Determination of Radioactivity Purity of Solid ~(219)Rn Source byγ-ray Spectrometry

Radioactivity purity of the solid 219Rn source made using 227Ac extracted from uranium ore were determined byγ-spectrometry.The activities of 227Th,223 Ra,219Rn and 211 Bi produced by the decay of 227Ac and the contents of 226 Ra,224 Ra which generates222 Rn,220Rn to affect the purity of actinide in this source were analyzed after 227 c in radioactive equilibrium with its daughter nuclides.The γ-ray energy used for the determination of these daughter nuclides of 227 c are 235.97,256.25 keV for 227Th,154.21 keV for 223 Ra,401.81 keV for 219Rn,and 351.059 keV for 211 Bi.Through the analysis,the results are acquired that their activities are(1 069±3),(1 079±5),(1 095±13),(1 096±14)and(11 089±4)Bq respectively,and the average activity of solid 219Rn source is(1 093±8)Bq.The activities of 226 Ra and 224 Ra in this source are5.12 Bq and 0.433 Bq respectively by theγ-ray energy as follows:238.632 keV of212Pb,583.191 keV of 208 Tl for 224 Ra,and 609.312,1 120.287 keV of 214 Bi for 226 Ra,as they are all far below(1 093±8)Bq,so the radioactivity purity of the solid 219Rn source is very high.The results show that the solid 219Rn source can be developed to the standards for the efficiency calibration of the delayed coincidence counting system.