[en] To study the free surface of liquids, a Reverans reflectometer with a vertical neutron scattering plane has been designed and is fabricated at Petersburg Nuclear Physics Institute. This reflectometer is intended to investigate surfaces and interfaces in liquid magnetic or nonmagnetic systems. The principles of reflectometer operation are described. The general view of the reflectometer with ready units is presented and its main technical parameters are given. The results of preliminary tests are reported

[en] The main directions of development of the project on the modernization and improvement of the REVERANS reflectometer, which is proposed to be installed at the PIK reactor (REVERANS-2), are described. They include the substitution of magnetic materials in instrument construction and the replacement of the autonomous table for samples; the equipment of the instrument with a polarimeter to measure the polarization components of incident and reflected neutron beams; and replacement of the electronics and mechanisms for moving the platforms. The REVERANS-2 parameters expected after modernization are given.

[en] The results of experimental verification of the feasibility of enhancing the efficiency of neutron-beam polarizers based on magnetized supermirrors are presented. The idea is to use both spin components of a neutron ensemble in a beam. The positive component is reflected from one magnetized mirror, and the negative component, which passes through it, is rotated by 180° and reflected from another mirror. Both beams were detected by a single detector. With the coefficients of reflection of spin components from the mirrors and the efficiency of rotation of the negative component factored in, an approximately twofold enhancement of the neutron intensity was obtained at an average polarization of ~66%. A monochromatic neutron beam was used in these experiments.

[en] Investigation of the magnetic structure of the diluted (Pd_0.984Fe_0.016)_0.95Mn_0.05 alloy at meso-and nanoscale levels by means of two techniques of small-angle polarized-neutron scattering (within a direct beam and beyond it) has been performed in the temperature range 10< T<60 K. The dependences of the neutron beam depolarization, the polarization rotation angle, and the polarization-dependent magnetic scattering cross section on a weak (0< H<40 A/cm) external magnetic field have been studied. A simple model of neutron beam depolarization by a sample with uniaxial magnetic anisotropy was used to analyze the results obtained. The experiment on polarized-neutron scattering in the so-called direct geometry showed the existence of a polarization-dependent scattering cross section. This scattering has left-right asymmetry and depends on temperature. Comparison of these results with the depolarization data leads to a conclusion about the existence of static chiral fluctuations in large-scale inhomogeneities

[en] Electron spin resonance (ESR) is used to study the neutron transmutation doping of silicon crystals enriched with ³⁰Si isotope: phosphorus donors and radiation defects produced in the course of transmutational doping are observed. The ESR signals related to the phosphorus uncontrolled impurity in ³⁰Si before transmutational doping (the P concentration is ∼10¹⁵ cm^-3) and phosphorus introduced by neutron irradiation with doses ∼1 x 10¹⁹ cm^-2 and ∼1 x 10²⁰ cm^-2 (the P concentrations are ∼5 x 10¹⁶ and ∼7 x 10¹⁷ cm^-3, respectively) are studied. As a result of drastic narrowing of the phosphorus ESR lines in ³⁰Si, the intensity of lines increased appreciably, which made it possible to measure the phosphorus concentration in the samples with a small volume (down to 10^-6 mm^-3). The methods for determining the concentration of P donors from hyperfine structure in the ESR spectra of isolated P atoms, exchange-related pairs, and clusters that consist of three, four, and more P donors are developed. In the region of high concentrations of P donors, in which case the hyperfine structure disappears, the concentration of P donors was estimated from the exchange-narrowed ESR line