Measurement of the E2/M1 ratio in the N->delta transition using the reaction p((gamma)over-right-arrow,p)pi(0)

Abstract

The small electric quadrupole E2 amplitude of the predominantly magnetic dipole M1 p --> Delta(1232) transition has been measured using 270 to 320 MeV tagged linearly polarized photons in the p(, p)pi(o) reaction at the Mainz Microtron MAMI. Differential cross sections and photon asymmetries were determined by measuring the recoil proton in the cylindrically symmetric 4 pi detector DAPHNE. From the proton angular distributions the ratio E2/M1 = -(2.5 +/- 0.2 +/- 0.2)% at the maximum of the Delta(1232) resonance has been derived