High-spin structure of Cl-37, intruder excitations, and the sd-fp shell gap

The structure of the N=20 nucleus 37Cl has been investigated in the 24Mg(16O,3p) reaction with a 70 MeV 16O beam. A complex level scheme extended up to an excitation energy of 17 MeV and spins (29/2+) and (27/2-) on positive and negative parity, respectively, has been established. Lifetimes for the new states have been investigated by the Doppler shift attenuation method. Large-scale shell-model calculations have been performed in a valence space involving orbitals in the sd and fp shells using the sdfp and SDPF-M effective interactions. The comparison with the experimental data indicates the need for slight changes of the sd-fp energy gaps produced by these interactions.