Electron scattering and charged pion photoproduction on12C and13C

Electron scattering and charged pion photoproduction at 200 MeV on¹²C and¹³C have been studied by the nuclear shell model to investigateM1 andE2 nuclear form factors of the isovector type. Starting with the Op-shell model of Hauge-Maripuu, the effects of core polarization by theM 3Y force and the one-pion-exchange current are taken into account. The effect of core polarization is found to be essential in both electron scattering and pion photoproduction, while the meson-exchange current, which also improves the calculated results, gives contributions of about 10%–15%.