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arXiv · 2011.10317

Origin of the in-orbit instrumental background of the Hard X-ray Imager onboard Hitomi

Kouichi Hagino·Hirokazu Odaka·Goro Sato·Tamotsu Sato·Hiromasa Suzuki·Tsunefumi Mizuno·Madoka Kawaharada·Masanori Ohno·Kazuhiro Nakazawa·Shogo B. Kobayashi·Hiroaki Murakami·Katsuma Miyake·Makoto Asai·Tatsumi Koi·Greg Madejski·Shinya Saito·Dennis H. Wright·Teruaki Enoto·Yasushi Fukazawa·Katsuhiro Hayashi·Jun Kataoka·Junichiro Katsuta·Motohide Kokubun·Philippe Laurent·Francois Lebrun·Olivier Limousin·Daniel Maier·Kazuo Makishima·Kunishiro Mori·Takeshi Nakamori·Toshio Nakano·Hirofumi Noda·Masayuki Ohta·Rie Sato·Hiroyasu Tajima·Hiromitsu Takahashi·Tadayuki Takahashi·Shin'ichiro Takeda·Takaaki Tanaka·Yukikatsu Terada·Hideki Uchiyama·Yasunobu Uchiyama·Shin Watanabe·Kazutaka Yamaoka·Yoichi Yatsu·Takayuki Yuasa
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Abstract

Understanding and reducing the in-orbit instrumental backgrounds are essential to achieving high sensitivity in hard X-ray astronomical observations. The observational data of the Hard X-ray Imager (HXI) on board the Hitomi satellite provides useful information on the background components, owing to its multi-layer configuration with different atomic numbers: the HXI consists of a stack of four layers of Si (Z = 14) detectors and one layer of CdTe (Z = 48, 52) detector surrounded by well-type BGO (Bi4Ge3O12) active shields. Based on the observational data, the backgrounds of top Si layer, the three underlying Si layers, and the CdTe layer are inferred to be dominated by different components, namely, low-energy electrons, albedo neutrons, and proton-induced radioactivation, respectively. Monte Carlo simulations of the in-orbit background of the HXI reproduce the observed background spectrum of each layer well, thereby verifying the above hypothesis quantitatively. In addition, we suggest the inclusion of an electron shield to reduce the background.

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Kouichi Hagino, Hirokazu Odaka, Goro Sato, Tamotsu Sato, Hiromasa Suzuki, Tsunefumi Mizuno, Madoka Kawaharada, Masanori Ohno, Kazuhiro Nakazawa, Shogo B. Kobayashi, Hiroaki Murakami, Katsuma Miyake, Makoto Asai, Tatsumi Koi, Greg Madejski, Shinya Saito, Dennis H. Wright, Teruaki Enoto, Yasushi Fukazawa, Katsuhiro Hayashi, Jun Kataoka, Junichiro Katsuta, Motohide Kokubun, Philippe Laurent, Francois Lebrun, Olivier Limousin, Daniel Maier, Kazuo Makishima, Kunishiro Mori, Takeshi Nakamori, Toshio Nakano, Hirofumi Noda, Masayuki Ohta, Rie Sato, Hiroyasu Tajima, Hiromitsu Takahashi, Tadayuki Takahashi, Shin'ichiro Takeda, Takaaki Tanaka, Yukikatsu Terada, Hideki Uchiyama, Yasunobu Uchiyama, Shin Watanabe, Kazutaka Yamaoka, Yoichi Yatsu, Takayuki Yuasa. 2020-11-20. Origin of the in-orbit instrumental background of the Hard X-ray Imager onboard Hitomi. https://doi.org/10.1117/1.jatis.6.4.046003

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