Radiative pion capture on 13C.

Abstract

It is found that the differential cross sections for $^{13}({\ensuremath{\pi}}^{+}$,\ensuremath{\gamma}${)}^{13}$N $_{\mathrm{g}.\mathrm{s}.}$ for 115.5 MeV kinetic energy pions can be understood within the framework of a distorted wave impulse approximation, suggesting that core polarization and precursor effects give small contributions. It is further found that, within the limits of current nuclear photopion theory, the data for the radiative capture process are incompatible with earlier measurements for the inverse reaction $^{13}(\ensuremath{\gamma}$,${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$${)}^{13}$N $_{\mathrm{g}.\mathrm{s}.}$. It is shown that the reconciliation of the two sets of data places stringent demands on possible modifications to the theory.