Direct measurement of the delay time for a neutron in a crystal in the case of the Laue diffraction

The dynamical Laue diffraction has been studied for a direct beam diffracte d from a thin (similar to 3.5 cm) alpha-quartz crystal at the Bragg angles close to 90 degrees. It is shown that diffraction occurs at Bragg angles up to 87 degrees. The time-of-flight method is used to measure the time of th e neutron presence in the crystal under the diffraction conditions. The tim e delay for a scattered neutron inside the crystal predicted earlier for th e Bragg angles close to 90 degrees is confirmed experimentally. The effecti ve velocity of the neutron propagation in a crystal measured at the inciden t-neutron velocity of 810 m/s and the diffraction angle of 87 degrees equal s (43 +/- 1) m/s. The result obtained confirms the possibility of increasin g, by an order of magnitude, the sensitivity of the diffraction method of d etermining the dipole moment of a neutron at Bragg angles close to 90 degre es predicted earlier theoretically. (C) 2000 MAIK "Nauka / Interperiodica".