Instruments and Experimental Techniques最新文献

The cryogenic system of the RED-100 two-phase emission detector has been modified to enable operation with liquid argon as a working medium with the aim of searching for the effect of coherent elastic scattering of reactor electron antineutrinos by argon nuclei.

A relatively simple circuit of a selective meter of constant and variable components of the total current of a photomultiplier when recording magnetic circular dichroism spectra in reflected light using the method of light-wave phase modulation with the help of a photoelastic modulator is presented. The circuit implements a method for measuring the photomultiplier anode current using a load resistance R_L and a buffer preamplifier. The variable current component is extracted via compensation of the constant component of the total signal. The experimental techniques are described that make it possible to determine the optimal R_L value for which the influence of the input shunt capacitance is minimal in the frequency band of ~100 kHz. The main source and level of the parasitic photocurrent not associated with the incident monochromatic radiation are determined. The meter testing showed high efficiency of its use in magnetic circular dichroism spectroscopy. An algorithm for spectrum recording is proposed taking the change in the circular dichroism effect polarity into account. The performance and efficiency of the developed meter are illustrated by an example of measuring the magnetic circular dichroism spectrum of a GaMnAs film.

A stepper electric motor has been designed to rotate a sample in an experimental cell inside a cryostat with ³He pumping. The device based on a rotor with crossed electrical windings, operates in an external magnetic field generated by a superconducting magnet. A prototype of the motor was mounted on a microwave spectrometer with a rectangular resonator. Test angular dependence of the magnetic resonance spectrum was obtained in a well-studied weak ferromagnet ({text{MnC}}{{{text{O}}}_{3}}) at temperatures 0.5–7.5 K in the range of angles ±100° from the initial position. Overheating of the cell and cryostat was studied and the heat release during operation of the mechanism was estimated.

Hundreds of 650 MHz superconducting radio-frequency (SRF) cavities with high intrinsic quality factor (Q₀) and accelerating gradient (E_acc) will be adopted for Circular Electron Positron Collider (CEPC). The values of Q₀ and E_acc are obtained during vertical test at 2.0 K. Hence, high accuracy of vertical test is essential for evaluating the performance of SRF cavity. The 650 MHz SRF cavities achieved very high Q₀ (6 × 10¹⁰) and E_acc (40 MV/m) during the vertical test. In our study, the error analysis of vertical test was conducted in the scalar case, in order to achieve high accuracy. The uncertainties of vertical test were obtained through calculation, which was approximately 3% for E_acc and less than 5% for Q₀. This result was reasonable and acceptable.

Ballistic design work has been carried out to assess the appearance and dimensions of the double-barrel launcher with an accelerating-channel length of up to 1 m. Based on the ballistic design, the development, design study, and manufacture of the double-barrel launcher have been performed. An ignition system has been developed, with which it is possible to throw two supercavitating strikers into an air or water environment simultaneously and with a programmable delay. Test experiments on throwing two supercavitating strikers into air and water have been conducted under the conditions of a hydroballistic stand.

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.