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Articles 31 - 60 of 209
Full-Text Articles in Astrophysics and Astronomy
Revision Of Empirical Electric Field Modeling In The Inner Magnetosphere Using Cluster Data, Hiroshi Matsui, Harlan E. Spence, Y. V. Khotyaintsev, P. A. Lindqvist
Revision Of Empirical Electric Field Modeling In The Inner Magnetosphere Using Cluster Data, Hiroshi Matsui, Harlan E. Spence, Y. V. Khotyaintsev, P. A. Lindqvist
Physics & Astronomy
Using Cluster data from the Electron Drift (EDI) and the Electric Field and Wave (EFW) instruments, we revise our empirically-based, inner-magnetospheric electric field (UNH-IMEF) model at 22.662 mV/m; K-p<1, 1K(p)<2, 2K(p)<3, 3K(p)<4, 4K(p)<5, and K(p)4(+). Patterns consist of one set of data and processing for smaller activities, and another for higher activities. As activity increases, the skewed potential contour related to the partial ring current appears on the nightside. With the revised analysis, we find that the skewed potential contours get clearer and potential contours get denser on the nightside and morningside. Since the fluctuating components are not negligible, standard deviations from the modeled values are included in the model. In this study, we perform validation of the derived model more extensively. We find experimentally that the skewed contours are located close to the last closed equipotential, consistent with previous theories. This gives physical context to our model and serves as one validation effort. As another validation effort, the derived results are compared with other models/measurements. From these comparisons, we conclude that our model has some clear advantages over the others.
An Imaging Neutron/Gamma-Ray Spectrometer, Amanda C. Madden, Peter F. Bloser, Dominique Fourguette, Liane Larocque, Matt Lewis, Jason S. Legere, Mark L. Mcconnell, Marissa Rouseau, James M. Ryan
An Imaging Neutron/Gamma-Ray Spectrometer, Amanda C. Madden, Peter F. Bloser, Dominique Fourguette, Liane Larocque, Matt Lewis, Jason S. Legere, Mark L. Mcconnell, Marissa Rouseau, James M. Ryan
Space Science Center
We present the test results of a neutron/gamma-ray imaging spectrometer for the identification and location of radioactive and special nuclear materials. Radioactive materials that could be fashioned into a radiation dispersal device typically emit gamma rays, while fissile materials such as uranium and plutonium emit both neutrons and gamma rays via spontaneous or induced fission. The simultaneous detection of neutrons and gamma rays is a clear indication of the presence of fissile material. The instrument works as a double-scatter telescope, requiring a neutron or gamma ray to undergo an interaction in two detectors to be considered a valid event. While …
A Statistical Analysis Of Electromagnetic Ion Cyclotron (Emic) Waves And Their Correlation To The 11-Year Solar Cycle, Erik A. Lindgren
A Statistical Analysis Of Electromagnetic Ion Cyclotron (Emic) Waves And Their Correlation To The 11-Year Solar Cycle, Erik A. Lindgren
Honors Theses and Capstones
This thesis presents a statistical analysis of EMIC waves measured at Halley Research Station from 2008 through 2012. An introduction covering the origin of and theory behind EMIC waves is provided, along with a background covering previous statistical research regarding EMIC waves. Guidelines regarding EMIC wave definition and analysis are described along with examples of how they were used. The data shows an increase in the total number of EMIC waves as well as the number and percentage of EMIC waves with maximum frequency above 1 Hz during the 5-year period. The results suggest that the total number of EMIC …
An Imaging Neutron/Gamma-Ray Spectrometer, James M. Ryan, Chris Bancroft, Peter F. Bloser, Dominique Fourguette, Liane Larocque, Jason S. Legere, Amanda C. Madden, Mark L. Mcconnell, Jane Pavlich, Greg Ritter, Greg Wassick, Marissa Rouseau
