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S Sofia - One of the best experts on this subject based on the ideXlab platform.
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the solar diameter and oblateness measured by the solar disk sextant on the 1992 september 30 Balloon Flight
The Astrophysical Journal, 1994Co-Authors: S Sofia, William S Heaps, L TwiggAbstract:This paper reports the results of a Balloon Flight of the Solar Disk Sextant (SDS) on 1992 September 30. This was the first Flight in which the SDS used a wedge assembly fabricated by molecular contact in order to eliminate the wedge angle variations observed in previous Flights. The instrument performed as designed. The main results obtained are values of the solar diameter for a number of discrete heliocentric latitudes, and the solar oblateness. The accuracy of the diameter values is better than 0.2 sec whereas the precision is approximately 1-2 mas. The equatorial solar diameter, at 1 AU, was 1919.06 sec +/- 0.12 sec, and the oblateness epsilon = 8.63 +/- 0.88 x 10(exp -6).
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preliminary results of a Balloon Flight of the solar disk sextant
The Astrophysical Journal, 1992Co-Authors: Eugene Maier, L Twigg, S SofiaAbstract:Preliminary results of a Balloon Flight on October 11, 1991, of the solar disk sextant (SDS) experiment are reported. The SDS is an instrument which measures the solar diameter at different orientations with respect to the solar polar axis. Fitting straight lines through two fixed-angle data sets with time as the independent variable yields slopes of (7.1 +/ - 1.5) x 10 exp -3 and (6.7 +/- 1.6) x 10 exp -3/mas s, consistent with the value of 6.47 x 10 exp -3/mas s expected from the earth's approach to the sun due to the orbital motion toward perihelion. Upon the instrument's rotation on its axis a sinusoidal component of the diameter measurement was observed in each rotation cycle, with a variable amplitude of about 150 mas. The present result is epsilon of (5.6 +/- 6.3) x 10 exp -6, about 30 deg offset from the polar-equator position. The absolute diameter obtained by means of the FFT definition is found to be 1919.269 +/- 0.240 arcsec or 1919.131 +/- 0.240 arcsec, depending on the orientation mode of the measurement.
L Twigg - One of the best experts on this subject based on the ideXlab platform.
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the solar diameter and oblateness measured by the solar disk sextant on the 1992 september 30 Balloon Flight
The Astrophysical Journal, 1994Co-Authors: S Sofia, William S Heaps, L TwiggAbstract:This paper reports the results of a Balloon Flight of the Solar Disk Sextant (SDS) on 1992 September 30. This was the first Flight in which the SDS used a wedge assembly fabricated by molecular contact in order to eliminate the wedge angle variations observed in previous Flights. The instrument performed as designed. The main results obtained are values of the solar diameter for a number of discrete heliocentric latitudes, and the solar oblateness. The accuracy of the diameter values is better than 0.2 sec whereas the precision is approximately 1-2 mas. The equatorial solar diameter, at 1 AU, was 1919.06 sec +/- 0.12 sec, and the oblateness epsilon = 8.63 +/- 0.88 x 10(exp -6).
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preliminary results of a Balloon Flight of the solar disk sextant
The Astrophysical Journal, 1992Co-Authors: Eugene Maier, L Twigg, S SofiaAbstract:Preliminary results of a Balloon Flight on October 11, 1991, of the solar disk sextant (SDS) experiment are reported. The SDS is an instrument which measures the solar diameter at different orientations with respect to the solar polar axis. Fitting straight lines through two fixed-angle data sets with time as the independent variable yields slopes of (7.1 +/ - 1.5) x 10 exp -3 and (6.7 +/- 1.6) x 10 exp -3/mas s, consistent with the value of 6.47 x 10 exp -3/mas s expected from the earth's approach to the sun due to the orbital motion toward perihelion. Upon the instrument's rotation on its axis a sinusoidal component of the diameter measurement was observed in each rotation cycle, with a variable amplitude of about 150 mas. The present result is epsilon of (5.6 +/- 6.3) x 10 exp -6, about 30 deg offset from the polar-equator position. The absolute diameter obtained by means of the FFT definition is found to be 1919.269 +/- 0.240 arcsec or 1919.131 +/- 0.240 arcsec, depending on the orientation mode of the measurement.
Peter F. Bloser - One of the best experts on this subject based on the ideXlab platform.
