The first demonstration of the concept of "narrow-FOV Si/CdTe semiconductor Compton camera"

Abstract

The Soft Gamma-ray Detector (SGD), to be deployed onboard the {\it ASTRO-H} satellite, has been developed to provide the highest sensitivity observations of celestial sources in the energy band of 60-600~keV by employing a detector concept which uses a Compton camera whose field-of-view is restricted by a BGO shield to a few degree (narrow-FOV Compton camera). In this concept, the background from outside the FOV can be heavily suppressed by constraining the incident direction of the gamma ray reconstructed by the Compton camera to be consistent with the narrow FOV. We, for the first time, demonstrate the validity of the concept using background data taken during the thermal vacuum test and the low-temperature environment test of the flight model of SGD on ground. We show that the measured background level is suppressed to less than 10\% by combining the event rejection using the anti-coincidence trigger of the active BGO shield and by using Compton event reconstruction techniques. More than 75\% of the signals from the field-of-view are retained against the background rejection, which clearly demonstrates the improvement of signal-to-noise ratio. The estimated effective area of 22.8~cm${}^2$ meets the mission requirement even though not all of the operational parameters of the instrument have been fully optimized yet.

arXiv comment40 pages, 12 figures, accepted for publication in Nuclear Inst. and Methods in Physics Research, A

References in corpus (12)

• The first COMPTEL Source Catalogue
• The ASTRO-H Mission
• The ASTRO-H X-ray Observatory
• Event reconstruction in high resolution Compton telescopes
• The Si/CdTe semiconductor Compton camera of the ASTRO-H Soft Gamma-ray Detector (SGD)
• Observation of Diffuse Cosmic and Atmospheric Gamma Rays at Balloon Altitudes with an Electron-tracking Compton Camera
• The Advanced Compton Telescope Mission
• Soft Gamma-ray Detector for the ASTRO-H Mission
• Detection and Imaging of the Crab Nebula with the Nuclear Compton Telescope
• The MEGA Advanced Compton Telescope Project
• Compton scattering sequence reconstruction algorithm for the liquid xenon gamma-ray imaging telescope (LXeGRIT)
• Design and Performance of the Soft Gamma-ray Detector for the NeXT mission

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• First i-TED demonstrator: a Compton imager with Dynamic Electronic Collimation
• Detection of polarized gamma-ray emission from the Crab nebula with Hitomi Soft Gamma-ray Detector
• Optimization of Timepix3-based conventional Compton camera using electron track algorithm
• Study of the Polarimetric Performance of a Si/CdTe Semiconductor Compton Camera for the Hitomi Satellite
• Reconstruction of multiple Compton scattering events in MeV gamma-ray Compton telescopes towards GRAMS: the physics-based probabilistic model
• Compton Telescopes for Gamma-ray Astrophysics