampling Mapping

NASA Technical Reports Server (NTRS)

Smith, Jeffrey, S.; Aronstein, David L.; Dean, Bruce H.; Lyon, Richard G.

2012-01-01

The performance of an optical system (for example, a telescope) is limited by the misalignments and manufacturing imperfections of the optical elements in the system. The impact of these misalignments and imperfections can be quantified by the phase variations imparted on light traveling through the system. Phase retrieval is a methodology for determining these variations. Phase retrieval uses images taken with the optical system and using a light source of known shape and characteristics. Unlike interferometric methods, which require an optical reference for comparison, and unlike Shack-Hartmann wavefront sensors that require special optical hardware at the optical system's exit pupil, phase retrieval is an in situ, image-based method for determining the phase variations of light at the system s exit pupil. Phase retrieval can be used both as an optical metrology tool (during fabrication of optical surfaces and assembly of optical systems) and as a sensor used in active, closed-loop control of an optical system, to optimize performance. One class of phase-retrieval algorithms is the iterative transform algorithm (ITA). ITAs estimate the phase variations by iteratively enforcing known constraints in the exit pupil and at the detector, determined from modeled or measured data. The Variable Sampling Mapping (VSM) technique is a new method for enforcing these constraints in ITAs. VSM is an open framework for addressing a wide range of issues that have previously been considered detrimental to high-accuracy phase retrieval, including undersampled images, broadband illumination, images taken at or near best focus, chromatic aberrations, jitter or vibration of the optical system or detector, and dead or noisy detector pixels. The VSM is a model-to-data mapping procedure. In VSM, fully sampled electric fields at multiple wavelengths are modeled inside the phase-retrieval algorithm, and then these fields are mapped to intensities on the light detector, using the properties of the detector and optical system, for comparison with measured data. Ultimately, this model-to-data mapping procedure enables a more robust and accurate way of incorporating the exit-pupil and image detector constraints, which are fundamental to the general class of ITA phase retrieval algorithms.

Imaging arrangement and microscope

DOEpatents

Pertsinidis, Alexandros; Chu, Steven

2015-12-15

An embodiment of the present invention is an imaging arrangement that includes imaging optics, a fiducial light source, and a control system. In operation, the imaging optics separate light into first and second tight by wavelength and project the first and second light onto first and second areas within first and second detector regions, respectively. The imaging optics separate fiducial light from the fiducial light source into first and second fiducial light and project the first and second fiducial light onto third and fourth areas within the first and second detector regions, respectively. The control system adjusts alignment of the imaging optics so that the first and second fiducial light projected onto the first and second detector regions maintain relatively constant positions within the first and second detector regions, respectively. Another embodiment of the present invention is a microscope that includes the imaging arrangement.

Modulation transfer function of a triangular pixel array detector.

PubMed

Karimzadeh, Ayatollah

2014-07-01

The modulation transfer function (MTF) is the main parameter that is used to evaluate image quality in electro-optical systems. Detector sampling MTF in most electro-optical systems determines the cutoff frequency of the system. The MTF of the detector depends on its pixel shape. In this work, we calculated the MTF of a detector with an equilateral triangular pixel shape. Some new results were found in deriving the MTF for the equilateral triangular pixel shape.

Experimental study on detection of electrostatic discharges generated by polymer granules inside a metal silo

NASA Astrophysics Data System (ADS)

Choi, Kwangseok; Mogami, Tomofumi; Suzuki, Teruo

2014-04-01

To detect electrostatic discharges generated by polymer granules within a metal silo, we developed a novel and simple electrostatic discharge detector that utilizes a photosensor. The novel detector consists of a photosensor module in a metal cylinder, an optical band-pass filter, a quartz glass, a power supply, an amplifier for the photosensor module, and a digital oscilloscope. In this study, we conducted experiments at a real pneumatic powder transport facility that includes a metal silo to evaluate the novel detector using polypropylene granules. To determine the performance of the novel detector, we observed the electrostatic discharge within the metal silo using a conventional image intensifier system. The results obtained from the experiments show that the novel detector worked well in this study. The signals obtained with the novel detector were identical to the electrostatic discharges obtained with the conventional image intensifier system. The greatest advantage of this novel detector is that it is effective even when placed under external lights. In addition, the influence of various optical band-pass filters on the performance of the novel detector was discussed. Our study confirmed that an optical band-pass filter with a center wavelength of λ 330 nm (λ1/2: 315-345 nm) was the best performer among the optical band-pass filters used in this study.

Experimental study on detection of electrostatic discharges generated by polymer granules inside a metal silo.

PubMed

Choi, Kwangseok; Mogami, Tomofumi; Suzuki, Teruo

2014-04-01

To detect electrostatic discharges generated by polymer granules within a metal silo, we developed a novel and simple electrostatic discharge detector that utilizes a photosensor. The novel detector consists of a photosensor module in a metal cylinder, an optical band-pass filter, a quartz glass, a power supply, an amplifier for the photosensor module, and a digital oscilloscope. In this study, we conducted experiments at a real pneumatic powder transport facility that includes a metal silo to evaluate the novel detector using polypropylene granules. To determine the performance of the novel detector, we observed the electrostatic discharge within the metal silo using a conventional image intensifier system. The results obtained from the experiments show that the novel detector worked well in this study. The signals obtained with the novel detector were identical to the electrostatic discharges obtained with the conventional image intensifier system. The greatest advantage of this novel detector is that it is effective even when placed under external lights. In addition, the influence of various optical band-pass filters on the performance of the novel detector was discussed. Our study confirmed that an optical band-pass filter with a center wavelength of λ 330 nm (λ1/2: 315-345 nm) was the best performer among the optical band-pass filters used in this study.

Design of fiber optic probes for laser light scattering

NASA Technical Reports Server (NTRS)

Dhadwal, Harbans S.; Chu, Benjamin

1989-01-01

A quantitative analysis is presented of the role of optical fibers in laser light scattering. Design of a general fiber optic/microlens probe by means of ray tracing is described. Several different geometries employing an optical fiber of the type used in lightwave communications and a graded index microlens are considered. Experimental results using a nonimaging fiber optic detector probe show that due to geometrical limitations of single mode fibers, a probe using a multimode optical fiber has better performance, for both static and dynamic measurements of the scattered light intensity, compared with a probe using a single mode fiber. Fiber optic detector probes are shown to be more efficient at data collection when compared with conventional approaches to measurements of the scattered laser light. Integration of fiber optic detector probes into a fiber optic spectrometer offers considerable miniaturization of conventional light scattering spectrometers, which can be made arbitrarily small. In addition static and dynamic measurements of scattered light can be made within the scattering cell and consequently very close to the scattering center.

Examination system utilizing ionizing radiation and a flexible, miniature radiation detector probe

DOEpatents

Majewski, S.; Kross, B.J.; Zorn, C.J.; Majewski, L.A.

1996-10-22

An optimized examination system and method based on the Reverse Geometry X-Ray{trademark} (RGX{trademark}) radiography technique are presented. The examination system comprises a radiation source, at least one flexible, miniature radiation detector probe positioned in appropriate proximity to the object to be examined and to the radiation source with the object located between the source and the probe, a photodetector device attachable to an end of the miniature radiation probe, and a control unit integrated with a display device connected to the photodetector device. The miniature radiation detector probe comprises a scintillation element, a flexible light guide having a first end optically coupled to the scintillation element and having a second end attachable to the photodetector device, and an opaque, environmentally-resistant sheath surrounding the flexible light guide. The probe may be portable and insertable, or may be fixed in place within the object to be examined. An enclosed, flexible, liquid light guide is also presented, which comprises a thin-walled flexible tube, a liquid, preferably mineral oil, contained within the tube, a scintillation element located at a first end of the tube, closures located at both ends of the tube, and an opaque, environmentally-resistant sheath surrounding the flexible tube. The examination system and method have applications in non-destructive material testing for voids, cracks, and corrosion, and may be used in areas containing hazardous materials. In addition, the system and method have applications for medical and dental imaging. 5 figs.

Examination system utilizing ionizing radiation and a flexible, miniature radiation detector probe

DOEpatents

Majewski, Stanislaw; Kross, Brian J.; Zorn, Carl J.; Majewski, Lukasz A.

1996-01-01

An optimized examination system and method based on the Reverse Geometry X-Ray.RTM. (RGX.RTM.) radiography technique are presented. The examination system comprises a radiation source, at least one flexible, miniature radiation detector probe positioned in appropriate proximity to the object to be examined and to the radiation source with the object located between the source and the probe, a photodetector device attachable to an end of the miniature radiation probe, and a control unit integrated with a display device connected to the photodetector device. The miniature radiation detector probe comprises a scintillation element, a flexible light guide having a first end optically coupled to the scintillation element and having a second end attachable to the photodetector device, and an opaque, environmentally-resistant sheath surrounding the flexible light guide. The probe may be portable and insertable, or may be fixed in place within the object to be examined. An enclosed, flexible, liquid light guide is also presented, which comprises a thin-walled flexible tube, a liquid, preferably mineral oil, contained within the tube, a scintillation element located at a first end of the tube, closures located at both ends of the tube, and an opaque, environmentally-resistant sheath surrounding the flexible tube. The examination system and method have applications in non-destructive material testing for voids, cracks, and corrosion, and may be used in areas containing hazardous materials. In addition, the system and method have applications for medical and dental imaging.

Ionizing laser propagation and spectral phase determination

NASA Astrophysics Data System (ADS)

Mittelberger, D. E.; Nakamura, K.; Lehe, R.; Gonsalves, A. J.; Benedetti, C.; Mao, H.-S.; Daniels, J.; Dale, N.; Swanson, K. K.; Esarey, E.; Leemans, W. P.

2017-03-01

Ionization-induced blueshifting is investigated through INF&RNO simulations and experimental studies at the Berkeley Laboratory Laser Accelerator (BELLA) Center. The effects of spectral phase and optical compression are explored. An in-situ method for verifying the spectral phase of an intense laser pulse at focus is presented, based on the effects of optical compression on the morphology of the blueshifted laser spectra.

Fiber optic crossbar switch for automatically patching optical signals

NASA Technical Reports Server (NTRS)

Bell, C. H. (Inventor)

1983-01-01

A system for automatically optically switching fiber optic data signals between a plurality of input optical fibers and selective ones of a plurality of output fibers is described. The system includes optical detectors which are connected to each of the input fibers for converting the optic data signals appearing at the respective input fibers to an RF signal. A plurality of RF to optical signal converters are arranged in rows and columns. The output of each of the optical detectors are each applied to a respective row of optical signal converted for being converters back to an optical signal when the particular optical signal converter is selectively activated by a dc voltage.

System and method for determination of the reflection wavelength of multiple low-reflectivity bragg gratings in a sensing optical fiber

NASA Technical Reports Server (NTRS)

Moore, Jason P. (Inventor)

2009-01-01

A system and method for determining a reflection wavelength of multiple Bragg gratings in a sensing optical fiber comprise: (1) a source laser; (2) an optical detector configured to detect a reflected signal from the sensing optical fiber; (3) a plurality of frequency generators configured to generate a signal having a frequency corresponding to an interferometer frequency of a different one of the plurality of Bragg gratings; (4) a plurality of demodulation elements, each demodulation element configured to combine the signal produced by a different one of the plurality of frequency generators with the detected signal from the sensing optical fiber; (5) a plurality of peak detectors, each peak detector configured to detect a peak of the combined signal from a different one of the demodulation elements; and (6) a laser wavenumber detection element configured to determine a wavenumber of the laser when any of the peak detectors detects a peak.

Simple electronic apparatus for the analysis of radioactively labeled gel electrophoretograms

DOEpatents

Goulianos, Konstantin; Smith, Karen K.; White, Sebastian N.

1982-01-01

A high resolution position sensitive radiation detector for analyzing radiation emanating from a source, constructed of a thin plate having an elongated slot with conductive edges acting as a cathode, a charged anode wire positioned within 0.5 mm adjacent the source and running parallel to the slot and centered therein, an ionizable gas ionized by radiation emanating from the source provided surrounding the anode wire in the slot, a helical wire induction coil serving as a delay line and positioned beneath the anode wire for detecting gas ionization and for producing resulting ionization signals, and processing circuits coupled to the induction coil for receiving ionization signals induced therein after determining therefrom the location along the anode wire of any radiation emanating from the source. An ionization gas of 70% Ar, 29% Isobutane, 0.6% Freon 13BI, and 0.4% Methylal is used.

Ionization detection system for aerosols

DOEpatents

Jacobs, Martin E.

1977-01-01

This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system utilizes a measuring ionization chamber which is modified to minimize false alarms and reductions in sensitivity resulting from changes in ambient temperature. In the preferred form of the modification, an annular radiation shield is mounted about the usual radiation source provided to effect ionization in the measuring chamber. The shield is supported by a bimetallic strip which flexes in response to changes in ambient temperature, moving the shield relative to the source so as to vary the radiative area of the source in a manner offsetting temperature-induced variations in the sensitivity of the chamber.

Comparative Soot Diagnostics Experiment Looks at the Smoky World of Microgravity Combustion

NASA Technical Reports Server (NTRS)

Urban, David L.; Griffin, DeVon W.; Gard, Melissa Y.