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Initial results from the Advanced Scintillator Compton Telescope (ASCOT) Balloon Flight
2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS MIC), 2019Co-Authors: Tejaswita Sharma, Peter F. Bloser, Jason S Legere, Christopher M Bancroft, Colin Frost, Mark L. Mcconnell, James M. RyanAbstract:A medium-energy gamma-ray Compton telescope called the Advanced Scintillator Compton Telescope (ASCOT) was designed to address the existing need for observations in the gamma-ray energy range of 0.4 - 20 MeV. Built on the legacy of COMPTEL instrument onboard NASA's CGRO, ASCOT uses commercially available high-performance scintillators, such as Cerium Bromide (CeBr3) and p-terphenyl in conjunction with Silicon Photomultipliers (SiPM) as compact readout devices to improve the instrument response. ASCOT also makes use of the Time-of-Flight background rejection technique along with the hardware advancement, an important tool for effective imaging in this energy range. ASCOT was developed with the goal of imaging the Crab Nebula at MeV energies during a high-altitude Balloon Flight. The instrument was successfully launched by NASA from Palestine (TX) on 5th July 2018. It operated stably and observed the Crab for ~5 hours from an altitude of 120,000 ft. Based on pre-Flight calibrations and simulations results we expect a ~4.5 sigma detection of the Crab in the 0.2-2 MeV band. We present here the calibrated Flight data along with preliminary results. The findings from ASCOT will demonstrate an improvement in the energy, timing, and position resolution using this advanced technology.
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preparations for the advanced scintillator compton telescope ascot Balloon Flight
UV X-Ray and Gamma-Ray Space Instrumentation for Astronomy XX, 2017Co-Authors: Tejaswita Sharma, Peter F. Bloser, M Mcconnell, Jason S Legere, J M Ryan, Christopher M Bancroft, Alex M WrightAbstract:We describe our ongoing work to develop a new medium-energy gamma-ray Compton telescope using advanced scintillator materials combined with silicon photomultiplier readouts and fly it on a scientific Balloon. There is a need in high-energy astronomy for a medium-energy gamma-ray mission covering the energy range from approximately 0.4 - 20 MeV to follow the success of the COMPTEL instrument on CGRO. We believe that directly building on the legacy of COMPTEL, using relatively robust, low-cost, off-the-shelf technologies, is the most promising path for such a mission. Fortunately, high-performance scintillators, such as Cerium Bromide (CeBr3) and p-terphenyl, and compact readout devices, such as silicon photomultipliers (SiPMs), are already commercially available and capable of meeting this need. We are now constructing an Advanced Scintillator Compton Telescope (ASCOT) with SiPM readout, with the goal of imaging the Crab Nebula at MeV energies from a high-altitude Balloon Flight. We expect a ~4-sigma detection at ~1 MeV in a single transit. We present calibration results of the detector modules, and updated simulations of the Balloon instrument sensitivity. If successful, this project will demonstrate that the energy, timing, and position resolution of this technology are sufficient to achieve an order of magnitude improvement in sensitivity in the medium-energy gamma-ray band, were it to be applied to a ~1 cubic meter instrument on a long-duration Balloon or Explorer platform.
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Balloon Flight test of a compton telescope based on scintillators with silicon photomultiplier readouts
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2016Co-Authors: Peter F. Bloser, Jason S Legere, J M Ryan, Christopher M Bancroft, M McconnellAbstract:Abstract We present the results of the first high-altitude Balloon Flight test of a concept for an advanced Compton telescope making use of modern scintillator materials with silicon photomultiplier (SiPM) readouts. There is a need in the fields of high-energy astronomy and solar physics for new medium-energy gamma-ray (~0.4–10 MeV) detectors capable of making sensitive observations of both line and continuum sources over a wide dynamic range. A fast scintillator-based Compton telescope with SiPM readouts is a promising solution to this instrumentation challenge, since the fast response of the scintillators permits both the rejection of background via time-of-Flight (ToF) discrimination and the ability to operate at high count rates. The Solar Compton Telescope (SolCompT) prototype presented here was designed to demonstrate stable performance of this technology under Balloon-Flight conditions. The SolCompT instrument was a simple two-element Compton telescope, consisting of an approximately one-inch cylindrical stilbene crystal for a scattering detector and a one-inch cubic LaBr 3 :Ce crystal for a calorimeter detector. Both scintillator detectors were read out by 2×2 arrays of Hamamatsu S11828-3344 MPPC devices. Custom front-end electronics provided optimum signal rise time and linearity, and custom power supplies automatically adjusted the SiPM bias voltage to compensate for temperature-induced gain variations. A tagged calibration source, consisting of ~240 nCi of 60 Co embedded in plastic scintillator, was placed in the field of view and provided a known source of gamma rays to measure in Flight. The SolCompT Balloon payload was launched on 24 August 2014 from Fort Sumner, NM, and spent ~3.75 h at a float altitude of ~123,000 ft. The instrument performed well throughout the Flight. After correcting for small (~10%) residual gain variations, we measured an in-Flight ToF resolution of ~760 ps (FWHM). Advanced scintillators with SiPM readouts continue to show great promise for future gamma-ray instruments.
