A phenomenological explanation is proposed for the pronounced peaks observed in some coincidence spectra of the ${}_{}{}^2{}_{}{}^{}\mathrm{H}\mathrm{}(d,pd)n$ reaction at low relative energies in the proton-neutron system. It is shown that the density-of-states formalism of Phillips, Griffy, and Biedenharn which includes explicitly the fact that the $p-n$ system is produced in a spatially localized state can describe the observed spectral shapes with the pure, isospin-allowed, ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ proton-neutron final-state interaction. In addition, the model satisfactorily describes the case of low relative energy between the deuteron and neutron.

• Received 20 February 1973

DOI:https://doi.org/10.1103/PhysRevC.8.403