Tagged linearly polarized photons have been used at the Mainz Microtron MAMI for simultaneous measurements of the p(\vec{ \gamma},p)\pi^0 and p(\vec{ \gamma},\pi^+)n reaction channels to study the \gamma N \to \Delta(1232) transition. The energy dependence of the magnetic dipole M_{ 1+}^{ 3/2} and electric quadrupole E_{ 1+}^{ 3/2} amplitudes have been extracted from these data in the photon energy range from 270 to 420 MeV. The E2/M1 ratio for the \gamma N \to \Delta(1232) transition has been determined to be - (2.5+-0.1_{ stat}+-0.2_{ sys}) % at the resonance position delta_{ 33}=90^0.
Categories: nucl-ex nucl-th