Small-angle diffractometer of polarized neutrons SANS-2 is designed for studies in the fields of materials science (defects, porous), the physics of metals (distinct phases, clusters), technology of nanostructures and nanomaterials (membranes, photonic crystals), physics of the magnetic structures and superconductors (ferromagnetic spirals, spin correlations in the ferromagnetic), physics and chemistry of colloidal particles, microemulsions, colloidal solutions and liquid crystals. The functional scheme of the instrument is present in the fig.1.
Fig. 1 The functional scheme of SANS-2
1 – neutron guide, 2 – velocity selector, 3 – collimation diaphragm with circle and rectangular apertures, 4 – transmission polarizer, 5 – neutron guide, 6 – collimator, 7 – RF adiabatic flipper, 8 – sample position, 9 – positive-sensitive detector
For monochromatization of the neutron beam the velocity selector is used (Fig. 2), the rotation speed of which is within range of 3100÷28000 rpm. It corresponds the wavelength range of 4.5 to 41 Å, respectively. The results of test the velocity selector are presented at the table:
Fig. 2 The velocity selector
А new transmission polarizer for instrument developed (Fig. 3). It consists of a set of silicon wafers with supermirror CoFe/TiZr (m = 2) coating. We have two polarizers with the next parameters:
Fig. 3 Compact polarizer. Side view
Sample area SANS-2 has a two electromagnet BE-25 and BE-15, with a maximum value of generated magnetic field up to 2.5 and 1.5T, respectively. Each magnet has a Brucker Magnet Power Supply B-MN 200/60 to BE-25 and B-MN 155/45 to BE-15 with the control unit. Fig. 4 shows an electromagnet BE-25 and linear table for samples.
Fig. 4. Sample environment for SANS-2
The control software for the neutron experiments based on LabView enables one to carry out measurements. Mechanical control is done using IXE-A-RS and IXEα-A-RS controllers.
The assembly and check of the operation of the components and mechanisms of the small-angle diffractometer SANS-2 are currently carried out in the neutron guide hall of the reactor PIK (fig. 5).
Fig. 5 Current view of small-angle neutron diffractometer SANS-2 for PIK Reactor