Standardization of Nal (Tl) Based Gamma Spectrometer for the Environmental Radioactivity Measurements

摘要

The natural radionuclides ~(238)U, ~(232)Th are embedded in geological materials in low quantities, which continuously emit ionizing radiations through the various daughter products of the decay chain. In the present work the performance of the newly installed 4"×4" Nal (Tl) based gamma ray spectrometer in our laboratory was studied for its use in environmental radioactivity measurements. Standard procedure was followed for the collection and preparation of sample for gamma spectrometric measurements. The spectrum was analyzed using a PC based 1 k MCA (winTMCA 32 scinti SPEC). The analysis of complex spectra from the detector due to ~(238)U, ~(232)Th and ~(40)K was carried out by least squares method. The same samples were also analyzed using a high resolution HPGe detector based gamma spectrometer and the results obtained were in agreement, validating the method of analysis of environmental radioactivity using Nal (Tl) detector and subsequent analysis of spectral data by least squares method. It is also important to note that Nal (Tl) detector can be used instead of HPGe detector, which is very costly and difficult to maintain in remote areas.