Instruments and Experimental Techniques最新文献

The paper deals with the design and parameters of thin scintillation counters, not more than several mm thick, with a large geometric aperture. Such counters with high light yield and, accordingly, with high detection efficiency of charged particles are widely used in nuclear and particle physics, as well as in facilities for beta contamination monitoring of clothing and various objects by extracting signals of low-energy electrons against a background of gamma radiation. In these applications just the minimum thickness of the scintillator with the required large geometric dimensions of the detector determines the high efficiency of the counters.

A device is presented that has a temperature converter made in the form of a mesh made of a material with low thermal conductivity and a thermal imager. Its use makes it possible to record the air-flow temperature field layer by layer, which indirectly determines the configuration and dimensions of the vortex structures at the outlets of the vortex tube. It has been established that the parameters and structure of the outgoing flows of both cooled and heated air from a counterflow vortex tube with axial outlets depend on the ratio of the areas of the flow sections of the diaphragm and diffuser.

Original experimental methods for studying the dislocation structure and mechanical properties of solids developed at the Andronikashvili Institute of Physics are described: (1) a method for exciting mechanical vibrations of an ionic crystal, (2) a high-quality tuning fork of a new type (three-reed), (3) a method of crystal deformation by shear, (4) a method for generating dislocations of the same mechanical sign, (5) a method for determining the parameters of the relaxation process, and (6) a vibrating superconductor method.

We describe a method and a setup based on it which has been used to measure the production cross sections of the delayed-neutron precursors (⁹Li, ¹⁶C, and ¹⁷N) and the fractional delayed-neutron yields in interactions between relativistic protons with an energy of 1 GeV and target nuclei with mass numbers in the range of 12−238. Measurements have been made at the synchrocyclotron facility of the Petersburg Institute of Nuclear Physics (PNPI), Gatchina. The measured cross section for the generation of ¹⁷N nuclei versus the mass of target nuclei are shown as an illustration of the method. The fractional delayed-neutron yields in interactions of relativistic protons with ²³⁸U nuclei are also presented.

A hybrid muon hodoscope for muonography of large-scale objects was created at the Scientific and Educational Center NEVOD (MEPhI). The hodoscope multichannel detection system consists of a scintillation strip detector and a drift tube detector and is designed to record tracks of charged particles, mainly muons. The scintillation strip detector is an independent track detector that forms the initial track position and the trigger signal for the drift tube detector. The article describes the design of a scintillation strip detector and principles of operation of the readout electronics and also provides the main technical characteristics.

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.

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.

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.