Loss free counting using digital γ-ray spectrometer for short lived radionuclides and its applications to NAA

A loss-free counting system with digital spectrometer was used for γ-ray measurements in rapidly varying dead time condition. This spectrometer is designed for counting sample at higher dead time experienced for short lived radionuclides of activation and fission products. Dead time correction for long-lived nuclides with constant dead time is done by live time counting mode, whereas for varying dead time during counting the live time counting mode does not work properly. ORTEC's digital spectrometer with zero dead time (ZDT) mode is reported to work for both long-lived and short-lived radionuclides. The instrument was tested for its applicability for long-lived radionuclides using 60Co (radionuclides of interest) and 57Co and 22Na (dead time sources). The count rates of 1173 and 1332 keV of 60Co were found constant in dead time ranges of 2-80%. The spectrometer is being used for counting the samples obtained after irradiation in pneumatic carrier facilities (PCF) of Dhruva and CIRUS reactors