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Articles 31 - 60 of 159
Full-Text Articles in Physical Sciences and Mathematics
Position Resolution In Labr3 And Lacl3 Scintillators Using Position-Sensitive Photomultiplier Tubes, Peter F. Bloser, Mark L. Mcconnell, John R. Macri, James M. Ryan, Justin Baker
Position Resolution In Labr3 And Lacl3 Scintillators Using Position-Sensitive Photomultiplier Tubes, Peter F. Bloser, Mark L. Mcconnell, John R. Macri, James M. Ryan, Justin Baker
Space Science Center
Advanced scintillator materials such as LaBr3:Ce and LaCl3:Ce hold great promise for future hard X-ray and gamma-ray astrophysics missions due to their high density, high light output, good linearity, and fast decay times. Of particular importance for future space-based imaging instruments, such as coded-aperture telescopes, is the precise spatial location of individual gamma-ray interactions. We have investigated the position and energy resolution achievable within monolithic (5 cm × 5 cm × 1 cm) LaBr3:Ce and LaCl3:Ce crystals using position-sensitive light readout devices, including a position-sensitive photomultiplier tube and a multi-anode photomultiplier tube. We present the results of these tests and …
Radiation Damage And Activation From Proton Irradiation Of Advanced Scintillators, Peter F. Bloser, Mark L. Mcconnell, John R. Macri, P J. Bruillard, James M. Ryan, W Hajdas
Radiation Damage And Activation From Proton Irradiation Of Advanced Scintillators, Peter F. Bloser, Mark L. Mcconnell, John R. Macri, P J. Bruillard, James M. Ryan, W Hajdas
Space Science Center
We present results from a proton accelerator beam test to measure radiation damage and activation in advanced scintillator materials. Samples of LaBr3:Ce and LaCl3:Ce were exposed to protons from 40-250 MeV at the Proton Irradiation Facility of the Paul Scherrer Institute in Switzerland. Twelve energy bands were used to simulate the spectrum of the South Atlantic Anomaly (SAA), with different samples exposed to the equivalent of 4 months, 1 year, and 5 years of SAA passage. No significant decrease in light output was found due to radiation damage, indicating that these new scintillator materials are radiation tolerant. High-resolution spectra of …
Optimization Of Single-Sided Charge-Sharing Strip Detectors, L A. Hamel, M Benoit, B Donmez, John R. Macri, Mark L. Mcconnell, T Narita, James M. Ryan
Optimization Of Single-Sided Charge-Sharing Strip Detectors, L A. Hamel, M Benoit, B Donmez, John R. Macri, Mark L. Mcconnell, T Narita, James M. Ryan
Space Science Center
Simulation of the charge sharing properties of single-sided CZT strip detectors with small anode pads are presented. The effect of initial event size, carrier repulsion, diffusion, drift, trapping and detrapping are considered. These simulations indicate that such a detector with a 150 µm pitch will provide good charge sharing between neighboring pads. This is supported by a comparison of simulations and measurements for a similar detector with a coarser pitch of 225 µm that could not provide sufficient sharing. The performance of such a detector used as a gamma-ray imager is discussed.
