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Bragg diffraction at grazing incidence of neutrons from a magnetic film decomposed into a set of ferromagnetic domains is considered within the frame of the distorted wave Born approximation. It is shown that the diffracted intensity measured as a function of angles of incidence and exit in the direction normal to the surface can provide information on the lateral distribution of domain magnetization. Theoretical results are illustrated by measurements of a mono-crystalline film of iron.

A linear detector of thermal neutrons, developed at the Laboratory for High Energies (Joint Institute for Nuclear Research), is used in the polarized-neutron spectrometer of the aAe-2 reactor (JINR). The data are acquired in the regime of frame-by-frame survey to select neutrons with a wavelength λ = 1—12 A by the time of flight. The neutron-detection efficiency is ~70% for a wavelength of 2 A. The detector exhibits a low sensitivity to γ -rays, a dif- ferential nonlinearity of ~1.5%, and a spatial resolution of ~1.5 mm at counting rates of ~10 5 events/s.

The new multifunctional reflectometer GRAINS is under construction at the modernized high flux IBR-2 pulsed reactor (IBR-2M) of the FLNP JINR (Dubna, Russia). The principal feature of this reflectometer, the horizontal sample plane (or vertical scattering plane), enables the study of liquid-containing interfaces. The reflectometer will operate in the time-of-flight regime with constant sample illumination during measurements. The important advantage is the constant angular resolution with unvaried background. The additional modes of the GRAINS reflectometer comprise (1) off-specular scattering and GISANS, which are measured simultaneously in the TOF regime at a 2D position-sensitive detector; (2) angular encoding in the horizontal plane, which is provided by a Larmor precession region limited by current sheets in front of the sample; (3) 3D polarimetry in reflection, which is provided by a Larmor precession region around the sample position. The design of the reflectometer is optimised to take better advantage of an exceptionally broad wavelength band of the new cold moderator at the IBR-2M. The set-up will open up principally new possibilities for investigations in the field of interface nano-science at the IBR-2M reactor.