1997-01-01

From an economic standpoint, soot is one of the most important combustion intermediates and products. It is a major industrial product and is the dominant medium for radiant heat transport in most flames used to generate heat and power. The nonbuoyant structure of most flames of practical interest (turbulent flames) makes the understanding of soot processes in microgravity flames important to our ability to predict fire behavior on Earth. In addition, fires in spacecraft are considered a credible possibility. To respond to this risk, NASA has flown fire (or smoke) detectors on Skylab and the space shuttles and included them in the International Space Station design. The design of these detectors, however, was based entirely on normal gravity (1g) data. The detector used in the shuttle fleet is an ionization detector, whereas the system planned for the space station uses forward scattering of near-infrared light. The ionization detector, which is similar to smoke detectors used in homes, has a comparative advantage for submicron particulates. In fact, the space shuttle model uses a separation system that makes it blind to particles larger than a micron (believed to be dust). In the larger size range, the lightscattering detector is most sensitive. Without microgravity smoke data, the difference in the particle size sensitivities of the two detectors cannot be evaluated. As part of the Comparative Soot Diagnostics (CSD) experiment, these systems were tested to determine their response to particulates generated during long periods of low gravity. This experiment provided the first such measurements toward understanding soot processes on Earth and for designing and implementing improved spacecraft smoke detection systems. The objectives of CSD were to examine how particulates form from a variety of sources and to quantify the performance of several diagnostic techniques. The sources tested included four overheated materials (paper, silicone rubber, Teflon-coated (DuPont) wire, and Kapton-coated (DuPont) wires), each tested at three heating rates, and a candle tested at three air velocities. Paper, silicone rubber, and wire insulation, materials found in spacecraft crew cabins, were selected because of their different smoke properties. The candle yielded hydrocarbon soot typical of many 1g flames. Four diagnostic techniques were employed: thermophoretic sampling collected particulates for size analysis; laser light extinction measurements near the source tallied total particulate production; and laser light scattering and ionization detector measurements far from the particulate source provided data for evaluating the performance of smoke detection systems for these particulate sources.

Development of an iterative reconstruction method to overcome 2D detector low resolution limitations in MLC leaf position error detection for 3D dose verification in IMRT.

PubMed

Visser, R; Godart, J; Wauben, D J L; Langendijk, J A; Van't Veld, A A; Korevaar, E W

2016-05-21

The objective of this study was to introduce a new iterative method to reconstruct multi leaf collimator (MLC) positions based on low resolution ionization detector array measurements and to evaluate its error detection performance. The iterative reconstruction method consists of a fluence model, a detector model and an optimizer. Expected detector response was calculated using a radiotherapy treatment plan in combination with the fluence model and detector model. MLC leaf positions were reconstructed by minimizing differences between expected and measured detector response. The iterative reconstruction method was evaluated for an Elekta SLi with 10.0 mm MLC leafs in combination with the COMPASS system and the MatriXX Evolution (IBA Dosimetry) detector with a spacing of 7.62 mm. The detector was positioned in such a way that each leaf pair of the MLC was aligned with one row of ionization chambers. Known leaf displacements were introduced in various field geometries ranging from  -10.0 mm to 10.0 mm. Error detection performance was tested for MLC leaf position dependency relative to the detector position, gantry angle dependency, monitor unit dependency, and for ten clinical intensity modulated radiotherapy (IMRT) treatment beams. For one clinical head and neck IMRT treatment beam, influence of the iterative reconstruction method on existing 3D dose reconstruction artifacts was evaluated. The described iterative reconstruction method was capable of individual MLC leaf position reconstruction with millimeter accuracy, independent of the relative detector position within the range of clinically applied MU's for IMRT. Dose reconstruction artifacts in a clinical IMRT treatment beam were considerably reduced as compared to the current dose verification procedure. The iterative reconstruction method allows high accuracy 3D dose verification by including actual MLC leaf positions reconstructed from low resolution 2D measurements.

Review on the characteristics of radiation detectors for dosimetry and imaging

NASA Astrophysics Data System (ADS)

Seco, Joao; Clasie, Ben; Partridge, Mike

2014-10-01

The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of multi-slice CT and digital x-ray imaging systems, with silver halide films now largely obsolete for many applications. Nuclear medicine has benefited from more sensitive, faster and higher-resolution detectors delivering ever-higher SPECT and PET image quality. PET/MR systems have been enabled by the development of gamma ray detectors that can operate in high magnetic fields. These huge advances in imaging have enabled equally impressive steps forward in radiotherapy delivery accuracy, with 4DCT, PET and MRI routinely used in treatment planning and online image guidance provided by cone-beam CT. The challenge of ensuring safe, accurate and precise delivery of highly complex radiation fields has also both driven and benefited from advances in radiation detectors. Detector systems have been developed for the measurement of electron, intensity-modulated and modulated arc x-ray, proton and ion beams, and around brachytherapy sources based on a very wide range of technologies. The types of measurement performed are equally wide, encompassing commissioning and quality assurance, reference dosimetry, in vivo dosimetry and personal and environmental monitoring. In this article, we briefly introduce the general physical characteristics and properties that are commonly used to describe the behaviour and performance of both discrete and imaging detectors. The physical principles of operation of calorimeters; ionization and charge detectors; semiconductor, luminescent, scintillating and chemical detectors; and radiochromic and radiographic films are then reviewed and their principle applications discussed. Finally, a general discussion of the application of detectors for x-ray nuclear medicine and ion beam imaging and dosimetry is presented.

RESONEUT: A detector system for spectroscopy with (d,n) reactions in inverse kinematics

NASA Astrophysics Data System (ADS)

Baby, L. T.; Kuvin, S. A.; Wiedenhöver, I.; Anastasiou, M.; Caussyn, D.; Colbert, K.; Quails, N.; Gay, D.

2018-01-01

The RESONEUT detector setup is described, which was developed for resonance spectroscopy using (d,n) reactions with radioactive beams in inverse kinematics and at energies around the Coulomb barrier. The goal of experiments with this setup is to determine the spectrum and proton-transfer strengths of the low-lying resonances, which have an impact on astrophysical reaction rates. The setup is optimized for l = 0 proton transfers in inverse kinematics, for which most neutrons are emitted at backward angles with energies in the 80-300 keV range. The detector system is comprised of 9 p-terphenyl scintillators as neutron detectors, two annular silicon-strip detectors for light charged particles, one position-resolving gas ionization chamber for heavy ion detection, and a barrel of NaI-detectors for the detection of γ-rays. The detector commissioning and performance characteristics are described with an emphasis on the neutron-detector components.

Ultra-thin plasma radiation detector

DOEpatents

Friedman, Peter S.

2017-01-24

A position-sensitive ionizing-radiation counting detector includes a radiation detector gas chamber having at least one ultra-thin chamber window and an ultra-thin first substrate contained within the gas chamber. The detector further includes a second substrate generally parallel to and coupled to the first substrate and defining a gas gap between the first substrate and the second substrate. The detector further includes a discharge gas between the substrates and contained within the gas chamber, where the discharge gas is free to circulate within the gas chamber and between the first and second substrates at a given gas pressure. The detector further includes a first electrode coupled to one of the substrates and a second electrode electrically coupled to the first electrode. The detector further includes a first discharge event detector coupled to at least one of the electrodes for detecting a gas discharge counting event in the electrode.

Calibration methods and tools for KM3NeT

NASA Astrophysics Data System (ADS)

Kulikovskiy, Vladimir

2016-04-01

The KM3NeT detectors, ARCA and ORCA, composed of several thousands digital optical modules, are in the process of their realization in the Mediterranean Sea. Each optical module contains 31 3-inch photomultipliers. Readout of the optical modules and other detector components is synchronized at the level of sub-nanoseconds. The position of the module is measured by acoustic piezo detectors inside the module and external acoustic emitters installed on the bottom of the sea. The orientation of the module is obtained with an internal attitude and heading reference system chip. Detector calibration, i.e. timing, positioning and sea-water properties, is overviewed in this talk and discussed in detail in this conference. Results of the procedure applied to the first detector unit ready for installation in the deep sea will be shown.

Prompt ionization in the CRIT II barium releases. [Critical Ionization Tests

NASA Technical Reports Server (NTRS)

Torbert, R. B.; Kletzing, C. A.; Liou, K.; Rau, D.

1992-01-01

Observations of electron and ion distributions inside a fast neutral barium jet in the ionosphere show significant fluxes within 4 km of release, presumably related to beam plasma instability processes involved in the Critical Ionization Velocity (CIV) effect. Electron fluxes exceeding 5 x 10 exp 12/sq cm-str-sec-keV were responsible for ionizing both the streaming barium and ambient oxygen. Resulting ion fluxes seem to be consistent with 1-2 percent ionization of the fast barium, as reported by optical observations, although the extended spatial distribution of the optically observed ions is difficult to reconcile with the in situ observations. When the perpendicular velocity of the neutrals falls below critical values, these processes shut off. Although these observations resemble the earlier Porcupine experimental results (Haerendel, 1982), theoretical understanding of the differences between these data and that of earlier negative experiments is still lacking.

Electron gyroharmonic effects in ionization and electron acceleration during high-frequency pumping in the ionosphere.

PubMed

Gustavsson, B; Leyser, T B; Kosch, M; Rietveld, M T; Steen, A; Brändström, B U E; Aso, T

2006-11-10

Optical emissions and incoherent scatter radar data obtained during high-frequency electromagnetic pumping of the ionospheric plasma from the ground give data on electron energization in an energy range from 2 to 100 eV. Optical emissions at 4278 A from N2+ that require electrons with energies above the 18 eV ionization energy give the first images ever of pump-induced ionization of the thermosphere. The intensity at 4278 A is asymmetric around the ionospheric electron gyroharmonic, being stronger above the gyroresonance. This contrasts with emissions at 6300 A from O(1D) and of electron temperature enhancements, which have minima at the gyroharmonic but have no apparent asymmetry. This direct evidence of pump-induced ionization contradicts previous indirect evidence, which indicated that ionization is most efficiently produced when the pump frequency was below the gyroharmonic.

Electrode structure of a compact microwave driven capacitively coupled atomic beam source

NASA Astrophysics Data System (ADS)

Shimabukuro, Yuji; Takahashi, Hidenori; Wada, Motoi

2018-01-01

A compact magnetic field free atomic beam source was designed, assembled and tested the performance to produce hydrogen and nitrogen atoms. A forced air-cooled solid-state microwave power supply at 2.45 GHz frequency drives the source up to 100 W through a coaxial transmission cable coupled to a triple stub tuner for realizing a proper matching condition to the discharge load. The discharge structure of the source affected the range of operation pressure, and the pressure was reduced by four orders of magnitude through improving the electrode geometry to enhance the local electric field intensity. Optical emission spectra of the produced plasmas indicate production of hydrogen and nitrogen atoms, while the flux intensity of excited nitrogen atoms monitored by a surface ionization type detector showed the signal level close to a source developed for molecular beam epitaxy applications with 500 W RF power.

Method and apparatus for reading thermoluminescent phosphors

DOEpatents

Braunlich, Peter F.; Tetzlaff, Wolfgang

1987-01-01

An apparatus and method for rapidly reading thermoluminescent phosphors to determine the amount of luminescent energy stored therein. The stored luminescent energy is interpreted as a measure of the total exposure of the thermoluminescent phosphor to ionizing radiation. The thermoluminescent phosphor reading apparatus uses a laser to generate a laser beam. The laser beam power level is monitored by a laser power detector and controlled to maintain the power level nearly constant. A shutter or other laser beam interrupting means is used to control exposure of the thermoluminescent phosphor to the laser beam. The laser beam can be equalized using an optical equalizer so that the laser beam has an approximately uniform power density across the beam. The heated thermoluminescent phosphor emits a visible or otherwise detectable luminescent emission which is measured as an indication of the radiation exposure of the thermoluminescent phosphors. Also disclosed are preferred signal processing and control circuits.

