𝛽 decay of neutron-rich 76Cu and the structure of 76Zn

Abstract

The 𝛽 decay of 76Cu to the levels of 76Zn was studied at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Lab (ORNL). A purified 76Cu beam was developed and data were recorded for the decay of the 𝐴=76 decay chain using four high-purity germanium (HPGe) clover detectors at the Low-energy Radioactive Ion Beam Spectroscopy Station (LeRIBSS). In this measurement, data on γ-ray emission following 𝛽 decay, including 𝛽⁢𝛾 and 𝛾⁢𝛾 coincidences, were collected and 𝛾⁢𝛾 spectra were analyzed to identify the statistically significant coincidences. From this analysis, we propose a level scheme for 76Zn which contains a total of 59 energy levels up to 6.0 MeV containing 105 𝛾 rays. We have identified an additional 53 𝛾 rays associated with this decay which could not be place in the decay scheme due to insufficient coincidence information or no energy match to identified levels. No 𝛾 rays from states in 75Zn fed in the delayed-neutron branch were observed even though other 𝛾 rays in the 𝐴=75 decay chain were observed. Spin and parity assignments are proposed for some levels based on comparison to systematics and shell model calculations.