Improvements in calibration of GSO scintillators in the Suzaku hard X-ray detector

Shin'Ya Yamada, Kazuo Makishima, Kazuhiro Nakazawa, Motohide Kokubun, Madoka Kawaharada, Takao Kitaguchi, Shin Watanabe, Hiromitsu Takahashi, Hirofumi Noda, Hiroyuki Nishioka, Kazuyoshi Hiragi, Katsuhiro Hayashi, Kenta Nakajima, Makoto Tashiro, Makoto Sasano, Sho Nishino, Shunsuke Torii, Soki Sakurai, Tadayuki Takahashi, Tsunefumi MizunoTeruaki Enoto, Takayuki Yuasa, Takaaki Tanaka, Tomomi Kouzu, Toshio Nakano, Yasushi Fukazawa, Yukikatsu Terada, Yasunobu Uchiyama, Wataru Iwakiri

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Improvements of the in-orbit calibration of GSO scintillators in the Hard X-ray Detector aboard Suzaku are reported. To resolve an apparent change in the energy scale of GSO, which appeared across the launch for unknown reasons, consistent and thorough re-analyses of both pre-launch and in-orbit data have been performed. With laboratory experiments using spare hardware, the pulse-height offset, corresponding to zero energy input, was found to change by ∼0.5% of the full analog voltage scale, depending on the power supply. Furthermore, by carefully calculating all of the light outputs of secondaries from activation lines used in the in-orbit gain determination, their energy deposits in GSO were found to be effectively lower, by several percent, than their nominal energies. Taking both of these effects into account, the in-orbit data agree with the on-ground measurements within ∼5%, without employing the artificial correction introduced in previous work (Kokubun et al. 2007, PASJ, 59, S53). With this knowledge, we updated the data processing, the response, and the auxiliary files of GSO, and reproduced the HXD-PIN and HXD-GSO spectra of the Crab Nebula over 12-300 keV by a broken power-law with a break energy of ∼110 keV.

Original languageEnglish
Pages (from-to)S645-S656
JournalPublications of the Astronomical Society of Japan
Issue numberSPEC. ISSUE 3
Publication statusPublished - 2011 Nov 25
Externally publishedYes


  • Instrumentation: Detectors
  • X-rays: General
  • X-rays: Individual (Crab Nebula)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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