Beta-decay study of ^79-81Cu using VANDLE

Beta-decays of neutron-rich Cu isotopes with N≥50 carry information on the major neutron-orbit spin partners expected in the beta-decay of doubly-magic ⁷⁸Ni [1]. The decay of Cu nuclei with N>50 is also impacted by the N=50 shell gap. These nuclei are strong beta-delayed neutron emitters and the energy distribution of the neutrons becomes vital to studying the beta-decay to neutron-unbound states.

An experiment was performed at RIBF, Japan, aiming to measure the energy of beta-delayed neutrons from the nuclei in the ⁷⁸Ni region using time-of-flight spectroscopy with VANDLE [2] and YSO implantation detector [3]. In this contribution, the first measurement of the beta-decay strength to neutron-unbound states in the beta decay of ⁷⁹Cu is reported. Furthermore, the results are compared to the prediction of the shell-model calculation using NuShellX [4]. Finally, the model in agreement with the experiment is used to predict the beta decay of ⁷⁸Ni.