A New Half-Life Value of ⁷⁹Se

In the recent charts of the nuclides an accepted half-life of ⁷⁹Se is only an upper limit, < 6.5 x 10⁴ a. In this letter, A new half-life of ⁷⁹Se has been measured to be (1.13 ± 0.17) x 10⁶a. The number of ⁷⁹Se atoms was determined from measured ⁷⁹Se /Se ratios with the accelerator mass spectrometry technique and the decay rate of ⁷⁹Se was determined by counting the emitted β rays with a liquid scintillation spectrometer.