Rapid Monte Carlo simulation of detector DQE(f)

PubMed Central

Star-Lack, Josh; Sun, Mingshan; Meyer, Andre; Morf, Daniel; Constantin, Dragos; Fahrig, Rebecca; Abel, Eric

2014-01-01

Purpose: Performance optimization of indirect x-ray detectors requires proper characterization of both ionizing (gamma) and optical photon transport in a heterogeneous medium. As the tool of choice for modeling detector physics, Monte Carlo methods have failed to gain traction as a design utility, due mostly to excessive simulation times and a lack of convenient simulation packages. The most important figure-of-merit in assessing detector performance is the detective quantum efficiency (DQE), for which most of the computational burden has traditionally been associated with the determination of the noise power spectrum (NPS) from an ensemble of flood images, each conventionally having 107 − 109 detected gamma photons. In this work, the authors show that the idealized conditions inherent in a numerical simulation allow for a dramatic reduction in the number of gamma and optical photons required to accurately predict the NPS. Methods: The authors derived an expression for the mean squared error (MSE) of a simulated NPS when computed using the International Electrotechnical Commission-recommended technique based on taking the 2D Fourier transform of flood images. It is shown that the MSE is inversely proportional to the number of flood images, and is independent of the input fluence provided that the input fluence is above a minimal value that avoids biasing the estimate. The authors then propose to further lower the input fluence so that each event creates a point-spread function rather than a flood field. The authors use this finding as the foundation for a novel algorithm in which the characteristic MTF(f), NPS(f), and DQE(f) curves are simultaneously generated from the results of a single run. The authors also investigate lowering the number of optical photons used in a scintillator simulation to further increase efficiency. Simulation results are compared with measurements performed on a Varian AS1000 portal imager, and with a previously published simulation performed using clinical fluence levels. Results: On the order of only 10–100 gamma photons per flood image were required to be detected to avoid biasing the NPS estimate. This allowed for a factor of 107 reduction in fluence compared to clinical levels with no loss of accuracy. An optimal signal-to-noise ratio (SNR) was achieved by increasing the number of flood images from a typical value of 100 up to 500, thereby illustrating the importance of flood image quantity over the number of gammas per flood. For the point-spread ensemble technique, an additional 2× reduction in the number of incident gammas was realized. As a result, when modeling gamma transport in a thick pixelated array, the simulation time was reduced from 2.5 × 106 CPU min if using clinical fluence levels to 3.1 CPU min if using optimized fluence levels while also producing a higher SNR. The AS1000 DQE(f) simulation entailing both optical and radiative transport matched experimental results to within 11%, and required 14.5 min to complete on a single CPU. Conclusions: The authors demonstrate the feasibility of accurately modeling x-ray detector DQE(f) with completion times on the order of several minutes using a single CPU. Convenience of simulation can be achieved using GEANT4 which offers both gamma and optical photon transport capabilities. PMID:24593734

Rapid Monte Carlo simulation of detector DQE(f)

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

Star-Lack, Josh, E-mail: josh.starlack@varian.com; Sun, Mingshan; Abel, Eric

2014-03-15

Purpose: Performance optimization of indirect x-ray detectors requires proper characterization of both ionizing (gamma) and optical photon transport in a heterogeneous medium. As the tool of choice for modeling detector physics, Monte Carlo methods have failed to gain traction as a design utility, due mostly to excessive simulation times and a lack of convenient simulation packages. The most important figure-of-merit in assessing detector performance is the detective quantum efficiency (DQE), for which most of the computational burden has traditionally been associated with the determination of the noise power spectrum (NPS) from an ensemble of flood images, each conventionally having 10{supmore » 7} − 10{sup 9} detected gamma photons. In this work, the authors show that the idealized conditions inherent in a numerical simulation allow for a dramatic reduction in the number of gamma and optical photons required to accurately predict the NPS. Methods: The authors derived an expression for the mean squared error (MSE) of a simulated NPS when computed using the International Electrotechnical Commission-recommended technique based on taking the 2D Fourier transform of flood images. It is shown that the MSE is inversely proportional to the number of flood images, and is independent of the input fluence provided that the input fluence is above a minimal value that avoids biasing the estimate. The authors then propose to further lower the input fluence so that each event creates a point-spread function rather than a flood field. The authors use this finding as the foundation for a novel algorithm in which the characteristic MTF(f), NPS(f), and DQE(f) curves are simultaneously generated from the results of a single run. The authors also investigate lowering the number of optical photons used in a scintillator simulation to further increase efficiency. Simulation results are compared with measurements performed on a Varian AS1000 portal imager, and with a previously published simulation performed using clinical fluence levels. Results: On the order of only 10–100 gamma photons per flood image were required to be detected to avoid biasing the NPS estimate. This allowed for a factor of 10{sup 7} reduction in fluence compared to clinical levels with no loss of accuracy. An optimal signal-to-noise ratio (SNR) was achieved by increasing the number of flood images from a typical value of 100 up to 500, thereby illustrating the importance of flood image quantity over the number of gammas per flood. For the point-spread ensemble technique, an additional 2× reduction in the number of incident gammas was realized. As a result, when modeling gamma transport in a thick pixelated array, the simulation time was reduced from 2.5 × 10{sup 6} CPU min if using clinical fluence levels to 3.1 CPU min if using optimized fluence levels while also producing a higher SNR. The AS1000 DQE(f) simulation entailing both optical and radiative transport matched experimental results to within 11%, and required 14.5 min to complete on a single CPU. Conclusions: The authors demonstrate the feasibility of accurately modeling x-ray detector DQE(f) with completion times on the order of several minutes using a single CPU. Convenience of simulation can be achieved using GEANT4 which offers both gamma and optical photon transport capabilities.« less

Search for metastable heavy charged particles with large ionization energy loss in p p collisions at s = 13 TeV using the ATLAS experiment

DOE PAGES

Aaboud, M.; Aad, G.; Abbott, B.; ...

2016-06-28

This study presents a search for massive charged long-lived particles produced in pp collisions at √s = 13TeV at the LHC using the ATLAS experiment. The data set used corresponds to an integrated luminosity of 3.2 fb –1. Many extensions of the Standard Model predict the existence of massive charged long-lived particles, such as R-hadrons. These massive particles are expected to be produced with a velocity significantly below the speed of light, and therefore to have a specific ionization higher than any Standard Model particle of unit charge at high momenta. The Pixel subsystem of the ATLAS detector is usedmore » to measure the ionization energy loss of reconstructed charged particles and to search for such highly ionizing particles. The search presented here has much greater sensitivity than a similar search performed using the ATLAS detector in the √s = 8TeV data set, thanks to the increase in expected signal cross section due to the higher center-of-mass energy of collisions, to an upgraded detector with a new silicon layer close to the interaction point, and to analysis improvements. No significant deviation from Standard Model background expectations is observed, and lifetime-dependent upper limits on R-hadron production cross sections and masses are set. Gluino R-hadrons with lifetimes above 0.4 ns and decaying to qq¯ plus a 100 GeV neutralino are excluded at the 95% confidence level, with lower mass limit ranging between 740 and 1590 GeV. In the case of stable R-hadrons the lower mass limit at the 95% confidence level is 1570 GeV.« less

SU-E-I-107: Suitability of Various Radiation Detectors Used in Radiation Therapy for X-Ray Dosimetry in Computed Tomography.

PubMed

Liebmann, M; Poppe, B; von Boetticher, H

2012-06-01

Assessment of suitability for X-ray dosimetry in computed tomography of various ionization chambers, diodes and two-dimensional detector arrays primarily used in radiation therapy. An Oldelft X-ray simulation unit was used to irradiate PTW 60008, 60012 dosimetry diodes, PTW 23332, 31013, 31010, 31006 axial symmetrical ionization chambers, PTW 23343, 34001 plane parallel ionization chambers and PTW Starcheck and 2D-Array seven29 as well as a prototype Farmer chamber with a copper wall. Peak potential was varied from 50 kV up to 125 kV and beam qualities were quantified through half-value-layer measurements. Energy response was investigated free in air as well as in 2 cm depth in a solid water phantom and refers to a manufacturer calibrated PTW 60004 diode for kV-dosimetry. The thimble ionization chambers PTW 31010, 31013, the uncapsuled diode PTW 60012 and the PTW 2D-Array seven29 exhibit an energy response deviation in the investigated energy region of approximately 10% or lower thus proving good usability in X-ray dosimetry if higher spatial resolution is needed or rotational irradiations occur. It could be shown that in radiation therapy routinely used detectors are usable in a much lower energy region. The rotational symmetry is of advantage in computed tomography dosimetry and enables dose profile as well as point dose measurements in a suitable phantom for estimation of organ doses. Additional the PTW 2D-Array seven29 can give a quick overview of radiation fields in non-rotating tasks. © 2012 American Association of Physicists in Medicine.

End-to-end tests using alanine dosimetry in scanned proton beams

NASA Astrophysics Data System (ADS)

Carlino, A.; Gouldstone, C.; Kragl, G.; Traneus, E.; Marrale, M.; Vatnitsky, S.; Stock, M.; Palmans, H.

2018-03-01

This paper describes end-to-end test procedures as the last fundamental step of medical commissioning before starting clinical operation of the MedAustron synchrotron-based pencil beam scanning (PBS) therapy facility with protons. One in-house homogeneous phantom and two anthropomorphic heterogeneous (head and pelvis) phantoms were used for end-to-end tests at MedAustron. The phantoms were equipped with alanine detectors, radiochromic films and ionization chambers. The correction for the ‘quenching’ effect of alanine pellets was implemented in the Monte Carlo platform of the evaluation version of RayStation TPS. During the end-to-end tests, the phantoms were transferred through the workflow like real patients to simulate the entire clinical workflow: immobilization, imaging, treatment planning and dose delivery. Different clinical scenarios of increasing complexity were simulated: delivery of a single beam, two oblique beams without and with range shifter. In addition to the dose comparison in the plastic phantoms the dose obtained from alanine pellet readings was compared with the dose determined with the Farmer ionization chamber in water. A consistent systematic deviation of about 2% was found between alanine dosimetry and the ionization chamber dosimetry in water and plastic materials. Acceptable agreement of planned and delivered doses was observed together with consistent and reproducible results of the end-to-end testing performed with different dosimetric techniques (alanine detectors, ionization chambers and EBT3 radiochromic films). The results confirmed the adequate implementation and integration of the new PBS technology at MedAustron. This work demonstrates that alanine pellets are suitable detectors for end-to-end tests in proton beam therapy and the developed procedures with customized anthropomorphic phantoms can be used to support implementation of PBS technology in clinical practice.

High-speed photodetectors.

PubMed

Anderson, L K; McMurtry, B J

1966-10-01

This paper is intended as a status report on high-speed detectors for the visible and near-infrared portion of the optical spectrum. Both vacuum and solid-state detectors are discussed, with the emphasis on those devices which can be used as direct (noncoherent) detectors of weak optical signals modulated at microwave frequencies. The best detectors for this application have internal current gain and in this regard the relevant properties and limitations of high-frequency secondary emission multiplication in vacuum tube devices and avalanche multiplication in p-n junctions are summarized.

Measurement of Nuclear Recoils in the CDMS II Dark Matter Search

NASA Astrophysics Data System (ADS)

Fallows, Scott M.

The Cryogenic Dark Matter Search (CDMS) experiment is designed to directly detect elastic scatters of weakly-interacting massive dark matter particles (WIMPs), on target nuclei in semiconductor crystals composed of Si and Ge. These scatters would occur very rarely, in an overwhelming background composed primarily of electron recoils from photons and electrons, as well as a smaller but non-negligible background of WIMP-like nuclear recoils from neutrons. The CDMS~II generation of detectors simultaneously measure ionization and athermal phonon signals from each scatter, allowing discrimination against virtually all electron recoils in the detector bulk. Pulse-shape timing analysis allows discrimination against nearly all remaining electron recoils taking place near detector surfaces. Along with carefully limited neutron backgrounds, this experimental program allowed for "background-free'' operation of CDMS~II at Soudan, with less than one background event expected in each WIMP-search analysis. As a result, exclusionary upper-limits on WIMP-nucleon interaction cross section were placed over a wide range of candidate WIMP masses, ruling out large new regions of parameter space. These results, like any others, are subject to a variety of systematic effects that may alter their final interpretations. A primary focus of this dissertation will be difficulties in precisely calibrating the energy scale for nuclear recoil events like those from WIMPs. Nuclear recoils have suppressed ionization signals relative to electron recoils of the same recoil energy, so the response of the detectors is calibrated differently for each recoil type. The overall normalization and linearity of the energy scale for electron recoils in CDMS~II detectors is clearly established by peaks of known gamma energy in the ionization spectrum of calibration data from a 133Ba source. This electron-equivalent keVee) energy scale enables calibration of the total phonon signal (keVt) by enforcing unity yield for electron recoils, in aggregate. Subtracting an event's Luke phonon contribution from its calibrated total phonon energy (keV t), as measured by the ionization signal, results in a valid measure of the true recoil energy (keVr) for both electron and nuclear recoils. I discuss systematic uncertainties affecting the reconstruction of this recoil energy, the primary analysis variable, and use several methods to constrain their magnitude. I present the resulting adjusted WIMP limits and discuss their impact in the context of current and projected constraints on the parameter space for WIMP interactions.

Neutron Fluence and Energy Reconstruction with the LNE-IRSN/MIMAC Recoil Detector MicroTPC at 27 keV

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

Maire, D.; Lebreton, L.; Querre, Ph.

2015-07-01

The French Institute for Radiation protection and Nuclear Safety (IRSN), designated by the French Metrology Institute (LNE) for neutron metrology, is developing a time projection chamber using a Micromegas anode: microTPC. This work is carried out in collaboration with the Laboratory of Subatomic Physics and Cosmology (LPSC). The aim is to characterize the energy distribution of neutron fluence in the energy range 8 keV - 5 MeV with a primary procedure. The time projection chambers are gaseous detectors able to measure charged particles energy and to reconstruct their track if a pixelated anode is used. In our case, the gasmore » is used as a (n, p) converter in order to detect neutrons down to few keV. Coming from elastic collisions with neutrons, recoil protons lose a part of their kinetic energy by ionizing the gas. The ionization electrons are drifted toward a pixelated anode (2D projection), read at 50 MHz by a self-triggered electronic system to obtain the third track dimension. The neutron energy is reconstructed event by event thanks to proton scattering angle and proton energy measurements. The scattering angle is deduced from the 3D track. The proton energy is obtained by charge collection measurements, knowing the ionization quenching factor (i.e. the part of proton kinetic energy lost by ionizing the gas). The fluence is calculated thanks to the detected events number and the simulation of the detector response. The μTPC is a new reliable detector able to measure energy distribution of the neutron fluence without unfolding procedure or prior neutron calibration contrary to usual gaseous counters. The microTPC is still being developed and measurements have been carried out at the AMANDE facility, with neutrons energies going from 8 keV to 565 keV. After the context and the μ-TPC working principle presentation, measurements of the neutron energy and fluence at 27 keV and 144 keV are shown and compared to the complete detector response simulation. This work shows the first direct reconstruction of neutron energy and fluence, simultaneously, at 27.2 keV in a continuous irradiation mode. (authors)« less

Neutron fluence and energy reconstruction with the IRSN recoil detector μ-TPC at 27 keV, 144 keV and 565 keV

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

Maire, D.; Lebreton, L.; Richer, J.P.

