Study of C12(γ→,p)11B reactions with polarized photons at energy 40-65 MeV

Abstract

The photon beam asymmetry of the ${}^{12}C{(\overrightarrow{\gamma },p_{01})}^{11}B$ and ${}^{12}C{(\overrightarrow{\gamma },p_{2-6})}^{11}B$ reactions has been measured in the energy range 40–65 MeV, using a tagged, linearly-polarized photon beam at the MAX-lab facility in Sweden. The asymmetry of the ${}^{12}C{(\overrightarrow{\gamma },p_{01})}^{11}B$ reaction to ground and first excited state of ${}^{11}B$ is $\Sigma \approx 0.82$ over the measured energy range. The main contribution to the ${}^{12}C{(\overrightarrow{\gamma },p_{2-6})}^{11}B$ reaction to higher excited states comes from processes in which the residual nucleus is in the $3/2^{-}$(5.02 MeV) or $7/2^{-}$(6.74 MeV) excited states. The asymmetry of this reaction is $\Sigma \approx 0.6$, close to the value for free deuteron photodisintegration.