Phase modulation of a neutron wave and diffraction of ultracold neutrons on a moving grating

Abstract We report the result of the experiment of UCN diffraction on a moving grating. The resulting spectrum is found to be discrete in good agreement with theory. This purely quantum effect may be interpret as a result of phase modulation of the neutron wave or as diffraction in time. Also, this experiment demonstrates the validity of the Galilean transformation of the neutron wave function in a new and very clear way.