Coherent and Non-Coherent Double Diffractive Production of QQˉ Q \bar {Q} - pairs in Collisions of Heavy Ions at High Energies

The double coherent and non-coherent diffractive production of heavy quark - antiquark pairs ($Q \bar{Q}$) in heavy ion scattering at high energies (LHC) is considered. The total and differential cross sections of these processes with the formation of $c \bar{c}$ and $b \bar{b}$ pairs in $pp$, $CaCa$ and $PbPb$ collisions are evaluated. The contribution of the considered mechanisms is a few per cent of the number of heavy quark - antiquark pairs obtained in the processes of hard (QCD) scattering, and it will be taken into account in the registration of $c$, $b$ quarks or, for instance, in the study of the heavy quarkonia suppression effects in Quark - Gluon Plasma, in the search for intermediate mass Higgs bosons and so on. It is shown that the cross section of the coherent scattering process is great enough. This makes it suitable for studying collective effects in nuclear interactions at high energies. An example of such effects is given: large values of the invariant mass of a $Q \bar{Q}$pair, M_{Q \bar{Q}} \gsim 100 GeV, in association with a large rapidity gap between diffractive jets $\Delta \eta > 5$.Comment: 22 pages, 5(.eps) figures, 3 tables, LaTe

On the methodics of mathematical modelling of pollution of hydrolithosphere by petroleum products (exemplified by Kursk oil terminal)

A potential threat of pollution of hydrolithosphere with petroleum and its products due to accidental and technological leaks on a certain industrial object has been analyzed. The author's method of mathematical modelling is described that allows to perform an adequate dynamic modelling of a petroleum products lens in an aquifer. Execution of the resulting model allows to forecast behavior of petroleum products in the conditions of a real geological and hydro-geological cross-sectio

Broadband Superfluorescent Source Based on Bismuth-Doped GeO2-SiO2 Fiber

The first bismuth-doped superfluorescent fibersource operating at 1.44-μm was developed. Atpump power of 200 mW and pump wavelength of1310 nm, its output signal reaches 57 mW withspectrum width of 25 nm

Geotechnical monitoring during construction in difficult soil conditions

This paper describes problems of construction on weak, subsidence and heaving soils in engineering and geological conditions o f Kursk cit

405-nm pumped Ce3+-doped silica fiber for broadband fluorescence from cyan to red

A pure Ce-doped silica fiber is fabricated using modified chemical vapor deposition (MCVD) technique. Fluorescence characteristics of a Ce-doped silica fiber are experimentally investigated with continuous wave pumping from 440 nm to 405 nm. Best pump absorption and broad fluorescence spectrum is observed for ~ 405 nm laser. Next, the detailed analysis of spectral response as a function of pump power and fiber length is performed. It is observed that a -10dB spectral width of ~ 280 mn can be easily achieved with different combinations of the fiber length and pump power. Lastly, we present, for the first time to the best of our knowledge, a broadband fluorescence spectrum with -10dB spectral width of 301 nm, spanning from ~ 517.36 nm to ~ 818 nm, from such fibers with non-UV pump lasers

The forecast of changes in the natural and technogenic conditions of the built-up territory on the example of the "Northern" district of the city of Kursk

This article presents the results of engineering and geological surveys on the built-up territory of the Kursk city agglomeration. A hydroisogypsum map was built, the flow filtrationrate was calculated, and it’s direction was determined. Protective measures were also proposed to prevent flooding of the built-up are

Analysis of hadron production in nucleus-nucleus interactions up to and out of kinematical limit of free NN-collisions in the frame of FRITIOF model

In the framework of the modified FRITIOF model, the inclusive spectra of the cumulative $\pi ^0$-, $\pi ^-$-mesons and protons produced in the nucleus-nucleus interactions at 4.5 GeV/c/nucleon and 4.2 GeV/c/nucleon are calculated. It is shown that the model reproduces qualitatively, and in some cases quantitatively the main experimental regularities of $\pi$-mesons production, and "soft" part of the proton spectra. According to the model the production of the cumulative particles is connected with the mechanism of the "soft" nucleon-nucleon interaction.Comment: 12 pages, 11 figure

IR Bismuth active centers in optical fibers: Combined excitation-emission spectroscopy

3D excitation-emission luminescence spectra of Bi-doped optical fibers of various compositions were measured in a wide wavelength range 450-1700 nm. Such luminescence spectra were obtained for Bi-doped pure silica and germania fibers, and for Bi-doped Al- or P-codoped silica fibers (at room and liquid nitrogen temperatures). The energy level schemes of IR bismuth active centers in pure silica and germania core fibers were derived from spectra obtained. The energy level schemes similarity of bismuth active centers in these two types of fibers was revealed.Comment: 12pages, 7 figures, 5 table

E-band Telecom-Compatible 40 dB Gain High-Power Bismuth-doped Fiber Amplifier with Record Power Conversion Efficiency

Multi-band transmission is one of the key practical solutions to cope with the continuously growing demand on the capacity of optical communication networks without changing the huge existing fiber base. However, ultra-broadband communication requires the development of novel power efficient optical amplifiers operating beyond C- and L-bands, and this is a major research and technical challenge comparable to the introduction of the seminal erbium-doped fiber amplifiers that dramatically changed the optical communication sector. There are several types of optical fibers operating beyond C- and L-bands that can be used for the development of such amplifiers, specifically the fibers doped with neodymium, praseodymium, thulium, and bismuth. However, among these, Bi-doped fibers are of special interest as the most promising amplification medium because, unlike the others, different Bi-associated active centers allow amplification in an enormous band of overall width of 700 nm (1100–1800 nm). Such spectral coverage can be obtained by using different host materials, such as aluminosilicate, phosphosilicate, silica, and germanosilicate glasses. Here, we report a novel Bi-doped fiber amplifier with record characteristics for E-band amplification, including the highest power conversion efficiency among telecom-compatible E-band amplifiers reported to date. This bismuth-doped fiber amplifier (BDFA) features a maximum gain of 39.8 dB and a minimal noise figure of 4.6 dB enabled by 173 m Bi-doped fiber length. The maximum achieved power conversion efficiency of 38% is higher than that of L-band Er-doped fiber amplifiers. This performance demonstrates the high potential of BDFA for becoming the amplifier of choice in modern multi-band optical communication networks