An Imaging Neutron/Gamma-Ray Spectrometer, James M. Ryan, Chris Bancroft, Peter F. Bloser, Dominique Fourguette, Liane Larocque, Jason S. Legere, Amanda C. Madden, Mark L. Mcconnell, Jane Pavlich, Greg Ritter, Greg Wassick, Marissa Rouseau
Space Science Center
We present the design and development of a dual-species, neutron/γ-ray imaging spectrometer for the identification and location of radioactive and special nuclear materials (SNM). Real-time detection and identification is important for locating fissile materials. These materials, specifically uranium and plutonium, emit neutrons and γ rays via spontaneous or induced fission. Co-located neutron and γ-ray emissions are a sure sign of fissile material, requiring very few spatially correlated events for a significant detection. Our instrument design detects neutrons and γ rays from all sources in its field of view, constructs images of the emission pattern, and reports the spectra for both …
Development Of A Telescope For Medium-Energy Gamma-Ray Astronomy, Stanley D. Hunter, Peter F. Bloser, Michael P. Dion, Georgia A. Denolfo, Jason S. Legere, Mark L. Mcconnell, Suzanne F. Nowicki, James M. Ryan, Seunghee Son, Floyd Stecker
Development Of A Telescope For Medium-Energy Gamma-Ray Astronomy, Stanley D. Hunter, Peter F. Bloser, Michael P. Dion, Georgia A. Denolfo, Jason S. Legere, Mark L. Mcconnell, Suzanne F. Nowicki, James M. Ryan, Seunghee Son, Floyd Stecker
Space Science Center
The Advanced Energetic Pair Telescope (AdEPT) is being developed at GSFC as a future NASA MIDEX mission to explore the medium-energy (5–200 MeV) gamma-ray range. The enabling technology for AdEPT is the Three- Dimensional Track Imager (3-DTI), a gaseous time projection chamber. The high spatial resolution 3-D electron tracking of 3-DTI enables AdEPT to achieve high angular resolution gamma-ray imaging via pair production and triplet production (pair production on electrons) in the medium-energy range. The low density and high spatial resolution of 3-DTI allows the electron positron track directions to be measured before they are dominated by Coulomb scattering. Further, …
Joint Astrophysics Nascent Universe Satellite:. Utilizing Grbs As High Redshift Probes, P. W. A. Roming, S. G. Bilen, D. N. Burrows, A Falcone, D. B. Fox, T. L. Herter, J. A. Kennea, Mark L. Mcconnell, J. A. Nousek
Joint Astrophysics Nascent Universe Satellite:. Utilizing Grbs As High Redshift Probes, P. W. A. Roming, S. G. Bilen, D. N. Burrows, A Falcone, D. B. Fox, T. L. Herter, J. A. Kennea, Mark L. Mcconnell, J. A. Nousek
Physics & Astronomy
The Joint Astrophysics Nascent Universe Satellite (JANUS) is a multiwavelength cosmology mission designed to address fundamental questions about the cosmic dawn. It has three primary science objectives: (1) measure the massive star formation rate over 5 ≤ z ≤ 12 by discovering and observing high-z gamma-ray bursts (GRBs) and their afterglows, (2) enable detailed studies of the history of reionization and metal enrichment in the early Universe, and (3) map the growth of the first supermassive black holes by discovering and observing the brightest quasars at z ≥ 6. A rapidly slewing spacecraft and three science instruments – the X-ray …
Grounded, In High Orbit: Undergraduate Space Research At The University Of New Hampshire, George Clark, Morgan O’Neill
Grounded, In High Orbit: Undergraduate Space Research At The University Of New Hampshire, George Clark, Morgan O’Neill
Inquiry Journal 2011
No abstract provided.
Recalibrating The Star Sensor: From The Ibex Satellite To The Renu Rocket, Joshua French
Recalibrating The Star Sensor: From The Ibex Satellite To The Renu Rocket, Joshua French
Inquiry Journal 2011
No abstract provided.
