Energy dependence of two-step (p,t) cross sections

Abstract

The energy dependence of two-step distorted-wave Born approximation calculations is studied for unnaturalparity state excitations by the ($p,t$) reaction involving ($p,{p}^{\ensuremath{'}},t$), ($p,t,{t}^{\ensuremath{'}}$), and ($p,d,t$) processes. The calculations which provide rapidly decreasing cross sections with an increase in the incident energy are found to be quite consistent with the observed results for the $^{18}\mathrm{O}(p,t)^{16}\mathrm{O}$ (8.88 MeV, ${2}^{\ensuremath{-}}$) reaction at the energy range of ${E}_{p}=20\ensuremath{-}45$ MeV. The remarkable difference of kinematical features between one-step and twostep processes is pointed out and the importance of higher-order effects for one-step allowed transitions is apparently indicated.NUCLEAR REACTIONS Energy dependence of second-order DWBA cross sections, $^{18}\mathrm{O}(p,t)^{16}\mathrm{O}$ (8.88 MeV, ${2}^{\ensuremath{-}}$) and (9.85 MeV, ${2}^{+}$) $E=20.0\ensuremath{-}43.6$ MeV.