The experimental angular distributions of several multinucleon transfer reactions induced by ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ on ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ have been measured and compared with distorted-wave reaction calculations. The shape and relative intensities of the data can be reproduced by theoretical calculations which seem to open the way for this type of study of structure of nuclei in the middle of the $2s-1d$ shell. On the other hand, we have not found it possible either to reproduce the shapes of the angular distributions with an optical potential derived from an elastic scattering analysis or to correctly calculate the absolute values of the cross sections. These difficulties which are similar to those encountered in other heavy-ion reaction studies will require extended improvements in the current formulations of the theory for the reaction processes.

NUCLEAR REACTIONS ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$(${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$), ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$(${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$), ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$(${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$), ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$(${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$), and ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$(${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{O}$) $E_{{}_{}{}^{18}{}_{}{}^{}\mathrm{O}}=56\mathrm{}$ MeV—angular distribution measured between 5° and 35° laboratory angles—distorted wave reaction analysis; shell-model structure analysis.

• Received 15 June 1979

DOI:https://doi.org/10.1103/PhysRevC.20.2130