A Portable Neutron Spectroscope (Nspect) For Detection, Imaging And Identification Of Nuclear Material, James M. Ryan, Chris Bancroft, Peter F. Bloser, U Bravar, Dominique Fourguette, Colin Frost, Liane Larocque, Mark L. Mcconnell, Jason S. Legere, Jane Pavlich, Greg Ritter, Greg Wassick, Joshua Wood, R S. Woolf
A Portable Neutron Spectroscope (Nspect) For Detection, Imaging And Identification Of Nuclear Material, James M. Ryan, Chris Bancroft, Peter F. Bloser, U Bravar, Dominique Fourguette, Colin Frost, Liane Larocque, Mark L. Mcconnell, Jason S. Legere, Jane Pavlich, Greg Ritter, Greg Wassick, Joshua Wood, R S. Woolf
Space Science Center
We have developed, fabricated and tested a prototype imaging neutron spectrometer designed for real-time neutron source location and identification. Real-time detection and identification is important for locating materials. These materials, specifically uranium and transuranics, emit neutrons via spontaneous or induced fission. Unlike other forms of radiation (e.g. gamma rays), penetrating neutron emission is very uncommon. The instrument detects these neutrons, constructs images of the emission pattern, and reports the neutron spectrum. The device will be useful for security and proliferation deterrence, as well as for nuclear waste characterization and monitoring. The instrument is optimized for imaging and spectroscopy in the …
Simulations Of A Monolithic Lanthanum Bromide Gamma-Ray Detector, Camden Ertley, Chris Bancroft, Peter F. Bloser, Taylor Connor, Jason S. Legere, Mark L. Mcconnell, James M. Ryan
Simulations Of A Monolithic Lanthanum Bromide Gamma-Ray Detector, Camden Ertley, Chris Bancroft, Peter F. Bloser, Taylor Connor, Jason S. Legere, Mark L. Mcconnell, James M. Ryan
Space Science Center
We have been working on the development of a detector design for a large area coded aperture imaging system operating in the 10-600 keV energy range. The detector design is based on an array of Lanthanum Bromide (LaBr3) scintillators, each directly coupled to a Hamamatsu 64-channel multi-anode photomultiplier tube (MAPMT). This paper focuses on the development of the GEANT4-based simulations as an aid in the optimization of the detector design. The simulations have been validated by comparisons with various laboratory data sets. We will summarize the current status and latest findings from this study.
Plans For The First Balloon Flight Of The Gamma-Ray Polarimeter Experiment (Grape), Taylor Connor, Chris Bancroft, Peter F. Bloser, Jason S. Legere, Mark L. Mcconnell, James M. Ryan
Plans For The First Balloon Flight Of The Gamma-Ray Polarimeter Experiment (Grape), Taylor Connor, Chris Bancroft, Peter F. Bloser, Jason S. Legere, Mark L. Mcconnell, James M. Ryan
Space Science Center
We have developed a design for a hard X-ray polarimeter operating in the energy range from 50 to 500 keV. This modular design, known as GRAPE (Gamma-Ray Polarimeter Experiment), has been successfully demonstrated in the lab using partially polarized gamma-ray sources and using fully polarized photon beams at Argonne National Laboratory. In June of 2007, a GRAPE engineering model, consisting of a single detector module, was flown on a high altitude balloon flight to further demonstrate the design and to collect background data. We are currently preparing a much larger balloon payload for a flight in the fall of 2011. …
Development Of The Advance Energetic Pair Telescope (Adept) For Medium-Energy Gamma-Ray Astronomy, Stanley D. Hunter, Peter F. Bloser, Michael P. Dion, Mark L. Mcconnell, Georgia A. Denolfo, Seunghee Son, James M. Ryan, Floyd Stecker
Development Of The Advance Energetic Pair Telescope (Adept) For Medium-Energy Gamma-Ray Astronomy, Stanley D. Hunter, Peter F. Bloser, Michael P. Dion, Mark L. Mcconnell, Georgia A. Denolfo, Seunghee Son, James M. Ryan, Floyd Stecker
Space Science Center
Progress in high-energy gamma-ray science has been dramatic since the launch of INTEGRAL, AGILE and FERMI. These instruments, however, are not optimized for observations in the medium-energy (~0.3< Eγ < ~200 MeV) regime where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. We outline some of the major science goals of a medium-energy mission. These science goals are best achieved with a combination of two telescopes, a Compton telescope and a pair telescope, optimized to provide significant improvements in angular resolution and sensitivity. In this paper we describe the design of the Advanced Energetic Pair Telescope (AdEPT) based on the Three-Dimensional Track Imager (3-DTI) detector. This technology achieves excellent, mediumenergy sensitivity, angular resolution near the kinematic limit, and gamma-ray polarization sensitivity, by high resolution 3-D electron tracking. We describe the performance of a 30×30×30 cm3 prototype of the AdEPT instrument.
