Improvements in the Evaluation of ~(137)Cs Deposit from Spectra Obtained by Field In Situ NaI ― Spectrometry

摘要

After the decay of other shortlived gamma-emitters ~(137)Cs remained the only important gamma-emitter from the Chernobyl fallout. Its deposition can therefore be successfully studied by field NaI-spectrometry. The conversion factors from the measured dose rate to the deposition depend both on the depth distribution of Cs in soil and the density. The corrections due to the inhomogenity of the soil have been calculated for the conversion factors. The relaxation length z_0 (parameter of the Cs depth distribution) has been estimated from the relative amount of the scattered gamma rays below the Cs peak.