CHARGED-PARTICLE SPECTRA - 90 MEV PROTONS ON AL-27, NI-58, ZR-90, AND BI-209

Complete charged light-particle (Z≤2, A≤4) energy spectra were measured for 90 MeV protons on Al27, Ni58, Zr90, and Bi209 and 100 MeV protons on Ni58. The energy spectra show a strong angular dependence and the spectral shapes at a given angle for the same particle type are similar in the high-energy continuum for all target nuclei. The non-equilibrium, charged light-particle yields show an A13 dependence and are approximately given by (200±10)A13(mb). One striking feature is the similarity of the shapes of the p, d, and t spectra, if the spectra are shifted by an appropriate binding energy. The relative intensity is approximately p:d:t 1:110:1100 at all angles. In the backward directions (θ140°) the spectra exhibit characteristic evaporation behavior with approximately the same slope for each target nucleus for a given observed particle. The slopes of the evaporation peaks (corresponding to a temperature of 2-3 MeV) for the different particle type are also rather similar. The experimental results were analyzed within the framework of the pre-equilibrium exciton model together with the evaporation theory. The pre-equilibrium exciton model using a 2p-1h initial configuration generally reproduces the experimental angle-integrated energy spectra reasonably well in shape, but underestimates especially the proton yield in the region of high-energy continuums. NUCLEAR REACTION: Al27, Ni58, Zr90, Bi209 (p, xp), (p, xd), (p, xt), (p, xHe3), (p, xα), Ep=90 MeV; θL=20°-40°, Ni58 (p, xp), (p, xd), (p, xt), (p, xHe3), (p, xα), Ep=100 MeV; θL=15°-155°, measured d2σdΩdε, deduced dσdε and σ(E). Comparisons with preequilibrium exciton and evaporation models. © 1979 The American Physical Society.