Determine whether the N=60 shape-transition effect extends to selenium

Determine experimentally whether the moderate flattening of the two-neutron separation-energy trend associated with the N=60 shape transition continues down to selenium isotopes, in order to establish the extent of the nuclear-structure effect responsible for forming the A=103 r-process abundance peak.

Background

The paper attributes the solar-system ruthenium and rhodium abundance enhancement near mass number A=103 partly to a flattening of the two-neutron separation-energy trend around neutron number N=60. This feature is associated with the sudden onset of nuclear deformation in neutron-rich nuclei around A=100 and affects the isotopic pathways followed by the light-element r-process.

Experimental evidence indicates that the onset of deformation becomes more gradual toward lower proton numbers, including krypton. The paper states that a moderate flattening remains consistent with formation of the A=103 peak, but whether the same effect persists in selenium has not yet been established experimentally. Resolving this issue would help map the relevant shape transition and constrain the nuclear conditions required for producing the rhodium and ruthenium peak.