Simple method for measurement of radioactivity of cesium-134

Hirade, Tetsuya  ; Sakai, Hiroaki; Minei, Shuntaro

After the TEPCO Fukushima Nuclear power plant accident, there are several radio isotopes released from the plant. To detect these radioisotopes, photo-peaks on the energy spectra obtained by HPGe semiconductor detectors or scintillation detectors are used. The detection efficiency is in invers proportion to square of the distance between the detector and the radioisotopes. Therefore the detector and the sample must be inside of the heavy and expensive shield box made of lead. Cs-134 is the only radioisotope emitting several -rays in our environment, now. In the case of the simultaneous measurement of the -rays from Cs-134, the detection efficiency can be in invers proportion to the fourth power of the distance, and hence the shield is not needed. Therefore, this method can be applied not just in laboratory.