Shape coexistence and the N = 20 shell closure far from stability by inelastic scattering

Abstract

Following mass measurements in the region N = 20 and N = 28, we have studied inelastic nuclear scattering for the nuclei 34Si, 33Al and 32Mg. No evidence for a low-lying shape isomeric 0+ state was found in 34Si, and an upper limit for the population cross-section could be established, rendering its existence very unlikely. A new transition was found in 33Al, that is a good candidate for a 2p-2h state and therefore a determination of the 2p-2h gap at N = 20. Inelastic nuclear scattering strongly excites 3- states, as seen in 34Si. A strong transition was found in 32Mg that should correspond to the first 3- in this nucleus, lying very low as compared to theory and systematics in this region.