加速器质谱中心知识库

The key to effective Be-10 measurements by AMS is to efficiently suppress the interference of the isobar B-10 and at the same time optimize Be-10 transmission. In this work, a new approach of measuring Be-10 by AMS has been studied. It uses the super-halogen anion of beryllium, BeF3-, which inherently suppresses B-10 interference by nearly 5 orders of magnitude because the accompanying BF3- anion is rarely formed. The resulting B-10 suppression factor is not as high as that achieved with energy degrader foils, but the B-10 and Be-10 separation in the final ionization detector was found to result in sufficient total B-10 suppression for Be-10(2+) to be counted directly at similar to 6 MeV energies. Although the stripping yield from (BeF3-)-Be-10 to Be-10(2+) is not as large as that from (BeF3-)-Be-10, this inefficiency is compensated by avoiding the reduction in transmission due to charge fraction splitting and optical transmission losses after the degrader foil. This paper summarizes our first observation of the direct Be-10(2+) counting approach using the 3 MV multi-element system at the Xi'an AMS. (C) 2015 Elsevier B.V. All rights reserved.