Measurement of the $\mathit{E}2/\mathit{M}1$ Ratio in the $\mathit{N}\to \mathit{\Delta }$ Transition using the reaction $\mathit{p}(\overrightarrow{\gamma },\mathit{p}){\pi }^{\mathit{o}}$

The small electric quadrupole $E2\mathrm{}$ amplitude of the predominantly magnetic dipole $M1\mathrm{}$ $p\to \Delta \left(1232\right)$ transition has been measured using 270 to 420 MeV tagged linearly polarized photons in the $p(\overrightarrow{\gamma },p){\pi }^o$ 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 $E2\mathrm{}/M1=-(2.5\pm 0.2\pm 0.2)\%$ at the maximum of the $\Delta \left(1232\right)$ resonance has been derived.