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Articles 121 - 150 of 209
Full-Text Articles in Astrophysics and Astronomy
Recent Laboratory Tests Of A Hard X-Ray Solar Flare Polarimeter, Mark L. Mcconnell, John R. Macri, M Mcclish, Jack Ryalls
Recent Laboratory Tests Of A Hard X-Ray Solar Flare Polarimeter, Mark L. Mcconnell, John R. Macri, M Mcclish, Jack Ryalls
Space Science Center
We report on the development of a Compton scatter polarimeter for measuring the linear polarization of hard X-rays (50 - 300 keV) from solar flares. Such measurements would be useful for studying the directivity (or beaming) of the electrons that are accelerated in solar flares. We initially used a simple prototype polarimeter to successfully demonstrate the reliability of our Monte Carlo simulation code and to demonstrate our ability to generate a polarized photon source in the lab. We have recently fabricated a science model based on a modular design concept that places a self-contained polarimeter module on the front-end of …
Fiberglast: A Scintillating Fiber Approach To The Glast Mission, Geoffrey N. Pendleton, W Robert Binns, Martin W. Israel, P L. Hink, M L. Cherry, W Paciesas, R M. Kippen, Robert S. Mallozzi, Thomas A. Parnell, Gerald J. Fishman, O T. Tumer, Mark J. Christl, Robert B. Wilson, J Buckley, Georgia A. Richardson, Surasak Phengchamnan, Keith R. Rielage, Gerald Karr, Donald B. Wallace, James M. Ryan, Mark L. Mcconnell, John R. Macri
Fiberglast: A Scintillating Fiber Approach To The Glast Mission, Geoffrey N. Pendleton, W Robert Binns, Martin W. Israel, P L. Hink, M L. Cherry, W Paciesas, R M. Kippen, Robert S. Mallozzi, Thomas A. Parnell, Gerald J. Fishman, O T. Tumer, Mark J. Christl, Robert B. Wilson, J Buckley, Georgia A. Richardson, Surasak Phengchamnan, Keith R. Rielage, Gerald Karr, Donald B. Wallace, James M. Ryan, Mark L. Mcconnell, John R. Macri
Space Science Center
FiberGLAST is a scintillating fiber gamma-ray detector designed for the GLAST mission. The system described below provides superior effective area and field of view for modest cost and risk. An overview of the FiberGLAST instrument is presented, as well as a more detailed description of the principle elements of the primary detector volume. The triggering and readout electronics are described, and Monte Carlo Simulations of the instrument performance are presented.
Beam Test Results For The Fiberglast Instrument, Robert S. Mallozzi, R M. Kippen, Geoffrey N. Pendleton, W Paciesas, Georgia A. Richardson, Surasak Phengchamnan, Gerald Karr, Donald B. Wallace, Gerald J. Fishman, Thomas A. Parnell, Robert B. Wilson, Mark J. Christl, W Robert Binns, P L. Hink, Martin W. Israel, Keith R. Rielage, John W. Epstein, Paul F. Dowkontt, J Buckley, James M. Ryan, John R. Macri, Mark L. Mcconnell, O T. Tumer, M L. Cherry, T G. Guzik, J G. Stacy, S C. Kappadath, Muzaffer Atac, Katsushi Arisaka, David B. Cline, Yuriy Pischalnikov
Beam Test Results For The Fiberglast Instrument, Robert S. Mallozzi, R M. Kippen, Geoffrey N. Pendleton, W Paciesas, Georgia A. Richardson, Surasak Phengchamnan, Gerald Karr, Donald B. Wallace, Gerald J. Fishman, Thomas A. Parnell, Robert B. Wilson, Mark J. Christl, W Robert Binns, P L. Hink, Martin W. Israel, Keith R. Rielage, John W. Epstein, Paul F. Dowkontt, J Buckley, James M. Ryan, John R. Macri, Mark L. Mcconnell, O T. Tumer, M L. Cherry, T G. Guzik, J G. Stacy, S C. Kappadath, Muzaffer Atac, Katsushi Arisaka, David B. Cline, Yuriy Pischalnikov
Space Science Center
The FiberGLAST scintillating fiber telescope is a large-area instrument concept for NASA's GLAST program. The detector is designed for high-energy gamma-ray astronomy, and uses plastic scintillating fibers to combine a photon pair tracking telescope and a calorimeter into a single instrument. A small prototype detector has been tested with high energy photons at the Thomas Jefferson National Accelerator Facility. We report on the result of this beam test, including scintillating fiber performance, photon track reconstruction, angular resolution, and detector efficiency.
