Collective enhancement in nuclear level density of Ga72 and Ga71 from γ

The $\ensuremath{\gamma}$-gated proton spectra measured in the reactions $^{64}\mathrm{Ni}(^{9}\mathrm{Be},\mathrm{p}2\mathrm{n})^{70}\mathrm{Ga}$ and $^{64}\mathrm{Ni}(^{9}\mathrm{Be},\mathrm{pn})^{71}\mathrm{Ga}$, have been utilized to probe the collective enhancement in nuclear level density (NLD) of two oblate deformed nuclei $^{71}\mathrm{Ga}$ and $^{72}\mathrm{Ga}$. It is seen that the $\ensuremath{\gamma}$-gated proton spectrum are reasonably explained by using the large value of the inverse level density parameter ($k=11.2$ MeV) in the NLD prescription of the Fermi gas model. The large value of $k$ indicates rotational enhancement, which is consistent with the earlier results in other mass regions. Furthermore, a rotational enhancement factor has been included in the NLD and used in the statistical model calculation keeping the systematic value of $=8.6$ MeV. It explains the $\ensuremath{\gamma}$-gated proton spectrum nicely, which indicates the presence of collective enhancement in the NLD. The extracted enhancement factors are found to be $8.0+/\ensuremath{-}2.0$ and $5.5+/\ensuremath{-}1.0$ and vanish at around 15, 18 MeV excitation energies for $^{71}\mathrm{Ga}, ^{72}\mathrm{Ga}$, respectively. Present observations are consistent with the previous results obtained by Pandit et al. [Phys. Rev. C 97, 041301(R) (2018)] and Mohanto et al. [Phys. Rev. C 100, 011602(R) (2019)].