Mass Measurements of Neutron-Deficient Yb Isotopes and Nuclear Structure at the Extreme Proton-Rich Side of the N=82 Shell

High-accuracy mass measurements of neutron-deficient Yb isotopes have been performed at TRIUMF using TITAN's multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). For the first time, an MR-TOF-MS was used on line simultaneously as an isobar separator and as a mass spectrometer, extending the measurements to two isotopes further away from stability than otherwise possible. The ground state masses of Yb-150,Yb- 153 and the excitation energy of Yb-151(m) were measured for the first time. As a result, the persistence of the N = 82 shell with almost unmodified shell gap energies is established up to the proton drip line. Furthermore, the puzzling systematics of the h(11/2) -excited isomeric states of the N = 81 isotones are unraveled using state-of-the-art mean field calculations.

Automated summary

High-accuracy mass measurements of neutron-deficient Yb isotopes were conducted at TRIUMF using TITAN's MR-TOF-MS, which was utilized as both an isobar separator and a mass spectrometer for the first time. This study confirmed the stability of the N = 82 shell and provided insights into the excited states of N = 81 isotopes.