Mass measurement of neutron-rich isotopes from 51Ca to 72Ni

The ground state masses of thirty-nine neutron-rich nuclei from 51Ca to 72Ni have been measured using the Time-of-Flight Isochronous (TOFI) spectrometer. Eight of these masses have been measured for the first time and thirty-one are remeasurements of neutron-rich nuclei previously reported. Good agreement between these results and a previous TOFI experiment was observed except for the most neutron-rich isotopes of vanadium through iron with the present results being more bound and in better agreement with theory. The low binding energy of 68Ni, as indicated by an unreasonably low two-neutron separation energy, suggests the presence of a high-lying, long-lived isomeric state in this nucleus. (orig.)