The 29Si(p, d) 28Si and 30Si(p,t) 28Si reactions and the mixing of 1p hole and 2p particle configurations in 28Si

Abstract

Levels in 28Si with excitation energies up to 12 MeV have been investigated with the 29Si(p,d) 28Si and 30Si(p, t) 28Si reactions at an incident energy of 35 MeV. Angular momenta and spectroscopic factors have been obtained from a DWBA analysis of the angular distributions. Spin and parity assignments of 2 − for the 9.76 MeV level and (1, 2) − for the 9.93 MeV level of 28Si have been established. The usefulness of the 30Si(p, t) 28Si reaction as a spectroscopic tool appears to be limited since states with unnatural parity were excited with similar cross sections as most natural parity states. The emphasis lies on a discussion of the negative parity states. Considerable l = 1 spectroscopic strength was found at energies close to the expected position of 1p hole states. Arguments are brought forward in favour of a 1p assignment to the l = 1 transfer. A strong mixing of 1p hole and 2p particle configurations is concluded for the negative parity states of 28Si.