The β decay of the πf5/2 ground state of 77Cu studied with 225 MeV and 0.2 MeV purified radioactive beams

Isobarically purified beams of 77Cu with energies of 225 and 0.2 MeV were used at the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory to study β decay into states in 77Zn. Data taken at 225 MeV allowed the determination of absolute branching ratios relative to the decay of 77Cu for this β decay as well as its daughters. From these we obtained a refined β-delayed neutron emission probability of 30.3(22)% and a probability that the decay proceeds through 77Zng of 49.1(26)%. A total of 64 γ rays were placed in a level scheme for 77Zn containing 35 excited states including one state above the neutron separation energy, whereas two γ rays were observed for the βn branch to states in 76Zn. The growth and decay curves of some prominent γ rays indicate a single β-decaying state with a half-life of 480(9) ms. The decay pattern for 77Cu, with observed feeding of 8(3)% to 7/2+ 77Zng and 6(3)% to 1/2- 77Znm, in contrast to the large feeding observed for decay of πp3/2 73Cug to 1/2- 73Zng, strongly suggests a πf5/2 ground state for the studied 77Cu activity.