Low-Energy Protons Produced in the Deuteron Bombardment of Nuclei

When nuclei are bombarded by fast deuterons a continuous spectrum of protons is observed at energies corresponding to $Q<-2.2\mathrm{}$ Mev. The shape and angular distribution of this continuum were studied for several targets, from Li to Au, with 14.8-Mev deuterons. The angular distributions are strongly peaked at or close to 0° for light elements; for heavy elements the peak broadens and moves to ∼50°. The energy spectra shows a peak which, with increasing angle moves to lower energies for light elements, and moves to higher energies for heavy elements. All features of the results are explained using a semiclassical theory in which the deuteron is broken up in the external field of the nucleus. The breakup occurs at or near the nuclear surface for light elements, but quite far out from it in heavy elements. Observed cross sections are far larger than theoretical predictions for either Coulomb or nuclear breakup.