Comprehensive mass measurement study of ^252Cf fission fragments with MRTOF-MS and masses of neutron-rich Ce isotopes

We report the mass measurements of neutron-rich isotopes produced via spontaneous fission of ^252Cf using a multi-reflection time-of-flight mass spectrograph. The mass of ^155Ce is determined experimentally for the first time. A discrepancy between the experimental and literature values was found for the mass of ^127Sb, which was previously deduced through indirect measurements. In comparison with several theoretical predictions, both the values and the trend of the mass excesses of ^152-155Ce cannot be consistently explained. The wide-range and simultaneous mass measurements of the multi-reflection time-of-flight mass spectrograph enable us to reexamine existing mass data. The new measurements suggest corrections to the present values, including data from previous Penning trap mass measurements.