Null Fizeau effect for thermal neutrons in moving matter

Abstract

We have carried out an interferometer experiment to determine the phase shift of slow neutrons caused by the motion of a material medium. Within experimental error, we confirm the theoretical prediction of a null result for the case when the medium moves inside stationary boundaries. Upper limits on the energy dependence of neutron-nucleus potential and on the wavelength dependence of s-wave neutron scattering lengths are deduced.