Further Studies Of Single-Sided Charge-Sharing Czt Strip Detectors, B Donmez, John R. Macri, Mark L. Mcconnell, James M. Ryan, Mark Widholm, T Narita, L A. Hamel
Further Studies Of Single-Sided Charge-Sharing Czt Strip Detectors, B Donmez, John R. Macri, Mark L. Mcconnell, James M. Ryan, Mark Widholm, T Narita, L A. Hamel
Space Science Center
We report progress in the study of a thick CZT strip detector module designed to perform gamma-ray spectroscopy and 3-D imaging. We report preliminary performance measurements of 7.5 mm thick single-sided charge-sharing strip detector prototype devices. This design features both row and column contacts on the anode surface. This electron-only approach addresses problems associated with poor hole transport in CZT that limit the thickness and energy range of double-sided strip detectors. This work includes laboratory and simulation studies aimed at developing compact, efficient, detector modules for 0.05 to 1 MeV gamma measurements while minimizing the number and complexity of the …
Imaging Solar Neutrons Below 10 Mev In The Inner Heliosphere, U Bravar
Imaging Solar Neutrons Below 10 Mev In The Inner Heliosphere, U Bravar
Space Science Center
Inner heliosphere measurements of the Sun can be conducted with the proposed Solar Sentinel spacecraft and mission. One of the key measurements that can be made inside the orbit of the Earth is that of lower energy neutrons that arise in flares from nuclear reactions. Solar flare neutrons below 10 MeV suffer heavy weak-decay losses before reaching 1 AU. For heliocentric radii as close as 0.3 AU, the number of surviving neutrons from a solar event is dramatically greater. Neutrons from 1-10 MeV provide a new measure of heavy ion interactions at low energies, where the vast majority of energetic …
Caster: A Concept For A Black Hole Finder Probe Based On The Use Of New Scintillator Technologies, Mark L. Mcconnell, Peter F. Bloser, G L. Case, M L. Cherry, J Cravens, T G. Guzik, K Hurley, R M. Kippen, John R. Macri, R S. Miller, W Paciesas, James M. Ryan, B Schaefer, J G. Stacy, W T. Vestrand, J P. Wefel
Caster: A Concept For A Black Hole Finder Probe Based On The Use Of New Scintillator Technologies, Mark L. Mcconnell, Peter F. Bloser, G L. Case, M L. Cherry, J Cravens, T G. Guzik, K Hurley, R M. Kippen, John R. Macri, R S. Miller, W Paciesas, James M. Ryan, B Schaefer, J G. Stacy, W T. Vestrand, J P. Wefel
Space Science Center
The primary scientific mission of the Black Hole Finder Probe (BHFP), part of the NASA Beyond Einstein program, is to survey the local Universe for black holes over a wide range of mass and accretion rate. One approach to such a survey is a hard X-ray coded-aperture imaging mission operating in the 10-600 keV energy band, a spectral range that is considered to be especially useful in the detection of black hole sources. The development of new inorganic scintillator materials provides improved performance (for example, with regards to energy resolution and timing) that is well suited to the BHFP science …
Gas Micro-Well Track Imaging Detectors For Gamma-Ray Astronomy, Peter F. Bloser, S Hunter, James M. Ryan, Mark L. Mcconnell, John R. Macri
Gas Micro-Well Track Imaging Detectors For Gamma-Ray Astronomy, Peter F. Bloser, S Hunter, James M. Ryan, Mark L. Mcconnell, John R. Macri
Space Science Center
We describe our program to develop gas micro-well detectors (MWDs) as three-dimensional charged particle trackers for use in advanced gamma-ray telescope concepts. A micro-well detector consists of an array of individual micro-patterned gas proportional counters opposite a planar drift electrode. The well anodes and cathodes may be connected in X and Y strips, respectively, to provide two-dimensional imaging. When combined with transient digitizer electronics, which record the time signature of the charge collected in the wells of each strip, full three-dimensional reconstruction of charged-particle tracks in large gas volumes is possible. Such detectors hold great promise for advanced Compton telescope …
