Binding energies of ground and isomeric states in neutron-rich ruthenium isotopes : Measurements at JYFLTRAP and comparison to theory

Abstract

We report on precision mass measurements of 113,115,117Ru performed with the JYFLTRAP double Penning trap mass spectrometer at the Accelerator Laboratory of University of Jyväskylä. The phase-imaging ion-cyclotron-resonance technique was used to resolve the ground and isomeric states in 113,115Ru and enabled for the first time a measurement of the isomer excitation energies, Ex(113Rum)=100.5(8) keV and Ex(115Rum)=129(5) keV. The ground state of 117Ru was measured using the time-of-flight ion-cyclotron-resonance technique. The new mass-excess value for 117Ru is around 36 keV lower and seven times more precise than the previous literature value. With the more precise ground-state mass values, the evolution of the two-neutron separation energies is further constrained and a similar trend as predicted by the BSkG1 model is obtained up to the neutron number N=71.