Remeasurement of the Half-Life of ⁷⁹Se with the Projectile X-Ray Detection Method

Remeasurement of the half-life of ⁷⁹Se has been carried out with the projectile x-ray detection (PXD) in accelerator mass spectrometry. We made two major improvements over our earlier ⁷⁹Se half-life determination Nucl. Instrum. Methods B 123 (1997) 403. Fristly, the PXD technique has been used for separation of ⁷⁹Se and ⁷⁵Se from ⁷⁹Br and ⁷⁵As isobars respectively. Secondly, the half-life of ⁷⁹Se has been measured relative to the known precise half-life of ⁷⁵Se (119.79 ± 0.04d). A more reliable half-life of ⁷⁹Se measured with the PXD technique is (2.95 ± 0.38)x10⁵y, about a factor of one lower than the previous value, 1.1 x 10⁶y. The problems in the previous measurement are discussed.