Mega: A Medium-Energy Gamma-Ray Astronomy Mission Concept, Peter F. Bloser, James M. Ryan, Mark L. Mcconnell, John R. Macri, U Bravar, G Kanbach, R Andritsche, M Ajello, A Zoglauer, S Hunter, B F. Phlips, Eric Wulf, Dieter H. Hartman, R S. Miller, W Paciesas, Allen Zych, R M. Kippen, W T. Vestrand, M L. Cherry, T G. Guzik, J G. Stacy, J P. Wefel, V Reglero, G Dicocco, J Cravens
Mega: A Medium-Energy Gamma-Ray Astronomy Mission Concept, Peter F. Bloser, James M. Ryan, Mark L. Mcconnell, John R. Macri, U Bravar, G Kanbach, R Andritsche, M Ajello, A Zoglauer, S Hunter, B F. Phlips, Eric Wulf, Dieter H. Hartman, R S. Miller, W Paciesas, Allen Zych, R M. Kippen, W T. Vestrand, M L. Cherry, T G. Guzik, J G. Stacy, J P. Wefel, V Reglero, G Dicocco, J Cravens
Space Science Center
The Medium Energy Gamma-ray Astronomy (MEGA) telescope concept will soon be proposed as a MIDEX mission. This mission would enable a sensitive all-sky survey of the medium-energy gamma-ray sky (0.4 - 50 MeV) and bridge the huge sensitivity gap between the COMPTEL and OSSE experiments on the Compton Gamma Ray Observatory, the SPI and IBIS instruments on INTEGRAL, and the visionary Advanced Compton Telescope (ACT) mission. The scientific goals include, among other things, compiling a much larger catalog of sources in this energy range, performing far deeper searches for supernovae, better measuring the galactic continuum and line emissions, and identifying …
Atmospheric Neutron Measurements With The Sontrac Science Model, U Bravar, E O. Fluckiger, Kevin Godin, Zachary C. Hansen, John R. Macri, Mark L. Mcconnell, R S. Miller, M R. Moser, James M. Ryan
Atmospheric Neutron Measurements With The Sontrac Science Model, U Bravar, E O. Fluckiger, Kevin Godin, Zachary C. Hansen, John R. Macri, Mark L. Mcconnell, R S. Miller, M R. Moser, James M. Ryan
Space Science Center
–The SOlar Neutron TRACking (SONTRAC) telescope was originally developed to measure the energy spectrum and incident direction of neutrons produced in solar flares, in the energy range 20 - 250 MeV. While developed primarily for solar physics, the SONTRAC detector may be employed in virtually any application requiring both energy measurement and imaging capabilities. The SONTRAC Science Model (SM) is presently being operated at the University of New Hampshire (UNH) as a ground-based instrument to investigate the energy spectrum, zenith and azimuth angle dependence of the cosmic-ray induced sea-level atmospheric neutron flux. SONTRAC measurements are based on the non-relativistic double …
Continued Studies Of Single-Sided Charge-Sharing Czt Strip Detectors, B Donmez, John R. Macri, Mark L. Mcconnell, James M. Ryan, Mark Widholm, L A. Hamel, T Narita
Continued Studies Of Single-Sided Charge-Sharing Czt Strip Detectors, B Donmez, John R. Macri, Mark L. Mcconnell, James M. Ryan, Mark Widholm, L A. Hamel, T Narita
Space Science Center
In this paper, we report progress in the study of thick single-sided charge-sharing cadmium zinc telluride (CZT) strip detector modules designed to perform gammaray spectroscopy and 3-D imaging. We report on continuing laboratory and simulation measurements of prototype detectors with 11×11 unit cells (15×15×7.5mm3 ). We report preliminary measurements of the 3-D spatial resolution. Our studies are aimed at developing compact, efficient, detector modules for 0.05 to 1 MeV gamma measurements while minimizing the number and complexity of the electronic readout channels. This is particularly important in space-based coded aperture and Compton telescope instruments that require large area, large volume …
Development Of The Fast Neutron Imaging Telescope, U Bravar, P J. Bruillard, E O. Fluckiger, John R. Macri, A L. Mackinnon, Mark L. Mcconnell, M R. Moser, James M. Ryan, R S. Woolf
Development Of The Fast Neutron Imaging Telescope, U Bravar, P J. Bruillard, E O. Fluckiger, John R. Macri, A L. Mackinnon, Mark L. Mcconnell, M R. Moser, James M. Ryan, R S. Woolf
Space Science Center
