(p,p′γ) spin-flip measurement for1+states inC12atEp=23.5−27MeV

An out-of-plane ($p$,$p^{\prime }\gamma$) angular correlation measurement has been made to determine the spin-flip contribution to the ($p$,$p^{\prime }$) cross sections for the $1^{+}$, $T=0\mathrm{}$ ($Q=-12.71\mathrm{}$ MeV) and $1^{+}$, $T=1\mathrm{}$ ($Q=-15.11\mathrm{}$ MeV) excitations in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at proton energies near 27 MeV. A definite isospin dependence is observed in the experimental spin-flip angular distributions for the two states. Microscopic distorted wave calculations based on a realistic $G$ matrix interaction give a rough account of the trends in the spin-flip data, but underestimate the experimental differential cross sections. It is concluded that reaction contributions calculated in the distorted wave approximation are insufficient to gain a complete understanding of the data.