A Fast Scintillator Compton Telescope For Medium-Energy Gamma-Ray Astronomy, Peter F. Bloser, James M. Ryan, Jason S. Legere, Manuel Julien, Chris Bancroft, Mark L. Mcconnell, Mark Wallace, R M. Kippen, Shawn Tornga
A Fast Scintillator Compton Telescope For Medium-Energy Gamma-Ray Astronomy, Peter F. Bloser, James M. Ryan, Jason S. Legere, Manuel Julien, Chris Bancroft, Mark L. Mcconnell, Mark Wallace, R M. Kippen, Shawn Tornga
Space Science Center
The field of medium-energy gamma-ray astronomy urgently needs a new mission to build on the success of the COMPTEL instrument on the Compton Gamma Ray Observatory. This mission must achieve sensitivity significantly greater than that of COMPTEL in order to advance the science of relativistic particle accelerators, nuclear astrophysics, and diffuse backgrounds, and bridge the gap between current and future hard X-ray missions and the high-energy Fermi mission. Such an increase in sensitivity can only come about via a dramatic decrease in the instrumental background. We are currently developing a concept for a low-background Compton telescope that employs modern scintillator …
Advanced Characterization And Simulation Of Sonne: A Fast Neutron Spectrometer For Solar Probe Plus, R S. Woolf, James M. Ryan, Peter F. Bloser, U Bravar, E O. Fluckiger, Jason S. Legere, A L. Mackinnon, Procheta Mallik, Mark L. Mcconnell, B Pirard
Advanced Characterization And Simulation Of Sonne: A Fast Neutron Spectrometer For Solar Probe Plus, R S. Woolf, James M. Ryan, Peter F. Bloser, U Bravar, E O. Fluckiger, Jason S. Legere, A L. Mackinnon, Procheta Mallik, Mark L. Mcconnell, B Pirard
Space Science Center
SONNE, the SOlar NeutroN Experiment proposed for Solar Probe Plus, is designed to measure solar neutrons from 1-20 MeV and solar gammas from 0.5-10 MeV. SONNE is a double scatter instrument that employs imaging to maximize its signal-to-noise ratio by rejecting neutral particles from non-solar directions. Under the assumption of quiescent or episodic small-flare activity, one can constrain the energy content and power dissipation by fast ions in the low corona. Although the spectrum of protons and ions produced by nanoflaring activity is unknown, we estimate the signal in neutrons and γ−rays that would be present within thirty solar radii, …
Grape: A Balloon-Borne Gamma-Ray Polarimeter, Mark L. Mcconnell, Chris Bancroft, Peter F. Bloser, Taylor Connor, Jason S. Legere, James M. Ryan
Grape: A Balloon-Borne Gamma-Ray Polarimeter, Mark L. Mcconnell, Chris Bancroft, Peter F. Bloser, Taylor Connor, Jason S. Legere, James M. Ryan
Space Science Center
The Gamma-RAy Polarimeter Experiment (GRAPE) is a concept for an astronomical hard X-ray Compton polarimeter operating in the 50 - 500 keV energy band. The instrument has been optimized for wide-field polarization measurements of transient outbursts from energetic astrophysical objects such as gamma-ray bursts and solar flares. The GRAPE instrument is composed of identical modules, each of which consists of an array of scintillator elements read out by a multi-anode photomultiplier tube (MAPMT). Incident photons Compton scatter in plastic scintillator elements and are subsequently absorbed in inorganic scintillator elements; a net polarization signal is revealed by a characteristic asymmetry in …
A New Low-Background Compton Telescope Using Labr3 Scintillator, Peter F. Bloser, James M. Ryan, Jason S. Legere, Manuel Julien, Chris Bancroft, Mark L. Mcconnell, Mark Wallace, R M. Kippen, Shawn Tornga
A New Low-Background Compton Telescope Using Labr3 Scintillator, Peter F. Bloser, James M. Ryan, Jason S. Legere, Manuel Julien, Chris Bancroft, Mark L. Mcconnell, Mark Wallace, R M. Kippen, Shawn Tornga
Space Science Center
