Measurement of the half-life of 79Se with PX-AMS

The half-life of Se-79 has been re-measured with projectile X-rays detection (PXD) in accelerator mass spectrometry after a new PXD system had been set up in China Institute of Atomic Energy (CIAE). The PXD technique has been used for separation of Se-79 from its isobar, Br-79. The detection efficiency of Se-79 K, X-rays is obtained from that of Se-80 after energy correction. The atom number of Se-79 in each sample is deduced from the measured ratios of Se-79/Se. From the measured decay rates of each sample, the half-life is deduced to be (2.80 +/- 0.36) x 105 a. In order to check the reliability of the result of Se-79 half-life, the Se-75 half-life is also measured with PX-AMS method. The measured half-life of 15 Se is in good agreement with well-known literature value. (C) 2002 Elsevier Science B.V. All rights reserved.