Propagation of neutron de Broglie waves inside the slot cut in a single Si crystal

It was recently proposed (by Dombeck et al) to search for a Neutron Electric Dipole Moment (EDM) by means of the neutron multiple Bragg back-scattering. The dynamical diffraction analysis of the proposed experiment is the subject of this paper. The neutron wave modes were calculated for the case of the infinitely long slot cut inside of a thick Si crystal parallel to the crystallographic planes and placed in a steady magnetic field. The calculated neutron modes have a discrete spectrum of a momenta along the direction of the slot axis. The external magnetic field causes some particular discrete modes to become degenerate. However, the Schwinger and EDM interactions of neutrons with the slot walls break this degeneracy, which in turn leads to the complicated motion of the neutron polarization vector along the slot axis. The spin deviation from the starting direction is accumulated during neutron motion in slot. The energy spectrum of neutrons transmitted through the slot contains several peaks instead of one existing for the case of the ultra back-scattering regime.