Production of very neutron-rich nuclei with a Ge-76 beam

Production cross sections for neutron-rich nuclei from the fragmentation of a Ge-76 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 (Cl-50, Ar-53, K-55,K-56, Ca-57,Ca-58, Sc-59,Sc-60,Sc-61, Ti-62,Ti-63, V-65,V-66, Cr-68, and Mn-70). 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 Ca-58 show anomalously large production cross sections.