Triplet energy differences and the low lying structure of $^{62}$Ga
Résumé
Background: Triplet energy differences (TED) can be studied to yield information on isospin-non-conserving
interactions in nuclei.
Purpose: The systematic behavior of triplet energy differences (TED) of T = 1, J π = 2+ states is examined. The
A = 62 isobar is identified as having a TED value that deviates significantly from an otherwise very consistent
trend. This deviation can be attributed to the tentative assignments of the pertinent states in 62Ga and 62Ge.
Methods: An in-beam γ -ray spectroscopy experiment was performed to identify excited states in 62Ga using
Gamma-Ray Energy Tracking In-Beam Nuclear Array with the S800 spectrometer at NSCL using a two-nucleon
knockout approach. Cross-section calculations for the knockout process and shell-model calculations have been
performed to interpret the population and decay properties observed.
Results: Using the systematics as a guide, a candidate for the transition from the T = 1, 2+ state is identified.
However, previous work has identified similar states with different J π assignments. Cross-section calculations
indicate that the relevant T = 1, 2+ state should be one of the states directly populated in this reaction.
Conclusions: As spins and parities were not measurable, it is concluded that an unambiguous identification of
the first T = 1, 2+ state is required to reconcile our understanding of TED systematics.