2015-07-01

The French Institute for Radioprotection and Nuclear Safety (IRSN), associated to the French Metrology Institute (LNE), is developing a time projection chamber using a Micromegas anode: μ-TPC. This work is carried out in collaboration with the Laboratory of Subatomic Physics and Cosmology (LPSC). The aim is to characterize with a primary procedure the energy distribution of neutron fluence in the energy range 8 keV - 1 MeV. The time projection chambers are gaseous detectors, which are able to measure charged particles energy and to reconstruct their track if a pixelated anode is used. In our case, the gas is usedmore » as a (n, p) converter in order to detect neutrons down to few keV. Coming from elastic collisions with neutrons, recoil protons lose a part of their kinetic energy by ionizing the gas. The ionization electrons are drifted toward a pixelated anode (2D projection), read at 50 MHz by a self-triggered electronic system to obtain the third track dimension. The neutron energy is reconstructed event by event thanks to proton scattering angle and proton energy measurements. The scattering angle is deduced from the 3D track. The proton energy is obtained by charge collection measurements, knowing the ionization quenching factor (i.e. the part of proton kinetic energy lost by ionizing the gas). The fluence is calculated thanks to the detected events number and the simulated detector response. The μ-TPC is a new reliable detector which enables to measure energy distribution of the neutron fluence without deconvolution or neutron calibration contrary to usual gaseous counters. The μ-TPC is still being developed and measurements have been carried out at the AMANDE facility, with neutrons energies going from 8 keV to 565 keV. After the context and the μ-TPC working principle presentation, measurements of the neutron energy and fluence at 27.2 keV, 144 keV and 565 keV are shown and compared to the complete detector simulation. This work shows the first direct reconstruction of neutron energy and fluence, simultaneously, at 27.2 keV in a continuous irradiation mode. (authors)« less

Electromagnetic Launch Optical Telemetry Feasibility Study

DTIC Science & Technology

2007-10-01

responsivity R(λ) of the ThorLab PDA55-switchable gain, amplified silicon detectors...and collected by a telescope, which amplified both the narrow-band optical signal and the broadband optical noise of the muzzle flash generated by the...used, unfiltered. These detectors have a 3.6 mm × 3.6 mm active area, a 10-MHz bandwidth, a 15-V/mA transimpedance gain, and an optical responsivity of

Advanced readout methods for superheated emulsion detectors

NASA Astrophysics Data System (ADS)

d'Errico, F.; Di Fulvio, A.

2018-05-01

Superheated emulsions develop visible vapor bubbles when exposed to ionizing radiation. They consist in droplets of a metastable liquid, emulsified in an inert matrix. The formation of a bubble cavity is accompanied by sound waves. Evaporated bubbles also exhibit a lower refractive index, compared to the inert gel matrix. These two physical phenomena have been exploited to count the number of evaporated bubbles and thus measure the interacting radiation flux. Systems based on piezoelectric transducers have been traditionally used to acquire the acoustic (pressure) signals generated by bubble evaporation. Such systems can operate at ambient noise levels exceeding 100 dB; however, they are affected by a significant dead time (>10 ms). An optical readout technique relying on the scattering of light by neutron-induced bubbles has been recently improved in order to minimize measurement dead time and ambient noise sensitivity. Beams of infra-red light from light-emitting diode (LED) sources cross the active area of the detector and are deflected by evaporated bubbles. The scattered light correlates with bubble density. Planar photodiodes are affixed along the detector length in optimized positions, allowing the detection of scattered light from the bubbles and minimizing the detection of direct light from the LEDs. A low-noise signal-conditioning stage has been designed and realized to amplify the current induced in the photodiodes by scattered light and to subtract the background signal due to intrinsic scattering within the detector matrix. The proposed amplification architecture maximizes the measurement signal-to-noise ratio, yielding a readout uncertainty of 6% (±1 SD), with 1000 evaporated bubbles in a detector active volume of 150 ml (6 cm detector diameter). In this work, we prove that the intensity of scattered light also relates to the bubble size, which can be controlled by applying an external pressure to the detector emulsion. This effect can be exploited during the readout procedure to minimize shadowing effects between bubbles, which become severe when the latter are several thousands. The detector we used in this work is based on superheated C-318 (octafluorocyclobutane), emulsified in 100 μm ± 10% (1 SD) diameter drops in an inert matrix of approximately 150 ml. The detector was operated at room temperature and ambient pressure.

Comparison of Air Fluorescence and Ionization Measurements of E.M. Shower Depth Profiles: Test of a UHECR Detector Technique

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

Belz, J.; Cao, Z.; Huentemeyer, P.

Measurements are reported on the fluorescence of air as a function of depth in electromagnetic showers initiated by bunches of 28.5 GeV electrons. The light yield is compared with the expected and observed depth profiles of ionization in the showers. It validates the use of atmospheric fluorescence profiles in measuring ultra high energy cosmic rays.

Improved Optical-Fiber Temperature Sensors

NASA Technical Reports Server (NTRS)

Rogowski, Robert S.; Egalon, Claudio O.

1993-01-01

In optical-fiber temperature sensors of proposed type, phosphorescence and/or fluorescence in temperature-dependent coating layers coupled to photodetectors. Phosphorescent and/or fluorescent behavior(s) of coating material(s) depend on temperature; coating material or mixture of materials selected so one can deduce temperature from known temperature dependence of phosphorescence and/or fluorescence spectrum, and/or characteristic decay of fluorescence. Basic optical configuration same as that of optical-fiber chemical detectors described in "Making Optical-Fiber Chemical Detectors More Sensitive" (LAR-14525).

Position, Orientation and Velocity Detection of Unmanned Underwater Vehicles (UUVs) Using an Optical Detector Array

PubMed Central

Pe’eri, Shachak; Thein, May-Win; Rzhanov, Yuri; Celikkol, Barbaros; Swift, M. Robinson

2017-01-01

This paper presents a proof-of-concept optical detector array sensor system to be used in Unmanned Underwater Vehicle (UUV) navigation. The performance of the developed optical detector array was evaluated for its capability to estimate the position, orientation and forward velocity of UUVs with respect to a light source fixed in underwater. The evaluations were conducted through Monte Carlo simulations and empirical tests under a variety of motion configurations. Monte Carlo simulations also evaluated the system total propagated uncertainty (TPU) by taking into account variations in the water column turbidity, temperature and hardware noise that may degrade the system performance. Empirical tests were conducted to estimate UUV position and velocity during its navigation to a light beacon. Monte Carlo simulation and empirical results support the use of the detector array system for optics based position feedback for UUV positioning applications. PMID:28758936

THE ORIGIN AND OPTICAL DEPTH OF IONIZING RADIATION IN THE 'GREEN PEA' GALAXIES

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

Jaskot, A. E.; Oey, M. S.

2013-04-01

Although Lyman-continuum (LyC) radiation from star-forming galaxies likely drove the reionization of the universe, observations of star-forming galaxies at low redshift generally indicate low LyC escape fractions. However, the extreme [O III]/[O II] ratios of the z = 0.1-0.3 Green Pea galaxies may be due to high escape fractions of ionizing radiation. To analyze the LyC optical depths and ionizing sources of these rare, compact starbursts, we compare nebular photoionization and stellar population models with observed emission lines in the Peas' Sloan Digital Sky Survey (SDSS) spectra. We focus on the six most extreme Green Peas, the galaxies with themore » highest [O III]/[O II] ratios and the best candidates for escaping ionizing radiation. The Balmer line equivalent widths and He I {lambda}3819 emission in the extreme Peas support young ages of 3-5 Myr, and He II {lambda}4686 emission in five extreme Peas signals the presence of hard ionizing sources. Ionization by active galactic nuclei or high-mass X-ray binaries is inconsistent with the Peas' line ratios and ages. Although stacked spectra reveal no Wolf-Rayet (WR) features, we tentatively detect WR features in the SDSS spectra of three extreme Peas. Based on the Peas' ages and line ratios, we find that WR stars, chemically homogeneous O stars, or shocks could produce the observed He II emission. If hot stars are responsible, then the Peas' optical depths are ambiguous. However, accounting for emission from shocks lowers the inferred optical depth and suggests that the Peas may be optically thin. The Peas' ages likely optimize the escape of LyC radiation; they are old enough for supernovae and stellar winds to reshape the interstellar medium, but young enough to possess large numbers of UV-luminous O or WR stars.« less

Proportional counter device for detecting electronegative species in an air sample

DOEpatents

Allman, Steve L.; Chen, Fang C.; Chen, Chung-Hsuan

1994-01-01

Apparatus for detecting an electronegative species comprises an analysis chamber, an inlet communicating with the analysis chamber for admitting a sample containing the electronegative species and an ionizable component, a radioactive source within the analysis chamber for emitting radioactive energy for ionizing a component of the sample, a proportional electron detector within the analysis chamber for detecting electrons emitted from the ionized component, and a circuit for measuring the electrons and determining the presence of the electronegative species by detecting a reduction in the number of available electrons due to capture of electrons by the electronegative species.

Proportional counter device for detecting electronegative species in an air sample

DOEpatents

Allman, S.L.; Chen, F.C.; Chen, C.H.

1994-03-08

Apparatus for detecting an electronegative species comprises an analysis chamber, an inlet communicating with the analysis chamber for admitting a sample containing the electronegative species and an ionizable component, a radioactive source within the analysis chamber for emitting radioactive energy for ionizing a component of the sample, a proportional electron detector within the analysis chamber for detecting electrons emitted from the ionized component, and a circuit for measuring the electrons and determining the presence of the electronegative species by detecting a reduction in the number of available electrons due to capture of electrons by the electronegative species. 2 figures.

Xenon detector with high energy resolution for gamma-ray line emission registration

NASA Astrophysics Data System (ADS)

Novikov, Alexander S.; Ulin, Sergey E.; Chernysheva, Irina V.; Dmitrenko, Valery V.; Grachev, Victor M.; Petrenko, Denis V.; Shustov, Alexander E.; Uteshev, Ziyaetdin M.; Vlasik, Konstantin F.

2014-09-01

A description of the xenon detector (XD) for gamma-ray line emission registration is presented. The detector provides high energy resolution and is able to operate under extreme environmental conditions (wide temperature range and unfavorable acoustic action). Resistance to acoustic noise as well as improvement in energy resolution has been achieved by means of real-time digital pulse processing. Another important XD feature is the ionization chamber's thin wall with composite housing, which significantly decreases the mass of the device and expands its energy range, especially at low energies.

Simulation of the GEM detector for BM@N experiment

NASA Astrophysics Data System (ADS)

Baranov, Dmitriy; Rogachevsky, Oleg

2017-03-01

The Gas Electron Multiplier (GEM) detector is one of the basic parts of the BM@N experiment included in the NICA project. The simulation model that takes into account features of signal generation process in an ionization GEM chamber is presented in this article. Proper parameters for the simulation were extracted from data retrieved with the help of Garfield++ (a toolkit for the detailed simulation of particle detectors). Due to this, we are able to generate clusters in layers of the micro-strip readout that correspond to clusters retrieved from a real physics experiment.

Modeling of radiation damage recovery in particle detectors based on GaN

NASA Astrophysics Data System (ADS)

Gaubas, E.; Ceponis, T.; Pavlov, J.

2015-12-01

The pulsed characteristics of the capacitor-type and PIN diode type detectors based on GaN have been simulated using the dynamic and drift-diffusion models. The drift-diffusion current simulations have been implemented by employing the commercial software package Synopsys TCAD Sentaurus. The bipolar drift regime has been analyzed. The possible internal gain in charge collection through carrier multiplication processes determined by impact ionization has been considered in order to compensate carrier lifetime reduction due to radiation defects introduced into GaN material of detector.

High-Rydberg Xenon Submillimeter-Wave Detector

NASA Technical Reports Server (NTRS)

Chutjian, Ara

1987-01-01

Proposed detector for infrared and submillimeter-wavelength radiation uses excited xenon atoms as Rydberg sensors instead of customary beams of sodium, potassium, or cesium. Chemically inert xenon easily stored in pressurized containers, whereas beams of dangerously reactive alkali metals must be generated in cumbersome, unreliable ovens. Xenon-based detector potential for infrared astronomy and for Earth-orbiter detection of terrestrial radiation sources. Xenon atoms excited to high energy states in two stages. Doubly excited atoms sensitive to photons in submillimeter wavelength range, further excited by these photons, then ionized and counted.

Optical delay encoding for fast timing and detector signal multiplexing in PET

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

Grant, Alexander M.; Levin, Craig S., E-mail: cslevin@stanford.edu; Molecular Imaging Program at Stanford

2015-08-15

Purpose: The large number of detector channels in modern positron emission tomography (PET) scanners poses a challenge in terms of readout electronics complexity. Multiplexing schemes are typically implemented to reduce the number of physical readout channels, but often result in performance degradation. Novel methods of multiplexing in PET must be developed to avoid this data degradation. The preservation of fast timing information is especially important for time-of-flight PET. Methods: A new multiplexing scheme based on encoding detector interaction events with a series of extremely fast overlapping optical pulses with precise delays is demonstrated in this work. Encoding events in thismore » way potentially allows many detector channels to be simultaneously encoded onto a single optical fiber that is then read out by a single digitizer. A two channel silicon photomultiplier-based prototype utilizing this optical delay encoding technique along with dual threshold time-over-threshold is demonstrated. Results: The optical encoding and multiplexing prototype achieves a coincidence time resolution of 160 ps full width at half maximum (FWHM) and an energy resolution of 13.1% FWHM at 511 keV with 3 × 3 × 5 mm{sup 3} LYSO crystals. All interaction information for both detectors, including timing, energy, and channel identification, is encoded onto a single optical fiber with little degradation. Conclusions: Optical delay encoding and multiplexing technology could lead to time-of-flight PET scanners with fewer readout channels and simplified data acquisition systems.« less

Ionized-Cluster Beam/Partially Ionized Beam Deposition of Electro- Optical and Nonlinear Optical Organic Materials and Device Development

DTIC Science & Technology

1993-08-29

4’- CH3 O--\\\\4 4N -2 nitrostilbene NO 2J (MMONS) 4’-dimethylamfino OCH3 -N-4-stylbazolium j, o3 - 200 3125 1000 tosylate (DAST)or 0 3 (CH3)2N CH3 Styrylpyridinium PH cyanine dye 400 1490 470 ( SPCD ) SO4 (CH3 ½2N lh3 20

A study of a 63 K radiative cooler for the advanced moisture and temperature sounder. [earth-orbiting IR spectrometer for atmospheric measurements

NASA Technical Reports Server (NTRS)

Salazar, R.; Evans, N.

