Inclusive proton production cross sections in(d,xp)reactions induced by 100 MeV deuterons

Abstract

Energy spectra and angular distributions of protons emitted from the inclusive $(d,xp)$ reaction on ${}^{9}\mathrm{Be},$ ${}^{12}\mathrm{C},$ ${}^{27}\mathrm{Al},$ ${}^{58}\mathrm{Ni},$ ${}^{93}\mathrm{Nb},$ ${}^{181}\mathrm{Ta},$ ${}^{208}\mathrm{Pb},$ and ${}^{238}\mathrm{U}$ were measured at an incident deuteron energy of 100 MeV. The protons were detected at laboratory scattering angles of $6\ifmmode^\circ\else\textdegree\fi{}$ to $120\ifmmode^\circ\else\textdegree\fi{}$ and $8\ifmmode^\circ\else\textdegree\fi{}$ to $120\ifmmode^\circ\else\textdegree\fi{}$ for the targets with $9<~A<~27$ and $A>~58,$ respectively. Two triple-element and three double-element detector telescopes allowed for a low energy detection threshold of 4 to 8 MeV. The experimental results are presented in double-differential as well as angle- and energy-integrated cross sections. For all the nuclei studied, the energy spectra at forward angles show pronounced deuteron breakup peaks centered around approximately half of the incident deuteron energy. Qualitatively the energy spectra are similar for all nuclei at a given angle except in the region of the low-energy evaporation peak. As a function of target mass the evaporation cross sections are found to increase up to $A=58$ after which they decrease again. The total preequilibrium proton cross section is roughly $(280\ifmmode\pm\else\textpm\fi{}{60)A}^{1/3} \mathrm{mb}.$ The angular distributions at the high emission energies are strongly forward peaked while the distributions of the low-energy protons are almost isotropic. The LAHET code system (LCS) was applied to calculate the proton production cross sections. Standard LCS calculations are found to underpredict the experimental cross sections at the very forward angles on the heavy target nuclei $(A\ensuremath{\gtrsim}58).$ By adding incoherently the Coulomb breakup cross section of the deuteron to the LCS calculations the experimental cross sections are reproduced to within 10%. Although preequilibrium processes are a necessary ingredient in the LCS calculations of the large-angle cross sections, this code still fails to predict the experimental evaporation distributions.