Instruments and Experimental Techniques最新文献

The research investigates the distribution of intensity and energy of X-ray radiation in the detector plane for three pulsed X-ray sources. The sources generate nanosecond duration radiation pulses with different maximum voltages: 90, 320, and 615 kV. The X-ray tubes of these sources are designed in a coaxial form, with a tantalum disc as the autoemission cathode, which has an internal hole whose diameter depends on the maximum voltage of the source. The anode is a sharpened tungsten rod with a diameter of 4 mm. Due to the electrode design, which allows for a relatively small focal spot at high voltages, the distribution of radiation intensity across the detector area differs from the classical Gaussian distribution. This difference is observed for sources with maximum voltages above 300 kV. The ability to obtain high-energy radiation allows for the application of these sources in obtaining dual-energy X-ray images. The dependence of the distribution of radiation with different effective energies across the detector area is investigated for efficient use of dual-energy processing.

The article describes a prototype device for monitoring the level of phase separation, which can be used for operational control of the delayed coking process in the petrochemical industry. A scheme and design of an experimental device developed by the authors, consisting of an organic plastic scintillator and an array of silicon photomultipliers, is presented. A computer simulation of the response of a scintillation detector under conditions of the actual geometry of the coke drum is presented. Experimental results demonstrating the performance of the device are presented.

The paper presents a description of a device for studying the emission spectra of phosphors for laser lighting systems when they are affected by laser radiation with λ = 405–450 nm with different values of power and current. The scheme of the device driver and its component base is described in detail. When using a laser device, the authors of the work obtained the values of the luminous flux depending on various values of current and electric power. The use of a thermal imager made it possible to register the thermal fields formed during this kind of impact. Based on the results of the work, it was concluded that the design of a laser device with adjustable current strength and electrical power obtained in the course of the work makes it possible to carry out various applied scientific research related to the study of the effect of laser radiation on matter.

A successful LINAC operation at Synchrotron Radiation Facility−Siberian Circular Photon Source (SRF SKIF) is directly related to the improvement of diagnostic methods for measuring the transverse profile and longitudinal distribution of the beam charge, which, in turn, requires the use of new materials or methods for their production. The thermal outgassing has been measured from aerogel and electrophoretically deposited P43 phosphor used in the LINAC diagnostic system of SRF SKIF.

The results of a study of three methods for determining the phase of signals from a heterodyne microwave interferometer are presented: phase calculation by processing digitized signals using software methods; direct phase measurement with an AD8302 detector; and phase measurements by quadrature detection. The results of phase measurements obtained by these methods are compared. The values of errors of each method are estimated and ways to minimize them are considered.

A hybrid muon hodoscope for muonography of large-scale objects has been created in the Scientific and Educational Centre NEVOD (MEPhI) with the participation of the National Research Center “KI”–IHEP. The multichannel detecting system of the hodoscope consists of a scintillation strip detector and a detector on drift tubes and is designed to detect tracks of charged particles, mainly muons, flying through the detector volume. The drift tube detector is an important recording element of the muon hodoscope, providing high angular and spatial accuracy of muon track reconstruction. The article describes the design of the drift tube detector, the principles of operation of the readout electronics, and also provides the main technical characteristics.

The schematic diagram and design of an electrostatic lens for correction and additional focusing of a beam coming out of a magnetron-type ion source are described. A drawing of such a lens is presented.

Optical time domain reflectometer (OTDR) is the most basic and widely used equipment in optical fiber detection. Its performance and trace analysis ability play a decisive role in the maintenance of optical fiber. Traditional OTDR event detection methods rely on manual definition of pulse characteristics, require professional prior knowledge, and require high signal-to-noise ratio. The traditional preprocessing methods such as smoothing and denoising have some actual signal characteristics weakened or even disappeared. UNet is the most classical U-structured network model applied to medical image segmentation. It can learn a very robust model for edge extraction by using a small amount of data. Inspired by this, we propose the first OTDR event detection method based on the improved 1D UNet, which makes full use of the convolution neural network to automatically extract signal features. It can be applied to small sample data sets and it can accurately identify multiple types of events such as power injection, reflection, drop, end and echo events, with an average detection rate of 90%. Compared with the EXFO FastReporter software widely used in the industry, our method shows a stronger ability to resist noise interference, and the detection of echo events in high noise areas reaches 89%.

A regular monodisperse flow of spherical microtargets of solid hydrogen or deuterium with a variable diameter of several tens of micrometers and a frequency from several tens to several hundreds of kilohertz is in demand as internal targets in physical experiments at accelerators. The paper is devoted to the modification and launching of a prototype cryogenic corpuscular hydrogen target in which the gas entering the facility is transformed into a flow of spherical microtargets. Processes of cryogenic cooling and liquefaction of the gas, formation of a liquid microjet, and its controlled monodisperse disintegration into equal-sized drops are realized in the target, and they are followed by freezing of the drops and formation of microtargets upon injection into vacuum. The target prototype is composed of the cryogenic, vacuum, and gas systems as well as the systems for control and optical diagnostics of microtarget parameters. The modified target prototype provided monodisperse regimes of generation of microtargets with a diameter of 20–50 μm at a generation frequency of 260–465 kHz.

The design and parameters of scintillation detectors of Compton polarimeters for measuring photons formed during the annihilation of electron-positron pairs at rest are considered. The discussed setup makes it possible to measure and compare the polarization correlations of scattered annihilation photons in these two quantum states. The amplitude parameters of scatterers and scattered photon detectors obtained from preliminary tests of these detectors using radioactive gamma sources, as well as in the process of collecting experimental data, are given. The possibility of measuring and comparing the polarization correlations of scattered annihilation photons is shown.