Abstract
Accurate mass measurements of neutron-rich iron and cobalt isotopes and have been realized with the JYFLTRAP double Penning-trap mass spectrometer. With novel ion-manipulation techniques, the masses of the ground states and the isomer in have been extracted for the first time. The measurements remove ambiguities in the previous mass values and yield a smoother trend on the mass surface, extending it beyond . The moderate subshell gap has been found to weaken below , a region known for shape coexistence and increased collectivity. The excitation energy for the intruder state in has been determined for the first time and is compared to large-scale shell-model calculations. The new mass values also reduce significantly mass-related uncertainties for the astrophysical rapid neutron-capture process calculations.
- Received 8 May 2019
- Revised 6 February 2020
- Accepted 18 March 2020
DOI:https://doi.org/10.1103/PhysRevC.101.041304
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