Energy dependence of the analyzing power for theC12(p→,π+)C13reaction with polarized protons of 200 to 250 MeV

Abstract

The analyzing power angular distributions ${A}_{y}(\ensuremath{\theta})$ for the $^{13}\mathrm{C}_{\mathrm{g}.\mathrm{s}.}$ as well as for several $^{13}\mathrm{C}$* excited state transitions from the $^{12}\mathrm{C}$($\stackrel{\ensuremath{\rightarrow}}{p}$, ${\ensuremath{\pi}}^{+}$)$^{13}\mathrm{C}$ reaction are reported as a function of incident proton energy from 200 to 250 MeV. For the first time in reactions of the type $A(\stackrel{\ensuremath{\rightarrow}}{p},{\ensuremath{\pi}}^{+})A+1$, a dramatic energy dependence is observed for the analyzing power. A dependence of the shape of the analyzing power on the nature of the excited nuclear state is also observed. The cross section for the $^{13}\mathrm{C}_{\mathrm{g}.\mathrm{s}.}$ transition shows indication of backward peaking not observed at energies below 225 MeV.NUCLEAR REACTIONS $^{12}\mathrm{C}$($\stackrel{\ensuremath{\rightarrow}}{p}$, ${\ensuremath{\pi}}^{+}$)$^{13}\mathrm{C}_{\mathrm{g}.\mathrm{s}.}$ and several excited states, polarized protons, ${T}_{p}=200\ensuremath{-}250$ MeV; measured ${A}_{y}(\ensuremath{\theta})$, $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}(\ensuremath{\theta})$.