Half-life of the 15/2+ state of i 135: A test of E2 seniority relations

Abstract

The half-life of the 15/21+ state of the 3-valence-proton nucleus I135 has been measured to be 1.74(8) ns using the EXILL-FATIMA mixed array of Ge and LaBr3 detectors. The nuclei were produced following the cold neutron-induced fission of a U235 target at the PF1B beam line of the Institut Laue-Langevin. The extracted B(E2;15/2+→11/2+) value enabled a test of seniority relations for the first time between E2 transition rates. Large-scale shell-model calculations were performed for Te134 and I135, and reinterpreted in a single-orbit approach. The results show that the two-body component of the E2 operator can be large whereas energy shifts due to the three-body component of the effective interaction are small.