One-proton and two-proton stripping between 26Mg, 27Al and 28Si

Abstract

The reactions 26Mg(τ, n) 28Si and 27Al(d, n) 28Si have been investigated with the time-of-flight method at 5.7 and 6 MeV bombarding energy, respectively. Deuterons and α-particles from the 26Mg(τ, d) 27Al and 26Mg(τ, α) 25Mg reactions at E τ = 11 MeV have been detected in a solid-state counter telescope. Angular distributions are extracted, and for the one-nucleon transfer reactions, analysed with DWBA to yield l-values and spectroscopic factors. These are compared to the results of previous measurements. Together with data from a previous 28Si(n, d) 27Al study, the transition strengths of the one-proton transfer reactions are compared to the predictions of the unified model both in strong and weak coupling. The 26Mg(τ, d) 27Al results are compatible with a strong coupling description for a deformation η = 2 of both nuclei. The (n, d) as well the (d, n) reaction between 27Al and 28Si contradict both versions of the unified model. Predictions from a TDA treatment of p-h states in 28Si are also compared to the 27Al(d, n) strengths. The 26Mg(τ, n) 28Si data indicate an appreciable amount of core excitation in the 28Si ground state.