Gamma-ray astronomy in the MeV range suffers from weak fluxes from sources and high background in the nuclear energy range. The background comes primarily from neutron-induced gamma rays, with the neutrons being produced by cosmic-ray interactions in the Earth's atmosphere, the spacecraft, and the instrument. Compton telescope designs often suppress this background by requiring coincidences in multiple detectors and a narrow time-of-flight (ToF) acceptance window. The COMPTEL experience on the Compton Gamma Ray Observatory shows that a 1.9-ns ToF resolution is insufficiently narrow to achieve the required low background count rate. Furthermore, neutron interactions in the detectors themselves generate an …
A Compton Telescope For Remote Location And Identification Of Radioactive Material, Peter F. Bloser, Jason S. Legere, Shirley M. Dame, Mark L. Mcconnell, U Bravar, James M. Ryan
A Compton Telescope For Remote Location And Identification Of Radioactive Material, Peter F. Bloser, Jason S. Legere, Shirley M. Dame, Mark L. Mcconnell, U Bravar, James M. Ryan
Space Science Center
The spare detectors from NASA's Compton Gamma-Ray Observatory COMPTEL instrument have been reconfigured to demonstrate the capability at ground level to remotely locate and identify sources of gamma radiation. The gamma-ray experimental telescope assembly (GRETA) employs two 28 cm diameter scintillation detectors separated by 95 cm: one 8.5 cm thick liquid scintillator detector and one 7.5 cm thick NaI(Tl) detector. The assembly electronics and real-time data acquisition system measures the energy deposits and time-of-flight for each coincident detection and compiles histograms of total energy and incident angle as computed using the kinematics of Compton scattering. GRETA's field of view is …
Grb Polarimetry With Poet, Mark L. Mcconnell, L Angelini, Matthew Baring, Scott Barthelmy, J Kevin Black, Peter F. Bloser, B Dennis, A G. Emslie, J Greiner, W Hajdas, A K. Harding, H Hartmann, J E. Hill, Kunihito Ioka, Philip Kaaret, G Kanbach, D Kniffen, Jason S. Legere, John R. Macri, R Morris, Takashi Nakamura, N Produit, James M. Ryan, Takanori Sakamoto, Kenji Toma, X Wu, Ryo Yamazaki, Bing Zhang
Grb Polarimetry With Poet, Mark L. Mcconnell, L Angelini, Matthew Baring, Scott Barthelmy, J Kevin Black, Peter F. Bloser, B Dennis, A G. Emslie, J Greiner, W Hajdas, A K. Harding, H Hartmann, J E. Hill, Kunihito Ioka, Philip Kaaret, G Kanbach, D Kniffen, Jason S. Legere, John R. Macri, R Morris, Takashi Nakamura, N Produit, James M. Ryan, Takanori Sakamoto, Kenji Toma, X Wu, Ryo Yamazaki, Bing Zhang
Space Science Center
POET (Polarimeters for Energetic Transients) represents a concept for a Small Explorer (SMEX) satellite mission, whose principal scientific goal is to understand the structure of GRB sources through sensitive X‐ray and γ‐ray polarization measurements. The payload consists of two wide field‐of‐view (FoV) instruments: a Low Energy Polarimeter (LEP) capable of polarization measurements in the energy range from 2–15 keV and a high energy polarimeter (Gamma‐Ray Polarimeter Experiment or GRAPE) that would measure polarization in the 60–500 keV energy range. The POET spacecraft provides a zenith‐pointed platform for maximizing the exposure to deep space. Spacecraft rotation provides a means of effectively …
Statistical Properties Of Gamma‐Ray Burst Polarization, Kenji Toma, Takanori Sakamoto, Bing Zhang, J E. Hill, Mark L. Mcconnell, Peter F. Bloser, Ryo Yamazaki, Kunihito Ioka, Takashi Nakamura
Statistical Properties Of Gamma‐Ray Burst Polarization, Kenji Toma, Takanori Sakamoto, Bing Zhang, J E. Hill, Mark L. Mcconnell, Peter F. Bloser, Ryo Yamazaki, Kunihito Ioka, Takashi Nakamura
Space Science Center
The emission mechanism and the origin and structure of magnetic fields in gamma‐ray burst (GRB) jets are among the most important open questions concerning the nature of the central engine of GRBs. In spite of extensive observational efforts, these questions remain to be answered and are difficult or even impossible to infer with the spectral and lightcurve information currently collected. Polarization measurements will lead to unambiguous answers to several of these questions. Recent developments in X‐ray and γ‐ray polarimetry techniques have demonstrated a significant increase in sensitivity enabling several new mission concepts, e.g. POET (Polarimeters for Energetic Transients), providing wide …
