A generalised model and calculation of the hyperfine interaction constant for anomalous muonium in the crystalline lattice of silicon

A new microscopic model of anomalous muonium for the elemental semiconductors is proposed. The relevant configuration consisting of both a diamagrentic molecule Si−Mu and an unpaired orbital e⁻ is contained into a semivacancy of the real lattice. By using the unrestricted Hartree-Fock computational method the principal properties of the system are established. A dynamical version of the model together with a question on the formation of such system are discussed.     

Low temperature gas purification on ultradispersed oxide catalysts

Catalysts on the basis of ultradispersed powders of complex oxides of transition metals have been studied in the process of low temperature deep oxidation of organic compounds.     

Matter effect in neutrino oscillations for long-baseline experiments

This paper is devoted to the matter effect and its role in Long-Baseline experiments. As examples, the NOvA and DUNE experiments will be discussed.     

Study of the feasibility of distributed cathodic arc as a plasma source for development of the technology for plasma separation of SNF and radioactive wastes

One of the key problems in the development of plasma separation technology is designing a plasma source which uses condensed spent nuclear fuel (SNF) or nuclear wastes as a raw material. This paper covers the experimental study of the evaporation and ionization of model materials (gadolinium, niobium oxide, and titanium oxide). For these purposes, a vacuum arc with a heated cathode on the studied material was initiated and its parameters in different regimes were studied. During the experiment, the cathode temperature, arc current, arc voltage, and plasma radiation spectra were measured, and also probe measurements were carried out. It was found that the increase in the cathode heating power leads to the decrease in the arc voltage (to 3 V). This fact makes it possible to reduce the electron energy and achieve singly ionized plasma with a high degree of ionization to fulfill one of the requirements for plasma separation of SNF. This finding is supported by the analysis of the plasma radiation spectrum and the results of the probe diagnostics.     

2,4,5,7-Tetranitrofluorescein in solutions: novel type of tautomerism in hydroxyxanthene series as detected by various spectral methods

Stepwise dissociation and tautomerism of 2,4,5,7-tetranitrofluorescein (TNF) were studied by using vis-spectroscopy in dimethylsulfoxide (DMSO), in aqueous acetone, and in cetyl-trimethylammonium chloride (CTAC) micellar solutions at ionic strength of the bulk phase 4.00M KCl. The pK(a) values in DMSO and 90 mass% (CH3)2CO as well as the 'apparent'pK(a)(a) values of the substance in micellar media were determined spectrophotometrically. The neutral (molecular) form H2R is found to be completely converted into the colorless lactone. Moreover, the lactonic structure, yellow due to 'nitrophenolate' absorption band, predominates also in the case of TNF dianion R2-. Contrary to the unsubstituted fluorescein, and like 2,4,5,7-tetrabromofluorescein (eosin), the monoanion HR- of TNF with lambda(max) 522-525 nm and E(max) approximately (60-62)x10(3) dm(3)mol(-1)cm(-1) exists mainly as a deeply and intensively colored structure with non-ionized carboxylic and ionized hydroxylic group; its fluorescence spectra in various media are registered. In 90% acetone, the Stokes shift is 1.17x10(3)cm(-1), fluorescence lifetime equals 2.3 ns. An extremely expressed trend to dianion-lactone formation of R2- ion of TNF is confirmed in the systems studied. For TNF in DMSO, in aqueous acetone, in surfactant micelles, and in trichloromethane extracts of ionic associatiates with N(n-Bu)4+ and N(n-Hept)4+, the deeply colored 'quinon-phenolate' dianion, typical for all hydroxyxanthenes, is not registered at all. The sequence of dissociation of functional groups in solution is confirmed using IR spectroscopy in DMSO.     

Experiments on the gravity effect on the109Ag gamma resonance

The temperature dependence of the ¹⁰⁹Ag γ-ray self-absorption was investigated for the horizontal and vertical directions of emission. The source was a single-crystal silver plate containing atoms of parent radionuclide ¹⁰⁹Cd. Gamma-radiation of this γ-source and that of the monitoring γ-source, ⁵⁷Co, were registered by a pair of Ge(Li)-detectors. As a result of cooling the source from 77 K to ~12 K a relative decrease was observed of the intensity of the horizontally emitted γ-rays equal to 0.00064±0.00044. For the vertical direction the corresponding intensity change turned out to be -0.00047±0.00051. Although these data, as one would see, give some evidence for the possible effect of the gravitation on the resonant γ-ray absorption, future measurements must show if these results aren’t a consequence of any apparatus effect. The ways for developments in this study are discussed and some hindrances are considered. This revised version was published online in August 2006 with corrections to the Cover Date.     

Detector electronics for experiments at the large hadron collider

The state of the art of a tracking detector and calorimeter electronics that are being developed for experiments at the Large Hadron Collider (LHC) is discussed. Construction of the detectors is briefly described. The problems of fabrication of integrated circuits based on a radiation-resistant technology are considered, as well as the solution to the problem of microconnections between sensitive elements and readout amplifiers in two-coordinate semiconductor detectors. The parameters and block diagrams of both analog and digital integrated circuits are given; these circuits are used for amplifying and shaping the signals measured by tracking detectors of elementary particles and calorimeters. The contributions of Russian experimenters and physicists of the Joint Institute for Nuclear Research to the development of detector electronics for experiments at the LHC is described.     

On symbolic-numerical representation of the evolution operator for finite-dimensional quantum systems

A symbolic algorithm to generate the multilayer operator-difference schemes for solving the evolution problem of the time-dependent Schrödinger equation is elaborated. An additional gauge transformation of operator-difference schemes to make good use of the finite-element discretization is applied. The efficiency of the generated numerical schemes until the sixth order with respect to the time step and until the seventh order with respect to the spatial step is demonstrated by calculations of some finite-dimensional quantum systems in external fields.     

Thin films of palladium oxide for gas sensors

Thin films of PdO obtained by thermal oxidation of Pd films in air in the temperature range of 240–800°C were characterized using fast electron diffraction, transmission electron microscopy, and optical spectroscopy. The PdO films were found to be non-stoichiometric. With increasing oxidation temperature, the deviation of the PdO film composition from the stoichiometric component ratio becomes less pronounced. The resistivity response of PdO films to the presence of ozone in air was studied for the first time and good prospects for using this material for gas sensors are demonstrated.