We report on the development of a next generation neutron telescope, with imaging and energy measurement capabilities, sensitive to neutrons in the 2-20 MeV energy range. The Fast Neutron Imaging Telescope (FNIT) was initially conceived to study solar neutrons as a candidate instrument for the Inner Heliosphere Sentinels (IHS) program under formulation at NASA. This detector is now being adapted to locate Special Nuclear Material (SNM) for homeland security purposes by detecting fission neutrons and reconstructing the image of their source. In either case, the detection principle is based on multiple elastic neutron-proton scatterings in organic scintillator. By reconstructing the …
A Hard X-Ray Polarimeter Designed For Transient Astrophysical Sources, Mark L. Mcconnell, Peter F. Bloser, Jason S. Legere, John R. Macri, T Narita
A Hard X-Ray Polarimeter Designed For Transient Astrophysical Sources, Mark L. Mcconnell, Peter F. Bloser, Jason S. Legere, John R. Macri, T Narita
Space Science Center
— This paper discusses the latest progress in the development of GRAPE (Gamma-Ray Polarimeter Experiment), a hard X-ray Compton Polarimeter. The purpose of GRAPE is to measure the polarization of hard X-rays in the 50-300 keV energy range. We are particularly interested in X-rays that are emitted from solar flares and gamma-ray bursts (GRBs). Accurately measuring the polarization of the emitted radiation from these sources will lead, to a better understating of both the emission mechanisms and source geometries. The GRAPE design consists of an array of plastic scintillators surrounding a central high-Z crystal scintillator. We can monitor individual Compton …
Mega: The Next Generation Medium Energy Gamma-Ray Telescope, James M. Ryan, R Andritsche, Peter F. Bloser, J Cravens, M L. Cherry, G Dicocco, T G. Guzik, Dieter H. Hartman, Stanley D. Hunter, G Kanbach, R M. Kippen, J Kurfess, John R. Macri, Mark L. Mcconnell, R S. Miller, W Paciesas, B F. Phlips, V Reglero, J G. Stacy, Mark Strickman, W T. Vestrand, J P. Wefel, Eric Wulf, A Zoglauer, Allen Zych
Mega: The Next Generation Medium Energy Gamma-Ray Telescope, James M. Ryan, R Andritsche, Peter F. Bloser, J Cravens, M L. Cherry, G Dicocco, T G. Guzik, Dieter H. Hartman, Stanley D. Hunter, G Kanbach, R M. Kippen, J Kurfess, John R. Macri, Mark L. Mcconnell, R S. Miller, W Paciesas, B F. Phlips, V Reglero, J G. Stacy, Mark Strickman, W T. Vestrand, J P. Wefel, Eric Wulf, A Zoglauer, Allen Zych
Space Science Center
The MEGA mission would enable a sensitive all-sky survey of the medium-energy ?-ray sky (0.3-50 MeV). This mission will bridge the huge sensitivity gap between the COMPTEL and OSSE experiments on the Compton Gamma Ray Observatory, the SPI and IBIS instruments on INTEGRAL and the visionary ACT mission. It will, among other things, serve to compile a much larger catalog of sources in this energy range, perform far deeper searches for supernovae, better measure the galactic continuum emission as well as identify the components of the cosmic diffuse emission. The large field of view will allow MEGA to continuously monitor …
Caster: A Scintillator-Based Black Hole Finder Probe, Mark L. Mcconnell, M L. Cherry, T G. Guzik, R M. Kippen, James M. Ryan, John R. Macri, R S. Miller, W Paciesas, B Schaefer, J G. Stacy, J P. Wefel, W T. Vestrand
Caster: A Scintillator-Based Black Hole Finder Probe, Mark L. Mcconnell, M L. Cherry, T G. Guzik, R M. Kippen, James M. Ryan, John R. Macri, R S. Miller, W Paciesas, B Schaefer, J G. Stacy, J P. Wefel, W T. Vestrand
Space Science Center
The primary scientific mission of the Black Hole Finder Probe (BHFP), part of the NASA Beyond Einstein program, is to survey the local Universe for black holes over a wide range of mass and accretion rate. One approach to such a survey is a hard X-ray coded-aperture imaging mission operating in the 10-600 keV energy band, a spectral range that is considered to be especially useful in the detection of black hole sources. The development of new inorganic scintillator materials provides improved performance (for example, with regards to energy resolution and timing) that is well suited to the BHFP science …
