Application of a CZT detector to in-situ environmental radioactivity measurement in Fukushima area

Kowatari, Munehiko; Kubota, Takumi*; Shibahara, Yuji*; Fujii, Toshiyuki*; Takamiya, Koichi*; Mizuno, Satoshi*; Yamana, Hajimu*

Instead of conventional Ge semiconductor detectors and NaI(Tl) scintillation spectrometers, an application of a CZT whose crystal has the dimension of 1 cm cubic semiconductor to the in-situ environmental radio-activity measurement was attempted in deeply affected areas in Fukushima region. A CZT detector does not have such a high resolution of peaks, comparing a Ge detector. However, it is found that a CZT has enough characteristics to properly determine radio-activity of Cs and Cs in soil, throughout the in-situ measurement campaign in deeply affected area within 5 km from the Fukushima Dai-ichi Nuclear Power Plant, where dose rates exceed 50 Sv h. Results of radioactivity concentration in soil ranged between 1 and 500 kBq m and seem consistent to those obtained by the air-borne measurement.