Comparison of theSi28(O16,C12)S32andSi28(O18,C14)S32reactions at

Abstract

Cross-section angular distributions of the $^{28}\mathrm{Si}$($^{16}\mathrm{O}$, $^{12}\mathrm{C}$)$^{32}\mathrm{S}$ and the $^{28}\mathrm{Si}$($^{18}\mathrm{O}$, $^{14}\mathrm{C}$)$^{32}\mathrm{S}$ reactions leading to lowlying states in $^{32}\mathrm{S}$ and the $^{18}\mathrm{O}$+$^{28}\mathrm{Si}$ elastic scattering have been measured at 60 MeV incident energy. Optical model parameters were obtained by the analysis of the measured $^{18}\mathrm{O}$+$^{28}\mathrm{Si}$ elastic scattering and the analysis of existing $^{16}\mathrm{O}$+$^{28}\mathrm{Si}$ elastic scattering data. The exact finite-range distorted-wave Born approximation analysis of the ($^{16}\mathrm{O}$, $^{12}\mathrm{C}$) reaction data showed that the transfer data could only be reproduced using a surface-transparent set of optical model parameters. On the contrary no optical model parameters could be found which provide simultaneously good fits of the $^{18}\mathrm{O}$+$^{28}\mathrm{Si}$ elastic scattering and the ($^{18}\mathrm{O}$, $^{14}\mathrm{C}$) transfer data. The transfer data could be reproduced however, using optical model parameters which do not describe elastic scattering data. Relative spectroscopic factors were extracted for both transfer reactions and are compared with previous results of ($^{16}\mathrm{O}$, $^{12}\mathrm{O}$) and ($^{6}\mathrm{Li}$,$d$) reaction studies. In addition we determined spectroscopic factors of the $^{28}\mathrm{Si}$($^{12}\mathrm{C}$, $^{8}\mathrm{Be}$) $^{32}\mathrm{S}$ reaction by reanalyzing existing data. The comparision suggests the conclusion that the ($^{16}\mathrm{O}$, $^{12}\mathrm{C}$) and ($^{18}\mathrm{O}$, $^{14}\mathrm{C}$) reactions proceed through different reaction mechanisms.