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

作者：Yamamoto Seiichi^*; Ogata Yoshimune

来源：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment , 2014, 753: 19-23.

DOI：10.1016/j.nima.2014.03.030

• GAGG
• Well counter
• Radiocesium
• X-ray

After the Fukushima nuclear disaster, social concern about radiocesium (Cs-137 and Cs-134) 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 rathocesium is highly desired. We developed a compact and highly efficient radiocesium detector to detect similar to 32 keV X-rays from radiocesium instead of high energy gamma photons. A 1-mm thick GAGG scintillator was selected to effectively detect similar to 32 keV X-rays from Cs-137 to reduce the influence of ambient radiation. Four sets of 25 mm x 25 mm x 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 similar to 32 keV X-rays. The counting efficiency for he X-rays from radiocesium (mixture of Cs-137 and Cs-134) was 4.5%. In measurements of the low level rathocesium mixture, a photo-peak of similar to 32 keV X-rays can clearly be distinguished from the background. The minimum detectable activity (MDA) was estimated to be similar to 100 Bq/kg for 1000s measurement. The results show that our developed GAGG well counter is promising for the detection of radiocesium in food.

• 出版日期2014-7-21