Complete Hydrogen and Helium Particle Spectra from 30- to 60-MeV Proton Bombardment of Nuclei withA=12 to 209and Comparison with the Intranuclear Cascade Model

Abstract

Differential cross sections for the production of proton, deuteron, triton, helium-3, and $\alpha$ particles from as many as 10 targets ($A=12-209\mathrm{}$) were measured using 29-, 39-, and 62-MeV incident protons. The particles were detected, with $\approx 0.2$-MeV [full width at half maximum (FWHM)] energy resolution for protons, over a secondary energy range of $\approx 2-6 \mathrm{to} 62$ MeV in a total absorption telescope composed of three solid-state detectors. Representative results are shown for cross sections differential in energy and angle, as well as for angle-and energy-integrated cross sections. For incident 60-MeV protons the integral magnitude of the nonevaporation charged-particle production is found to be $\sim {10}^2{A}^{\frac{1}{3}}$ mb. Fewer protons but more complex particles were measured for carbon and oxygen targets than expected from an $A^{\frac{1}{3}}$ dependence for either component alone. The continuum cross sections for $z=1\mathrm{}$ particles at a given angle (mb ${\mathrm{sr}}^{-1\mathrm{}}$ Me${\mathrm{V}}^{-1\mathrm{}}$) are nearly independent of incident energy when measured with incident protons in the 30- to 60- MeV energy range. Nonevaporation production of complex particles ($A\ge 2$) is 25-40% of that for protons. The proton spectra have been compared with predictions from the intranuclear cascade model. Differential spectral predictions compare well with the measured spectra for angles in the range ∼25-60°, and relatively poor predictions for small and large angles are more favorable when reflection and refraction by the potential well are included. Evidence is given that predictions for backward angles are greatly improved by allowing proton scattering from nucleon pairs within the model nucleus, but the $A$-dependent underprediction at extreme forward angles is not understood at all. The calculated angle-integrated spectra reproduce the measured spectral shape but consistently predict $\approx 30\%$ too few nonevaporation protons for targets with $A\ge 27$.