Cross-shell excitations in 30Al and 30Si at high spin

Yrast and near-yrast states in 30Al and 30Si have been populated to high spin with the fusion–evaporation reaction in inverse kinematics. The level schemes for these two isobars have been extended up to J∼9ℏ at 9.4 and 15.5 MeV, respectively. Their decay schemes indicate that cross-shell excitations dominate at high spin, where negative-parity structures exist. Positive-parity states are compared to the results of shell-model calculations using the USD, USDA, and USDB effective interactions. The negative-parity levels are compared to predictions of the WBP interaction and the recently-developed WBP-a Hamiltonian, by allowing 1p–1h excitations to fp-shell orbitals. The results suggest that single-neutron excitations to the 0f7/2 orbital play a significant role at high spin.