Single-Sided Czt Strip Detectors, John R. Macri, B Donmez, Mark Widholm, L A. Hamel, Manuel Julien, T Narita, James M. Ryan, Mark L. Mcconnell
Single-Sided Czt Strip Detectors, John R. Macri, B Donmez, Mark Widholm, L A. Hamel, Manuel Julien, T Narita, James M. Ryan, Mark L. Mcconnell
Space Science Center
We report progress in the study of thick CZT strip detectors for 3-d imaging and spectroscopy and discuss two approaches to device design. We present the spectroscopic, imaging, detection efficiency and response uniformity performance of prototype devices. Unlike double-sided strip detectors, these devices feature both row and column contacts implemented on the anode surface. This electron-only approach circumvents problems associated with poor hole transport in CZT that normally limit the thickness and energy range of double-sided strip detectors. These devices can achieve similar performance to pixel detectors. The work includes laboratory and simulation studies aimed at developing compact, efficient, detector …
Dedicated Polarimeter Design For Hard X-Ray And Soft Gamma-Ray Astronomy, Mark L. Mcconnell, J Ledoux, John R. Macri, James M. Ryan
Dedicated Polarimeter Design For Hard X-Ray And Soft Gamma-Ray Astronomy, Mark L. Mcconnell, J Ledoux, John R. Macri, James M. Ryan
Space Science Center
We have developed a modular design for a hard X-ray and soft gamma-ray polrimeter that we call GRAPE (Gamma RAy Polarimeter Experiment). Optimized for the energy range of 50-300 keV, the GRAPE design is a Compton polarimeter based on the use of an array of plastic scintillator scattering elements in conjunction with a centrally positioned high-Z calorimeter detector. Here we shall review the results from a laboratory model of the baseline GRAPE design. The baseline design uses a 5-inch diameter position sensitive PMT (PSPMT) for readout of the plastic scintillator array and a small array of CsI detectors for measurement …
Future Prospects For High Energy Polarimetry Of Gamma‐Ray Bursts, Mark L. Mcconnell
Future Prospects For High Energy Polarimetry Of Gamma‐Ray Bursts, Mark L. Mcconnell
Space Science Center
The recent detection of linear polarization from GRB120206 has piqued the interest of the community in this relatively unexplored avenue of research. Here, we review the current status and prospects for GRB polarimetry at hard X‐ray and soft γ‐ray energies. After reviewing the most recent results, we present a brief survey of current and planned experiments that are capable of making GRB polarization measurements in the energy range between 30 keV and 30 MeV.
Single-Sided Czt Strip Detectors, John R. Macri, L A. Hamel, Manuel Julien, R S. Miller, B Donmez, Mark L. Mcconnell, James M. Ryan, Mark Widholm
Single-Sided Czt Strip Detectors, John R. Macri, L A. Hamel, Manuel Julien, R S. Miller, B Donmez, Mark L. Mcconnell, James M. Ryan, Mark Widholm
Space Science Center
We report progress in the study of thick CZT strip detectors for 3-D imaging and spectroscopy and discuss two approaches to device design. Unlike double-sided strip detectors, these devices feature both row and column contacts implemented on the anode surface. This electron-only approach circumvents problems associated with poor hole transport in CZT that normally limit the thickness and energy range of double-sided strip detectors. The work includes laboratory and simulation studies aimed at developing compact, efficient, detector modules for 0.05 to 1 MeV gamma radiation measurements while minimizing the number and complexity of the electronic readout channels. These devices can …
Hard X-Ray Polarimeter For Gamma-Ray Bursts And Solar Flares, Mark L. Mcconnell, J Ledoux, John R. Macri, James M. Ryan
Hard X-Ray Polarimeter For Gamma-Ray Bursts And Solar Flares, Mark L. Mcconnell, J Ledoux, John R. Macri, James M. Ryan
Space Science Center
