The cross sections for the production of three most neutron-deficient zinc isotopes, ${}^{54–56}\mathrm{Zn}$, in the projectile fragmentation of ${}^{78}\mathrm{Kr}$ at 345 MeV/nucleon on a beryllium target, were measured. Although the results are smaller by over an order of magnitude from those obtained with a ${}^{58}\mathrm{Ni}$ beam at 75 MeV/nucleon on a nickel target, the rates of reaction products are found to be larger in the case of high-energy fragmentation of ${}^{78}\mathrm{Kr}$. The experimental cross sections for the most neutron-deficient isotopes of even-$Z$ nuclei between zinc and krypton were analyzed in the framework of the abrasion-ablation model. A very good agreement with the data was found when the nuclear masses predicted by a particular variant of the Hartree-Fock-Bogoliubov mass model were used. The prospects for the observation of more exotic isotopes in this region are discussed in context of $2p$ radioactivity.

• Received 29 June 2021
• Accepted 23 November 2021

DOI:https://doi.org/10.1103/PhysRevC.104.064610