Gamma Spectra of Non-Enriched Thorium Sources using PIN Photodiode and PMT based Detectors

Jithin Bhagavathi, Swapna Gora, V.V.V. Satyanarayana, O.S.K.S Sastri and B.P Ajith

Central University of Himachal Pradesh

Gamma spectra of non-enriched Thorium Nitrate ThNO 3 salt is studied using an indigenously developed, low-cost portable gamma spectrometer, based on CsI scintillator mated to a PIN photodiode. The results of our study are compared with commercially available detectors based on NaI scintillators coupled to PMT detectors, that come with a certain cost and are bulky. Even though the intensity of various peaks are relatively less prominent in the spectrum obtained with the photodiode detector as compared to the PMT based one under same experimental conditions, longer duration for data collection and analysis using log plots were able to aid in reliable identification of all the dominant peaks in the source. The experiment gives good insights into nuclear radiation processes and various interactions that take place within the detectors. Finally, we repeated the experiment with a sample of Monazite from the sands of Kerala and confirmed the presence of Thorium deposits in it, thus proving the effectiveness of our portable gamma spectrometer for studying environmental radiation.