Production cross sections for neutron-rich nuclei from the fragmentation of a ${}^{76}\mathrm{Ge}$ beam at 132 MeV/u were measured. The longitudinal momentum distributions of 34 neutron-rich isotopes of elements $13⩽Z⩽27$ were scanned using a novel experimental approach of varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei, including 15 isotopes first observed in this work. These are the most neutron-rich nuclides of the elements $17⩽Z⩽25$ (${}^{50}\mathrm{Cl}$, ${}^{53}\mathrm{Ar}$, ${}^{55,56}\mathrm{K}$, ${}^{57,58}\mathrm{Ca}$, ${}^{59,60,61}\mathrm{Sc}$, ${}^{62,63}\mathrm{Ti}$, ${}^{65,66}\mathrm{V}$, ${}^{68}\mathrm{Cr}$, and ${}^{70}\mathrm{Mn}$). A one-body $Q_g$ systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. Some of the fragments near ${}^{58}\mathrm{Ca}$ show anomalously large production cross sections.

• Received 10 June 2009

DOI:https://doi.org/10.1103/PhysRevC.80.034609