Vol 59, No 1 (2016)

Detector calibration plays an important role in improving of image quality and increasing performance of positron emission tomography (PET) systems. To achieve this aim, raw data coordinate event-byevent are mapped to the index of the crystal in which the particle is absorbed. We proposed and tested subtractive clustering and Hough transform algorithms to determine crystal peak position and generate an appropriate look-up table. The results show superiority of Hough transform to the subtractive clustering and other methods because this algorithm determines position of all peaks, even in irregular and unclear data. The acquired results can be beneficial for all of the medical imaging instruments such as PET and single-photon emission computed tomography detectors based on pixilated scintillators.

Results of the analysis of literature sources on development of microelectronic signal acquisition and processing units for ionizing radiation detectors in large-scale physical experiments are given. The basic parameters of these units, such as the channel number, power consumption per channel, conversion coefficient and noise level are summarized in the generalizing table. Conclusions on the performed analysis are made and trends in the design and implementation of the considered units manufactured as applications specific integrated circuits are noted.

Triggered vacuum switch (TVS) is one of the important switch apparatuses in the high pulsed power system, which takes the vacuum as insulation and arc-extinguishing medium of main gap. The conduction of TVS is the arcing process of vacuum arc in practice. So, it is meaningful to research on the vacuum arc characteristics for the high current application of TVS. A six-gap rod electrode system is studied in this paper. It is made up of 3 pairs of rod electrodes, i.e., spatially interleaved rods of opposite polarity on a ring. The arc development under different high currents is tested and discussed, based on the electrical characteristics of the vacuum arc voltage and arc resistance. The variety of arc voltage shows the parallel arcing and the transfer process in the multi-channel, which is benefit to maintain the diffusion of vacuum arc. A TVS sample based on multi-rod electrode has carried high current of 225 kA in peak and charge transfer of 45 C in a pulse.

The relevance of simulation of the electromagnetic compatibility tests is justified. The developed technique for synthesizing the models and printed-circuit boards that are used in measurements of components are described in detail. The frequency dependences of the reflection coefficients of a capacitor and inductor for surface mounting were measured in a range up to 40 GHz. Multi-resonance models consist of RLC elements. The verification of the models on the basis of the RMS deviation showed an acceptable coincidence with the measurement results.

The purpose of this review is to give experts, who use electronic procedures in experiments or measurements in applied areas, whenever it is possible, the complete picture of the past 5-year rapid development of application specific integrated circuits for readouts and processing of signals from up-to-date nuclear particle detectors. Due to the large information content, the review is formally divided into two parts. The evolution history of the application specific integrated circuits for different types of detectors is considered in the first part. Both parts have the common classification table, common numeration of cited papers, drawings, and formulas.

Performance of the gas-filled detector prototypes based on the GEM, TGEM, and Micromegas technologies was studied on the test beam of the CERN PS accelerator. Three-component mixtures based on Ar and He were used as the working gas. For all tested detector prototypes, the gas amplification factors were measured, and the detection efficiencies, cluster distributions, and the radii of the charge cloud collected on the readout electrode were estimated.

A tri-band high-resolution spectrometer, which was designed for performing diagnostics on the ITER facility using the charge-exchange recombination spectroscopy (CXRS), is described. The CXRS allows measurements of such plasma parameters as the ion temperature, the speed of the toroidal and poloidal plasma rotation, and the concentration of light impurities. The spectrometer is based on three transparent holographic diffraction gratings and is designed to operate simultaneously in three spectral bands: 468 ± 6 nm, 529 ± 6 nm, and 656 ± 8 nm. The results of measuring the main performance parameters of the transparent diffraction gratings and the spectrometer as a whole are presented. It was established that the characteristics of the developed spectrometer satisfy the requirements for the spectroscopic equipment for the ITER CXRS diagnostic system.

A pulsed soft-X-ray detector consisting of a high-current photomultiplier tube and a thin-film polystyrene-based plastic scintillator was developed. Its characteristics were investigated by detecting quasimonochromatic 0.84-keV X-ray pulses. The dependence of the scintillator light output on the photon energy flux density was obtained. The average effective thickness of the surface non-scintillating (“dead”) layer affecting the spectral response of this detector type was estimated.

A model of the setup for determining the ²³⁵U content of a fuel assembly for WWER-440 reactors is described. The setup operates based on the digital technology for discriminating neutron and photon scintillation responses. An AmLi source is used as an external neutron source. A three-channel system for detecting fission particle coincidences is based on EJ-309 scintillators. A set of digital codes for obtaining and analyzing neutron-neutron (nn), neutron-γ (nγ), and γ-γ (γγ) coincidences has been developed. Dependences of double coincidences have been experimentally obtained and analyzed with the aim of determining the ²³⁵U content of the fuel assembly. It is shown that fission neutrons and coincidences of the nn and nn + γn + nγ types are the best informative parameters for the ²³⁵U content of the fuel assembly.

The design of a vibration-control platform on the basis of magnetorheological (MR) elastomers is described. The platform is designed for protecting precision equipment and instruments against external vibrations at frequencies of up to 200 Hz and amplitudes of up to 100 µm. The platform contains four active dampers on the basis of MR elastomers and four elastic-support units with a mass corrector using which the platform is adjusted to a required equipment mass and a required resonance frequency. The proposed platform provides passive vibration isolation at a level of ∼10 dB at frequencies of from 0.5 to 30 Hz and vibration amplitudes of up to 500 µm. The results of experimental studies of transient processes (the minimum transient-process time is 30 ms), the transfer coefficient of the vibration-displacement amplitude, and the mechanical hysteresis are presented.

The design of an ionization-type pressure measuring transducer is described. The meter has two output channels: for electron and ion currents. The conversion range varies from 10^–3 to 10 Torr. The calibration characteristics are in good agreement with the predicted data of the classical impact-ionization theory. The standard calibration error is 7%. The calibrations of the meter were confirmed at the “Rostest-Moscow” Federal Budget Institution. To check the possibility of using the transducer for studying the middle atmosphere using meteorological rockets, the bench tests of the transducer for shock loads of up to 200 g were performed.

The presented paper is focused on possibilities of research of rheological properties of liquids with use of the device based on the principle of electromagnetic levitation. The device works on the principle of damping of the levitated body vibrations by the liquid. Levitation is ensured by feedback control of the magnetic field using an optical barrier. Vibrations are excited by controlled interruptions of electromagnetic field. Thanks to this principle it is possible to investigate the liquid of non-Newtonian character, as well as liquids susceptible to clinging on spindles of rotational viscometers. The equipment was calibrated using silicate oil standards and its performance was compared with commercially used models of viscometers Anton Paar FRS1600 (viscosity range 3 mPa s–20 Pa s, precision 0.5%, temperature range 300–1600°C) and Brookfield DV-III Ultra (viscosity range 1.4 mPa s–20 Pa s, precision 1%, temperature range 100–1600°C).

Technique and procedure for measurements of the heat transfer coefficient in experimental research of heat transfer at the liquid-solid interface are submitted. The technique enables to use the metal film applied to the surface both to heat the surface and to measure the surface temperature, thus minimizing uncontrolled heat loss and reducing the measurement uncertainty.