Coded-Aperture X-Ray/Gamma-Ray Telescope For Arc-Minute Localization Of Gamma-Ray Bursts, M L. Cherry, P P. Altice, D L. Band, J Buckley, T G. Guzik, P L. Hink, S C. Kappadath, John R. Macri, J L. Matteson, Mark L. Mcconnell, Terence J. O'Neill, James M. Ryan, K R. Slavis, J G. Stacy, Allen Zych
Coded-Aperture X-Ray/Gamma-Ray Telescope For Arc-Minute Localization Of Gamma-Ray Bursts, M L. Cherry, P P. Altice, D L. Band, J Buckley, T G. Guzik, P L. Hink, S C. Kappadath, John R. Macri, J L. Matteson, Mark L. Mcconnell, Terence J. O'Neill, James M. Ryan, K R. Slavis, J G. Stacy, Allen Zych
Space Science Center
MARGIE will be a large-area, wide field-of-view, hard x- ray/gamma-ray imaging telescope capable of providing accurate positions for faint gamma-ray bursts in near-real- time and of performing a sensitive survey of both steady and transient cosmic sources. The instrument is designed to image faint bursts at the low-intensity end of the log N - log S distribution. MARGIE was recently selected by NASA for a mission-concept study for an Ultra Long Duration Balloon flight. We describe a program to develop an instrument based on the new detector technology of either cadmium zinc telluride room-temperature semiconductors or pixelated cesium iodide scintillators …
Recent Progress In The Development Of A Solar Neutron Tracking Device (Sontrac), James M. Ryan, Wenhui Li, John R. Macri, Mark L. Mcconnell, Carlos Castaneda, Juan L. Romero
Recent Progress In The Development Of A Solar Neutron Tracking Device (Sontrac), James M. Ryan, Wenhui Li, John R. Macri, Mark L. Mcconnell, Carlos Castaneda, Juan L. Romero
Space Science Center
We report the results of recent calibration data analysis of a prototype scintillating fiber tracking detector system designed to perform imaging, spectroscopy and particle identification on 20 to 250 MeV neutrons and protons. We present the neutron imaging concept and briefly review the detection principle and the prototype description. The prototype detector system records ionization track data on an event-by-event basis allowing event selection criteria to be used in the off-line analysis. Images of acrylic phantoms from the analysis of recent proton beam calibrations are presented as demonstrations of the particle identification, imaging and energy measurement capabilities. The measured position …
Development And Testing Of A Fiber/Multianode Photomultiplier System For Use On Fiberglast, Keith R. Rielage, Katsushi Arisaka, Muzaffer Atac, W Robert Binns, J Buckley, M L. Cherry, Mark J. Christl, David B. Cline, Paul F. Dowkontt, John W. Epstein, Gerald J. Fishman, T G. Guzik, P L. Hink, Martin H. Israel, S C. Kappadath, Gerald Karr, R M. Kippen, Daniel Leopold, Mark L. Mcconnell, John R. Macri, Robert S. Mallozzi, W Paciesas, Thomas A. Parnell, Geoffrey N. Pendleton, Surasak Phengchamnan, Yuriy Pischalnikov, Georgia A. Richardson, James M. Ryan, J G. Stacy, O T. Tumer, Gerald J. Vissor, Donald B. Wallace, Robert B. Wilson
Development And Testing Of A Fiber/Multianode Photomultiplier System For Use On Fiberglast, Keith R. Rielage, Katsushi Arisaka, Muzaffer Atac, W Robert Binns, J Buckley, M L. Cherry, Mark J. Christl, David B. Cline, Paul F. Dowkontt, John W. Epstein, Gerald J. Fishman, T G. Guzik, P L. Hink, Martin H. Israel, S C. Kappadath, Gerald Karr, R M. Kippen, Daniel Leopold, Mark L. Mcconnell, John R. Macri, Robert S. Mallozzi, W Paciesas, Thomas A. Parnell, Geoffrey N. Pendleton, Surasak Phengchamnan, Yuriy Pischalnikov, Georgia A. Richardson, James M. Ryan, J G. Stacy, O T. Tumer, Gerald J. Vissor, Donald B. Wallace, Robert B. Wilson
Space Science Center
A scintillating fiber detector is currently being studied for the NASA Gamma-Ray Large Area Space Telescope (GLAST) mission. This detector utilizes modules composed of a thin converter sheet followed by an x, y plane of scintillating fibers to examine the shower of particles created by high energy gamma-rays interacting in the converter material. The detector is composed of a tracker with 90 such modular planes and a calorimeter with 36 planes. The two major component of this detector are the scintillating fibers and their associated photodetectors. Here we present current status of development and test result of both of these. …
