TY - JOUR
T1 - Origin of the in-orbit instrumental background of the Hard X-ray Imager onboard Hitomi
AU - Hagino, Kouichi
AU - Odaka, Hirokazu
AU - Sato, Goro
AU - Sato, Tamotsu
AU - Suzuki, Hiromasa
AU - Mizuno, Tsunefumi
AU - Kawaharada, Madoka
AU - Ohno, Masanori
AU - Nakazawa, Kazuhiro
AU - Kobayashi, Shogo B.
AU - Murakami, Hiroaki
AU - Miyake, Katsuma
AU - Asai, Makoto
AU - Koi, Tatsumi
AU - Madejski, Greg
AU - Saito, Shinya
AU - Wright, Dennis H.
AU - Enoto, Teruaki
AU - Fukazawa, Yasushi
AU - Hayashi, Katsuhiro
AU - Kataoka, Jun
AU - Katsuta, Junichiro
AU - Kokubun, Motohide
AU - Laurent, Philippe
AU - Lebrun, François
AU - Limousin, Olivier
AU - Maier, Daniel
AU - Makishima, Kazuo
AU - Mori, Kunishiro
AU - Nakamori, Takeshi
AU - Nakano, Toshio
AU - Noda, Hirofumi
AU - Ohta, Masayuki
AU - Sato, Rie
AU - Tajima, Hiroyasu
AU - Takahashi, Hiromitsu
AU - Takahashi, Tadayuki
AU - Takeda, Shin'Ichiro
AU - Tanaka, Takaaki
AU - Terada, Yukikatsu
AU - Uchiyama, Hideki
AU - Uchiyama, Yasunobu
AU - Watanabe, Shin
AU - Yamaoka, Kazutaka
AU - Yatsu, Yoichi
AU - Yuasa, Takayuki
N1 - Funding Information:
We acknowledge all the Hitomi team members, including many graduate students, for their great contributions to the HXI and the Hitomi project. We acknowledge the support of Ministry of Education, Culture, Sports, Science, and Technology/Japan Society for the Promotion of Science (JSPS)/ KAKENHI under Grant Nos. 24105007, 15H03639, 25287059, 24244014, and 16H02170, and the JSPS Core-to-Core Program. All the members from the U.S. acknowledge support received from the NASA Science Mission Directorate. Stanford and Stanford Linear Accelerator Center (SLAC) members acknowledge support via Department of Energy contract to SLAC National Accelerator Laboratory DE-AC3-76SF00515 and NASA under Grant No. NNX15AM19G. French members acknowledge support from the Centre National d’Etudes Spatiales.
Publisher Copyright:
© The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
PY - 2020/10/1
Y1 - 2020/10/1
N2 - Understanding and reducing 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) onboard the Hitomi satellite provide useful information on the background components due to its multilayer configuration with different atomic numbers: The HXI consists of a stack of four layers of Si (Z = 14) detectors and one layer of cadmium telluride (CdTe) (Z = 48, 52) detector surrounded by well-Type Bi4Ge3O12 active shields. Based on the observational data, the backgrounds of the 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 quantitatively verifying the above hypothesis. In addition, we suggest the inclusion of an electron shield to reduce the background.
AB - Understanding and reducing 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) onboard the Hitomi satellite provide useful information on the background components due to its multilayer configuration with different atomic numbers: The HXI consists of a stack of four layers of Si (Z = 14) detectors and one layer of cadmium telluride (CdTe) (Z = 48, 52) detector surrounded by well-Type Bi4Ge3O12 active shields. Based on the observational data, the backgrounds of the 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 quantitatively verifying the above hypothesis. In addition, we suggest the inclusion of an electron shield to reduce the background.
KW - ASTRO-H
KW - Hitomi
KW - background
KW - hard x-ray imager
KW - hard x-rays
KW - simulation
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U2 - 10.1117/1.JATIS.6.4.046003
DO - 10.1117/1.JATIS.6.4.046003
M3 - Article
AN - SCOPUS:85098732976
SN - 2329-4124
VL - 6
JO - Journal of Astronomical Telescopes, Instruments, and Systems
JF - Journal of Astronomical Telescopes, Instruments, and Systems
IS - 4
M1 - 046003
ER -