Experimental Study of Gamma-Ray Spectra Using Natural Radioactivity

This paper proposes an experimental teaching scheme of gamma energy spectrum based on natural radionuclides to replace traditional artificial radioactive sources (such as 137Cs, 60Co). The experiment utilized 176Lu in lutetium oxide and 40K in potassium chloride as natural gamma-ray sources. Analysis indicated that the radioactive activity of the materials used in the experiment was far below the upper limit for exempted radioactive source activities stipulated by national standards, and there was no radiation safety risk. Energy spectra were collected using a NaI (Tl) scintillation spectrometer. The energy spectrum characteristics of 176Lu (88keV, 202keV, 307keV) and 40K (1461keV) were analyzed, and multi-peak energy calibration was completed (linear correlation coefficient >0. 999). The experiment further measured and analyzed the environmental radioactive background energy spectrum and the absorption characteristics of copper sheets for gamma rays. The linear attenuation coefficient was measured accurately (relative standard uncertainty<5%). The research results show that natural radioactive materials can effectively support the teaching of gamma energy spectrum experiments, expand the content of traditional gamma energy spectrum experiments, lower the threshold for setting up experiments for colleges and institutions without radioactive source qualifications, and provide safe and economical experimental solutions.