Energy And Position Resolution Of A Cdznte Gamma-Ray Detector With Orthogonal Coplanar Anodes, O Tousignant, L A. Hamel, Pierre C. Dufour, F Joly, John R. Macri, Mark L. Mcconnell, James M. Ryan, V T. Jordanov
Energy And Position Resolution Of A Cdznte Gamma-Ray Detector With Orthogonal Coplanar Anodes, O Tousignant, L A. Hamel, Pierre C. Dufour, F Joly, John R. Macri, Mark L. Mcconnell, James M. Ryan, V T. Jordanov
Space Science Center
We report on the simulation, construction and performance of prototype CZT imaging detectors employing orthogonal coplanar anodes. These detectors employ a novel electrode geometry with non-collecting anode strips in 1D and collecting anode pixels, interconnected in rows, in the orthogonal dimensions. These detectors retain the spectroscopic and detection efficiency advantages of single carried charge sensing devices as well as the principal advantage of conventional strip detectors with orthogonal anode and cathode strips, i.e. an N X N array of imagin pixels are realized with only 2N electronic channels. Charge signals induced on the various electrodes of a prototype detector with …
A Scintillating Plastic Fiber Tracking Detector For Neutron And Proton Imaging And Spectroscopy, James M. Ryan, John R. Macri, Mark L. Mcconnell, Richard A. Messner, Wenhui Li, Hansford H. Cutlip, Quihua Zheng, Carlos Castaneda, Juan L. Romero
A Scintillating Plastic Fiber Tracking Detector For Neutron And Proton Imaging And Spectroscopy, James M. Ryan, John R. Macri, Mark L. Mcconnell, Richard A. Messner, Wenhui Li, Hansford H. Cutlip, Quihua Zheng, Carlos Castaneda, Juan L. Romero
Space Science Center
We report the results of recent calibration data analysis of a prototype scintillating fiber tracking detector system designed to perform imaging, spectroscopy and particle identification on 20 to 250 MeV neutrons and protons. We present the neutron imaging concept and briefly review the detection principle and the prototype description. The prototype detector system records ionization track data on an event-by-event basis allowing event selection criteria to be used in the off-line analysis. Images of acrylic phantoms from the analysis of recent proton beam calibrations (14 to 65 MeV range) are presented as demonstrations of the particle identification, imaging and energy …
Development Of A Hard X-Ray Polarimeter For Astrophysics, Mark L. Mcconnell, John R. Macri, M Mcclish, James M. Ryan, D J. Forrest, W T. Vestrand
Development Of A Hard X-Ray Polarimeter For Astrophysics, Mark L. Mcconnell, John R. Macri, M Mcclish, James M. Ryan, D J. Forrest, W T. Vestrand
Space Science Center
We have been developing a Compton scatter polarimeter for measuring the linear polarization of hard X-rays (100-300 keV) from astrophysical sources. A laboratory prototype polarimeter has been used to successfully demonstrate the reliability of our Monte Carlo simulation code and to demonstrate our ability to generate a polarized photon source in the lab. Our design concept places a self-containedpolarimeter module on the front-end of a a 5-inch position sensitive PMT (PSPMT). We are currently working on the fabrication of a science model based on this PSPMT concept. Although the emphasis of our development effort is towards measuring hard X-rays from …
Development Of A Hard X-Ray Polarimeter For Astrophysics, Mark L. Mcconnell, John R. Macri, M Mcclish, James M. Ryan, D J. Forrest, W T. Vestrand
Development Of A Hard X-Ray Polarimeter For Astrophysics, Mark L. Mcconnell, John R. Macri, M Mcclish, James M. Ryan, D J. Forrest, W T. Vestrand
Space Science Center
