Identification of new germanium isotopes in fission: Decay properties and nuclear charge distribution in the A = 78 to 84 mass region

Abstract

By means of a fast radiochemical separation, germanium was isolated at short time intervals from 235U irradiated with thermal neutrons. By extrapolating γ- or β-activities of known descendants, the half-lives of the following isotopes were determined, several of these being unreported previously: 78 Ga: 4.8±1.3 s, 79 Ge: 41.1±4.3 s, 80 Ge: 24.5±1.0 s, 81 Ge: 10.1±0.8 s, 82 Ge: 4.60±0.35 s, 83 Ge: 1.9±0.4 s, 84 Ge: 1.2±0.3 s . It is shown that 82Ge decays only to the low-spin isomer of 82As whose half-life was redetermined as 22.6±1.4 s. The main γ-ray energies and intensities were measured for the longer-lived isotopes and partial schemes are given for the decay of 81Ge, 81As and 82As. From the relative fission-yield measurements, nuclear-charge distribution is discussed for this mass region.