In connection with a proposed explanation of the anisotropy observed in the scattering of neutrons from various elements at energies of a few hundred kev, the order of magnitude of the neutron polarizability is estimated by making use of data on photoproduction of pions. A polarizability $\alpha$ greater than ∼2×${10}^{-42\mathrm{}}$ ${\mathrm{cm}}^3$ appears unlikely on this basis. There remains an unexplained factor of ∼50 which has to be accounted for either in the polarizability or by providing another explanation of the neutron scattering anisotropy. The possibility of explaining the anisotropy on the basis of ordinary scattering theory does not appear to be excluded. The exact proportionality of the coefficient of $cos\theta$ to the neutron momentum does call for an $r^{-4\mathrm{}}$ type of potential, but it is not clear whether the energy dependence of the coefficient is sufficiently well determined by the data and whether the compound nucleus features of the interaction are capable of explaining the observations. Nevertheless, a few less usual effects are estimated. These are the interaction of the neutron moment with the vacuum polarization charge and with the external electric field of the nucleus as well as its interaction with the electric charge density at the nuclear surface. The latter is hard to distinguish from other nuclear effects. The former two effects are small and do not resemble the observed effects.

• Received 17 November 1958

DOI:https://doi.org/10.1103/PhysRev.114.830