We have been developing a Compton scatter polarimeter for measuring the linear polarization of hard X-rays (100-300 keV) from astrophysical sources. A laboratory prototype polarimeter has been used to successfully demonstrate the reliability of our Monte Carlo simulation code and to demonstrate our ability to generate a polarized photon source in the lab. Our design concept places a self-containedpolarimeter module on the front-end of a a 5-inch position sensitive PMT (PSPMT). We are currently working on the fabrication of a science model based on this PSPMT concept. Although the emphasis of our development effort is towards measuring hard X-rays from …
Sontrac—A Low Background, Large Area Solar Neutron Spectrometer, James M. Ryan, D Holslin, John R. Macri, Mark L. Mcconnell, Cornelia B. Wunderer
Sontrac—A Low Background, Large Area Solar Neutron Spectrometer, James M. Ryan, D Holslin, John R. Macri, Mark L. Mcconnell, Cornelia B. Wunderer
Space Science Center
SONTRAC is a scintillating fiber neutron detector designed to measure solar flare neutrons from a balloon or spacecraft platform. The instrument is comprised of alternating orthogonal planes of scintillator fibers viewed by photomultiplier tubes and image intensifier/CCD camera optics. It operates by tracking the paths of recoil protons from the double scatter of 20 to 200 MeV neutrons off hydrogen in the plastic scintillator, thereby providing the necessary information to determine the incident neutron direction and energy. SONTRAC is also capable of detecting and measuring high-energy gamma rays >20 MeV as a “solid-state spark chamber.” The self-triggering and track imaging …
Mev Measurements Of Gamma-Ray Bursts By Cgro-Comptel, A Connors, W Collmar, W Hermsen, S C. Kappadath, R M. Kippen, L Kuiper, Mark L. Mcconnell, F Pelaez, James M. Ryan, V Schonfelder, M Varendorff, O R. Williams, C Winkler, C A. Young
Mev Measurements Of Gamma-Ray Bursts By Cgro-Comptel, A Connors, W Collmar, W Hermsen, S C. Kappadath, R M. Kippen, L Kuiper, Mark L. Mcconnell, F Pelaez, James M. Ryan, V Schonfelder, M Varendorff, O R. Williams, C Winkler, C A. Young
Space Science Center
Since the launch of the Compton Gamma-Ray Observatory in April 1991, the imaging COMPTEL telescope has accumulated positions and 0.75–30 MeV spectra of more than thirty gamma-ray bursts within its ∼π sr field of view. In an ongoing collaboration with BACODINE/GCN, COMPTEL positions are relayed to a global network of multiwavelength observers in near real time (∼10 minutes). Here we summarize the MeV properties, and present spatial, spectral, and temporal data for the latest of these events, GRB 970807. In concurrence with earlier SMM and current BATSE, OSSE, and EGRET measurements, COMPTEL data add to the accumulating evidence that GRB …
A Hard X-Ray Solar Flare Polarimeter Design Based On Scintillating Fibers, James M. Ryan, Mark L. Mcconnell, D J. Forrest, John R. Macri, M Mcclish, W T. Vestrand
A Hard X-Ray Solar Flare Polarimeter Design Based On Scintillating Fibers, James M. Ryan, Mark L. Mcconnell, D J. Forrest, John R. Macri, M Mcclish, W T. Vestrand
Space Science Center
We have developed a design for a Compton scatter polarimeter to measure the polarization of hard X-rays (50–300 keV) from solar flares. The modular design is based on an annular array of scintillating fibers coupled to a 5-inch position-sensitive PMT. Incident photons scatter from the fiber array into a small array of NaI detectors located at the center of the annulus. The location of the interactions in both the fiber array and in the NaI array can be used to measure the linear polarization of the incident flux. This compact design may be well-suited to a variety of astrophysical applications. …
Prototype For Sontrac: A Scintillating Plastic Fiber Detector For Solar Neutron Spectroscopy, James M. Ryan, Janis Baltgalvis, D Holslin, John R. Macri, Mark L. Mcconnell, Cornelia B. Wunderer, Aaron R. Polichar
