Preparation Method of Gamma-ray Disk Source Using Commercially Available Chemical Reagents

An estimation method of detection efficiencies for γ-ray spectrometry has been developed using standard sources consisting of natural radionuclides of 40K and 176Lu included in commercially available chemical reagents. The γ-ray standard source was prepared in the shape of membrane disk by dropping aqueous solution of KCl or Lu2O3 and gelatin reagents on a glass fiber membrane. Detection efficiencies were calculated using both areas of photo peaks in γ-ray spectra and weights of the chemical reagents. Detection efficiencies in the energy range from 202 to 1461 keV can be obtained by determination of the standard source. Experimental results of activity concentrations in radioactive standard materials were in good agreement with the certified value. The present method using the γ-ray disk source was applicable to determination for short-lived radionuclides in rainwater sample collected on the chelating resin disk. The method enables to estimate activities of several radionuclides in environmental samples outside a radiation controlled area.