Triplet energy differences and the low lying structure of Ga 62

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(pi) = 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 Ga-62 and Ge-62. Methods: An in-beam gamma-ray spectroscopy experiment was performed to identify excited states in Ga-62 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(pi) 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.