Neutron spin optics in a noncentrosymmetric crystals as a way for nEDM search. New experimental results

An optical effect of a neutron spin rotation in the noncentrosymmetric quartz crystal was investigated. The effect was caused by the Schwinger interaction of the moving neutron with the strong electric field affects the neutron in noncentrosymmetric crystal. Value and sign of the effect depend on a deviation of the neutron energy from the Bragg one. We proposed to use the second crystal placed in parallel position to the main one to select the neutron with the given deviation parameter. It was shown that we could control and tune the value and sign of the electric field acting on the registered neutron by heating (or cooling) of the second crystal. The value of this field can reach ∼ 1 × 10 8 V/cm that gives us the real perspectives to improve essentially the present sensitivity to measure the neutron electric dipole moment (EDM) by the crystal diffraction technique.