Gas Electron Multiplier (GEM) based coordinate detectors are used at different high energy physics centres and at Budker Institute of Nuclear Physics particularly. These detectors possess a spatial ...resolution in ten micron scale together with high rate capability up to 107 cm−2s−1. Thus, the precise investigation of best possible spatial resolution, achieved with GEM-detectors, is the subject of interest. The experimental data, accumulated by the moment, gives the possibility to compare it with the simulation results. The simulation of applied detector configurations includes transport of electrons through the detector and tracking of avalanche evolution inside the working volume, as well as obtaining signal distribution on the readout strips. The spatial resolution, obtained in the simulation of an individual detector, is found to be essentially better (the difference is about two standard deviations) than the experimental results. Further efforts to find out the reasons of the contradiction between the simulation and measurements were made. In particular, the simulation of complete experimental set-up (including tracking detectors) was performed. The results of individual detector simulation and the simulation of complete set-up were determined to generally coincide.
We study the causes and signs of degradation of cementite in chromium-nickel cast iron used for the production of massive forming rolls and the specific features of structural formation in cementite ...under the influence of operating temperatures and local strains formed in the rolls in the course of their operation. For this purpose, we use the procedure of high-temperature vacuum etching in order to detect dislocations, scanning electron microscopy, and the method of optical-mathematical description of the phases and their heterogeneity. It is shown that the degradation of cementite is connected with the formation of dislocation structures and diffusion, which promote the formation of new types of carbide phases with nonstoichiometric compositions, quasicrystalline graphite, and also ferrite and bainite. Possible combinations of newly formed phases are identified. They are also responsible for the stability of carbides. By analyzing the results of our studies of the degradation of cementite (regarded as a structural component specifying the level of hardness of the operating cast iron), we give recommendations concerning the possibility of improvement of stability of the cementite structure and decreasing the level of stresses in the rolls.
A review is presented of the latest technologies for vertex detectors that can be used in experiments at the NICA collider. These technologies include both the novel pixel detectors with new ...ultralight radiation-transparent carbon composite structures and cooling systems. The efficiency of reconstructing
D
meson decay is estimated for the developed detector complexes, and the possibility of using these complexes to study the formation of clusters of cold, dense quark-gluon matter inside nuclei are studied.
The spatial resolution of GEM based tracking detectors has been simulated and measured. The simulation includes the GEANT4 based transport of high energy electrons with careful accounting for atomic ...relaxation processes including emission of fluorescent photons and Auger electrons and custom post-processing, including accounting for diffusion, gas amplification fluctuations, the distribution of signals on readout electrodes, electronics noise and a particular algorithm of the final coordinate calculation (center of gravity). The simulation demonstrates that a minimum of the spatial resolution of about 10
μ
m can be achieved with strip pitches from 250
μ
m to 300
μ
m. For larger pitches the resolution is quickly degrading reaching 80-100
μ
m at a pitch of 500
μ
m. The spatial resolution of low-material triple-GEM detectors for the DEUTRON facility at the VEPP-3 storage ring is measured at the extracted beam facility of the VEPP-4M collider. The amount of material in these detectors is reduced by etching the copper of the GEMs electrodes and using a readout structure on a thin kapton foil rather than on a glass fibre plate. The exact amount of material in one DEUTRON detector is measured by studying multiple scattering of 100 MeV electrons in it. The result of these measurements is X/X0 = 2.4×10
−3
corresponding to a thickness of the copper layers of the GEM foils of 3
μ
m. The spatial resolution of one DEUTRON detector is measured with 500 MeV electrons and the measured value is equal to 35 ± 1
μ
m for orthogonal tracks.
The multilayer ion-plasma coating TiN/CrN, 6 layers of CrN and 5 lauers of TiN, for hardening of piston rings is proposed. It is established that as a result of hardening, the wear rate of rings ...decreases 15.7 times. A new method for estimating the residual thickness of the coating, which gives recommendations for improving the quality of coatings, is proposed.
The primary aim of this monograph is to provide a systematic state-of-the-art summary of the light scattering of bioparticles, including a brief consideration of analytical and numerical methods for ...computing electromagnetic scattering by single particles, a detailed discussion of the instrumental approach used in measurement of light scattering, an analysis of the methods used in solution of the inverse light scattering problem, and an introduction of the results dealing with practical analysis of biosamples. Considering the widespread need for this information in optics, remote sensing, engineering, medicine, and biology, the book is useful to many graduate students, scientists, and engineers working on various aspects of electromagnetic scattering and its applications.
Spatial resolution of triple-GEM detectors Kudryavtsev, V.N.; Maltsev, T.V.; Shekhtman, L.I.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2019, Letnik:
936
Journal Article
Recenzirano
Gas Electron Multiplier (GEM) based detectors are widely used in numerous collider experiments and, in particular, at the Budker Institute of Nuclear Physics (BINP). In order to determine the best ...possible spatial resolution, the simulation of charged particle registration process is accomplished. The simulation shows that spatial resolution is definitely less than 20μm for applied operation configurations. The simulation of electron transport through single GEM and through GEM-cascade shows that an electron cluster is compressed by GEM holes and an effective transverse diffusion is reduced by approximately 15% as maximum. The experimental part of the work is devoted to the operability tests of the designed detector with orthogonal strips readout with a pitch of 250μm and the measurements of its characteristics including the dependence of gain on GEM-voltage, the registration efficiency and the spatial resolution. Spatial resolution of the studied detector is measured as 31.5±0.9(stat.)−7.5+6.9(syst.)μm.
Genetic resistance to anticoagulants caused by mutations in the
Vkorc1
gene of the most invasive rodent species—Norway rats and house mice, has not been studied in Russia. We analyzed the variability ...of the
Vkorc1
gene in house mice and Norway rats in various settlements of Russia, and identified mutations responsible for resistance to rodenticides. Two exons of the
Vkorc1
gene were analyzed in 71 Norway rats from four cities (Moscow, Tyumen, Chita, Rostov-on-Don) and 108 house mice from cities and small settlements (Moscow region, Tormosin, Nizhny Tsasuchei). Three Norway rats (15.8% of the studied individuals) in Moscow have a heterozygous state the Tyr139Ser mutation, which is responsible for resistance. House mice were not found to have mutations in the
Vkorc1
gene responsible for resistance to anticoagulants of the first and second generation in the Leu128Ser and Tyr139Cys positions located in the third exon. However, in cities in the first exon, we identified two heterozygous mutations have not be described previously in the scientific literature: Lys58Arg and Ser31Trp. In Russia, the genetic resistance to rodenticides in settlements in the populations of house mice and Norway rats is significantly lower than in Western Europe.
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