Quasi-free Compton scattering by the neutron

Using non-tagged bremsstrahlung produced by a 130 MeV-20 μA c.w. electron beam of MAMI A quasi-free Compton scattering by the neutron was investigated via the 2H(γ, γ'n)1H reaction for lab scattering angles of θ sub(γ')=90deg and 135deg. The energy spectrum and angular distribution of recoiling neutrons were measured via time of flight and a plastic-scintillator hodoscope, respectively. Double-differential cross sections for quasi-free scattering by the neutron were determined on an absolute scale by normalizing to the Compton cross section of the proton. By comparing the experimental double-differential cross sections with predictions the electric polarizability of the neutron was determined, leading to anti αn=(10.7(+3.3-10.7))x10-4 fm3. Thus, the upper limit of anti αn is further reduced as compared to our previous result, but the lower limit is still consistent with zero. (orig.)