Comparison of inclusive neutron and proton spectra from 90-MeV protons on ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, and ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ indicate that single nucleon-nucleon scattering dominates the highenergy regions of forward-angle continuum spectra. The ratios of cross sections observed agree with ratios expected for scattering of the incident proton by a bound target nucleon. For ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, a plane-wave-impulse-approximation quasifree-scattering calculation fits forward-angle proton and neutron spectra simultaneously with the same normalization.

• Received 18 September 1980

DOI:https://doi.org/10.1103/PhysRevLett.46.226