Prototype For Sontrac: A Scintillating Plastic Fiber Detector For Solar Neutron Spectroscopy, James M. Ryan, Janis Baltgalvis, D Holslin, John R. Macri, Mark L. Mcconnell, Cornelia B. Wunderer, Aaron R. Polichar
Space Science Center
We report the scientific motivation for and performance measurements of a prototype detector system for SONTRAC, a solar neutron tracking experiment designed to study high- energy solar flare processes. The full SONTRAC instrument will measure the energy and direction of 20 to 200 MeV neutrons by imaging the ionization tracks of the recoil protons in a densely packed bundle of scintillating plastic fibers. The prototype detector consists of a 12.7 mm square bundle of 250 micrometer scintillating plastic fibers, 10 cm long. A photomultiplier detects scintillation light from one end of the fiber bundle and provides a detection trigger to …
A Prototype For Sontrac, A Scintillating Plastic Fiber Tracking Detector For Neutron Imaging And Spectroscopy, James M. Ryan, John R. Macri, Mark L. Mcconnell, C B. Wunderer, D Holslin, Aaron R. Polichar, Janis Baltgalvis
A Prototype For Sontrac, A Scintillating Plastic Fiber Tracking Detector For Neutron Imaging And Spectroscopy, James M. Ryan, John R. Macri, Mark L. Mcconnell, C B. Wunderer, D Holslin, Aaron R. Polichar, Janis Baltgalvis
Space Science Center
We report on tests of a prototype detector system designed to perform imaging and spectroscopy on 20 to 250 MeV neutrons. Although developed for the study of high-energy solar flare processes, the detection techniques employed for SONTRAC, the SOlar Neutron TRACking experiment, can be applied to measurements in a variety of disciplines including atmospheric physics, radiation therapy and nuclear materials monitoring. The SONTRAC instrument measures the energy and direction ofneutrons by detecting double neutron-proton scatters and recording images of the ionization tracks of the recoil protons in a densely packed bundle of scintillating plastic fibers stacked in orthogonal layers. By …
Activation In The Comptel Double-Scattering Gamma-Ray Telescope, D Morris, Mark L. Mcconnell, James M. Ryan, R Diehl, U Oberlack, V Schonfelder, M Varendorff, G Weidenspointer, H Deboer, K Bennett
Activation In The Comptel Double-Scattering Gamma-Ray Telescope, D Morris, Mark L. Mcconnell, James M. Ryan, R Diehl, U Oberlack, V Schonfelder, M Varendorff, G Weidenspointer, H Deboer, K Bennett
Space Science Center
Abstract-The COMPTEL gamma-ray telescope has been operating in low Earth orbit for six years, since the launch of the Compton Gamma-Ray Observatory in April 1991. Comparisons of data for different orbits and epochs show evidence of activation on time scales from minutes (27Mg, q,2=9.5 min) to years C2Na, q&.58 yr). The activation is correlated with both the orbital altitude and solar cosmic-ray modulation. Because it requires coincident measurements in two different detectors, COMPTEL is most susceptible to instrumental background events in which two or more photons are produced simultaneously.
Sontrac-A Low Background, Large Area Solar Neutron Spectrometer, C B. Wunderer, D Holslin, John R. Macri, Mark L. Mcconnell, James M. Ryan
Sontrac-A Low Background, Large Area Solar Neutron Spectrometer, C B. Wunderer, D Holslin, John R. Macri, Mark L. Mcconnell, James M. Ryan
Space Science Center
SONTRAC will measure 20-250 MeV neutrons from solar flares using scintillator fibers viewed by CCD cameras to track neutron-proton scatters. SONTRAC can also be used to track gamma rays above 20 MeV. Veto shields are used to reject all charged particles. Gamma-ray and neutron events have very different track densities, allowing discrimination between the two. Double neutron-proton scatters allow unambiguous determination of the incident neutron energy and direction. Therefore, SONTRAC is capable of rejecting almost all background except neutrons from the solar direction. SONTRAC would have detected the June 15, 1991 flare with 42σ for 20-100 MeV neutrons, having an …
