Level structures of 91Rb and 91Sr as populated in beta decay

Abstract

The decay of 7.9 s 91Kr and its 58 s daughter 91Rb have been studied with Ge(Li) plastic and NaI(Tl) detectors, singly and in coincidence, to determine the properties of states in 91Kr, 91Rb, and 91Sr. The energies and intensities of 9 gamma rays following the decay of 91Kr have been measured, locating levels at excitations of 0.1086, 0.5068, 0.7218, and 1.6154 MeV in91Rb. β–γ coincidence measurements involving the 0.1086, 0.5068, and 0.6132 MeV transitions have established the 91Kr – 91Rb mass differences as 5.08 ± 0.10 MeV.The energies and intensities of 36 gamma rays following the decay of 91Rb have been measured, identifying levels in 91Sr at 0.0931, 0.4392, 1.0414, 1.2306, 1.9426, 2.0643, 2.344, 2.6574, 2.9257, 3.6932, 3.737, 3.752, 3.935, 4.0785, 4.252, 4.265, and 4.497 MeV. The lifetime of the 0.093 MeV state is 91 ± 3 ns. The states at 2.6574, 3.6932, 4.0785, and 4.265 have negative parity.