We report on the development of a dedicated polarimeter design that is capable of studying the linear polarization of hard X-rays (50-300 keV) from gamma-ray bursts and solar flares. This compact design, based on the use of a large area position-sensitive PMT (PSPMT), is referred to as GRAPE (Gamma-RAy Polarimeter Experiment). The PSPMT is used to determine the Compton interaction location within an array of small plastic scintillator elements. Some of the photons that scatter within the plastic scintillator array are subsequently absorbed by a small centrally-located array of CsI(Tl) crystals that is read out by an independent multi-anode PMT. …
Development Of Czt Strip Detector Modules For 0.05- To 1-Mev Gamma-Ray Imaging And Spectroscopy, James M. Ryan, B Donmez, John R. Macri, M Mcclish, Mark L. Mcconnell, R S. Miller, Mark Widholm, L A. Hamel, Manuel Julien
Development Of Czt Strip Detector Modules For 0.05- To 1-Mev Gamma-Ray Imaging And Spectroscopy, James M. Ryan, B Donmez, John R. Macri, M Mcclish, Mark L. Mcconnell, R S. Miller, Mark Widholm, L A. Hamel, Manuel Julien
Space Science Center
We report progress in our study of cadmium zinc telluride (CZT) strip detectors featuring orthogonal coplanar anode contacts. We specifically report on the performance, characterization and stability of 5 and 10 mm thick prototype CZT detectors fabricated using material from several manufacturers. Our ongoing work includes laboratory and simulation studies aimed at optimizing and developing compact, efficient, high performance detector modules for 0.05 to 1 MeV gamma radiation measurements with space-based instrumentation. The coplanar anode strip configuration retains many of the performance advantages of pixel detectors yet requires far fewer electronic channels to perform both 3-d imaging and spectroscopy. Minimizing …
Nonsolar Astronomy With The Reuven Ramaty High Energy Solar Spectroscopic Imager (Rhessi), David M. Smith, Robert P. Lin, K Hurley, Wayne Coburn, G J. Hurford, Claudia Wigger, W Hajdas, Alex Zehnder, Mark L. Mcconnell
Nonsolar Astronomy With The Reuven Ramaty High Energy Solar Spectroscopic Imager (Rhessi), David M. Smith, Robert P. Lin, K Hurley, Wayne Coburn, G J. Hurford, Claudia Wigger, W Hajdas, Alex Zehnder, Mark L. Mcconnell
Space Science Center
The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is a NASA Small Explorer satellite designed to study hard x-ray and gamma-ray emission from solar flares. In addition, its high-resolution array of germanium detectors can see photons from high-energy sources throughout the Universe. Here we discuss the various algorithms necessary to extract spectra, lightcurves, and other information about cosmic gamma-ray bursts, pulsars, and other astrophysical phenomena using an unpointed, spinning array of detectors. We show some preliminary results and discuss our plans for future analyses. All RHESSI data are public, and scientists interested in participating should contact the principal author.
Hard X-Ray Polarimetry With The Ramaty High Energy Solar Spectroscopic Imager (Rhessi), Mark L. Mcconnell, David M. Smith, A G. Emslie, Robert P. Lin, James M. Ryan
Hard X-Ray Polarimetry With The Ramaty High Energy Solar Spectroscopic Imager (Rhessi), Mark L. Mcconnell, David M. Smith, A G. Emslie, Robert P. Lin, James M. Ryan
Space Science Center
Although designed primarily as a hard X-ray imager and spectrometer, the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is also capable of measuring the polarization of hard X-rays (20-100 keV) from solar flares. This capability arises from the inclusion of a small unobstructed Be scattering element that is strategically located within the cryostat that houses the array of nine germanium detectors. The Ge detectors are segmented, with both a front and rear active volume. Low energy photons (below about 100 keV) can reach a rear segment of a Ge detector only indirectly, by scattering. Low energy photons from the Sun …
Sontrac: An Imaging Spectrometer For Solar Neutrons, James M. Ryan, L Desorgher, E O. Fluckiger, John R. Macri, Mark L. Mcconnell, R S. Miller
Sontrac: An Imaging Spectrometer For Solar Neutrons, James M. Ryan, L Desorgher, E O. Fluckiger, John R. Macri, Mark L. Mcconnell, R S. Miller
