SUPERSLOW NEUTRONS AND THE DISPERSION LAW FOR NEUTRON WAVES IN MATTER

The behavior of superslow neutrons with velocities lower than approxim ate to 0.1 m/s cannot be described by employing the notion of an avera ge, or optical potential. Owing to the existence of such a region, the wave vector in the medium becomes complex when a scattering length of an individual nucleus is positive. As a consequence, slow infiltratio n deep into the substance of ultracold neutrons with energies lower th an the boundary energy takes place. Taking into account the weak absor ption results in the appearance of a second branch in the neutron wave spectrum. It is characterized by a significantly longer damping lengt h than predicted by the conventional theory of a complex potential. In the Conclusion possibilities of experimental verification of the theo ry are discussed.