The measurement system for Doppler broadening profiles with the coincidence technique using a NaI detector in colinear geometry with a Ge detector was developed. The principle of measurement system with the coincidence technique between the NaI detector and the Ge detector was described. Application of the system for the detection of vacancy-type defects introduced by electron irradiation in Czochralski- (Cz) grown Si was shown. Detail in the difference between the Doppler broadening profiles for Cz-Si and Si grown by the floating-zone method was also obtained.
The concentrations of 137Cs in water, sediment and fishes at the pond in Saitama prefecture were determined in order to elucidate the radioecology of 137Cs in limnological ecosystems. 137Cs concentration in water was 0.31±0.002 mBq/l (mean±standard error), and so indicated about 3 times higher than that (0.10mBq/l) for the river in our previous report. 137Cs concentrations in sediment, carp, Cyprinus carpio, crucian carp, Carassius auratus cuvieri, and Hakuren, Hypophthalmichthys molitrix, were about 20000, 1200, 2 400 and 3100 times higher than that of the water, respectively. These concentrations were higher than those of each sample for the river in our previous report. It was so suggested that137 Cs tended to be accumulated in these samples at the pond more than the nuclide in the river. Moreover, concentration ratios, concentration of137Cs in sediment, crucian carp and Hakuren to that of the water, were about 30, 2 and 3 times higher than these of 40K, respectively, except for carp of which 137Cs and40K concentration ratios were almost same. These results showed difference in accumulation mechanism between137Cs and40K in these samples, as well as137Cs transfer mechanism in the limnological ecosystems in part.