1981-01-01

A study was performed of cooling methods for a space-borne, earth observing infrared optical instrument, AMTS. Major requirements on the thermal design are an optics temperature below 200 K, a detector array temperature below 75 K, orbital lifetime of 3 to 5 years, a near polar, sun synchronous orbit with altitude near 800 km. Power dissipation of the detectors is 38 mW, in the optics compartment 1.4 W. Large radiative coolers positioned so as to be shielded from sun, spacecraft and earth result in predicted optics temperature of 156 K and detector temperature of 63 K.

Electro-optic Lightning Detector

NASA Technical Reports Server (NTRS)

Koshak, William J.; Solakiewicz, Richard J.

1996-01-01

The design, alignment, calibration, and field deployment of a solid-state lightning detector is described. The primary sensing component of the detector is a potassium dihydrogen phosphate (KDP) electro-optic crystal that is attached in series to a flat plate aluminum antenna; the antenna is exposed to the ambient thundercloud electric field. A semiconductor laser diode (lambda = 685 nm), polarizing optics, and the crystal are arranged in a Pockels cell configuration. Lightning-caused electric field changes are related to small changes in the transmission of laser light through the optical cell. Several hundred lightning electric field change excursions were recorded during five thunderstorms that occurred in the summer of 1998 at the NASA Marshall Space Flight Center (MSFC) in northern Alabama.

Electro-Optic Lightning Detector

NASA Technical Reports Server (NTRS)

Koshak, Willliam; Solakiewicz, Richard

1998-01-01

The design, alignment, calibration, and field deployment of a solid-state lightning detector is described. The primary sensing component of the detector is a potassium dihydrogen phosphate (KDP) electro-optic crystal that is attached in series to a flat plate aluminum antenna; the antenna is exposed to the ambient thundercloud electric field. A semiconductor laser diode (lambda = 685 nm), polarizing optics, and the crystal are arranged in a Pockels cell configuration. Lightning-caused electric field changes are then related to small changes in the transmission of laser light through the optical cell. Several hundred lightning electric field change excursions were recorded during 4 thunderstorms that occurred in the summer of 1998 at the NASA Marshall Space Flight Center (MSFC) in Northern Alabama.

Electro-Optic Lighting Detector

NASA Technical Reports Server (NTRS)

Koshak, William J.; Solakiewicz, Richard J.

1999-01-01

The design, alignment, calibration, and field deployment of a solid-state lightning detector is described. The primary sensing component of the detector is a potassium dihydrogen phosphate electro-optic crystal that is attached in series to a flat-plate aluminum antenna; the antenna is exposed to the ambient thundercloud electric field. A semiconductor laser diode (lambda = 685 nm), polarizing optics, and the crystal are arranged in a Pockels cell configuration. Lightning-caused electric field changes are related to small changes in the transmission of laser light through the optical cell. Several hundred lightning electric field change excursions were recorded during five thunderstorms that occurred in the summer of 1998 at the NASA Marshall Space Flight Center in northern Alabama.

Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber.

PubMed

Hršak, Hrvoje; Majer, Marija; Grego, Timor; Bibić, Juraj; Heinrich, Zdravko

2014-12-01

Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°-54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Influence of ionization on ultrafast gas-based nonlinear fiber optics.

PubMed

Chang, W; Nazarkin, A; Travers, J C; Nold, J; Hölzer, P; Joly, N Y; Russell, P St J

2011-10-10

We numerically investigate the effect of ionization on ultrashort high-energy pulses propagating in gas-filled kagomé-lattice hollow-core photonic crystal fibers by solving an established uni-directional field equation. We consider the dynamics of two distinct regimes: ionization induced blue-shift and resonant dispersive wave emission in the deep-UV. We illustrate how the system evolves between these regimes and the changing influence of ionization. Finally, we consider the effect of higher ionization stages.

Terahertz emission from ultrafast ionizing air in symmetry-broken laser fields

NASA Astrophysics Data System (ADS)

Kim, Ki-Yong; Glownia, James H.; Taylor, Antoinette J.; Rodriguez, George

2007-04-01

A transient photocurrent model is developed to explain coherent terahertz emission from air irradiated by a symmetry-broken laser field composed of the fundamental and its second harmonic laser pulses. When the total laser field is asymmetric across individual optical cycles, a nonvanishing electron current surge can arise during optical field ionization of air, emitting a terahertz electromagnetic pulse. Terahertz power scalability is also investigated, and with optical pump energy of tens of millijoules per pulse, peak terahertz field strengths in excess of 150 kV/cm are routinely produced.

Terahertz emission from ultrafast ionizing air in symmetry-broken laser fields.

PubMed

Kim, Ki-Yong; Glownia, James H; Taylor, Antoinette J; Rodriguez, George

2007-04-16

A transient photocurrent model is developed to explain coherent terahertz emission from air irradiated by a symmetry-broken laser field composed of the fundamental and its second harmonic laser pulses. When the total laser field is asymmetric across individual optical cycles, a nonvanishing electron current surge can arise during optical field ionization of air, emitting a terahertz electromagnetic pulse. Terahertz power scalability is also investigated, and with optical pump energy of tens of millijoules per pulse, peak terahertz field strengths in excess of 150 kV/cm are routinely produced.

Ionization of deep quantum wells: Optical trampoline effect

NASA Astrophysics Data System (ADS)

Perlin, E. Yu.; Levitskiĭ, R. S.

2007-02-01

A new mechanism of transitions of an electronic system from the ground state to states with excitation energies exceeding many times the energy of a light photon initiating the transitions has been considered. This mechanism is based on the so-called optical “trampoline” effect: one of the interacting electrons receives energy from another electron and, simultaneously absorbing a photon ħω, overcomes the energy gap significantly exceeding ħω. Ionization of deep quantum wells by low-frequency light of moderate intensity due to the optical trampoline effect was calculated.

SYNCHROTRON RADIATION, FREE ELECTRON LASER, APPLICATION OF NUCLEAR TECHNOLOGY, ETC. Employing a Cerenkov detector for the thickness measurement of X-rays in a scattering background

NASA Astrophysics Data System (ADS)

Li, Shu-Wei; Kang, Ke-Jun; Wang, Yi; Li, Jin; Li, Yuan-Jing; Zhang, Qing-Jun

2010-12-01

The variation in environmental scattering background is a major source of systematic errors in X-ray inspection and measurement systems. As the energy of these photons consisting of environmental scattering background is much lower generally, the Cerenkov detectors having the detection threshold are likely insensitive to them and able to exclude their influence. A thickness measurement experiment is designed to verify the idea by employing a Cerenkov detector and an ionizing chamber for comparison. Furthermore, it is also found that the application of the Cerenkov detectors is helpful to exclude another systematic error from the variation of low energy components in the spectrum incident on the detector volume.

Optical modeling of waveguide coupled TES detectors towards the SAFARI instrument for SPICA

NASA Astrophysics Data System (ADS)

Trappe, N.; Bracken, C.; Doherty, S.; Gao, J. R.; Glowacka, D.; Goldie, D.; Griffin, D.; Hijmering, R.; Jackson, B.; Khosropanah, P.; Mauskopf, P.; Morozov, D.; Murphy, A.; O'Sullivan, C.; Ridder, M.; Withington, S.

2012-09-01

The next generation of space missions targeting far-infrared wavelengths will require large-format arrays of extremely sensitive detectors. The development of Transition Edge Sensor (TES) array technology is being developed for future Far-Infrared (FIR) space applications such as the SAFARI instrument for SPICA where low-noise and high sensitivity is required to achieve ambitious science goals. In this paper we describe a modal analysis of multi-moded horn antennas feeding integrating cavities housing TES detectors with superconducting film absorbers. In high sensitivity TES detector technology the ability to control the electromagnetic and thermo-mechanical environment of the detector is critical. Simulating and understanding optical behaviour of such detectors at far IR wavelengths is difficult and requires development of existing analysis tools. The proposed modal approach offers a computationally efficient technique to describe the partial coherent response of the full pixel in terms of optical efficiency and power leakage between pixels. Initial wok carried out as part of an ESA technical research project on optical analysis is described and a prototype SAFARI pixel design is analyzed where the optical coupling between the incoming field and the pixel containing horn, cavity with an air gap, and thin absorber layer are all included in the model to allow a comprehensive optical characterization. The modal approach described is based on the mode matching technique where the horn and cavity are described in the traditional way while a technique to include the absorber was developed. Radiation leakage between pixels is also included making this a powerful analysis tool.

A microfabricated, low dark current a-Se detector for measurement of microplasma optical emission in the UV for possible use on-site

NASA Astrophysics Data System (ADS)

Abbaszadeh, Shiva; Karim, Karim S.; Karanassios, Vassili

2013-05-01

Traditionally, samples are collected on-site (i.e., in the field) and are shipped to a lab for chemical analysis. An alternative is offered by using portable chemical analysis instruments that can be used on-site (i.e., in the field). Many analytical measurements by optical emission spectrometry require use of light-sources and of spectral lines that are in the Ultra-Violet (UV, ~200 nm - 400 nm wavelength) region of the spectrum. For such measurements, a portable, battery-operated, fiber-optic spectrometer equipped with an un-cooled, linear, solid-state detector may be used. To take full advantage of the advanced measurement capabilities offered by state-of-the-art solid-state detectors, cooling of the detector is required. But cooling and other thermal management hamper portability and use on-site because they add size and weight and they increase electrical power requirements. To address these considerations, an alternative was implemented, as described here. Specifically, a microfabricated solid-state detector for measurement of UV photons will be described. Unlike solid-state detectors developed on crystalline Silicon, this miniaturized and low-cost detector utilizes amorphous Selenium (a-Se) as its photosensitive material. Due to its low dark current, this detector does not require cooling, thus it is better suited for portable use and for chemical measurements on-site. In this paper, a microplasma will be used as a light-source of UV photons for the a-Se detector. For example, spectra acquired using a microplasma as a light-source will be compared with those obtained with a portable, fiber-optic spectrometer equipped with a Si-based 2080-element detector. And, analytical performance obtained by introducing ng-amounts of analytes into the microplasma will be described.

A handheld laser-induced fluorescence detector for multiple applications.

PubMed

Fang, Xiao-Xia; Li, Han-Yang; Fang, Pan; Pan, Jian-Zhang; Fang, Qun

2016-04-01

In this paper, we present a compact handheld laser-induced fluorescence (LIF) detector based on a 450 nm laser diode and quasi-confocal optical configuration with a total size of 9.1 × 6.2 × 4.1 cm(3). Since there are few reports on the use of 450 nm laser diode in LIF detection, especially in miniaturized LIF detector, we systematically investigated various optical arrangements suitable for the requirements of 450 nm laser diode and system miniaturization, including focusing lens, filter combination, and pinhole, as well as Raman effect of water at 450 nm excitation wavelength. As the result, the handheld LIF detector integrates the light source (450 nm laser diode), optical circuit module (including a 450 nm band-pass filter, a dichroic mirror, a collimating lens, a 525 nm band-pass filter, and a 1.0mm aperture), optical detector (miniaturized photomultiplier tube), as well as electronic module (including signal recording, processing and displaying units). This detector is capable of working independently with a cost of ca. $2000 for the whole instrument. The detection limit of the instrument for sodium fluorescein solution is 0.42 nM (S/N=3). The broad applicability of the present system was demonstrated in capillary electrophoresis separation of fluorescein isothiocyanate (FITC) labeled amino acids and in flow cytometry of tumor cells as an on-line LIF detector, as well as in droplet array chip analysis as a LIF scanner. We expect such a compact LIF detector could be applied in flow analysis systems as an on-line detector, and in field analysis and biosensor analysis as a portable universal LIF detector. Copyright © 2015 Elsevier B.V. All rights reserved.

Multibeam interferometric illumination as the primary source of resolution in optical microscopy

NASA Astrophysics Data System (ADS)

Ryu, J.; Hong, S. S.; Horn, B. K. P.; Freeman, D. M.; Mermelstein, M. S.

2006-04-01

High-resolution images of a fluorescent target were obtained using a low-resolution optical detector by illuminating the target with interference patterns produced with 31 coherent beams. The beams were arranged in a cone with 78° half angle to produce illumination patterns consistent with a numerical aperture of 0.98. High-resolution images were constructed from low-resolution images taken with 930 different illumination patterns. Results for optical detectors with numerical apertures of 0.1 and 0.2 were similar, demonstrating that the resolution is primarily determined by the illuminator and not by the low-resolution detector. Furthermore, the long working distance, large depth of field, and large field of view of the low-resolution detector are preserved.

