The quantitative analysis of uranium and thorium in soil using HPGe gamma-ray spectrometry

Alpha spectrometry and ICP-MS (Inductively Coupled Plasma Mass Spectrometry) have been widely used to determine the radio-activities of 238U and ²³²Th. Even though these methods are useful to assess low level radioisotopes, several pretreatment are required to know the amounts of nuclides in the soil. HPGe gamma-ray spectrometry needs simple preparation to determine the quantitative analysis of uranium and thorium by measuring their decay products in the soil. According to the decay schemes of ²³⁸U and ²³²Th, the daughter nuclides are ²¹⁴Pb, ²¹⁴Bi, and ²²⁸Ac. They should be measured using gamma-ray spectrometry to use secular equilibrium. The purpose of this study is to perform the quantitative analysis of the concentration of ²³⁸U and ²³²Th in the soil using HPGe gamma-ray detector. The experiment was carried out to know the activities of ²³⁸U and ²³²Th using Absolute Method. There are several advantages to use HPGe detector instead of alpha spectrometry. The sample for gamma-ray spectrometry does not need complicated pretreatment processes comparing with the alpha spectrometry, which makes lots of waste. However, it is required to compare the quantitative analysis of uranium and thorium using alpha spectrometry with our results. Because the natural soil used for our experiment had low level radioactivity and uncertainty