Instruments and Experimental Techniques最新文献

The chirped pulse spectral interferometry method was used to measure the copper-target free surface motion velocity under the impact of an ultrashort laser pulse with an intensity of ~10¹⁸ W/cm². In order to obtain information on the motion of plasma layers with different electron densities, a two-channel interferometer was developed, which provides registration of hydrodynamic parameters of the target expansion process for the probe laser radiation at 1054 and 527-nm wavelengths. The spatial and temporal characteristics of the phase shift and the target reflectivity for the probe radiation were measured, and the two critical-density surfaces velocity evolution over time were reconstructed.

Formulas are given for calculating the coefficient of backscattered electrons depending on the material (atomic number Z), i.e., the chemical composition of a sample, and the energy E_B of the primary irradiating electrons. The calculation of the detectable signal of reflected electrons is given depending on Z, E_B, and the response function F of semiconductor detectors and detectors based on microchannel plates (MCPs). The calculation results are compared with the experimentally measured ones. A comparative analysis of the contrast of images of the composition of samples obtained for different types of detectors at different E_B is performed. The results of the research are intended to serve practical users and experimenters in scanning electron microscopy.

A trigger system of the Experimental Complex NEVOD (EC NEVOD) unique scientific facility is described. Detectors and setups that differ in area, physical principles of detection, and background counting rate are included in the EC NEVOD to detect various components of cosmic rays. Each detector is equipped with its own original data-acquisition and trigger system and is able to operate independently. In addition, the detectors are all combined by a single system of data triggering and synchronization. Features of the individual detector systems, their main characteristics and methods of their initialization and integration are presented.

A device was designed to measure the ultimate strength of various multilayer rods and has a wide application area, e.g., in construction. The basic requirements for the device were formulated; one special requirement was compliance with all the theoretical nuances of the method underlying it. The device was then designed and tested. As a result of the tests, good agreement was found between the obtained value of the average ultimate strength of fibers and the data from their specifications; this means that the resulting device meets all the presented requirements. It is believed that the device should improve the quality of both the primary electrical installation and the subsequent maintenance of various ready-made objects, including those intended only for communications.

Scintillation plastic strips with wave length shifting fibers are the basic elements of the sensitive volume of the reactor antineutrino detector DANSS. The need for the strip’s design improvement is caused by the limitations of the experiment sensitivity to the sterile neutrino searches due to the moderate energy resolution of the detector. The new design of the strips features much higher light output and better light collection homogeneity. A method is discussed of simultaneous light detection from both ends of each fiber. This doubles the number of detected photons and gives information on the longitudinal event coordinate. The paper reflects the details and the status of the detector upgrade together with the recent beam test results. The expected influence of the improvements on the sensitivity to the sterile neutrino is also considered.

An approach is proposed to creating a diagnostic system for studying the main plasma processes (acceleration and detachment of the plasma flow from the magnetic field lines) in the magnetic nozzle of an electrodeless plasma rocket thruster. The diagnostic system has been developed for the PN-3 setup, an electrodeless plasma rocket thruster prototype, in which this approach has been implemented.

This study is devoted to an optoacoustic study of the features of laser radiation absorption in an aqueous solution of the styryl-dye inclusion complex in cucurbituril. The research was performed on an experimental setup where a femtosecond regenerative amplifier based on chromium forsterite (Cr:F) was used as a pumping laser. The third harmonic of radiation with a wavelength of 420 nm and a pulse duration of 130 fs was used. Optoacoustic generation was produced in a quartz cuvette with the investigated solution, and the receiver of acoustic signals was a flat piezoceramic plate with a resonant frequency of 1 MHz. Optoacoustic signals were compared in a solution of pure Kr.1 styryl dye and the same dye in the presence of complexes with cucurbituril. With the same optical density of solutions, complexation leads to a more than twofold decrease in the optoacoustic response.

The goal of this work is to investigate the feasibility of using the Artix-7 FPGAs from Xilinx in a data acquisition system for the silicon tracking system of the BM@N experiment. Under conditions of relatively low radiation level, the FPGA can be used as an affordable alternative to the GBT link of radiation-tolerant chips currently used in modern high-energy physics experiments at CERN, FAIR, etc. This link of microcircuits was designed for data concentration from multichannel on-detector electronics and transmission via optical communication line to the electronic units of data postprocessing. The results of studies into the sensitivity of the selected FPGA to radiation damage from protons with energy of 1 GeV and estimated failure rate of configuration (CRAM) and block static memory (BRAM) under the conditions of application of this technical solution in the BM@N experiment are presented. Additionally, the results of the study into the efficiency of the implemented methods of error correction in the configuration memory of the tested FPGA are presented.

This study explains a magnetic levitation system to measure the material density with high accuracy. The main components of the magnetic levitation system are the paramagnetic solution, the two permanent magnets, and the digital camera. When the sample is submerged in a paramagnetic solution, it can be suspended at an equilibrium position between the two similar magnets with like poles facing each other. A 3D model is explained to facilitate the measuring process. The COMSOL simulation is performed to find suitable distance between the two magnets for measuring the material density up to 1.2 g/cm³. The magnetic levitation system is examined and verified using standard-density glass beads. Then, various samples (powder or solid) with different densities are tested. According to the obtained results, the magnetic levitation system can be used to measure and determine the material density with the maximum deviation of ±0.0003 g/cm³.

To visualize the region of nuclear reactions of DD-fusion, the method of registration of protons with energy E_p = 3.02 MeV, formed in the second neutron-free channel, which has the same probability as the reaction in the neutron channel, was used. The results of recordings on the CR-39 track detector of the plasma cumulation region using two different coding diaphragms and the results of estimating the number of reactions in targets with an inverted corona using this method are presented.