Determination of the E2/M1 ratio in the gamma N to Delta (1232) transition from a simultaneous measurement of p( gamma ,p) pi /sup 0/ and p( gamma , pi /sup +/)n

Abstract

Tagged linearly polarized photons have been used at the Mainz Microtron (MAMI) for simultaneous measurements of the p( gamma ,p) pi /sup 0/ and p( gamma , pi /sup +/)n reaction channels to study the gamma N to Delta (1232) transition. The energy dependence of the magnetic dipole M/sub 1+//sup 3/2/ and electric quadrupole E/sub 1+//sup 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+or-0.1/sub stat/+or-0.2/sub sys/)% at the resonance position ( delta /sub 33/=90 degrees ).