Design and performance of soft Gamma-ray detector for NeXT mission

H. Tajima, T. Kamae, G. Madejski, T. Mitani, K. Nakazawa, T. Tanaka, T. Takahashi, S. Watanabe, Y. Fukazawa, T. Ikagawa, J. Kataoka, M. Kokubun, K. Makishima, Y. Terada, M. Nomachi, M. Tashiro

Research output: Contribution to journalConference articlepeer-review


The Soft Gamma-ray Detector (SGD) on board NeXT (Japanese future high energy astrophysics mission) is a Compton telescope with narrow field of view (FOV), which utilizes Compton kinematics to enhance its background rejection capabilities. It is realized as a hybrid semiconductor gamma-ray detector which consists of silicon and CdTe (Cadmium Telluride) detectors. It can detect photons in a wide energy band (0.05-1 MeV) at a background level of 5 × 10 -7 counts/s/cm 2/keV; the silicon layers are required to improve the performance at a lower energy band (<0.3 MeV). Excellent energy resolution is the key feature of the SGD, allowing to achieve both high angular resolution and good background rejection capability. An additional capability of the SGD, its ability to measure gamma-ray polarization opens up a new window to study properties of astronomical objects. We will present the development of key technologies to realize the SGD; high quality CdTe, low noise front-end ASIC and bump bonding tecnology. Energy resolutions of 1.7 keV (FWHM) for CdTe pixel detectors and 1.1 keV for Si strip detectors have been measured. We also present the validation of MC simulation used to evaluate the performance of the SGD.

Original languageEnglish
Article numberN14-5
Pages (from-to)314-321
Number of pages8
JournalIEEE Nuclear Science Symposium Conference Record
Publication statusPublished - 2004
Externally publishedYes
Event2004 Nuclear Science Symposium, Medical Imaging Conference, Symposium on Nuclear Power Systems and the 14th International Workshop on Room Temperature Semiconductor X- and Gamma- Ray Detectors - Rome, Italy
Duration: 2004 Oct 162004 Oct 22


  • CdTe
  • Compton Camera
  • Gamma-ray astronomy detectors
  • Polarimetry
  • Silicon radiation detectors

ASJC Scopus subject areas

  • Radiation
  • Nuclear and High Energy Physics
  • Radiology Nuclear Medicine and imaging


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