Investigating the γ decay of Ni65 from particle- γ coincidence data

Abstract

The $\ensuremath{\gamma}$ decay of $^{65}\mathrm{Ni}$ has been studied from particle-$\ensuremath{\gamma}$ coincidence data on the $^{64}\mathrm{Ni}(d,p\ensuremath{\gamma})^{65}\mathrm{Ni}$ reaction. $\ensuremath{\gamma}$-ray spectra at excitation energies below ${E}_{x}\ensuremath{\approx}2\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$ have been studied and compared with previous measurements. Coincidences corresponding to ${E}_{x}\ensuremath{\approx}4.4--6.1\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$ have been used to constrain the shape of the nuclear level density and $\ensuremath{\gamma}$-strength function of $^{65}\mathrm{Ni}$ by means of the Oslo method. The experimental $\ensuremath{\gamma}$-strength function presents an enhancement at $\ensuremath{\gamma}$ energies below ${E}_{\ensuremath{\gamma}}\ensuremath{\approx}3\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$. In addition, a resonance-like structure centered at ${E}_{\ensuremath{\gamma}}\ensuremath{\approx}4.6\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$ is seen together with accumulated strength at ${E}_{\ensuremath{\gamma}}\ensuremath{\approx}2.6--3.6\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$. The obtained results contribute to the systematic study of $\ensuremath{\gamma}$ decay in the Ni isotopes, which is of great interest for the understanding of both single-particle and collective nuclear structure phenomena.