Coherent Knockout Amplitudes in Deuteron Stripping Reactions

The knockout amplitude, which is present with the stripping amplitude in a properly antisymmetrized formulation of the ($d,p$) stripping reaction, is computed for the C¹²(d,p)C¹³ and S³²(d,p)S³³ reactions. It is found to be much smaller than previous rough estimates had indicated and it is argued that this is a general occurrence. The calculation uses the distorted-wave Born approximation with a zero-range perturbation interaction, although the deuteron is approximated by a Hulth\'en wave function for the computation of the knockout amplitude. The stripping-forbidden B¹⁰(d,p)B11*(2.14 MeV) reaction is computed assuming it to be a pure knockout process. Poor agreement with the experimental data is obtained in forward directions. It is concluded that knockout cannot be the sole reaction mechanism.