A New Half-Life Value of 79 Se

In the recent charts of the nuclides an accepted half-life of 79Se is only an upper limit, < 6.5 × 104 a. In this letter, A new half-life of 79Se has been measured to be (1.13 ± 0.17) × 106 a. 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.