Effects on hard x-ray response of a double-sided Si strip detector caused by interstrip surface charge

Katsuma Miyake, Shinya Saito, Toshio Nakano, Kouichi Hagino, Shogo Kobayashi, Kazufumi Okuda, Taketo Miura, Goro Sato, Shin Watanabe, Motohide Kokubun, Kazuhiro Nakazawa, Shinichiro Takeda, Hiroyasu Tajima, Yasushi Fukazawa, Tadayuki Takahashi

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Citation (Scopus)

Abstract

We studied a surface effect of Double-sided Si Strip Detectors (DSSDs) in order to apply it for imaging spectroscopy of X-ray photons down to 5 keV for the first time. The Japanese cosmic X-ray satellite Hitomi, launched in February 2016, is equipped with the Hard X-ray Imager (HXI), which employs the DSSDs in 5-80 keV. In such a low energy band, the surface effect is non-negligible. When interstrip regions of p-side are irradiated, the DSSD sometimes show signals with negative pulse heights, presumably caused by positive surface charges between Si and SiO2 layers.1{5 The effect modifies the X-ray response of the HXI towards its low-energy end, below ∼ 10 keV. By irradiating the DSSD with uncollimated mono-energetic X-rays of different energies, we measured the fraction of the negative events to be 2% at 26.4 keV and 30% at 6.0 keV. Using an 8 keV colli- mated X-ray beam, we directly verified that the negative events originated from the interstrip gaps on the p-side where the SiO2 layers exist. The measured energy- and position- dependences can be modeled by assuming that the negative events are produced in approximately 25 μm deep and 120 μm wide interstrip regions. When the bias voltage are halved (from 350 V to 180 V), fraction of the negative events increased by a factor of ∼ 1:7, qualitatively consistent with this picture.

Original languageEnglish
Title of host publicationHard X-Ray, Gamma-Ray, and Neutron Detector Physics XVIII
EditorsArnold Burger, Stephen A. Payne, Larry A. Franks, Ralph B. James, Ralph B. James, Michael Fiederle
PublisherSPIE
ISBN (Electronic)9781510603271
DOIs
Publication statusPublished - 1 Jan 2016
EventSPIE Conference on Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVIII - San Diego, United States
Duration: 29 Aug 201631 Aug 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9968
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceSPIE Conference on Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVIII
CountryUnited States
CitySan Diego
Period29/08/1631/08/16

Keywords

  • DSSD
  • Hitomi
  • X-ray
  • detector
  • silicon

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