Efficiency calibration of Ge detector for I and Cs in soil samples and a simplified calculation of cascade summing corrections for volume source

Asai, Masato  ; Kaneya, Yusuke*; Sato, Tetsuya   ; Tsukada, Kazuaki  ; Oe, Kazuhiro; Sato, Nozomi; Toyoshima, Atsushi

To measure radioactivities in soil contaminated by the accident of the Fukushima Daiichi Nuclear Power Plant, efficiency calibration of Ge detectors for I, Cs, and Cs in volume sources was investigated. -ray detection efficiencies for these nuclei were determined precisely using standard soil samples containing Cs, Cs, Hf, and Zr. These standard sources were prepared by admixing radioactive solutions with soil, and point sources were made from the same solutions to determine their radioactivity concentrations. Cascade summing corrections for rays of Cs in soil samples were evaluated experimentally. To easily calculate the cascade summing corrections for volume sources, we examined a simplified method using averaged efficiencies, and evaluated its validity through a comparison of the calculated correction factors with the experimental ones.