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Proceedings Paper

Development of BGO active shield for the ASTRO-H soft gamma-ray detector
Author(s): Y. Hanabata; Y. Fukazawa; K. Yamaoka; H. Tajima; J. Kataoka; K. Nakazawa; H. Takahashi; T. Mizuno; M. Ohno; M. Kokubun; T. Takahashi; S. Watanabe; M. Tashiro; Y. Terada; C. Sasaki; K. Nakajima; T. Mizushima
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Paper Abstract

Soft Gamma-ray Detector (SGD:40-600 keV) will be mounted on the 6th Japanese X-ray observatory ASTROH to be launched in 2014. The main part of the SGD is a Compton camera with a narrow field of view and surrounded by BGO active shields (SGD-BGO). Via this combination, the SGD can achieve sensitivity more than ten times superior to the Suzaku/HXD. The BGO active shield will also function as a gamma-ray burst monitor as proven by the wide-band all-sky monitor (WAM) of the Suzaku/HXD. Avalanche Photodiodes (APDs) are used to read out scintillation lights from the BGO. The size of the former also means we need to focus on collecting light from large, complex-shaped BGO blocks. The significant leakage current of the APD means a lower temperature is preferred to minimize the noise while a higher temperature is preferred to simplify the cooling system. To optimize the BGO shape and the operating temperature, we tested the performance of the BGO readout system with various BGO shapes under different operating temperatures. We also apply waveform sampling by flash-ADC and digital filter instead of a conventional analog filter and ADC scheme to reduce the space and power of the circuit with increased flexibilities. As an active shield, we need to achieve a threshold level of 50-100 keV. Here, we report on the studies of threshold energy of active shield under various conditions and signal processings.

Paper Details

Date Published: 29 July 2010
PDF: 10 pages
Proc. SPIE 7732, Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray, 77323B (29 July 2010); doi: 10.1117/12.856745
Show Author Affiliations
Y. Hanabata, Hiroshima Univ. (Japan)
Y. Fukazawa, Hiroshima Univ. (Japan)
K. Yamaoka, Aoyama Gakuin Univ. (Japan)
H. Tajima, Kavli Institute for Particle Astrophysics and Cosmology, Stanford Univ. (United States)
J. Kataoka, Waseda Univ. (Japan)
K. Nakazawa, The Univ. of Tokyo (Japan)
H. Takahashi, Hiroshima Univ. (Japan)
T. Mizuno, Hiroshima Univ. (Japan)
M. Ohno, Japan Aerospace Exploration Agency (Japan)
M. Kokubun, Japan Aerospace Exploration Agency (Japan)
T. Takahashi, Japan Aerospace Exploration Agency (Japan)
S. Watanabe, Japan Aerospace Exploration Agency (Japan)
M. Tashiro, Saitama Univ. (Japan)
Y. Terada, Saitama Univ. (Japan)
C. Sasaki, Japan Aerospace Exploration Agency (Japan)
K. Nakajima, The Univ. of Tokyo (Japan)
T. Mizushima, Aoyama Gakuin Univ. (Japan)

Published in SPIE Proceedings Vol. 7732:
Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray
Monique Arnaud; Stephen S. Murray; Tadayuki Takahashi, Editor(s)

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