Nuclear Compton scattering from 12C

Nuclear Compton scattering — the elastic scattering of photons — from 12C has been studied at the Tagged-Photon Facility at MAX IV in Lund, Sweden. The differential cross section for the reaction was determined at laboratory angles of 60° and 120° in the energy range 65-95 MeV. The cross section for nuclear Compton scattering is related to the electric and magnetic polarisabilities of the proton and the neutron. The polarisabilities are fundamental structure constants that describe how nucleons are affected by an external electromagnetic field. The determination of the electric and magnetic polarisabilities of the neutron through measurements of the deuterium Compton scattering cross section is the goal of a recent large scale experimental effort spanning almost a decade at the Tagged-Photon Facility at MAX IV. The purpose of this experiment was twofold: to verify the procedure for normalisation of Compton scattering data by investigating 12C and comparing to a well-established and comprehensive existing body of data, and to determine whether the electric and magnetic polarisabilities of free nucleons are affected when they are bound inside a nucleus.