Observation of dynamical diffraction phase due to neutron spin precession through a ferromagnetic crystal of permalloy

We have, for the first time, observed neutron spin precession due to a dyna mical diffraction effect through a pair of ferromagnetic crystals of permal loy across a Bra,og condition of (200) by means of the neutron spin echo an d phase echo principles. In spite of the imperfect crystal, the shift of La rmor precession is enhanced in the rocking curve of the transmitted beams a t the magnetic Bragg condition. What was observed is a longer dwelling phas e of up arrow spin neutron wave function due to the multiple reflection pro cess of O-wave at Bragg reflection, against the rather freely passing oppos ite spin wave function. (C) 1999 Elsevier Science Ltd. All rights reserved.