Instruments and Experimental Techniques最新文献

A system for measuring the spatial distribution of the of beta radiation flux from the radiation source surface has been developed and studied. The principal element of the measuring system is a probe sensor based on scintillation optical fiber, the output optical signal from which is fed to the input of the photon counter and further processed by a microcontroller. Using the numerical modeling method and the Geant4 software libraries, the sensitivity parameters of the sensor element were calculated for the process of measuring the beta radiation flux from the surface of a 63Ni based flat source. The spatial distribution of the yield of beta electrons from a 1 × 1 cm² source and the dependence of the sensitivity of the probe on the distance to the source were experimentally studied. The experimental data are in good agreement with the results of the model calculation.

The results of experimental studies of the neutron field characteristics with an energy of 14.7 MeV created by the portable neutron generator NG-14 are presented. The measurements were made using a fast neutron radiometer based on a diamond detector. The neutron beam from the neutron generator’s target passed through a massive collimator made of steel. Analysis of the amplitude spectra of the diamond detector, caused by the registration of fast neutrons, made it possible to determine the following characteristics of the neutron field: the flux density of direct neutrons, the flux density of neutrons scattered in the collimator, and the energy spectrum of neutron radiation. Based on the obtained energy spectra, the kerma of neutron radiation in the water phantom and the dose rate of scattered neutrons behind the collimator with an energy higher than 0.5 MeV were calculated.

A setup that allows for measuring the scattering of a step ultra-wideband electromagnetic wave (subnanosecond front duration) by small-size objects is considered. The main feature of the setup is the selection of the nonlinear response component in a scattered signal with a continuous spectrum. The intensity of the test field achieved in the experiments is 135 W/m². It is shown that the threshold sensitivity for the object’s nonlinear response is limited mainly by the shift of local fragments of the recorded signals that occurs in the stroboscopic receiver. By correcting these shifts, a threshold sensitivity for the potential of a nonlinearly scattered field of no worse than 3.5 mV was obtained at a potential of a field scattered by the object not exceeding 520 mV. The results of testing the setup using linear and nonlinear standards with known parameters, as well as observing the nonlinear response of a small-sized electronic device, are presented.

This study presents an experimental investigation of turbulent flow characteristics within a wind-tunnel environment. A methodology was developed to analyze the parameters and characteristics of the turbulent flow in the wind tunnel’s test section. This methodology encompasses the determination of the reproducible range of air velocity, airflow velocity instability, nonuniformity of the airflow velocity field. The findings from the velocity field analysis demonstrate the feasibility of conducting aerodynamic tests on models subjected to a uniform flow within the wind tunnel.

The scintillation amplitude−coordinate spectrometer with a thickness of 0.58X₀ has been calibrated using cosmic radiation. The light signals in the spectrometer are detected by FEU-49 and FEU-85 photomultiplier tubes, which determine the amplitude and coordinate systems, respectively. It has been established that the relative amplitude and coordinate resolutions depend on the point of particle incidence on the spectrometer. The relative amplitude and coordinate resolutions measured at the center of the spectrometer appear to be the best, and their values are ~8.7% and ~1.6 cm, respectively.

The radiation patterns of broadband antennas have been measured in a laboratory using linear frequency modulation (LFM) of the signal. The investigations have been carried out on the basis of the Imitation−Full-scale Hydroacoustic Complex unique scientific installation (UNU “INGAK”) of the Department of Electrohydroacoustic and Medical Equipment at the Institute of Nanotechnologies, Electronics, and Instrumentation of Southern Federal University. A special feature of the experiment is that the antenna pattern data are recorded at once in the entire operating frequency band and the frequencies of interest are extracted by digital processing of the measured data.

A sample cell with increased efficiency compared to standard quartz capillaries for studying the structure of solutions by small-angle X-ray scattering (SAXS) has been developed and tested. The circular cross-section of the standard quartz capillary leads to a decrease in the effective aperture and the appearance of additional parasitic scattering. A special feature of the cell design is the presence of plane–parallel X-ray transparent windows, which provide a significant improvement in the signal-to-noise ratio of SAXS data compared to data obtained using standard imported capillaries. The cell design includes at least two identical microliter cavities for samples, which allows comparing the measured object with a reference solution in one experiment or using solutions with different chemical compositions (including concentrations). Test measurements for a standard capillary and the proposed cell were carried out, showing a significantly more isotropic scattering pattern when using the cell. Its advantages are the reusable cell design and replacement of imported products (quartz capillaries). The cell has been successfully tested for studying crystallization solutions of potassium dihydrophosphate and lysozyme protein at different temperatures.

The characteristics of an ion source with gas filling and electron injection were studied as part of the development of the ^229mTh isomeric state ion generator. Calculations of the distribution of the electric potential and electron density in the helium media were carried out. The efficiency of ion evacuation was measured. The created technique is characterized by high efficiency and speed in combination with the possibility of forming an intense ion beam of radioactive decay and nuclear reactions products.

This paper focuses on the evaluation of scanning devices for in-pile radiation measurement of the shut-down uranium–graphite reactors. The description of several generations of scanning devices is presented cause their design and configuration has been constantly improved in the light of experience and new objectives. Approaches and results of determining the metrological characteristics of γ- and neutron detectors of various types directly in reactor designs in which mixed radiation (α-, β-, γ-, and neutron radiation) prevails are considered. Estimates of the influence of the energy dependence of the sensitivity on the γ-detectors readings of different types, as well as the neutron detectors noise-immunity to γ-radiation, are presented.