Using a primary beam of ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ at 650 MeV/nucleon impinging on a beryllium target, production cross sections of proton-rich fragments from projectile fragmentation have been measured at the projectile-fragment separator FRS at Gesellschaft für Schwerionenforschung Darmstadt m.b.H. The experimental data ranging from nickel to scandium for isotopes close to stability as well as for fragments at the proton drip line are compared to predictions of the microscopic ISApace code, to calculations with a revised abrasion-ablation model and with the statistical abrasion model, and to the results of the empirical parametrization EPAX. Besides these systematic measurements, evidence for the particle stability of ${}_{}{}^{50}{}_{}{}^{}\mathrm{Ni}$ has been found for the first time, whereas the nuclei ${}_{}{}^{49}{}_{}{}^{}\mathrm{Co}$ and ${}_{}{}^{54}{}_{}{}^{}\mathrm{Cu}$ are shown to be unbound. These observations are compared to mass predictions.

• Received 27 May 1994

DOI:https://doi.org/10.1103/PhysRevC.50.2398