Space Science Center
An instrument capable of unambiguously determining the energy and direction of incident neutrons has important applications in solar physics-as well as environmental monitoring and medical/radiological sciences. The SONTRAC (SOlar Neutron TRACking) instrument is designed to operate in the neutron energy range of 20-250 MeV. The measurement principle is based on non-relativistic double scatter of neutrons off ambient protons (n-p scattering) within a block of densely packed scintillating fibers. Using this double-scatter mode it is possible to uniquely determine neutron energy and direction on an event-by-event basis. A fully operational science model of such an instrument has been built using 300 …
The Development Of Grape, A Gamma Ray Polarimeter Experiment, Mark L. Mcconnell, J Ledoux, John R. Macri, James M. Ryan
The Development Of Grape, A Gamma Ray Polarimeter Experiment, Mark L. Mcconnell, J Ledoux, John R. Macri, James M. Ryan
Space Science Center
The measurement of hard X‐ray polarization in γ‐ray bursts (GRBs) would add yet another piece of information in our effort to resolve the true nature of these enigmatic objects. Here we report on the development of a dedicated polarimeter design with a relatively large FoV that is capable of studying hard X‐ray polarization (50–300 keV) from GRBs. This compact design, based on the use of a large area position‐sensitive PMT (PSPMT), is referred to as GRAPE (Gamma‐RAy Polarimeter Experiment). The feature of GRAPE that is especially attractive for studies of GRBs is the significant off‐axis polarization response (at angles greater …
A Prototype Asic For Apd Array Readout Of Scintillating Plastic Fibers, John R. Macri, A L. Wintenerg, Mark Widholm, U Jagadish, J Ledoux, Mark L. Mcconnell, S Shane Frank, Hansford H. Cutlip
A Prototype Asic For Apd Array Readout Of Scintillating Plastic Fibers, John R. Macri, A L. Wintenerg, Mark Widholm, U Jagadish, J Ledoux, Mark L. Mcconnell, S Shane Frank, Hansford H. Cutlip
Space Science Center
We report on the development of custom front-end electronics for use with avalanche photodiode (APD) arrays as part of a NASA technology study for the readout of scintillating plastic fibers. APD arrays featuring 64 1 mm square pixels are used. We demonstrate that a pixel of these APD arrays coupled to relatively thin (0.25 mm) and short (15 cm) scintillating plastic fibers can be used to detect and measure the tracks of even minimum ionizing particles (MIPs). An applicationspecific integrated circuit (ASIC) implementation of the electronics is required to produce a detector sufficiently compact for practical use in a flight …
Readout And Performance Of Thick Czt Strip Detectors With Orthogonal Coplanar Anodes, John R. Macri, B Donmez, L A. Hamel, Manuel Julien, M Mcclish, Mark L. Mcconnell, R S. Miller, James M. Ryan, Mark Widholm
Readout And Performance Of Thick Czt Strip Detectors With Orthogonal Coplanar Anodes, John R. Macri, B Donmez, L A. Hamel, Manuel Julien, M Mcclish, Mark L. Mcconnell, R S. Miller, James M. Ryan, Mark Widholm
Space Science Center
We report progress in the study of CZT strip detectors featuring orthogonal coplanar anode contacts. The work includes laboratory and simulation studies aimed at optimizing and developing compact, efficient, high performance detector modules for 0.05 to 1 MeV gamma radiation measurements. The novel coplanar anode strip configuration retains many of the performance advantages of pixel detectors yet requires far fewer electronic channels to perform both 3-d imaging and spectroscopy. We report on studies aimed at determining an optimum configuration of the analog signal processing electronics to employ with these detectors. We report measurements of energy and spatial resolution in three …
Comptel Observations Of The Blazars 3c 454.3 And Cta 102, S Zhang, W Collmar, V Schonfelder, H Bloemen, W Hermsen, Mark L. Mcconnell, K Bennett, O R. Williams
Comptel Observations Of The Blazars 3c 454.3 And Cta 102, S Zhang, W Collmar, V Schonfelder, H Bloemen, W Hermsen, Mark L. Mcconnell, K Bennett, O R. Williams
