Speaker
Description
For the analysis natural radionuclides, gamma spectroscopy, alpha spectroscopy and liquid scintillation counter(LSC) were used. Among them, LSC was widely used because it can be applied alpha, beta and gamma emitting nuclides. But some low activity nuclides are not analyzed because most of the LSC used 20 mL vial. Therefore, some radionuclide, such as H-3, are needed concentration. To improve detection limit of the LSC, high volume LSC was used and performance was studied. LSC-LB7 was a unique detector structure with the vial up to 145 ml, three photomultiplier tubes, and reducing the effects of external radiation by the guard counter, anti-coincidence signal detection and massive layer of lead. Direct measurement is ensured without pre-processing, such as electrolytic enrichment, for ultra-low level H-3 measurement in the environmental samples. The counting efficiency, figure of merit(FOM) and MDA were compared conventional 20 mL vial used LSC. Counting efficiency was decreased due to the high volume but FOM and MDA was increased by using more than 7 times high volume used. The blank background was 2.18 ± 0.12 cpm when 145 mL vial was used. For the analysis of H-3, dead water and UltimGold LLT was used and 4.00 ± 0.29 cpm and 3.42 ± 0.97 cpm background were acquired when 145 mL and 20 mL vial was used.
