O18(p→,π−)19Ne and26Mg(p→,π−)27Si reactions atTp=201MeV

Angular distributions of the differential cross sections and analyzing powers of the ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$(p,${\pi }^{\mathrm{-}}$) and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$(p,${\pi }^{\mathrm{-}}$) reactions leading to both discrete final states and the continuum have been measured at $T_{\mathrm{p}=201\mathrm{}}$ MeV. The two reactions exhibit quite similar selectivities and angular distributions. For the ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$(p,${\pi }^{\mathrm{-}}$ ${)}^{19}$Ne reaction, the strongest transitions are to known high spin states, which are favored by the high momentum transfer of the reaction. These states are presumed to have predominantly two-particle–one-hole configurations with respect to the target nucleus because of the two-nucleon nature of the reaction mechanism. It is conjectured that the states most strongly populated in the ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$(p,${\pi }^{\mathrm{-}}$ ${)}^{27}$Si reaction have a similar structure.