ALICE is one of four main experiments at the Large Hadron Collider (CERN, Geneva). MEPHI is the member of the ALICE collaboration since 1996 year. Participation of the university professors in the ...international experiments of the highest level provides for their high scientific and knowledge level and therefore the level of their students and post-graduate students. Thus the students enter into scientific researches quite easily providing for the participation of Russian scientists in a large number of other international experiments.
The comparative study of sorption of polar substances acetonitrile and water into powders and membranes (>10 μm thick) of modified Hummers (HGO) and Brodie (BGO) graphite oxides was performed using ...isopiestic method (IM) and differential scanning calorimetry (DSC). Additional sorption data were obtained for pyridine and 1-octanol. Sorption measurements were accompanied by conventional XRD and XPS control. Electron paramagnetic resonance (EPR) was additionally used to characterize ordering of the membranes. The impact on sorption of synthetic procedure (Brodie or Hummers), method of making membranes, chemical nature of the sorbent, and method of sorption was systematically examined. It was demonstrated that variations in synthetic procedures within both Hummers and Brodie methods did not lead to changes in the sorption properties of the corresponding powders. Sorption of acetonitrile and pyridine was reduced by approximately half when switching from powders to membranes at ambient temperature. DSC measurements at a lower temperature gave equal sorption of acetonitrile into HGO powder and membranes. Water has demonstrated unique sorption properties. Equal sorption of water was measured for HGO membranes and powders at T = 298 K and at T = 273 K. It was demonstrated that lowering the orientational alignment of the membranes led to the increase of sorption. In practice this could allow one to tune sorption/swelling and transport properties of the GO membranes directly by adjusting their internal ordering without the use of any composite materials.
Solvothermal reduction of graphene oxide performed up to a sp2/sp3 ratio of 20 was demonstrated. The presence of chemical and structural defects was minimized by varying the treatment conditions and ...reduction agents to reduce their impact on electronic and optical properties. Using the interphase deposition technique both graphene oxide and reduced graphene oxide films were transferred onto ITO-coated glass substrates or SITAL for further analysis. The analysis of the electric characteristics of the reduced graphene oxide films showed high sheet resistance originated from grain boundary resistance. The optical transmittance of the films reached 30% for the most uniform coatings.
•Solvothermal reduction of graphene oxide (GO) increased the sp2/sp3 ratio up to 20.•Pure ethanol as a solvothermal reductant for GO provided less admixtures.•10-nm-thick RGO flakes were transferred onto SITAL using oil–water interface.•Sheet resistance of RGO was 2–5 × 106 Ω cm and varied between samples.•Poor electron transfer between individual RGO flakes results in poor conductivity.
The magnified images of thin wires, plastic, steel and lead plates which were obtained using linear microfocus hard bremsstrahlung generated through interaction of an 18 MeV electron beam with a ...13 μm thick Ta foil oriented along the internal beam of a B-18 betatron are presented. The images indicate high absorption contrast of the objects due to a small horizontal size of the radiation source the width of which is 115-fold smaller than the diameter of the electron beam. Some results have shown a few peculiarities in the images which were not earlier observed. Several results were compared with the ones obtained earlier using the microfocus bremsstrahlung generated by the 18 MeV electron beam of B-18 in a narrow Si target.
Silicon photomultipliers (SiPM) have found their use in various fields of industry and scientific experiments. This paper considers study of the SiPM possibility to detect low-intensity light pulses ...(down to single photons) under high-intensity background illumination. This may be useful for the development of laser rangefinders operating under natural light using SiPM as crucial photosensor. Moreover, the presented data describes some physical properties of LIDAR with SiPM under radiation exposure, which always affects its intrinsic noise.
The experimental results of studying the grazing interaction of microfocus bremsstrahlung with the edge surface of a plastic framework of the radiographic image quality standard Duplex IQI are ...presented. The results show that the edge contrast depends on the orientation of the edge surface and can be more complex than the two narrow bands of increased and decreased darkening on the X-ray radiographic pattern, which are determined by radiation refraction. The results were obtained using microfocus bremsstrahlung generated by grazing interaction of an internal electron beam of a B-18 betatron with an energy of 18 MeV with a surface of the Si target 50 or 8 μm thick and 4 mm long along the electron beam. The results are compared with the results on edge contrast obtained using the microfocus bremsstrahlung of a 450-keV X-ray tube with a focus size of 400 μm.
The first results of experiments demonstrating refraction contrast in magnified (x2.5) images obtained using the Bremsstrahlung gamma radiation of 18 MeV betatron with a narrow tantalum (Ta) target ...inside are presented. The Ta foil-target with a thickness of 13 urn and a length of 4 mm along the electron beam was mounted in a goniometer inside the chamber of the betatron to guide her along the electron beam. In this case, a linear microfocus source of Bremsstrahlung gamma radiation with vertical and horizontal dimensions of 1.5 and 0.013 mm, respectively, is realized for direct-forward emission of radiation. The obtained magnified images of rectangular steel plates with thicknesses in the region of 15-0.3 mm and lead foils with thickness of 25 urn demonstrated a high resolution of their edges due to the refraction contrast effect, which is realized due to the refraction of microfocus gamma radiation on the surfaces of the lateral faces of the samples.
The RED-100 (Russian Emission Detector) is being constructed for the experiment to search for elastic coherent neutrino scattering off atomic nuclei. This fundamental process was predicted several ...decades ago by the Standard Model of electroweak interactions but has not been discovered yet. The RED-100 is a two-phase emission xenon detector containing ∼200 kg of the liquid Xe (∼ 100 kg of that is in a fiducial volume). One of the possible sites to carry out the experiment is the SNS (Spallation Neutron Source) facility at Oak Ridge National Laboratory, USA. SNS is the world's most intense pulsed source of neutrinos and unique place to study neutrino properties. The energy spectrum of neutrinos produced at the SNS extends up to ∼ 50 MeV and satisfies coherence condition. These neutrinos give kinetic energies of Xe recoils up to a few tens of keV where the response of nuclear recoils is well-known from neutron calibrations of dark matter detectors. The detector will be deployed in the basement under the experimental hall at a distance of ∼30 meters from the SNS target. The expected signal and background (neutron and gamma) are estimated for this specific location. The detector details, current status and future plans are provided.
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