Study on AMS Measurement of ⁷⁹Se

As there is no ⁷⁹Se standard sample for measurement of ⁷⁹Se, the characterizations of ⁷⁹Se are conducted by isotope ratio of ⁷⁸Se/Se or ⁸⁰Se/Se since the abundances of ⁷⁸Se and ⁸⁰Se are well known. However, beams of ⁷⁸Se and ⁸⁰Se both exceed the upper limit of semiconductor detector resulting in measurement failure. As a result, attenuators were introduced into the CIAEAMS system with the aim to measure the ⁷⁹Se. The results indicate that the beam of ⁷⁸Se and ⁸⁰Se is decreased into the detecting range of semiconductor detector by two attenuators, which would improve measurement sensitivity and efficiency significantly. In addition, the uncertainty of measurement is reduced greatly and it lays the foundation for the accuracy measurement of the half life of ⁷⁹Se.