Experimental Evidence for a Two-Step Process in the ReactionF19(O16,N15)Ne20

A strong population of the "$j$-forbidden" $4^{+}$ level at 4.25 MeV in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ is found in the reaction ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$)${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ at 46-, 58-, and 68-MeV incident energy. It provides evidence for a two-step process. This result was expected for structural and kinematical reasons.