Effects of 241Am standard material powder with different matrices on the determination of gross alpha activity in water
Objective To understand the effects of 241Am standard material powder with different matrices on the determ-ination of gross alpha activity in water,and to provide a reference for the selection and use of alpha standard sources.Methods The alpha counting efficiency of 241Am standard material powder with different matrices was measured by low-background alpha and beta measuring instrument.The radiochemical recovery rate and whole process efficiency of gross al-pha activity in water were determined by spike experiments.Results The alpha counting efficiency of the 241Am standard material powder with four matrices was in the descending order of calcium carbonate,calcium carbonate and silica mixed matrix,calcium sulfate,and silica.The default chemical recovery rate is 1 when gross alpha activity in water is measured by thick source method.The use of 241Am standard material with calcium carbonate as a matrix resulted in about 35%decrease in gross alpha activity,and about 10%deviation was observed using 241Am standard material with silica or calcium carbon-ate and silica mixed matrices.The whole process efficiency of alpha activity in four spiked water samples with 241Am stand-ard solution and 241Am standard material powder with calcium carbonate,silica,or mixed matrix was 6.34%-7.30%.Conclusion Standard materials with different matrices demonstrate different self-absorption of alpha particles and various influence on the chemical recovery.When purchasing and using standard material powders for alpha activity measurement in laboratories,the composition of the matrix should be clarified as much as possible,and the gross alpha activity in water should be determined by measuring the whole process efficiency if necessary.
Gross alpha activity241Am standard materialChemical recoveryWhole process efficiency
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