Electroproduction and photoproduction of charged pions onAl27andV51at intermediate energies

Cross sections for electroproduction and photoproduction of charged pions on ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ and ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$ have been measured in the energy region 130-580 MeV by use of the activation method. Special care has been taken to subtract out background yields. Photoproduction cross sections have been calculated from the region just above threshold to the tail of the (3,3) resonance. $\pi$-nucleus final state interactions are taken into account through optical potentials. Calculated photoproduction cross sections are decomposed into multipoles which are used to derive relative bremsstrahlung-induced to electron-induced yields. The pronounced effect of final state interactions is pointed out and discussed.