Measurement of 137 Sup Cs and 7 Sup Be in Soil

7 Sup Be and 137Cs are two radionuclides present in soil as a result of atmospheric deposition. 137Cs has a half-life of 30.2 years and has been extensively used in soil erosion studies. Although 7 Sup Be has a relatively short half-life of 53 days, the potential of using 7 sup Be in estimating erosion rates, associated with short periods of time or individual events has already been recognised. The objective of this study was to measure the activity concentration of these two isotopes in soil using High Purity Germanium gamma ray spectrometry. Thirty five soil samples from different locations in Sri Lanka have been analysed. MOst of these samples (29) were collected from the Western Province while the rest were from remote locations such as Nuwera Eliya, Wasgamuwa, Girithale and Knackles. The gamma counting wad done using cylindrical and Marrinelli beaker geometries and the spectra were analysed using the software package ANGES developed by the International Atomic Energy Agency (IAEA). The efficiency calibration of the system for the two geometries was carried out using the IAEA standards of different densities