Precision mass measurements on neutron-rich Zn isotopes and their consequences on the astrophysical r-process

The rapid neutron-capture or the r-process is responsible for the origin of about half of the neutron-rich atomic nuclei in the universe heavier than iron. For the calculation of the abundances of those nuclei, atomic masses are required as one of the input parameters with very high precision. In the present work, the masses of the neutron-rich Zn isotopes $A$ = 71 to 81 lying in the r-process path have been measured in the ISOLTRAP experiment at ISOLDE/CERN. The mass of $^{81}$Zn has been measured directly for the first time. The half-lives of the nuclides ranged from 46.5 h $^{72}$Zn down to 290 ms $^{81}$Zn. In case of all the nuclides, the relative mass uncertainty $\delta$ m/m achieved was in the order of 10$^{-8}$ corresponding to a 100-fold improvement in precision over previous measurements.