Cdznte Strip Detectors As Sub-Millimeter Resolution Imaging Gamma Radiation Spectrometers, K Larson, V Boykin, M L. Cherry, J F. Courville, F P. Doty, A Drake, T G. Guzik, L A. Hamel, John R. Macri, M Mayer, Mark L. Mcconnell, James M. Ryan, O Tousignant
Cdznte Strip Detectors As Sub-Millimeter Resolution Imaging Gamma Radiation Spectrometers, K Larson, V Boykin, M L. Cherry, J F. Courville, F P. Doty, A Drake, T G. Guzik, L A. Hamel, John R. Macri, M Mayer, Mark L. Mcconnell, James M. Ryan, O Tousignant
Space Science Center
We report γ-ray detection performance measurements and computer simulations of a sub-millimeter pitch CdZnTe strip detector. The detector is a prototype for γ-ray measurements in the range of 20-600 keV. The prototype is a 1.5 mm thick, 64×64 orthogonal stripe CdZnTe detector of 0.375 mm pitch in both dimensions, with approximately one square inch of sensitive area. Using discrete laboratory electronics to process signals from an 8×8 stripe region of the prototype we measured good spectroscopic uniformity and sub-pitch (~0.2 mm) spatial resolution in both x and y dimensions. We present below measurements of the spatial uniformity, relative timing and …
Progress In The Study Of Cdznte Strip Detectors, O Tousignant, L A. Hamel, J F. Courville, P Paki, John R. Macri, K Larson, M Mayer, Mark L. Mcconnell, James M. Ryan
Progress In The Study Of Cdznte Strip Detectors, O Tousignant, L A. Hamel, J F. Courville, P Paki, John R. Macri, K Larson, M Mayer, Mark L. Mcconnell, James M. Ryan
Space Science Center
We report new performance measurements and computer simulations of a sub-millimeter pitch CdZnTe strip detector under study as a prototype imaging spectrometer for astronomical x-ray and gamma-ray observations. The prototype is 1.5 mm thick with 375 micron strip pitch in both the x and y dimensions. Previously reported work included demonstrations of half-pitch spatial resolution (approximately 190 microns) and good energy resolution and spectral uniformity. Strip detector efficiency measurements have also been presented. A model that includes the photon interaction, carrier transport and the electronics was developed that qualitatively reproduced the measurements. The new studies include measurements of the CdZnTe …
Galactic Black Hole Binaries: High-Energy Radiation, J E. Grove, J E. Grindlay, B A. Harmon, X M. Hua, D Kazanas, Mark L. Mcconnell
Galactic Black Hole Binaries: High-Energy Radiation, J E. Grove, J E. Grindlay, B A. Harmon, X M. Hua, D Kazanas, Mark L. Mcconnell
Space Science Center
Observations of galactic black hole candidates made by the instruments aboard the Compton GRO in the hard X-ray and γ-ray bands have significantly enhanced our knowledge of the phenomenology of the emission from these objects. Understanding these observations presents a formidable challenge to theoretical models of the accretion flow onto the compact object and of the physical mechanisms that generate high-energy radiation. Here we summarize the current state of observations and theoretical interpretation of the emission from black holecandidates above 20 keV. The all-sky monitoring capability of BATSE allows, for the first time, nearly continuous studies of the high-energy emission …
A Search For Gamma-Ray Flares From Black-Hole Candidates On Time Scales Of ∼1.5 Hours, R Vandijk, K Bennett, H Bloemen, R Diehl, W Hermsen, Mark L. Mcconnell, James M. Ryan, V Schonfelder
A Search For Gamma-Ray Flares From Black-Hole Candidates On Time Scales Of ∼1.5 Hours, R Vandijk, K Bennett, H Bloemen, R Diehl, W Hermsen, Mark L. Mcconnell, James M. Ryan, V Schonfelder
Space Science Center
Strong short-lived flares from black-hole candidates have been detected in the hard X-rayregime and possibly also at γ-ray energies. Here we present a search for short-lived flares in the 0.75–30 MeV COMPTEL data. No flares are found during the 5 viewing periods considered, with typical upper limits of a few times the Crab flux.
