Speaker
Dr
Masanori Ohno
(Hiroshima University)
Description
The Hard X-ray Imager (HXI) and the Soft Gamma-ray Detector (SGD), onboard instruments of Japanese 6th X-ray observatory, ASTRO-H, are
surrounded by the large number of BGO (Bi$_4$Ge$_3$O$_{12}$) scintillators for active shielding. These active shields are very important to reduce the
non X-ray background such as cosmic rays and/or gamma-rays from radioisotopes produced by activation of the detector materials themselves so that we can
achieve much higher sensitivity in the hard X-ray and soft gamma-ray band. In addition to the active shielding as the primary purpose, we can utilize the shield detectors of
SGD as the all-sky monitor with very large effective area for the transient phenomena such as gamma-ray bursts and soft gamma-ray repeaters.
In this year, we have finished to fabricate the flight model of HXI and SGD and we have performed the pre-flight calibrations, and now, we are in the stage
to develop and verify the gamma-ray response function of the detectors. The gamma-ray response of BGO active shields is very
complicated because they consist of various types of shape of large BGO crystals and incident gamma-rays would suffer multiple scattering in the detector,
and also resulting yield of scintillation lights changes depending on the incident position of the gamma-rays. To reproduce such complicate gamma-ray response, we developed
Geant4-based Monte-Carlo simulator including geometries of individual detector components. For the BGO active shields, we implement measured energy
resolution and energy threshold to reproduce the energy spectra and anti-coincidence triggers for the main detector. We also apply the simple empirical model to
calculate the variation of the light yield depending on the incident position of gamma-rays. We confirmed that our developed gamma-ray response successfully
reproduce the measurement within roughly 10% accuracy at this moment. In this contribution, we present a detail of our Monte-Calro simulator and
performance of the BGO detectors of HXI and SGD as both active shield and all-sky monitor.
Primary author
Dr
Masanori Ohno
(Hiroshima University)
Co-authors
Dr
Atsuhi Harayama
(ISAS/JAXA)
Ms
Chiho Okada
(Hiroshima Univeristy)
Dr
Goro Sato
(ISAS/JAXA)
Dr
Hideki Uchiyama
(Shizuoka Univeristy)
Mr
Hiroaki Murakami
(University of Tokyo)
Dr
Hirokazu Odaka
(ISAS/JAXA)
Mr
Hiroki Yoneda
(ISAS/JAXA)
Dr
Hiromitsu Takahashi
(Hiroshima University)
Prof.
Hiroyasu Tajima
(Nagoya University STEL)
Mr
Hiroyuki Shirakawa
(Hiroshima Univeristy)
Ms
Ikumi Edahiro
(Hiroshima Univeristy)
Dr
Jun Kataoka
(Waseda University)
Dr
Jun'ichiro Katsuta
(Hiroshima University)
Dr
Katsuhiro Hayashi
(ISAS/JAXA)
Mr
Katsuma Miyake
(University of Tokyo)
Mr
Kazufumi Okuda
(University of Tokyo)
Dr
Kazuhiro Nakazawa
(University of Tokyo)
Prof.
Kazuo Makishima
(University of Tokyo)
Dr
Kazutaka Yamaoka
(Nagoya University STEL)
Mr
Koh Ono
(University of Tokyo)
Dr
Madoka Kawaharada
(JAXA)
Mr
Masaomi Kinoshita
(Nagoya University STEL)
Mr
Masayuki Ohta
(ISAS/JAXA)
Ms
Miho Katsuragawa
(ISAS/JAXA)
Dr
Motohide Kokubun
(ISAS/JAXA)
Ms
Norie Ohashi
(Hiroshima University)
Dr
Rie Sato
(ISAS/JAXA)
Mr
Ryota Tomaru
(ISAS/JAXA)
Dr
Shin Watanabe
(ISAS/JAXA)
Dr
Shin'ichiro Takeda
(OIST)
Dr
Shin'ya Saito
(Rikkyo University)
Mr
Sho Habata
(Hiroshima Univeristy)
Mr
Shogo Kobayashi
(University of Tokyo)
Mr
Takafumi Kawano
(Hiroshima University)
Prof.
Takahashi Tadayuki
(ISAS/JAXA)
Dr
Takayuki Yuasa
(RIKEN)
Mr
Taketo Mimura
(Waseda University)
Dr
Toshio Nakano
(University of Tokyo)
Dr
Tsunefumi Mizuno
(Hiroshima University)
Prof.
Yasushi Fukazawa
(Hiroshima University)
Dr
Yasuyuki Tanaka
(Hiroshima University)
Dr
Yoichi Yatsu
(TITech)
Mr
Yoshihiro Furuta
(University of Tokyo)
Mr
Yusuke Uchida
(ISAS/JAXA)
Mr
Yuto Ichinohe
(ISAS/JAXA)
Mr
Yuuichi Kato
(University of Tokyo)
Ms
Yuuki Murota
(University of Tokyo)
Mr
Yuuki Wada
(University of Tokyo)
