A compact and high efficiency GAGG well counter for radiocesium concentration measurements

Seiichi Yamamoto*, Yoshimune Ogata

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


After the Fukushima nuclear disaster, social concern about radiocesium (137Cs and 134Cs) contamination in food increased. However, highly efficient instruments that can measure low level radioactivity are quite expensive and heavy. A compact, lightweight, and reliable radiation detector that can inexpensively monitor low level radiocesium is highly desired. We developed a compact and highly efficient radiocesium detector to detect ∼32 keV X-rays from radiocesium instead of high energy gamma photons. A 1-mm thick GAGG scintillator was selected to effectively detect ∼32 keV X-rays from 137Cs to reduce the influence of ambient radiation. Four sets of 25 mm×25 mm×1 mm GAGG plates, each of which was optically coupled to a triangular-shaped light guide, were optically coupled to a photomultiplier tube (PMT) to form a square-shaped well counter. Another GAGG plate was directly optically coupled to the PMT to form its bottom detector. The energy resolution of the GAGG well counter was 22.3% FWHM for 122 keV gamma rays and 32% FWHM for ∼32 keV X-rays. The counting efficiency for the X-rays from radiocesium (mixture of 137Cs and 134Cs) was 4.5%. In measurements of the low level radiocesium mixture, a photo-peak of ∼32 keV X-rays can clearly be distinguished from the background. The minimum detectable activity (MDA) was estimated to be ∼100 Bq/kg for 1000 s measurement. The results show that our developed GAGG well counter is promising for the detection of radiocesium in food.

Original languageEnglish
Pages (from-to)19-23
Number of pages5
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Publication statusPublished - 2014 Jul 21
Externally publishedYes


  • GAGG
  • Radiocesium
  • Well counter
  • X-ray

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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