  Measuring Compton scattered photons and recoil neutrons in coincidence,
quasi-free Compton scattering by the neutron has been investigated at MAMI
(Mainz) at $theta^{lab}_\gamma=136^o$ in an energy range from 200 to 400 MeV.
  From the data a polarizability difference of $\alpha_n - \beta_n = 9.8 \pm
3.6(stat)^{+2.1}_{-1.1}(syst)\pm 2.2(model)$ in units of $10^{-4}fm^3$ has been
determined. In combination with the polarizability sum $\alpha_n+\beta_n=
15.2\pm 0.5$ deduced from photo absorption data, the neutron electric and
magnetic polarizabilities, $\alpha_n=12.5\pm 1.8(stat)^{+1.1}_{-0.6}(syst)\pm
1.1(model)$ and $\beta_n = 2.7\mp 1.8(stat)^{+0.6}_{-1.1}(syst)\mp 1.1(model)$,
are obtained.
