Highly excited high spin states in 28Si populated through the 12C( 20Ne, α) reaction

Abstract

High spin states at 12.0–17.6 MeV in 28Si excited through the 12C( 20Ne, α) reaction have been investigated with a particle-particle angular correlation method. New spin-parity assignments ranging from 3 − to 10 + have been made, some of which are classified into an excited prolate band reported previously. Most states in this energy region are found to decay both by alpha and proton emission. Specifically, a new 6 + state found at 12.80 MeV is identified to be the lowest excited state whch has a large fraction of g 9 2 component. This is also supported by a successful reanalysis of the 27Al(α, t) 28Si reaction at 65 MeV by a DWBA calculation assuming g 9 2 transfer. These high-lying states also are discussed in terms of coexistence of oblate and prolate shape bands in 28Si. The particle decay property of these states in 28Si is also discussed comparatively with that in 32S.