The 28Si( 3He, 4He) 27Si reaction

Abstract

The angular distributions of the 28Si( 3He, 3He) 28Si and 28Si( 3He, 4He) 27Si reactions have been measured at E 3 He = 10 MeV for lab angles between 15° and 165°. The analysis of the elastic scattering with the optical model and the analysis of the ( 3He, 4He) angular distributions with the DWBA theory indicate that these reactions are mainly direct in nature. The l n values of the extracted neutrons are found to be 2, 0, 2 and 2 for, respectively, the ground state, and the first, second and fourth excited states of 27Si. The data for the third excited state give no evidence of a pick-up mechanism. The excitation functions of the ( 3He, 4He) reaction from 8 to 10.5 MeV bombarding energy show significant structure. Thus it appears that the detailed features of individual angular distributions may be distorted by interference of the predominant direct reaction mode with non-direct mechanisms. Within the limitations discussed in the text, spectroscopic factors of 2.0, 0.7, 0.5 and 1.3 were assigned to the ground state and the 0.78 MeV, 0.96 MeV and 2.65 MeV excited states, respectively.