Space Science Center
We have analyzed the two blazars of 3C 454.3 and CTA 102 using all available COMPTEL data from 1991 to 1999. In the 10–30 MeV band, emission from the general direction of the sources is found at the 4σ-level, being consistent with contributions from both sources. Below 10 MeV only 3C 454.3 is significantly detected, with the strongest evidence (5.6 σ) in the 3–10 MeV band. Significant flux variability is not observed for both sources, while a low emission is seen most of the years in the 3–10 MeV light curve for 3C 454.3. Its time-averaged MeV spectrum suggests a …
Comptel Gamma-Ray Observations Of The C4 Solar Flare On 20 January 2000, C A. Young, M B. Arndt, K Bennett, A Connors, H Debrunner, R Diehl, Mark L. Mcconnell, R S. Miller, G Rank, James M. Ryan, V Schonfelder, C Winkler
Comptel Gamma-Ray Observations Of The C4 Solar Flare On 20 January 2000, C A. Young, M B. Arndt, K Bennett, A Connors, H Debrunner, R Diehl, Mark L. Mcconnell, R S. Miller, G Rank, James M. Ryan, V Schonfelder, C Winkler
Space Science Center
The “Pre-SMM” (Vestrand and Miller 1998) picture of gamma-ray line (GRL) flares was that they are relatively rare events. This picture was quickly put in question with the launch of the Solar Maximum Mission (SMM). Over 100 GRL flares were seen with sizes ranging from very large GOES class events (X12) down to moderately small events (M2). It was argued by some (Bai 1986) that this was still consistent with the idea that GRL events are rare. Others, however, argued the opposite (Vestrand 1988; Cliver, Crosby and Dennis 1994), stating that the lower end of this distribution was just a …
The Milagro Gamma-Ray Observatory, J E. Mcenery, R Atkins, W Benbow, D Berley, M L. Chen, D G. Coyne, B L. Dingus, D E. Dorfan, R W. Ellsworth, D Evans, A Falcone, L Fleysher, R Fleysher, G Gisler, J A. Goodman, T J. Haines, C M. Hoffman, S Hugenberger, L A. Kelley, I Leonor, Mark L. Mcconnell, J F. Mccullough, R S. Miller, A I. Mincer, M F. Morales, P Nemethy, James M. Ryan, B Shen, A Shoup, C Sinnis, A J. Smith, G W. Sullivan, O T. Tumer, K Wang, M O. Wascko, S Westerhoff, D A. Williams, G B. Yodh
The Milagro Gamma-Ray Observatory, J E. Mcenery, R Atkins, W Benbow, D Berley, M L. Chen, D G. Coyne, B L. Dingus, D E. Dorfan, R W. Ellsworth, D Evans, A Falcone, L Fleysher, R Fleysher, G Gisler, J A. Goodman, T J. Haines, C M. Hoffman, S Hugenberger, L A. Kelley, I Leonor, Mark L. Mcconnell, J F. Mccullough, R S. Miller, A I. Mincer, M F. Morales, P Nemethy, James M. Ryan, B Shen, A Shoup, C Sinnis, A J. Smith, G W. Sullivan, O T. Tumer, K Wang, M O. Wascko, S Westerhoff, D A. Williams, G B. Yodh
Space Science Center
The Milagro water Cherenkov detector began full operation in January 2000. This detector is capable of monitoring the Northern sky at energies above 500 GeV for sources of equivalent strength to the Crab Nebula over one year of integration. We report on the current performance and sensitivity of Milagro.
Bayesian Multiscale Deconvolution Applied To Gamma-Ray Spectroscopy, C A. Young, A Connors, E Kolaczyk, Mark L. Mcconnell, G Rank, James M. Ryan, V Schonfelder
Bayesian Multiscale Deconvolution Applied To Gamma-Ray Spectroscopy, C A. Young, A Connors, E Kolaczyk, Mark L. Mcconnell, G Rank, James M. Ryan, V Schonfelder
Space Science Center
A common task in gamma-ray astronomy is to extract spectral information, such as model constraints and incident photon spectrum estimates, given the measured energy deposited in a detector and the detector response. This is the classic problem of spectral “deconvolution” or spectral inversion. The methods of forward folding (i.e., parameter fitting) and maximum entropy “deconvolution” (i.e., estimating independent input photon rates for each individual energy bin) have been used successfully for gamma-ray solar flares (e.g., Rank, 1997; Share and Murphy, 1995). These methods have worked well under certain conditions but there are situations were they don’t apply. These are: 1) …