Reassessment Of The 56co Emission From Sn 1991t, D Morris, K Bennett, H Bloemen, R Diehl, W Hermsen, G G. Lichti, Mark L. Mcconnell, James M. Ryan, V Schonfelder
Reassessment Of The 56co Emission From Sn 1991t, D Morris, K Bennett, H Bloemen, R Diehl, W Hermsen, G G. Lichti, Mark L. Mcconnell, James M. Ryan, V Schonfelder
Space Science Center
The detection of 56Co emission from SN 1991T has been previously reported at a level near the COMPTEL sensitivity threshold. The spectral analysis method, fitting the count spectrum to a background model plus a 56Co emission template, is subject to possible systematic effects which had not been thoroughly studied at that time. To better evaluate the significance of that ∼3.3σ detection, the same method has been applied to a grid of points with 5° spacing, out to 35° from the pointing direction, in each of 103 observing periods from phases 1 through 3. A dozen instances were found with a …
5 Years Of Crab Pulsar Observations With Comptel, R Much, K Bennett, C Winkler, R Diehl, G G. Lichti, V Schonfelder, H Steinle, A W. Strong, M Varendorff, W Hermsen, L Kuiper, R Van Der Meulen, A Connors, Mark L. Mcconnell, James M. Ryan, R Buccheri
5 Years Of Crab Pulsar Observations With Comptel, R Much, K Bennett, C Winkler, R Diehl, G G. Lichti, V Schonfelder, H Steinle, A W. Strong, M Varendorff, W Hermsen, L Kuiper, R Van Der Meulen, A Connors, Mark L. Mcconnell, James M. Ryan, R Buccheri
Space Science Center
Using the COMPTEL data of the first 5 years of the CGRO mission we have derived the average pulsed spectrum of the Crab Pulsar, as well as phase-resolved spectra of the pulsed emission of the Crab Pulsar. The spectra in the COMPTEL energy range (0.75 to 30 MeV) are compared to those in the neighboring energy bands. The pulsed flux has been examined for its stability. Pulsed lightcurves have been derived for different energy intervals. Preliminary results of this analysis are presented.
The Mev Spectrum Of Cygnus X-1 As Observed With Comptel, Mark L. Mcconnell, K Bennett, H Bloemen, W Collmar, W Hermsen, L Kuiper, R Much, James M. Ryan, V Schonfelder, H Steinle, A W. Strong, R Vandijk
The Mev Spectrum Of Cygnus X-1 As Observed With Comptel, Mark L. Mcconnell, K Bennett, H Bloemen, W Collmar, W Hermsen, L Kuiper, R Much, James M. Ryan, V Schonfelder, H Steinle, A W. Strong, R Vandijk
Space Science Center
The COMPTEL experiment on the Compton Gamma-Ray Observatory (CGRO) has observed the Cygnus region on several occasions since launch. These data represent the most sensitive observations to date of Cygnus X-1 in the 0.75–30 MeV range. The spectrum shows significant evidence for emission extending out to several MeV. These data alone suggest a need to modify the thermal Comptonization models or to incorporate some type of non-thermal emission mechanism. Here we report on the results of an analysis of selected COMPTEL data collected during the first three years of the CGRO mission. These data are then compared with contemporaneous data …
The Total Cosmic Diffuse Gamma-Ray Spectrum From 9 To 30 Mev Measured With Comptel, S C. Kappadath, James M. Ryan, K Bennett, H Bloemen, R Diehl, W Hermsen, Mark L. Mcconnell, V Schonfelder, M Varendorff, G Weidenspointer, C Winkler
The Total Cosmic Diffuse Gamma-Ray Spectrum From 9 To 30 Mev Measured With Comptel, S C. Kappadath, James M. Ryan, K Bennett, H Bloemen, R Diehl, W Hermsen, Mark L. Mcconnell, V Schonfelder, M Varendorff, G Weidenspointer, C Winkler
Space Science Center
A preliminary COMPTEL Cosmic Diffuse Gamma-Ray (CDG) spectrum from 800 keV to 30 MeV was presented earlier at the 3rd Compton Symposium. The COMPTEL results represent the first significant detection of the CDG radiation in the 9 to 30 MeV range. Using high-latitude data from the first 5 years of the mission we have performed a new detailed measurement of the 9 to 30 MeV spectrum with finer energy binning. The new improved results are in good agreement with our previous estimates and are compatible with power-law extrapolations from higher energies. The measured 9–30 MeV spectra from the Virgo and …
A Time Dependent Model For The Activation Of Comptel, M Varendorff, U Oberlack, G Weidenspointer, R Diehl, R Vandijk, Mark L. Mcconnell, James M. Ryan
A Time Dependent Model For The Activation Of Comptel, M Varendorff, U Oberlack, G Weidenspointer, R Diehl, R Vandijk, Mark L. Mcconnell, James M. Ryan
Space Science Center
