Instruments and Experimental Techniques最新文献

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.

The multicomponent gas analyzer has a wide range of applications, such as environmental monitoring, chemical reaction and industrial process control, accident prevention, exploration in the oil and gas industries, and biomedicine. Laser photoacoustic spectroscopy is the universal method for analyzing gaseous impurities due to its high selectivity, sensitivity, and fast response. This paper presents an automated gas analysis system based on the combined optical parametric oscillators tuning from 2.5 to 10.8 µm. The full width at half maximum of the spectral line is approximately 5.5 ± 0.5 cm^–1 in the range from 2.5 to 4.5 μm and approximately 2 ± 0.5 cm^–1 in the range from 4.5 to 10.8 μm. Using software installed on the control computer, the controller performs all necessary operations, including pumping, analysis, and removal of gas samples in the measuring complex. The paper presents experimentally recorded absorption spectra of gas mixtures of CO, CO₂, and CH₄ obtained using a differential photoacoustic detector.

The experiment on the placement of side acoustic steel screens at different heights from the radiating surface is described. The radiation patterns (RPs) have been recorded. The width of the main lobe of the RP in a vertical plane at a level of 0.707 is analyzed as a function of the heights at which the side acoustic shields are located.

To measure the spatial distribution of the magnetic field, both single Hall sensors and arrays of Hall sensors are used. In most cases, a one-dimensional ruler is sufficient. The finished device is called a measuring carriage. The rest of the article describes the first stage of its creation. This article consists in Hall sensor rejection, during which the sensors operate under extreme operating conditions (with increased electrical and thermal loads). During this so-called accelerated aging, the changes in the residual stress values, temperature coefficients, nonlinearity, and divergence of the sensitivity coefficient were monitored. This study can serve as a methodological guide in determining the selection criteria for Hall sensors for precision measuring systems. The need for aging sensors was shown to stabilize their long-term characteristics. In addition, the process of rejecting sensors according to the parameters of interest is described.

This article uses polydimethylsiloxane (PDMS) to package an improved fiber Bragg grating (FBG) temperature sensor. Unlike the structure of PDMS completely enveloping fiber gratings, we utilize microfluidic processing technology to construct a microchannel with a diameter of 150 μm in the area of the fiber gratings. It eliminates the thermal stress on the fiber grating in the radial direction. Through the force analysis of the fiber gratings in the packaged sensor, it can be found that eliminating the radial thermal stress is conducive to improving the axial coefficient of thermal expansion of the fiber gratings. The temperature sensing characteristics of this structure are verified by simulation and experiment. Both theoretical and experimental results have shown that this structure can effectively improve the temperature sensitivity of the sensor. In the experiment, the temperature sensitivity of the packaged sensor is 3.5 times higher than that of the standard fiber gratings. The temperature sensitivity of the sensor is 37.6 pm/°C. It is simple to manufacture, does not pollute the environment, and can accurately monitor the temperature of the complex environment. Therefore, it is an ideal model for temperature monitoring in complex environments such as the ocean and mine.

A high voltage electric-discharge device is considered that provides the production of steel, aluminum, and silicon particles with a size of less than 100 nm from granules placed in a chamber with running deionized water. The possibilities of significantly increasing the power of the developed device have been determined.