The internal momentum spectrum of p+n pairs produced in the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$(α,2α)pn reaction at 118 MeV was measured for those pairs whose c.m. was at rest after the reaction. This spectrum was calculated with a plane wave impulse approximation model, having no free parameters, for two $p_{3/2}$ nucleons initially bound in a harmonic oscillator potential. The calculation gave reasonable agreement with measured values of both the normalization of the spectrum and its dependence upon the p+n internal energy, when the final nucleons were described by Yamaguchi, Paris, or Reid wave functions and the data were reduced by the final-state energy prescription. Less satisfactory fits were obtained with p+n plane waves and/or the initial-state energy prescription.

• Received 26 April 1988

DOI:https://doi.org/10.1103/PhysRevC.38.2945