Levels ofCu61,Cu64,Ga67, andGa68Excited by the (p, n) Reaction

Neutron time-of-flight techniques were used to study the ($p, n$) reaction on the nuclei ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{67}{}_{}{}^{}\mathrm{Zn}$, and ${}_{}{}^{68}{}_{}{}^{}\mathrm{Zn}$. The locations of excited states in the residual nuclei were measured with an energy resolution of about 10 keV. The absolute excitation energies are accurate to ±2 keV for low-lying states and to ±5 to 7 keV for the highest states (2-3-MeV excitation). The following results were obtained: ${}_{}{}^{61}{}_{}{}^{}\mathrm{Cu}$, 17 levels (0 to 2.6 MeV); ${}_{}{}^{64}{}_{}{}^{}\mathrm{Cu}$, 66 levels (0 to 2.75 MeV); ${}_{}{}^{67}{}_{}{}^{}\mathrm{Ga}$, 57 levels (0 to 3.3 MeV); and ${}_{}{}^{68}{}_{}{}^{}\mathrm{Ga}$, 32 levels (0 to 1.6 MeV). Comparisons with other information on these nuclei indicate that the ($p, n$) reaction is a very effective tool for locating all the levels. The relative intensities of the neutron groups displayed distinctive patterns. However, quantitative yields of a succession of closely spaced proton energies showed typically 30% fluctuations. To maintain good energy resolution and yet reduce the fluctuations we averaged many individual runs in order to have more meaningful comparisons with the Hauser-Feshbach predictions. Spin assignments were made to 10-20 levels in ${}_{}{}^{64}{}_{}{}^{}\mathrm{Cu}$, ${}_{}{}^{67}{}_{}{}^{}\mathrm{Ga}$, and ${}_{}{}^{68}{}_{}{}^{}\mathrm{Ga}$. The results are generally consistent with other available information on spin parities.