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plans for the next grape Balloon Flight
Proceedings of SPIE, 2013Co-Authors: M Mcconnell, Peter F. Bloser, Taylor Connor, Camden Ertley, Jason S Legere, J M Ryan, Sambid K WastiAbstract:The Gamma RAy Polarimeter Experiment (GRAPE) was first flown on a 26-hour Balloon Flight in the fall of 2011. GRAPE consists of an array of Compton polarimeter modules (based on traditional scintillation technologies) designed to operate in the energy range from 50 keV up to 500 keV. The ultimate goal is to operate GRAPE in a wide FoV configuration for the study of gamma-ray bursts. For the first (demonstration) Balloon Flight, GRAPE was configured in a collimated mode to facilitate observations of known point sources. The Crab nebula/pulsar, the active Sun, and Cygnus X-1 were the primary targets for the first Flight. Although the Crab was detected, the polarization sensitivity was worse than expected. This paper will review the plans for the next GRAPE Balloon Flight, which is scheduled to take place in the fall of 2014 from Ft. Sumner, NM. These plans involve several modifications designed to improve the polarization sensitivity, including an expansion of the array of polarimeter modules from 16 to 24 and improvements to the instrument shielding. Sensitivity estimates of the resulting instrument, based on GEANT4 simulations, will be presented.
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Balloon Flight results of a FAst compton telescope (FACTEL)
2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS MIC), 2012Co-Authors: Manuel Julien, Peter F. Bloser, Jason S Legere, Christopher M Bancroft, Mark L. Mcconnell, James M. Ryan, Marc R. Kippen, Shawn TorngaAbstract:Current medium energy gamma-ray astronomy is limited by the intense atmospheric or local background radiation degrading the sensitivity of instruments. Compton Telescopes' background rejection capabilities can be significantly improved with no loss of effective area by narrowing as much as possible the event acceptance Time of Flight (ToF) window by using fast scintillators materials such as LaBr3. We present the Balloon test Flight results of the FAst Compton TELescope (FACTEL) prototype we built using LaBr3 scintillators, along with other techniques to reduce the neutron induced background. This 26 hour Flight from NASA's Columbia Scientific Balloon Facility at Fort Sumner, New Mexico, permitted us to evaluate the background rejection capabilities offered by our 1.2 ns ToF window compared to COMPTEL's 4 ns. We also report laboratory and Monte Carlo simulations results. We use these results to make a preliminary evaluation of the performance of a larger future instrument based on similar principles.
P Spinelli - One of the best experts on this subject based on the ideXlab platform.
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study of the combined particle identification capability of a transition radiation detector and a silicon imaging calorimeter during the ts93 Balloon Flight
Astroparticle Physics, 1997Co-Authors: R Bellotti, F Cafagna, M Castellano, M Circella, G De Cataldo, C De Marzo, N Giglietto, Bartolomeo Marangelli, A Raino, P SpinelliAbstract:Abstract The WiZard Collaboration is involved in a program studying the antimatter components of the cosmic rays. A transition radiation detector and a silicon-tungsten calorimeter with imaging capabilities have been built as part of this program. We present the combined performance of these two detectors for positron identification during a Balloon Flight on September 8, 1993. The Flight was dedicated to the measurement of the positron spectrum in the energy range 4–50 GeV and was launched from Ft. Summer, New Mexico.
R Bellotti - One of the best experts on this subject based on the ideXlab platform.
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study of the combined particle identification capability of a transition radiation detector and a silicon imaging calorimeter during the ts93 Balloon Flight
Astroparticle Physics, 1997Co-Authors: R Bellotti, F Cafagna, M Castellano, M Circella, G De Cataldo, C De Marzo, N Giglietto, Bartolomeo Marangelli, A Raino, P SpinelliAbstract:Abstract The WiZard Collaboration is involved in a program studying the antimatter components of the cosmic rays. A transition radiation detector and a silicon-tungsten calorimeter with imaging capabilities have been built as part of this program. We present the combined performance of these two detectors for positron identification during a Balloon Flight on September 8, 1993. The Flight was dedicated to the measurement of the positron spectrum in the energy range 4–50 GeV and was launched from Ft. Summer, New Mexico.
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performance of the caprice rich detector during the 1994 Balloon Flight
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 1996Co-Authors: G Barbiellini, M Boezio, U Bravar, R Bellotti, F Cafagna, G Basini, M Bocciolini, Massimo F Brancaccio, M Candusso, P CarlsonAbstract:A RICH detector capable of detecting unit charged particles, e.g. antiprotons and positrons, has been used successfully for the first time in a Balloon-borne magnet spectrometer. The thin and compact CAPRICE RICH detector uses a NaF solid radiator, TMAE vapour as photo converter and cathode pad readout in the photosensitive MWPC operated at low gain. 15 photoelectrons are detected per ring for β = 1, perpendicular incidence particles giving a resolution on the Cherenkov angle of 8 mrad, increasing to 14 mrad at 20°C incidence angle. Besides particle identification on an event-by-event basis it efficiently rejects multiparticle events and albedo particles.