A Compton Telescope For Remote Location And Identification Of Radioactive Material, James M. Ryan, Justin Baker, John R. Macri, Mark L. Mcconnell, Richard Carande
A Compton Telescope For Remote Location And Identification Of Radioactive Material, James M. Ryan, Justin Baker, John R. Macri, Mark L. Mcconnell, Richard Carande
Space Science Center
The spare detectors from NASA Compton Gamma-Ray Observatory COMPTEL instrument have been reconfigured to demonstrate the capability at ground level to remotely locate and identify sources of g radiation or the movement of material that might shield γ-ray sources. The Gamma-Ray Experimental Telescope Assembly (GRETA) employs two 28 cm diameter scintillation detectors separated by 81 cm: one 8.5 cm thick liquid scintillator detector and one 7.5 cm thick NaI(Tl) detector. The assembly electronics and real-time data acquisition system measures the energy deposits and time-of- flight for each coincident detection and compiles histograms of total energy and incident angle as computed …
Development And Performance Of The Fast Neutron Imaging Telescope For Snm Detection, James M. Ryan, U Bravar, E O. Fluckiger, John R. Macri, Mark L. Mcconnell, B Pirard, R S. Woolf
Development And Performance Of The Fast Neutron Imaging Telescope For Snm Detection, James M. Ryan, U Bravar, E O. Fluckiger, John R. Macri, Mark L. Mcconnell, B Pirard, R S. Woolf
Space Science Center
FNIT (the Fast Neutron Imaging Telescope), a detector with both imaging and energy measurement capabilities, sensitive to neutrons in the range 0.8-20 MeV, was initially conceived to study solar neutrons as a candidate design for the Inner Heliosphere Sentinel (IHS) spacecraft of NASA's Solar Sentinels program and successively reconfigured to locate fission neutron sources. By accurately identifying the position of the source with imaging techniques and reconstructing the Watt spectrum of fission neutrons, FNIT can detect samples of special nuclear material (SNM), including heavily shielded and masked ones. The detection principle is based on multiple elastic neutron-proton scatterings in organic …
Poet: Polarimeters For Energetic Transients, J E. Hill, Mark L. Mcconnell, Peter F. Bloser, Jason S. Legere, John R. Macri, James M. Ryan, Scott Barthelmy, L Angelini, Takanori Sakamoto, J Kevin Black, H Hartmann, Philip Kaaret, Bing Zhang, Kunihito Ioka, Takashi Nakamura, Kenji Toma, Ryo Yamazaki, X Wu
Poet: Polarimeters For Energetic Transients, J E. Hill, Mark L. Mcconnell, Peter F. Bloser, Jason S. Legere, John R. Macri, James M. Ryan, Scott Barthelmy, L Angelini, Takanori Sakamoto, J Kevin Black, H Hartmann, Philip Kaaret, Bing Zhang, Kunihito Ioka, Takashi Nakamura, Kenji Toma, Ryo Yamazaki, X Wu
Space Science Center
POET (Polarimeters for Energetic Transients) is a Small Explorer mission concept proposed to NASA in January 2008. The principal scientific goal of POET is to measure GRB polarization between 2 and 500 keV. The payload consists of two wide FoV instruments: a Low Energy Polarimeter (LEP) capable of polarization measurements in the energy range from 2–15 keV and a high energy polarimeter (Gamma‐Ray Polarimeter Experiment—GRAPE) that will measure polarization in the 60–500 keV energy range. Spectra will be measured from 2 keV up to 1 MeV. The POET spacecraft provides a zenith‐pointed platform for maximizing the exposure to deep space. …
Design Optimization And Performance Capabilities Of The Fast Neutron Imaging Telescope (Fnit), U Bravar, P J. Bruillard, E O. Fluckiger, Jason S. Legere, John R. Macri, A L. Mackinnon, Procheta Mallik, Mark L. Mcconnell, M R. Moser, B Pirard, James M. Ryan, R S. Woolf
Design Optimization And Performance Capabilities Of The Fast Neutron Imaging Telescope (Fnit), U Bravar, P J. Bruillard, E O. Fluckiger, Jason S. Legere, John R. Macri, A L. Mackinnon, Procheta Mallik, Mark L. Mcconnell, M R. Moser, B Pirard, James M. Ryan, R S. Woolf
