First measurement of the polarisation transfer on the proton in the reactions$H(\vec e,e'\vec p)$ and$D(\vec e,e'\vec p)$

Abstract

The measurement of the polarisation transfer to the proton in the reactions$H(\vec e,e'\vec p)$ and$D(\vec e,e'\vec p)$ performed with longitudinally polarised electrons in quasi-free kinematics is presented. The coincidence measurement was executed atQ ²≈8fm ⁻² using the 855 MeV, c.w. beam of the Mainz Microtron MAMI. The recoil polarisation was determined by means of a carbon analyser. The experiment shows that the binding of the nucleon does not modify the polarisationP _x of the recoil proton within an error ofΔ P _x/P_x≈10%. The measured polarisation agrees with recent theoretical predictions. Implications for the measurement of the electric form factor of the neutron using the$D(\vec e,e'\vec n)$ reaction are discussed.