Development of wideband X-ray and gamma-ray spectrometer using transmission-type, large-area APD

S. Tanaka, J. Kataoka, Y. Kanai, Y. Yatsu, M. Arimoto, M. Koizumi, N. Kawai, Y. Ishikawa, S. Kawai, N. Kawabata

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


The avalanche photodiode (APD) is a high-performance and compact light sensor recently applied in various fields of experimental physics. Among several types of APDs, the reach-through APD offers an advantage in direct X-ray detection, thanks to its thick depletion layer (≥ 100 μ m) in front of the amplification region. This type of APD is also sensitive to weak scintillation light from gamma-ray scintillators with a high quantum efficiency of ∼ 80 % (at λ ≃ 500 nm). In this paper, we propose a novel design of a compact X-ray-to-gamma-ray detector widely applicable between 1 keV and several hundreds of keV. The prototype consists of a reach-through APD (transmission type) optically coupled with a cubic CsI(Tl) crystal 4 × 4 × 4 mm3 in size. By applying the pulse shape discrimination technique to the APD output, we successfully discriminated the X-ray signals directly detected within the APD (1-40 keV), and gamma-ray signals absorbed in a CsI(Tl) scintillator (10-800 keV) located immediately behind the APD. Optimum FWHM energy resolutions of 15.1 ± 0.2 %, 6.6 ± 0.4 %, and 7.6 ± 0.1 % were obtained for 5.9 keV X-rays, 32 keV X-rays, and 662 keV gamma rays, respectively, measured at + 20 {ring operator} C. This stacked configuration is viable for various future applications in space science and nuclear medicine.

Original languageEnglish
Pages (from-to)562-568
Number of pages7
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Issue number2
Publication statusPublished - 2007 Nov 21
Externally publishedYes


  • Avalanche photodiode
  • Gamma-rays
  • Pulse shape discrimination
  • Scintillation detection

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


Dive into the research topics of 'Development of wideband X-ray and gamma-ray spectrometer using transmission-type, large-area APD'. Together they form a unique fingerprint.

Cite this