A formalism calculating the cross sections of intermediate-energy proton direct capture populating continuum states has been developed. The transition amplitude includes two terms corresponding to potential-scattering to potential-scattering transitions and potential-scattering to resonance-scattering transitions, respectively. The model is compared with available experimental data of the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$(p,${\gamma }_{19}$${)}^{12}$C reaction, and the results show that within the reasonable parameter limit the direct capture mechanism is able to account for a major feature of the measured data, and, in the present case, the contributions from the two terms are of the same order of magnitudes. The physical significance of the results is discussed.

• Received 5 February 1991

DOI:https://doi.org/10.1103/PhysRevC.46.1425