Studies on Dynamical Diffraction Phenomena of Neutrons Using Properties of Wave Fan

Dynamical diffraction phenomena of neutrons are studied with a highly parallel exploring beam which is obtained by selecting the central part of the wave fan. The 111 reflection of silicon single crystals is used with neutron wavelengths of 0.86Å and 1.50Å. (i) The rocking curve of the Bragg-case diffraction which is very close to the intrinsic diffraction curve of silk hat type with the reflection per cent of about 100% is measured with the double-crystal arrangement of parallel setting. The angular spread of the exploring beam, 0.065'', is used, which is 1/8.5 times the half-value width of the intrinsic curve. (ii) The minute deviation angle of the beam, 0.032'', refracted by a wedge-shaped germanium crystal is measured with the double-crystal arrangement of parallel setting, where the deviation angle is magnified to 59' in the wave fan of the second crystal. (iii) By using a neutron interferometer the change in the optical path due to a wedge-shaped material inserted is measured.