40 CFR 86.126-90 - Calibration of other equipment.

Code of Federal Regulations, 2010 CFR

2010-07-01

... according to good practice. Specific equipment requiring calibration are the gas chromatograph and flame ionization detector used in measuring methanol and the high pressure liquid chromatograph (HPLC) and...

40 CFR 86.526-90 - Calibration of other equipment.

Code of Federal Regulations, 2010 CFR

2010-07-01

... necessary according to good practice. Specific equipment requiring calibration is the gas chromatograph and flame ionization detector used in measuring methanol and the high pressure liquid chromatograph (HPLC...

40 CFR 86.126-90 - Calibration of other equipment.

Code of Federal Regulations, 2011 CFR

2011-07-01

... according to good practice. Specific equipment requiring calibration are the gas chromatograph and flame ionization detector used in measuring methanol and the high pressure liquid chromatograph (HPLC) and...

40 CFR 86.526-90 - Calibration of other equipment.

Code of Federal Regulations, 2011 CFR

2011-07-01

... necessary according to good practice. Specific equipment requiring calibration is the gas chromatograph and flame ionization detector used in measuring methanol and the high pressure liquid chromatograph (HPLC...

Optical characterization of ultra-sensitive TES bolometers for SAFARI

NASA Astrophysics Data System (ADS)

Audley, Michael D.; de Lange, Gerhard; Gao, Jian-Rong; Khosropanah, Pourya; Mauskopf, Philip D.; Morozov, Dmitry; Trappe, Neil A.; Doherty, Stephen; Withington, Stafford

2014-07-01

We have characterized the optical response of prototype detectors for SAFARI, the far-infrared imaging spectrometer for the SPICA satellite. SAFARI's three bolometer arrays will image a 2'×2' field of view with spectral information over the wavelength range 34—210 μm. SAFARI requires extremely sensitive detectors (goal NEP ~ 0.2 aW/√Hz), with correspondingly low saturation powers (~5 fW), to take advantage of SPICA's cooled optics. We have constructed an ultra-low background optical test facility containing an internal cold black-body illuminator and have recently added an internal hot black-body source and a light-pipe for external illumination. We illustrate the performance of the test facility with results including spectral-response measurements. Based on an improved understanding of the optical throughput of the test facility we find an optical efficiency of 60% for prototype SAFARI detectors.

SiPM electro-optical detection system noise suppression method

NASA Astrophysics Data System (ADS)

Bi, Xiangli; Yang, Suhui; Hu, Tao; Song, Yiheng

2014-11-01

In this paper, the single photon detection principle of Silicon Photomultipliers (SiPM) device is introduced. The main noise factors that infect the sensitivity of the electro-optical detection system are analyzed, including background light noise, detector dark noise, preamplifier noise and signal light noise etc. The Optical, electrical and thermodynamic methods are used to suppress the SiPM electro-optical detection system noise, which improved the response sensitivity of the detector. Using SiPM optoelectronic detector with a even high sensitivity, together with small field large aperture optical system, high cutoff narrow bandwidth filters, low-noise operational amplifier circuit, the modular design of functional circuit, semiconductor refrigeration technology, greatly improved the sensitivity of optical detection system, reduced system noise and achieved long-range detection of weak laser radiation signal. Theoretical analysis and experimental results show that the proposed methods are reasonable and efficient.

DEM analysis of FOXSI-2 microflare using AIA observations

NASA Astrophysics Data System (ADS)

Athiray Panchapakesan, Subramania; Glesener, Lindsay; Vievering, Juliana; Camilo Buitrago-Casas, Juan; Christe, Steven; Inglis, Andrew; Krucker, Sam; Musset, Sophie

2017-08-01

The second flight of Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket experiment was successfully completed on 11 December 2014. FOXSI makes direct imaging and spectral observation of the Sun in hard X-rays using grazing incidence optics modules which focus X-rays onto seven focal plane detectors kept at a 2m distance, in the energy range 4 to 20 keV, to study particle acceleration and coronal heating. Significant HXR emissions were observed by FOXSI during microflare events with A0.5 and A2.5 class, as classified by GOES, that occurred during FOXSI-2 flight.Spectral analysis of FOXSI data for these events indicate presence of plasma at higher temperatures (>10MK). We attempt to study the plasma content in the corona at different temperatures, characterized by the differential emission measure (DEM), over the FOXSI-2 observed flare regions using the Atmospheric Imaging Assembly (SDO/AIA) data. We utilize AIA observations in different EUV filters that are sensitive to ionized iron lines, to determine the DEM by using a regularized inversion method. This poster will show the properties of hot plasma as derived from FOXSI-2 HXR spectra with supporting DEM analysis using AIA observations.

Photon small-field measurements with a CMOS active pixel sensor.

PubMed

Spang, F Jiménez; Rosenberg, I; Hedin, E; Royle, G

2015-06-07

In this work the dosimetric performance of CMOS active pixel sensors for the measurement of small photon beams is presented. The detector used consisted of an array of 520  × 520 pixels on a 25 µm pitch. Dosimetric parameters measured with this sensor were compared with data collected with an ionization chamber, a film detector and GEANT4 Monte Carlo simulations. The sensor performance for beam profiles measurements was evaluated for field sizes of 0.5  × 0.5 cm(2). The high spatial resolution achieved with this sensor allowed the accurate measurement of profiles, beam penumbrae and field size under lateral electronic disequilibrium. Field size and penumbrae agreed within 5.4% and 2.2% respectively with film measurements. Agreements with ionization chambers better than 1.0% were obtained when measuring tissue-phantom ratios. Output factor measurements were in good agreement with ionization chamber and Monte Carlo simulation. The data obtained from this imaging sensor can be easily analyzed to extract dosimetric information. The results presented in this work are promising for the development and implementation of CMOS active pixel sensors for dosimetry applications.

Method for detecting and distinguishing between specific types of environmental radiation using a high pressure ionization chamber with pulse-mode readout

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

Degtiarenko, Pavel V.

An environmental radiation detector for detecting and distinguishing between all types of environmental radiation, including photons, charged particles, and neutrons. A large volume high pressure ionization chamber (HPIC) includes BF.sub.3 gas at a specific concentration to render the radiation detector sensitive to the reactions of neutron capture in Boron-10 isotope. A pulse-mode readout is connected to the ionization chamber capable of measuring both the height and the width of the pulse. The heavy charged products of the neutron capture reaction deposit significant characteristic energy of the reaction in the immediate vicinity of the reaction in the gas, producing a signalmore » with a pulse height proportional to the reaction energy, and a narrow pulse width corresponding to the essentially pointlike energy deposition in the gas. Readout of the pulse height and the pulse width parameters of the signals enables distinguishing between the different types of environmental radiation, such as gamma (x-rays), cosmic muons, and neutrons.« less

Method for selective detection of explosives in mass spectrometer or ion mobility spectrometer at parts-per-quadrillion level

DOEpatents

Ewing, Robert G.; Atkinson, David A.; Clowers, Brian H.

2015-09-01

A method for selective detection of volatile and non-volatile explosives in a mass spectrometer or ion mobility spectrometer at a parts-per-quadrillion level without preconcentration is disclosed. The method comprises the steps of ionizing a carrier gas with an ionization source to form reactant ions or reactant adduct ions comprising nitrate ions (NO.sub.3.sup.-); selectively reacting the reactant ions or reactant adduct ions with at least one volatile or non-volatile explosive analyte at a carrier gas pressure of at least about 100 Ton in a reaction region disposed between the ionization source and an ion detector, the reaction region having a length which provides a residence time (tr) for reactant ions therein of at least about 0.10 seconds, wherein the selective reaction yields product ions comprising reactant ions or reactant adduct ions that are selectively bound to the at least one explosive analyte when present therein; and detecting product ions with the ion detector to determine presence or absence of the at least one explosive analyte.

Dynamic conductivity and partial ionization in dense fluid hydrogen

NASA Astrophysics Data System (ADS)

Zaghoo, Mohamed

2018-04-01

A theoretical description for optical conduction experiments in dense fluid hydrogen is presented. Different quantum statistical approaches are used to describe the mechanism of electronic transport in hydrogen's high-temperature dense phase. We show that at the onset of the metallic transition, optical conduction could be described by a strong rise in atomic polarizability, due to increased ionization, whereas in the highly degenerate limit, the Ziman weak scattering model better accounts for the observed saturation of reflectance. The inclusion of effects of partial ionization in the highly degenerate region provides great agreement with experimental results. Hydrogen's fluid metallic state is revealed to be a partially ionized free-electron plasma. Our results provide some of the first theoretical transport models that are experimentally benchmarked, as well as an important guide for future studies.

Optical potential approach to the electron-atom impact ionization threshold problem

NASA Technical Reports Server (NTRS)

Temkin, A.; Hahn, Y.

1973-01-01

The problem of the threshold law for electron-atom impact ionization is reconsidered as an extrapolation of inelastic cross sections through the ionization threshold. The cross sections are evaluated from a distorted wave matrix element, the final state of which describes the scattering from the Nth excited state of the target atom. The actual calculation is carried for the e-H system, and a model is introduced which is shown to preserve the essential properties of the problem while at the same time reducing the dimensionability of the Schrodinger equation. Nevertheless, the scattering equation is still very complex. It is dominated by the optical potential which is expanded in terms of eigen-spectrum of QHQ. It is shown by actual calculation that the lower eigenvalues of this spectrum descend below the relevant inelastic thresholds; it follows rigorously that the optical potential contains repulsive terms. Analytical solutions of the final state wave function are obtained with several approximations of the optical potential.

Study of the degradation and recovery of the optical properties of H+-implanted ZnO pigments

NASA Astrophysics Data System (ADS)

Li, Chundong; Lv, Jinpeng; Yao, Shulong; Hu, Jiangang; Liang, Zhiqiang

2013-01-01

We studied the influences of proton implantation and oxygen post-annealing on the optical properties of ZnO pigments using a combination of Raman scattering, positron annihilation and photoluminescence techniques. Raman scattering results indicated that oxygen vacancies and interstitial zinc defects were produced after proton implantation. Positron annihilation spectroscopy and photoluminescence measurements demonstrated that the zinc vacancies do not contribute to the optical absorption, but give rise to the visible band emission. Interestingly, the proton implantation induced optical degradation can be annealed out at 800 °C in an O2 atmosphere. We conclude that the defect centers responsible for the optical absorption are primarily composed of VO+, ionized Zni and ionized Oi.

Quantum and semiclassical physics behind ultrafast optical nonlinearity in the midinfrared: the role of ionization dynamics within the field half cycle.

PubMed

Serebryannikov, E E; Zheltikov, A M

2014-07-25

Ultrafast ionization dynamics within the field half cycle is shown to be the key physical factor that controls the properties of optical nonlinearity as a function of the carrier wavelength and intensity of a driving laser field. The Schrödinger-equation analysis of a generic hydrogen quantum system reveals universal tendencies in the wavelength dependence of optical nonlinearity, shedding light on unusual properties of optical nonlinearities in the midinfrared. For high-intensity low-frequency fields, free-state electrons are shown to dominate over bound electrons in the overall nonlinear response of a quantum system. In this regime, semiclassical models are shown to offer useful insights into the physics behind optical nonlinearity.

Ionization Readout Electronics for SuperCDMS SNOLAB Employing a HEMT Front-End

NASA Astrophysics Data System (ADS)

Partridge, R.

2014-09-01

The SuperCDMS SNOLAB experiment seeks to deploy 200 kg of cryogenic Ge detectors employing phonon and ionization readout to identify dark matter interactions. One of the design challenges for the experiment is to provide amplification of the high impedance ionization signal while minimizing power dissipation and noise. This paper describes the design and expected performance of the ionization readout being developed for an engineering model of the SuperCDMS SNOLAB Ge Tower System. The readout features the use of a low-noise HEMT front end transistor operating at 4 K to achieve a power dissipation of 100 W per channel, local grounding to minimize noise injection, and biasing circuitry that allows precise control of the HEMT operating point.

Performance of the EDELWEISS-III experiment for direct dark matter searches

NASA Astrophysics Data System (ADS)

Armengaud, E.; Arnaud, Q.; Augier, C.; Benoît, A.; Bergé, L.; Bergmann, T.; Billard, J.; de Boissière, T.; Bres, G.; Broniatowski, A.; Brudanin, V.; Camus, P.; Cazes, A.; Chapellier, M.; Charlieux, F.; De Jésus, M.; Dumoulin, L.; Eitel, K.; Filosofov, D.; Foerster, N.; Fourches, N.; Garde, G.; Gascon, J.; Giuliani, A.; Grollier, M.; Gros, M.; Hehn, L.; Hervé, S.; Heuermann, G.; Humbert, V.; Jin, Y.; Juillard, A.; Kéfélian, C.; Kleifges, M.; Kozlov, V.; Kraus, H.; Kudryavtsev, V. A.; Le-Sueur, H.; Lin, J.; Maisonobe, R.; Mancuso, M.; Marnieros, S.; Menshikov, A.; Navick, X.-F.; Nones, C.; Olivieri, E.; Pari, P.; Paul, B.; Poda, D.; Queguiner, E.; Robinson, M.; Rodenas, H.; Rozov, S.; Sanglard, V.; Schmidt, B.; Scorza, S.; Siebenborn, B.; Tcherniakhovski, D.; Vagneron, L.; Weber, M.; Yakushev, E.; Zhang, X.; Zolotarova, A.

