Kyoto's event-driven x-ray astronomy SOI pixel sensor for the FORCE mission

Takeshi G. Tsuru, Hideki Hayashi, Katsuhiro Tachibana, Soudai Harada, Hiroyuki Uchida, Takaaki Tanaka, Yasuo Arai, Ikuo Kurachi, Koji Mori, Ayaki Takeda, Yusuke Nishioka, Nobuaki Takebayashi, Shoma Yokoyama, Kohei Fukuda, Takayoshi Kohmura, Kouichi Hagino, Kenji Ohno, Kohsuke Negishi, Keigo Yarita, Shoji KawahitoKeiichiro Kagawa, Keita Yasutomi, Sumeet Shrestha, Shunta Nakanishi, Hiroki Kamehama, Hideaki Matsumura

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

10 Citations (Scopus)


We have been developing monolithic active pixel sensors, X-ray Astronomy SOI pixel sensors, XRPIXs, based on a Silicon-On-Insulator (SOI) CMOS technology as soft X-ray sensors for a future Japanese mission, FORCE (Focusing On Relativistic universe and Cosmic Evolution). The mission is characterized by broadband (1-80 keV) X-ray imaging spectroscopy with high angular resolution (< 15 arcsec), with which we can achieve about ten times higher sensitivity in comparison to the previous missions above 10 keV. Immediate readout of only those pixels hit by an X-ray is available by an event trigger output function implemented in each pixel with the time resolution higher than 10 μsec (Event-Driven readout mode). It allows us to do fast timing observation and also reduces non-X-ray background dominating at a high X-ray energy band above 5{10 keV by adopting an anti-coincidence technique. In this paper, we introduce our latest results from the developments of the XRPIXs. (1) We successfully developed a 3-side buttable back-side illumination device with an imaging area size of 21.9 mm × 13.8 mm and an pixel size of 36 μm × 36 μm. The X-ray throughput with the device reaches higher than 0.57 kHz in the Event-Driven readout mode. (2) We developed a device using the double SOI structure and found that the structure improves the spectral performance in the Event-Driven readout mode by suppressing the capacitive coupling interference between the sensor and circuit layers. (3) We also developed a new device equipped with the Pinned Depleted Diode structure and confirmed that the structure reduces the dark current generated at the interface region between the sensor and the SiO2 insulator layers. The device shows an energy resolution of 216 eV in FWHM at 6.4 keV in the Event-Driven readout mode.

Original languageEnglish
Title of host publicationHigh Energy, Optical, and Infrared Detectors for Astronomy VIII
EditorsAndrew D. Holland, James Beletic
ISBN (Print)9781510619715
Publication statusPublished - 2018
EventHigh Energy, Optical, and Infrared Detectors for Astronomy VIII 2018 - Austin, United States
Duration: 10 Jun 201813 Jun 2018

Publication series

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


ConferenceHigh Energy, Optical, and Infrared Detectors for Astronomy VIII 2018
CountryUnited States


  • FORCE mission
  • Imaging
  • SOI Pixel Sensors
  • Spectroscopy
  • X-rays

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