Space Science Center
We describe the design optimization process and performance characterization of a next generation neutron telescope, with imaging and energy measurement capabilities, sensitive to neutrons in the 1-20 MeV energy range. The response of the Fast Neutron Imaging Telescope (FNIT), its efficiency in neutron detection, energy resolution and imaging capabilities were characterized through a combination of lab tests and Monte Carlo simulations. Monte Carlo simulations, together with experimental data, are also being used in the development and testing of the image reconstruction algorithm. FNIT was initially conceived to study solar neutrons as a candidate instrument for the Inner Heliosphere Sentinel (IHS) …
Using Lax Scintillator In A New Low-Background Compton Telescope, James M. Ryan, Peter F. Bloser, John R. Macri, Mark L. Mcconnell
Using Lax Scintillator In A New Low-Background Compton Telescope, James M. Ryan, Peter F. Bloser, John R. Macri, Mark L. Mcconnell
Space Science Center
The ability of Compton telescopes to perform imaging and spectroscopy in space depends directly on the speed and energy resolution of the calorimeter detectors in the telescope. The calorimeter detectors flown on space-borne or balloon-borne Compton telescopes have included NaI(Tl), CsI(Na), HPGe and liquid organic scintillator. By employing LaX scintillators for the calorimeter, one can take advantage of the unique speed and resolving power of the material to improve the instrument sensitivity and simultaneously enhance its spectroscopic performance and thus its imaging performance. We present a concept for a space-borne Compton telescope that employs LaX as a calorimeter and estimate …
A Burst Chasing X-Ray Polarimeter, Joanne E. Hill, Scott Barthelmy, J Kevin Black, Philip Deines-Jones, Keith Jahoda, Takanori Sakamoto, Philip Kaaret, Mark L. Mcconnell, Peter F. Bloser, John R. Macri, Jason S. Legere, James M. Ryan, Billy R. Smith Jr, Bing Zhang
A Burst Chasing X-Ray Polarimeter, Joanne E. Hill, Scott Barthelmy, J Kevin Black, Philip Deines-Jones, Keith Jahoda, Takanori Sakamoto, Philip Kaaret, Mark L. Mcconnell, Peter F. Bloser, John R. Macri, Jason S. Legere, James M. Ryan, Billy R. Smith Jr, Bing Zhang
Space Science Center
Gamma-ray bursts are one of the most powerful explosions in the universe and have been detected out to distances of almost 13 billion light years. The exact origin of these energetic explosions is still unknown but the resulting huge release of energy is thought to create a highly relativistic jet of material and a power-law distribution of electrons. There are several theories describing the origin of the prompt GRB emission that currently cannot be distinguished. Measurements of the linear polarization would provide unique and important constraints on the mechanisms thought to drive these powerful explosions. We present the design of …
Characterization Of Single-Sided Charge-Sharing Czt Strip Detectors For Gamma-Ray Astronomy, B Donmez, John R. Macri, James M. Ryan, Jason S. Legere, Mark L. Mcconnell, Mark Widholm, T Narita, L A. Hamel
Characterization Of Single-Sided Charge-Sharing Czt Strip Detectors For Gamma-Ray Astronomy, B Donmez, John R. Macri, James M. Ryan, Jason S. Legere, Mark L. Mcconnell, Mark Widholm, T Narita, L A. Hamel
Space Science Center
We report progress in the study of thick single-sided charge-sharing cadmium zinc telluride (CZT) strip detector modules designed to perform spectroscopy and 3-D imaging of gamma-rays. We report laboratory measurements including spectroscopy, efficiency and 3-D imaging capability of prototype detectors (15 × 15 × 7.5mm3) with 11×11 unit cells. We also report on Monte Carlo simulations (GEANT4 v7.1) to investigate the effect of multihits on detector performance in both spectroscopy and imaging. We compare simulation results with data obtained from laboratory measurements and discuss the implications for future strip detector designs.
