The accelerator mass spectrometry（AMS） is an effective method for the determination of the half-life of long-lived radionuclides. In this paper, we report a method for measurement of the half-life of ^79Se. The numb...The accelerator mass spectrometry（AMS） is an effective method for the determination of the half-life of long-lived radionuclides. In this paper, we report a method for measurement of the half-life of ^79Se. The number of ^79Se atoms was determined from measured ^79Se/Se absolute ratios with the AMS system at the China Institute of Atomic Energy and the decay rate of ^79Se was determined by counting the emitted β-rays with a liquid scintillation spectrometer. The major improvements of our measurements include using the high abundance of an ^79Se sample which was cooled for many years to exclude the interference of short-lived nuclides, the extraction of SeO-2molecular ions, that results in a suppression of the ^79Br background by as much as about five orders of magnitude. Also, an AMS measurement of the absolute ratio of ^79Se/Se was developed to avoid systematic errors. The results show that ^79Se/Se is（2.35±0.12）×10^-7in the reference sample and the radioactivity of ^79Se is（1.24±0.05） Bq/g, so the half-life of ^79Se is（2.78±0.18）×10^5a.展开更多
基金Supported by National Natural Science Foundation of China(11175266)
文摘The accelerator mass spectrometry（AMS） is an effective method for the determination of the half-life of long-lived radionuclides. In this paper, we report a method for measurement of the half-life of ^79Se. The number of ^79Se atoms was determined from measured ^79Se/Se absolute ratios with the AMS system at the China Institute of Atomic Energy and the decay rate of ^79Se was determined by counting the emitted β-rays with a liquid scintillation spectrometer. The major improvements of our measurements include using the high abundance of an ^79Se sample which was cooled for many years to exclude the interference of short-lived nuclides, the extraction of SeO-2molecular ions, that results in a suppression of the ^79Br background by as much as about five orders of magnitude. Also, an AMS measurement of the absolute ratio of ^79Se/Se was developed to avoid systematic errors. The results show that ^79Se/Se is（2.35±0.12）×10^-7in the reference sample and the radioactivity of ^79Se is（1.24±0.05） Bq/g, so the half-life of ^79Se is（2.78±0.18）×10^5a.
