Abstract
The 96Cd (N = Z = 48) is the heaviest open-shell even-even nucleus along the N = Z line, making it an ideal testing ground for studying isoscalar interactions and neutron-proton pairing near the proton drip line. Previous studies have left the contributions of isovector and isoscalar pairings in the low-lying states of 96Cd ambiguous due to the significant overlap between these pairing bases, necessitating further experimental data for clarification. Here, we report experimental observations of 96Cd from the RIBF facility at RIKEN. Gamma rays emitted from the 97Cd(p,pn)96Cd reaction were detected using the DALI2+ detector array. We measured the energies of low-lying excited states and the B(E2) value of the first 8+ state in 96Cd. These results are consistent with shell model calculations in which the T = 1 proton-neutron matrix elements are turned off, indicating the existence of isoscalar interactions in 96Cd. However, our findings differ significantly from calculations based on the spin-aligned pairing basis reported in the literature, suggesting a competition between isoscalar and isovector pairings. The Multi-Step Shell Model indicates that this competition arises from the strength of the spin-aligned pairing interaction, which may decrease as the nucleus approaches the doubly magic 100Sn along the N = Z line.
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