Vol 61, No 5 (2018)

A neutron spectrometer based on stilbene crystals has been developed by the Flerov Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research (Dubna, Russia). The timing resolution is determined as a function of the signal amplitude (σT = 0.18 ns at an amplitude of 1 MeV in the electron equivalent). The measured energy resolution of the detecting modules for γ rays is σE/E = 4.5% at E = 1 MeV. The quality of the n–γ discrimination is investigated. It is shown that reliable discrimination is possible, beginning with a deposited energy of 100 keV in the electron equivalent, which corresponds to the kinetic energy of recoil protons of ∼700 keV. The neutron spectrometer helps to significantly expand the experimental capabilities and to carry out correlation experiments with radioactive beams on the ACCULINNA-2 fragment separator at a new level of quality.

A prototype of a 2D detector based on specially designed straw tubes with cathode data readout has been developed and tested. This detector exhibits comparable accuracies in measuring radial and longitudinal coordinates. Its rate capability is similar to the capabilities of traditional detectors whose tubes are smaller by half in diameter.

A prototype of a transition radiation detector based on straw proportional chambers has been tested at the CERN SPS accelerator beams. A detailed Monte Carlo simulation program has been developed to describe the results obtained during these measurements. Some data obtained in beam tests and their comparison with simulation results are presented.

The calibration telescope system of the NEVOD Cherenkov water detector is described. Scintillation counters are used in the setup as detecting elements. The detection system is equipped with logical and amplitude channels and provides the calibration of the Cherenkov water detector. It can also be used to investigate the electron and muon components of an extensive air shower. A method for amplitude calibration of the scintillation counters is described, with which it is possible to estimate the number of detected charged particles. The results for the 1.5-year operation of the setup as a detector of extensive air showers are presented.

The telemetry, command, and precision control system of the GRIS (γ- and X-ray radiations of the Sun) instrument for the future GRIS-FKI-1 space experiment is described. This experiment is aimed at investigating nonstationary hard X- and γ-ray fluxes from the Sun onboard the International Space Station. Compared to the resources provided by onboard systems, the set of proposed hardware greatly expands the capabilities of the instrument in the acquisition of service data and control, including the precision control, of the detectors characteristics. The system also helps to improve the thermal conditions and calibrate the spectrometric detectors of the instrument during an experiment.

An atomic injector with a beam power of 1 MW for heating plasma in the TCV tokamak (Lausanne, Switzerland) by a beam of neutral atoms was developed and put into operation in 2015–2016 at the Budker Institute of Nuclear Physics SB RAS (Novosibirsk). Plasma in the injector is formed in a plasma emitter by a high-frequency magnetic field, which is created by a high-power semiconductor generator with an output power of 40 kW at a frequency of 4 MHz. The facility operates in the pulse mode with a pulse duration of 2 s and a pause of 5 min. The generator is manufactured in the form of a modular system consisting of 16 identical generator modules, whose high-frequency power is summed, control modules, and a power-supply source. The generator allows modulation of the output power in the range of 30–100% by changing the power-supply voltage. The general structure of the generator and its elements and the results of its commissioning are presented.

Six types of precision stabilized-current sources (power supplies) have been developed to correct the parameters of the electron beam at the European X-ray Free-Electron Laser. Power supplies are designed to feed the windings of corrector magnets with a direct current of up to 10 A. Based on the stability requirements of the electron beam, the permissible output current instability should be 10^–5 or less. All power supplies must satisfy the requirements of electromagnetic compatibility with the electronics of the free-electron laser. The circuit and design features of the power supplies are described and the test results are presented

A modified wire scanner and a new methodical approach were used to measure the profile, current, and phase portrait of a negative hydrogen ion beam injected into a tandem accelerator with vacuum insulation. The effect of the space charge and spherical aberration of the focusing lenses on the negative hydrogen ion beam is revealed. Recommendations are given, whose implementation will make it possible to increase the current of the proton beam from 5 to 10 mA in the accelerator, which is sufficient for boron neutron capture therapy of malignant tumors.

The MONICA satellite-based experiment is described. In this experiment, fluxes of cosmic-ray ions from H to Ni are investigated near the Earth in the energy range of 10–300 MeV/nucleon. The main scientific objectives of the MONICA experiment are to measure the ion and isotope compositions and the energy spectra of solar cosmic rays for individual solar events and to study the evolution of these characteristics over time. The MONICA experiment will help to investigate the ion and isotope composition of the anomalous component of cosmic rays, galactic cosmic rays, and nuclear fluxes in the Earth’s radiation belt. Observations of ion fluxes will be carried out using the MONICA high-aperture multilayer semiconductor spectrometer–telescope installed on board a spacecraft with a low-Earth circular polar orbit at a height of approximately 600 km. This orbit will make it possible to perform the method for measuring the charge of ions with energies above 10 MeV/nucleon, which is based on the use of the Earth’s magnetic field as a particle- charge separator. The geometric factor of the instrument is 100 cm² sr and the angular resolution is 1°.

The information on the spatial distribution of a magnetic field in a rather large volume is needed, for example, in magnetic-resonance tomography, when it is important to have a uniform magnetic field in the working region of a tomograph. The stages of the optimization of a magnetic-field sensor, which is used to adjust the magnetic-field homogeneity, are described. These stages are aimed at a decrease in the measurement errors that are associated with the parallel registration of several harmonics, which constitute the magnetic field. The results of calculations on the mathematical modeling of various configurations of the magnetic- field-uniformity sensor and the practical implementation of the chosen variant are presented.

A clamp for establishing a thermal contact between cryostat components in a vacuum is described. The contact is established by pressing heat conductors to each other using a permanent magnet and is broken or established by applying a current pulse of the required polarity to the winding around an iron magnetic core. The device is held in the open state by a second permanent magnet. Through the pressed contacts, a copper block with a mass of ∼600 g is cooled in the vacuum from the liquid-nitrogen temperature to the liquid- helium temperature within 4–5 h.

A technique that allows simultaneous measurements of vortex and wave motions of fluids is described. To record the vortex motion, a liquid surface is decorated with light particles of PA-12 polyamide with an average diameter of 30 μm and video filming of the motion of these particles is performed. The wave motion on the water surface is recorded using an improved method that we proposed earlier for spatial recording of waves on the surface of a transparent liquid; this involves video filming of a contrast stencil lying on the bottom of an experimental pool. The distortion of the video image of the stencil through the transparent liquid layer allows the vertical velocity component to be reconstructed.

A two-chamber calorimeter with industrial TEC1-12706 Peltier modules used as heat-flow sensors and heating elements is described. The measured temperature dependence of the volt–watt sensitivity in the temperature range from –180 to 50°С is presented. The features of the measuring technique are described. The measured temperature dependence of the specific heat of ice is shown.