Observation of Isospin Dependence on Analyzing Powers in Proton Inelastic Scattering

Differential cross sections and analyzing powers in inelastic scattering of 65- and 50- MeV polarized protons exciting the $1^{+}$ states at 12.71 MeV ($T=0\mathrm{}$) and 15.11 MeV ($T=1\mathrm{}$) in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ have been measured. There is a marked difference between the analyzing powers of the two states, which show an out-of-phase pattern in angular distribution. The exchange effect was found to contribute essentially to the isospin dependence from the results of distorted-wave Born-approximation calculations.