2017-08-01

We present the results of measurements demonstrating the efficiency of the EDELWEISS-III array of cryogenic germanium detectors for direct dark matter searches. The experimental setup and the FID (Fully Inter-Digitized) detector array is described, as well as the efficiency of the double measurement of heat and ionization signals in background rejection. For the whole set of 24 FID detectors used for coincidence studies, the baseline resolutions for the fiducial ionization energy are mainly below 0.7 keVee (FHWM) whereas the baseline resolutions for heat energies are mainly below 1.5 keVee (FWHM). The response to nuclear recoils as well as the very good discrimination capability of the FID design has been measured with an AmBe source. The surface β- and α-decay rejection power of Rsurf < 4 × 10-5 per α at 90% C.L. has been determined with a 210Pb source, the rejection of bulk γ-ray events has been demonstrated using γ-calibrations with 133Ba sources leading to a value of Rγ -mis-fid < 2.5 × 10-6 at 90% C.L.. The current levels of natural radioactivity measured in the detector array are shown as the rate of single γ background. The fiducial volume fraction of the FID detectors has been measured to a weighted average value of (74.6 ± 0.4)% using the cosmogenic activation of the 65Zn and 68,71Ge isotopes. The stability and uniformity of the detector response is also discussed. The achieved resolutions, thresholds and background levels of the upgraded EDELWEISS-III detectors in their setup are thus well suited to the direct search of WIMP dark matter over a large mass range.

High pressure xenon ionization detector

DOEpatents

Markey, J.K.

1989-11-14

A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0 to 30 C. 2 figs.

High pressure xenon ionization detector

DOEpatents

Markey, John K.

1989-01-01

A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0.degree. to 30.degree. C.

40 CFR 1065.260 - Flame-ionization detector.

Code of Federal Regulations, 2011 CFR

2011-07-01

... system for measuring THC, THCE, or CH4 must meet all of the verifications for hydrocarbon measurement in... flame. (e) Methane. FID analyzers measure total hydrocarbons (THC). To determine nonmethane hydrocarbons...

40 CFR 1065.260 - Flame-ionization detector.

Code of Federal Regulations, 2010 CFR

2010-07-01

... system for measuring THC, THCE, or CH4 must meet all of the verifications for hydrocarbon measurement in... flame. (e) Methane. FID analyzers measure total hydrocarbons (THC). To determine nonmethane hydrocarbons...

40 CFR 89.6 - Reference materials.

Code of Federal Regulations, 2011 CFR

2011-07-01

... November 89: Recommended Practice for Engine Testing with Low Temperature Charge Air Cooler Systems in a Dynamometer Test Cell 89.327-96 SAE Paper 770141: Optimization of a Flame Ionization Detector for...

Study of solid-conversion gaseous detector based on GEM for high energy X-ray industrial CT.

PubMed

Zhou, Rifeng; Zhou, Yaling

2014-01-01

The general gaseous ionization detectors are not suitable for high energy X-ray industrial computed tomography (HEICT) because of their inherent limitations, especially low detective efficiency and large volume. The goal of this study was to investigate a new type of gaseous detector to solve these problems. The novel detector was made by a metal foil as X-ray convertor to improve the conversion efficiency, and the Gas Electron Multiplier (hereinafter "GEM") was used as electron amplifier to lessen its volume. The detective mechanism and signal formation of the detector was discussed in detail. The conversion efficiency was calculated by using EGSnrc Monte Carlo code, and the transport course of photon and secondary electron avalanche in the detector was simulated with the Maxwell and Garfield codes. The result indicated that this detector has higher conversion efficiency as well as less volume. Theoretically this kind of detector could be a perfect candidate for replacing the conventional detector in HEICT.

Nanoparticle-coated micro-optofluidic ring resonator as a detector for microscale gas chromatographic vapor analysis.

PubMed

Scholten, K; Collin, W R; Fan, X; Zellers, E T

2015-05-28

A vapor sensor comprising a nanoparticle-coated microfabricated optofluidic ring resonator (μOFRR) is introduced. A multilayer film of polyether functionalized, thiolate-monolayer-protected gold nanoparticles (MPN) was solvent cast on the inner wall of the hollow cylindrical SiOxμOFRR resonator structure, and whispering gallery mode (WGM) resonances were generated with a 1550 nm tunable laser via an optical fiber taper. Reversible shifts in the WGM resonant wavelength upon vapor exposure were detected with a photodetector. The μOFRR chip was connected to a pair of upstream etched-Si chips containing PDMS-coated separation μcolumns and calibration curves were generated from the peak-area responses to five volatile organic compounds (VOCs). Calibration curves were linear, and the sensitivities reflected the influence of analyte volatility and analyte-MPN functional group affinity. Sorption-induced changes in film thickness apparently dominate over changes in the refractive index of the film as the determinant of responses for all VOCs. Peaks from the MPN-coated μOFRR were just 20-50% wider than those from a flame ionization detector for similar μcolumn separation conditions, reflecting the rapid response of the sensor for VOCs. The five VOCs were baseline separated in <1.67 min, with detection limits as low as 38 ng.

Nanoparticle-coated micro-optofluidic ring resonator as a detector for microscale gas chromatographic vapor analysis

NASA Astrophysics Data System (ADS)

Scholten, K.; Collin, W. R.; Fan, X.; Zellers, E. T.

2015-05-01

A vapor sensor comprising a nanoparticle-coated microfabricated optofluidic ring resonator (μOFRR) is introduced. A multilayer film of polyether functionalized, thiolate-monolayer-protected gold nanoparticles (MPN) was solvent cast on the inner wall of the hollow cylindrical SiOx μOFRR resonator structure, and whispering gallery mode (WGM) resonances were generated with a 1550 nm tunable laser via an optical fiber taper. Reversible shifts in the WGM resonant wavelength upon vapor exposure were detected with a photodetector. The μOFRR chip was connected to a pair of upstream etched-Si chips containing PDMS-coated separation μcolumns and calibration curves were generated from the peak-area responses to five volatile organic compounds (VOCs). Calibration curves were linear, and the sensitivities reflected the influence of analyte volatility and analyte-MPN functional group affinity. Sorption-induced changes in film thickness apparently dominate over changes in the refractive index of the film as the determinant of responses for all VOCs. Peaks from the MPN-coated μOFRR were just 20-50% wider than those from a flame ionization detector for similar μcolumn separation conditions, reflecting the rapid response of the sensor for VOCs. The five VOCs were baseline separated in <1.67 min, with detection limits as low as 38 ng.

Novel electro-optical coupling technique for magnetic resonance-compatible positron emission tomography detectors.

PubMed

Olcott, Peter D; Peng, Hao; Levin, Craig S

2009-01-01

A new magnetic resonance imaging (MRI)-compatible positron emission tomography (PET) detector design is being developed that uses electro-optical coupling to bring the amplitude and arrival time information of high-speed PET detector scintillation pulses out of an MRI system. The electro-optical coupling technology consists of a magnetically insensitive photodetector output signal connected to a nonmagnetic vertical cavity surface emitting laser (VCSEL) diode that is coupled to a multimode optical fiber. This scheme essentially acts as an optical wire with no influence on the MRI system. To test the feasibility of this approach, a lutetium-yttrium oxyorthosilicate crystal coupled to a single pixel of a solid-state photomultiplier array was placed in coincidence with a lutetium oxyorthosilicate crystal coupled to a fast photomultiplier tube with both the new nonmagnetic VCSEL coupling and the standard coaxial cable signal transmission scheme. No significant change was observed in 511 keV photopeak energy resolution and coincidence time resolution. This electro-optical coupling technology enables an MRI-compatible PET block detector to have a reduced electromagnetic footprint compared with the signal transmission schemes deployed in the current MRI/PET designs.

The solid state detector technology for picosecond laser ranging

NASA Technical Reports Server (NTRS)

Prochazka, Ivan

1993-01-01

We developed an all solid state laser ranging detector technology, which makes the goal of millimeter accuracy achievable. Our design and construction philosophy is to combine the techniques of single photon ranging, ultrashort laser pulses, and fast fixed threshold discrimination while avoiding any analog signal processing within the laser ranging chain. The all solid state laser ranging detector package consists of the START detector and the STOP solid state photon counting module. Both the detectors are working in an optically triggered avalanche switching regime. The optical signal is triggering an avalanche current buildup which results in the generation of a uniform, fast risetime output pulse.

Enhancement of the resolution of full-field optical coherence tomography by using a colour image sensor

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

Kalyanov, A L; Lychagov, V V; Smirnov, I V

2013-08-31

The influence of white balance in a colour image detector on the resolution of a full-field optical coherence tomograph (FFOCT) is studied. The change in the interference pulse width depending on the white balance tuning is estimated in the cases of a thermal radiation source (incandescent lamp) and a white light emitting diode. It is shown that by tuning white balance of the detector in a certain range, the FFOCT resolution can be increased by 20 % as compared to the resolution, attained with the use of a monochrome detector. (optical coherence tomography)

Advanced technologies for future ground-based, laser-interferometric gravitational wave detectors

PubMed Central

Hammond, Giles; Hild, Stefan; Pitkin, Matthew

2014-01-01

We present a review of modern optical techniques being used and developed for the field of gravitational wave detection. We describe the current state-of-the-art of gravitational waves detector technologies with regard to optical layouts, suspensions and test masses. We discuss the dominant sources and noise in each of these subsystems and the developments that will help mitigate them for future generations of detectors. We very briefly summarise some of the novel astrophysics that will be possible with these upgraded detectors. PMID:25705087

Integral Field Spectroscopy of Markarian 273: Mapping High-Velocity Gas Flows and an Off-Nucleus Seyfert 2 Nebula.

PubMed

Colina; Arribas; Borne

1999-12-10

Integral field optical spectroscopy with the INTEGRAL fiber-based system is used to map the extended ionized regions and gas flows in Mrk 273, one of the closest ultraluminous infrared galaxies. The Hbeta and [O iii] lambda5007 maps show the presence of two distinct regions separated by 4&arcsec; (3.1 kpc) along position angle (P.A.) 240 degrees. The northeastern region coincides with the optical nucleus of the galaxy and shows the spectral characteristics of LINERs. The southwestern region is dominated by [O iii] emission and is classified as a Seyfert 2. Therefore, in the optical, Mrk 273 is an ultraluminous infrared galaxy with a LINER nucleus and an extended off-nucleus Seyfert 2 nebula. The kinematics of the [O iii] ionized gas shows (1) the presence of highly disturbed gas in the regions around the LINER nucleus, (2) a high-velocity gas flow with a peak-to-peak amplitude of 2.4x103 km s-1, and (3) quiescent gas in the outer regions (at 3 kpc). We hypothesize that the high-velocity flow is the starburst-driven superwind generated in an optically obscured nuclear starburst and that the quiescent gas is directly ionized by a nuclear source, similar to the ionization cones typically seen in Seyfert galaxies.

Numerical calculation of nonlinear ultrashort laser pulse propagation in transparent Kerr media

NASA Astrophysics Data System (ADS)

Arnold, Cord L.; Heisterkamp, Alexander; Ertmer, Wolfgang; Lubatschowski, Holger

2005-03-01

In the focal region of tightly focused ultrashort laser pulses, sufficient high intensities to initialize nonlinear ionization processes are easily achieved. Due to these nonlinear ionization processes, mainly multiphoton ionization and cascade ionization, free electrons are generated in the focus resulting in optical breakdown. A model including both nonlinear pulse propagation and plasma generation is used to calculate numerically the interaction of ultrashort pulses with their self-induced plasma in the vicinity of the focus. The model is based on a (3+1)-dimensional nonlinear Schroedinger equation describing the pulse propagation coupled to a system of rate equations covering the generation of free electrons. It is applicable to any transparent Kerr medium, whose linear and nonlinear optical parameters are known. Numerical calculations based on this model are used to understand nonlinear side effects, such as streak formation, occurring in addition to optical breakdown during short pulse refractive eye surgeries like fs-LASIK. Since the optical parameters of water are a good first-order approximation to those of corneal tissue, water is used as model substance. The free electron density distribution induced by focused ultrashort pulses as well as the pulses spatio-temporal behavior are studied in the low-power regime around the critical power for self-focusing.

Radiation Test Results for a MEMS Microshutter Operating at 60 K

NASA Technical Reports Server (NTRS)

Rapchun, David A.; Buchner, Stephen; Moseley, Harvey; Meyer, Stephen E.; Ray, Knute; Tuttle, Jim; Quinn, Ed; Buchanan, Ernie; Bloom, Dave; Hait, Tom;

Contaminant Mass Transfer During Boiling in Fractured Geologic Media

DTIC Science & Technology

2011-04-01

on GC-ECD. Bromide was measured on a Dionex AS50 ion chromatography system equipped with a CD25 conductivity detector and a Dionex guard column...EDB Dibromethane EPICS Equilibrium Partitioning In Closed Systems FID Flame Ionized Detector GC Gas Chromatography IC Ion Chromatography ...International). Bromide was measured from filtered samples with a Dionex ion chromatograph (IC) with an AS11/AG11 column. The eluant for bromide

Monte Carlo Simulations of Electron Energy-Loss Spectra with the Addition of Fine Structure from Density Functional Theory Calculations.

PubMed

Attarian Shandiz, Mohammad; Guinel, Maxime J-F; Ahmadi, Majid; Gauvin, Raynald

2016-02-01

A new approach is presented to introduce the fine structure of core-loss excitations into the electron energy-loss spectra of ionization edges by Monte Carlo simulations based on an optical oscillator model. The optical oscillator strength is refined using the calculated electron energy-loss near-edge structure by density functional theory calculations. This approach can predict the effects of multiple scattering and thickness on the fine structure of ionization edges. In addition, effects of the fitting range for background removal and the integration range under the ionization edge on signal-to-noise ratio are investigated.