The Advanced Compton Telescope, S E. Boggs, J Kurfess, James M. Ryan, Elena Aprile, Neil Gehrels, R M. Kippen, Marc Leising, U Oberlack, Cornelia B. Wunderer, Allen Zych, Peter F. Bloser, M Harris, A Hoover, Alexei Klimenk, Dan Kocevski, Mark L. Mcconnell, Peter Milne, E I. Novikova, B F. Phlips, Mark Polsen, Steven Sturner, Derek Tournear, G Weidenspointer, Eric Wulf, A Zoglauer, Matthew Baring, John Beacom, Lars Bildsten, Charles Dermer, Dieter H. Hartman, Margarita Hernanz, David Smith, Sumner Starrfield
The Advanced Compton Telescope, S E. Boggs, J Kurfess, James M. Ryan, Elena Aprile, Neil Gehrels, R M. Kippen, Marc Leising, U Oberlack, Cornelia B. Wunderer, Allen Zych, Peter F. Bloser, M Harris, A Hoover, Alexei Klimenk, Dan Kocevski, Mark L. Mcconnell, Peter Milne, E I. Novikova, B F. Phlips, Mark Polsen, Steven Sturner, Derek Tournear, G Weidenspointer, Eric Wulf, A Zoglauer, Matthew Baring, John Beacom, Lars Bildsten, Charles Dermer, Dieter H. Hartman, Margarita Hernanz, David Smith, Sumner Starrfield
Space Science Center
The Advanced Compton Telescope (ACT), the next major step in gamma-ray astronomy, will probe the fires where chemical elements are formed by enabling high-resolution spectroscopy of nuclear emission from supernova explosions. During the past two years, our collaboration has been undertaking a NASA mission concept study for ACT. This study was designed to (1) transform the key scientific objectives into specific instrument requirements, (2) to identify the most promising technologies to meet those requirements, and (3) to design a viable mission concept for this instrument. We present the results of this study, including scientific goals and expected performance, mission design, …
Fnit: The Fast Neutron Imaging Telescope For Snm Detection, U Bravar, P J. Bruillard, E O. Fluckiger, John R. Macri, Mark L. Mcconnell, M R. Moser, James M. Ryan
Fnit: The Fast Neutron Imaging Telescope For Snm Detection, U Bravar, P J. Bruillard, E O. Fluckiger, John R. Macri, Mark L. Mcconnell, M R. Moser, James M. Ryan
Space Science Center
We report on recent progress in the development of the Fast Neutron Imaging Telescope (FNIT), a detector with both imaging and energy measurement capabilities, sensitive to neutrons in the 2-20 MeV range. FNIT was initially conceived to study solar neutrons as a candidate design for the Solar Sentinels program under formulation at NASA. This instrument is now being configured to locate fission neutron sources for homeland security purposes. By accurately identifying the position of the neutron source with imaging techniques and reconstructing the energy spectrum of fission neutrons, FNIT can locate problematic amounts of Special Nuclear Material (SNM), including heavily …
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.
Prospects For Grb Polarimetry With Grape, Mark L. Mcconnell, Peter F. Bloser, Jason S. Legere, John R. Macri, T Narita, James M. Ryan
Prospects For Grb Polarimetry With Grape, Mark L. Mcconnell, Peter F. Bloser, Jason S. Legere, John R. Macri, T Narita, James M. Ryan
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 scatters …