The structure of the CGRO satellite is irradiated by cosmic rays and trapped particles fromradiation belts. These incident particles produce radioactive nuclei in nuclear reactions with the satellite structure. Most of the radiation dose can be attributed to the passages through the South Atlantic Anomaly. The incident particle flux on the COMPTEL instrument is estimated from the event rate of a plastic scintillation detector. This event rate is modeled with a Neural Network simulation. The increase of the event rate during SAA passages is taken as a measure for the amount of induced radioactivity. A Neural Network Model is used …
Comptel All-Sky Imaging At 2.2 Mev, Mark L. Mcconnell, S Fletcher, K Bennett, H Bloemen, R Diehl, W Hermsen, James M. Ryan, V Schonfelder, A W. Strong, R Vandijk
Comptel All-Sky Imaging At 2.2 Mev, Mark L. Mcconnell, S Fletcher, K Bennett, H Bloemen, R Diehl, W Hermsen, James M. Ryan, V Schonfelder, A W. Strong, R Vandijk
Space Science Center
It is now generally accepted that accretion of matter onto a compact object (white dwarf, neutron star or black hole) is one of the most efficient processes in the universe for producing high energy radiations. Measurements of the γ-ray emission will provide a potentially valuable means for furthering our understanding of the accretion process. Here we focus on neutroncapture processes, which can be expected in any situation where energetic neutrons may be produced and where the liberated neutrons will interact with matter before they decay (where they have a chance of undergoing some type of neutron capture). Line emission at …
Diffuse Galactic Continuum Emission: Recent Studies Using Comptel Data, A W. Strong, R Diehl, V Schonfelder, K Bennett, Mark L. Mcconnell, James M. Ryan
Diffuse Galactic Continuum Emission: Recent Studies Using Comptel Data, A W. Strong, R Diehl, V Schonfelder, K Bennett, Mark L. Mcconnell, James M. Ryan
Space Science Center
COMPTEL full sky maximum entropy maps using 5 years of data have been produced using background estimates based on high-latitude observations. The Galactic diffuse emission can be studied using latitude and longitude profiles from these maps. Direct comparison of profiles with theoretical models is illustrated for the 10–30 MeV range. We demonstrate the presence of a broad latitude component, consistent with results from model-fitting studies. The method is also used to obtain model-independent broad-band spectra of the Galactic emission.
The Prompt Cosmic-Ray-Induced Background In The Orbiting Compton Telescope Comptel, James M. Ryan, S C. Kappadath, Mark L. Mcconnell, D Morris, V Schonfelder, M Varendorff, G Weidenspointer, W Hermsen, K Bennett
The Prompt Cosmic-Ray-Induced Background In The Orbiting Compton Telescope Comptel, James M. Ryan, S C. Kappadath, Mark L. Mcconnell, D Morris, V Schonfelder, M Varendorff, G Weidenspointer, W Hermsen, K Bennett
Space Science Center
The authors report the spectrum of background events that the COMPTEL instrument on ComptonGamma Ray Observatory experiences due to the instantaneous effects of cosmic rays. Otherbackgrounds are present in the data of this Compton telescope, but the components that closely follow the instantaneous flux of cosmic rays are the most identifiable. The background varies approximately linearly with the cosmic-ray intensity and exhibits a broad feature from about 1 to 10 MeV suggestive of the nuclear nature of the events. Above 10 MeV there is a marked change in the nature of thebackground that is not understood. It appears that the …
Evidence For Γ-Ray Flares In 3c 279 And Pks 1622-297 At ∼10 Mev, W Collmar, V Schonfelder, H Bloemen, J J. Blom, W Hermsen, Mark L. Mcconnell, J G. Stacy, K Bennett, O R. Williams
Evidence For Γ-Ray Flares In 3c 279 And Pks 1622-297 At ∼10 Mev, W Collmar, V Schonfelder, H Bloemen, J J. Blom, W Hermsen, Mark L. Mcconnell, J G. Stacy, K Bennett, O R. Williams
Space Science Center
The EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) has observed at energies above 100 MeV strong gamma-ray flares with short-term time variability from thegamma-ray blazars 3C 279 [1] and PKS 1622-297 [2]. During these flaring periods both blazarshave been detected by the COMPTEL experiment aboard CGRO at photon energies of ∼10 MeV, revealing simultaneous γ-ray activity down to these energies. For both cases the derived fluxes exceed those measured in previous observations, and 3C 279 shows an indication for time variability within the observational period. Both sources show evidence for ‘hard’ MeV spectra. In general the behaviour of both …