A Search for Long-Lived Doubly-Charged Higgs Boson Production in anti-p p Collisions at sqrt(s)=1.96 TeV using RunII CDF

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

Tuttle, Joshua P.; /Duke U.

2005-01-01

We present a search for a quasi-stable doubly-charged Higgs particle at CDF using the Fermilab Tevatron for {radical}s = 1.96 TeV. The data presented are from approximately 290 pb{sup -1} of integrated luminosity collected using the upgraded Run 2 Collider Detector at Fermilab. These data were taken between February, 2002 and February, 2004. The long-lived decay products of Z's are selected in the central detector region (|{eta}| < 1.0). They select events triggered on a muon candidate having p{sub T} > 18 GeV in the event. After offline reconstruction, they require two isolated tracks (p{sub T} > 20 GeV) inmore » the event, one of which points to a stub in a muon detector. Since the search is based on the increased ionization a doubly-charged particle would produce as it passes through the detector, they require that both tracks be highly ionizing for an event to be selected as a H{sup {+-}{+-}} candidate. No such candidates are observed in the data. They set a lower mass limit of 146 GeV on a quasi-stable H{sup {+-}{+-}} boson.« less

Photoionization sensor CES for non-invasive medical diagnostics

NASA Astrophysics Data System (ADS)

Mustafaev, Aleksandr; Rastvorova, Iuliia; Khobnya, Kristina; Podenko, Sofia

2016-10-01

Method CES (collisional electron spectroscopy), patented in Russia, the USA, Japan, China, Germany and Britain, allows to analyze the gaseous mixtures using electron spectroscopy under high pressures up to atmospheric without using vacuum. The design of VUV photoionization detector was developed based on this method. Such detector is used as a portable gas analyzer for continuous personal bio-medical monitoring. This detector measures energy of electrons produced in ionization with resonance photons, whose wavelength situated in the vacuum ultraviolet (VUV). Nowadays, micro plasma source of such photons on resonant line of Kr with energy of 10,6 eV is developed. Only impurities are ionized and detected by the VUV-emission, meanwhile the main components of air stay neutral that reduces background signal and increases the sensibility along with accuracy. The experimental facilities with VUV photoionization sensors CES are constructed with the overall sizes about 10*10*1 mm. The watt consumption may comprise less than 1W. Increase of electrometer amplifier's sensibility and more high-aperture construction are used today to increase the sensibility of CES-detectors. The wide range of detectable molecules and high sensitivity allow the development of portable device, which can become the base of the future preventive medicine. Work supported by Foundation for Assistance to Small Innovative Enterprises in Science and Technology.

The role of fiberoptics in remote temperature measurement

NASA Technical Reports Server (NTRS)

Vanzetti, Riccardo

1988-01-01

The use of optical fibers in conjunction with infrared detectors and signal processing electronics represents the latest advance in the field of non-contact temperature measurement and control. The operating principles and design of fiber-optic radiometric systems are discussed and the advantages and disadvantages of using optical fibers are addressed. Signal processing requirements and various infrared detector types are also described. Several areas in which infrared fiber-optic instrumentation is used for temperature monitoring and control are discussed.

Optical performance of prototype horn-coupled TES bolometer arrays for SAFARI

NASA Astrophysics Data System (ADS)

Audley, Michael D.; de Lange, Gert; Gao, Jian-Rong; Khosropanah, Pourya; Hijmering, Richard; Ridder, Marcel L.

2016-07-01

The SAFARI Detector Test Facility is an ultra-low background optical testbed for characterizing ultra-sensitive prototype horn-coupled TES bolmeters for SAFARI, the grating spectrometer on board the proposed SPICA satellite. The testbed contains internal cold and hot black-body illuminators and a light-pipe for illumination with an external source. We have added reimaging optics to facilitate array optical measurements. The system is now being used for optical testing of prototype detector arrays read out with frequency-domain multiplexing. We present our latest optical measurements of prototype arrays and discuss these in terms of the instrument performance.

Isotropically sensitive optical filter employing atomic resonance transitions

DOEpatents

Marling, John B.

1981-01-01

An ultra-high Q isotropically sensitive optical filter or optical detector employing atomic resonance transitions. More specifically, atomic resonance transitions utilized in conjunction with two optical bandpass filters provide an optical detector having a wide field of view (.about.2.pi. steradians) and very narrow acceptance bandwidth approaching 0.01 A. A light signal to be detected is transmitted through an outer bandpass filter into a resonantly absorbing atomic vapor, the excited atomic vapor then providing a fluorescence signal at a different wavelength which is transmitted through an inner bandpass filter. The outer and inner bandpass filters have no common transmission band, thereby resulting in complete blockage of all optical signals that are not resonantly shifted in wavelength by the intervening atomic vapor. Two embodiments are disclosed, one in which the light signal raises atoms contained in the atomic vapor from the ground state to an excited state from which fluorescence occurs, and the other in which a pump laser is used to raise the atoms in the ground state to a first excited state from which the light signal then is resonantly absorbed, thereby raising the atoms to a second excited state from which fluorescence occurs. A specific application is described in which an optical detector according to the present invention can be used as an underwater detector for light from an optical transmitter which could be located in an orbiting satellite.

Development and Characterization of 6Li-doped Liquid Scintillator Detectors for PROSPECT

NASA Astrophysics Data System (ADS)

Gaison, Jeremy; Prospect Collaboration

2016-09-01

PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, is a phased reactor antineutrino experiment designed to search for eV-scale sterile neutrinos via short-baseline neutrino oscillations and to make a precision measurement of the 235U reactor antineutrino spectrum. A multi-ton, optically segmented detector will be deployed at Oak Ridge National Laboratory's (ORNL) High Flux Isotope Reactor (HFIR) to measure the reactor spectrum at baselines ranging from 7-12m. A two-segment detector prototype with 50 liters of active liquid scintillator target has been built to verify the detector design and to benchmark its performance. In this presentation, we will summarize the performance of this detector prototype and describe the optical and energy calibration of the segmented PROSPECT detectors.

Dead layer on silicon p-i-n diode charged-particle detectors

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

Wall, B. L.; Amsbaugh, John F.; Beglarian, A.

Abstract Semiconductor detectors in general have a dead layer at their surfaces that is either a result of natural or induced passivation, or is formed during the process of making a contact. Charged particles passing through this region produce ionization that is incompletely collected and recorded, which leads to departures from the ideal in both energy deposition and resolution. The silicon p-i-n diode used in the KATRIN neutrinomass experiment has such a dead layer. We have constructed a detailed Monte Carlo model for the passage of electrons from vacuum into a silicon detector, and compared the measured energy spectra tomore » the predicted ones for a range of energies from 12 to 20 keV. The comparison provides experimental evidence that a substantial fraction of the ionization produced in the "dead" layer evidently escapes by discussion, with 46% being collected in the depletion zone and the balance being neutralized at the contact or by bulk recombination. The most elementary model of a thinner dead layer from which no charge is collected is strongly disfavored.« less

Use of GaN as a Scintillating Ionizing Radiation Detector

NASA Astrophysics Data System (ADS)

Wensman, Johnathan; Guardala, Noel; Mathur, Veerendra; Alasagas, Leslie; Vanhoy, Jeffrey; Statham, John; Marron, Daniel; Millett, Marshall; Marsh, Jarrod; Currie, John; Price, Jack

2017-09-01

Gallium nitride (GaN) is a III/V direct bandgap semiconductor which has been used in light emitting diodes (LEDs) since the 1990s. Currently, due to a potential for increased efficiency, GaN is being investigated as a replacement for silicon in power electronics finding potential uses ranging from data centers to electric vehicles. In addition to LEDs and power electronics though, doped GaN can be used as a gamma insensitive fast neutron detector due to the direct band-gap, light propagation properties, and response to ionizing radiations. Investigation of GaN as a semiconductor scintillator for use in a radiation detection system involves mapping the response function of the detector crystal over a range of photon and neutron energies, and measurements of light generation in the GaN crystal due to proton, alpha, and nitrogen projectiles. In this presentation we discuss the measurements made to date, and plausible interpretations of the response functions. This work funded in part by the Naval Surface Warfare Center, Carderock Division In-house Laboratory Independent Research program.

Sources of Ionizing Radiation in Interplanetary Space

NASA Image and Video Library

2013-05-30

This illustration depicts the two main types of radiation that NASA Radiation Assessment Detector RAD onboard Curiosity monitors, and how the magnetic field around Earth affects the radiation in space near Earth.

Optical detectors for GaAs MMIC integration: Technology assessment

NASA Technical Reports Server (NTRS)

Claspy, P. C.; Bhasin, K. B.

1989-01-01

Fiber optic links are being considered to transmit digital and analog signals in phased array antenna feed networks in space communications systems. The radiating elements in these arrays will be GaAs monolithic microwave integrated circuits (MMIC's) in numbers ranging from a few hundred to several thousand. If such optical interconnects are to be practical it appears essential that the associated components, including detectors, be monolithically integrated on the same chip as the microwave circuitry. The general issue of monolithic integration of microwave and optoelectronic components is addressed from the point of view of fabrication technology and compatibility. Particular attention is given to the fabrication technology of various types of GaAs optical detectors that are designed to operate at a wavelength of 830 nm.

Sensitive gas chromatographic detection of acetaldehyde and acetone using a reduction gas detector

NASA Technical Reports Server (NTRS)

O'Hara, Dean; Singh, Hanwant B.

1988-01-01

The response of a newly available mercuric oxide Reduction Gas Detector (RGD-2) to subpicomole and larger quantities of acetaldehyde and acetone is tested. The RGD-2 is found to be capable of subpicomole detection for these carbonyls and is more sensitive than an FID (Flame Ionization Detector) by an order of magnitude. Operating parameters can be further optimized to make the RGD-2 some 20-40 times more sensitive than an FID. The detector is linear over a wide range and is easily adapted to a conventional gas chromatograph (GC). Such a GC-RGD-2 system should be suitable for atmospheric carbonyl measurements in clean as well as polluted environments.

Field test of optical and electrical fire detectors in simulated fire scenes in a cable tunnel

NASA Astrophysics Data System (ADS)

Fan, Dian; Ding, Hongjun; Wang, Dorothy Y.; Jiang, Desheng

2014-06-01

This paper presents the testing results of three types of fire detectors: electrical heat sensing cable, optical fiber Raman temperature sensing detector, and optical fiber Bragg grating (FBG) temperature sensing detector, in two simulated fire scenes in a cable tunnel. In the small-scale fire with limited thermal radiation and no flame, the fire alarm only comes from the heat sensors which directly contact with the heat source. In the large-scale fire with about 5 °C/min temperature rising speed within a 3-m span, the fire alarm response time of the fiber Raman sensor and FBG sensors was about 30 seconds. The test results can be further used for formulating regulation for early fire detection in cable tunnels.

Fabrication of superconducting nanowire single-photon detectors by nonlinear femtosecond optical lithography

NASA Astrophysics Data System (ADS)

Minaev, N. V.; Tarkhov, M. A.; Dudova, D. S.; Timashev, P. S.; Chichkov, B. N.; Bagratashvili, V. N.

2018-02-01

This paper describes a new approach to the fabrication of superconducting nanowire single-photon detectors from ultrathin NbN films on SiO2 substrates. The technology is based on nonlinear femtosecond optical lithography and includes direct formation of the sensitive element of the detector (the meander) through femtosecond laser exposure of the polymethyl methacrylate resist at a wavelength of 525 nm and subsequent removal of NbN using plasma-chemical etching. The nonlinear femtosecond optical lithography method allows the formation of planar structures with a spatial resolution of ~50 nm. These structures were used to fabricate single-photon superconducting detectors with quantum efficiency no worse than 8% at a wavelength of 1310 nm and dark count rate of 10 s-1 at liquid helium temperature.

Prototype positron emission tomography insert with electro-optical signal transmission for simultaneous operation with MRI.

PubMed

Olcott, Peter; Kim, Ealgoo; Hong, Keyjo; Lee, Brian J; Grant, Alexander M; Chang, Chen-Ming; Glover, Gary; Levin, Craig S

2015-05-07

The simultaneous acquisition of PET and MRI data shows promise to provide powerful capabilities to study disease processes in human subjects, guide the development of novel treatments, and monitor therapy response and disease progression. A brain-size PET detector ring insert for an MRI system is being developed that, if successful, can be inserted into any existing MRI system to enable simultaneous PET and MRI images of the brain to be acquired without mutual interference. The PET insert uses electro-optical coupling to relay all the signals from the PET detectors out of the MRI system using analog modulated lasers coupled to fiber optics. Because the fibers use light instead of electrical signals, the PET detector can be electrically decoupled from the MRI making it partially transmissive to the RF field of the MRI. The SiPM devices and low power lasers were powered using non-magnetic MRI compatible batteries. Also, the number of laser-fiber channels in the system was reduced using techniques adapted from the field of compressed sensing. Using the fact that incoming PET data is sparse in time and space, electronic circuits implementing constant weight codes uniquely encode the detector signals in order to reduce the number of electro-optical readout channels by 8-fold. Two out of a total of sixteen electro-optical detector modules have been built and tested with the entire RF-shielded detector gantry for the PET ring insert. The two detectors have been tested outside and inside of a 3T MRI system to study mutual interference effects and simultaneous performance with MRI. Preliminary results show that the PET insert is feasible for high resolution simultaneous PET/MRI imaging for applications in the brain.