The $\beta$ and delayed-neutron decay properties of neutron rich $^{76-79}$Cu

Results of studies performed at the HRIBF on the $\beta$-decay of $^{76-79}$Cu isotopes are reported. Transmission through a charge exchange cell and isobar separator removed Zn from the ISOL beams and allowed fine tuning to obtain higher Cu concentrations. The $\beta$-delayed neutron probabilities of $^{76}$Cu and $^{77}$Cu were deduced from comparison of the intensities of $\gamma$ rays in the Zn daughter isotopes and found to be 4(1)\% and 38(4)\%, respectively. For $^{78}$Cu, the yrast decay sequence transitions at 730, 891, and 907 keV suggest the highest feeding is to the $6^+$ state with no population of the $8^+$ isomer. For the r-process critical nuclide $^{79}$Cu we observed for the first time the 730 keV $\gamma$ ray from the delayed-neutron branch thus solidifying this transition as the $2^+ \rightarrow 0^+$ transition in $^{78}$Zn.