Development of BGO active shield for the ASTRO-H soft Gamma-ray Detector

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

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


Soft Gamma-ray Detector (SGD:40-600 keV) will be mounted on the 6th Japanese X-ray observatory ASTRO-H 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.

Original languageEnglish
Title of host publicationSpace Telescopes and Instrumentation 2010
Subtitle of host publicationUltraviolet to Gamma Ray
Publication statusPublished - 2010 Oct 20
EventSpace Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray - San Diego, CA, United States
Duration: 2010 Jun 282010 Jul 2

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceSpace Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray
Country/TerritoryUnited States
CitySan Diego, CA


  • Active shield
  • SGD
  • Soft gamma-rays

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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