81 research outputs found

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

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    The double coherent and non-coherent diffractive production of heavy quark - antiquark pairs (QQˉQ \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 ccˉc \bar{c} and bbˉb \bar{b} pairs in pppp, CaCaCaCa and PbPbPbPb 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 cc, bb 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 QQˉQ \bar{Q}pair, M_{Q \bar{Q}} \gsim 100 GeV, in association with a large rapidity gap between diffractive jets Δη>5\Delta \eta > 5.Comment: 22 pages, 5(.eps) figures, 3 tables, LaTe

    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

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    In the framework of the modified FRITIOF model, the inclusive spectra of the cumulative π0\pi ^0-, π\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 π\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

    Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

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    This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process.Comment: 10 pages, 14MB, accepted by FAIR STI in May 2009, editors: Inti Lehmann (chair), Andrea Bersani, Yuri Lobanov, Jost Luehning, Jerzy Smyrski, Technical Coordiantor: Lars Schmitt, Bernd Lewandowski (deputy), Spokespersons: Ulrich Wiedner, Paola Gianotti (deputy

    Feasibility studies of the time-like proton electromagnetic form factor measurements with PANDA at FAIR

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    The possibility of measuring the proton electromagnetic form factors in the time-like region at FAIR with the \PANDA detector is discussed. Detailed simulations on signal efficiency for the annihilation of pˉ+p\bar p +p into a lepton pair as well as for the most important background channels have been performed. It is shown that precision measurements of the differential cross section of the reaction pˉ+pe++e\bar p +p \to e^++ e^- can be obtained in a wide angular and kinematical range. The individual determination of the moduli of the electric and magnetic proton form factors will be possible up to a value of momentum transfer squared of q214q^2\simeq 14 (GeV/c)2^2. The total pˉ+pe++e\bar p +p\to e^++e^- cross section will be measured up to q228q^2\simeq 28 (GeV/c)2^2. The results obtained from simulated events are compared to the existing data. Sensitivity to the two photons exchange mechanism is also investigated.Comment: 12 pages, 4 tables, 8 figures Revised, added details on simulations, 4 tables, 9 figure

    Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR

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    Simulation results for future measurements of electromagnetic proton form factors at \PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel pˉpe+e\bar p p \to e^+ e^- is studied on the basis of two different but consistent procedures. The suppression of the main background channel, i.e.\textit{i.e.} pˉpπ+π\bar p p \to \pi^+ \pi^-, is studied. Furthermore, the background versus signal efficiency, statistical and systematical uncertainties on the extracted proton form factors are evaluated using two different procedures. The results are consistent with those of a previous simulation study using an older, simplified framework. However, a slightly better precision is achieved in the PandaRoot study in a large range of momentum transfer, assuming the nominal beam conditions and detector performance

    Глобальное бремя туберкулеза в России и в мире как проблема общественного здоровья (историко-аналитический обзор)

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    Based on an analysis of archive materials, scientific publications and official statistics obtained from 56 sources, the global tuberculosis burden was assessed. In 1918 in Russia, tuberculosis mortality made 360 cases per 100,000 population, exceeding that in other industrial countries: in England this rate was 113.0; in the USA – 148.0; in Switzerland – 201.0; in Italy – 209.0; in France – 226.0; in Germany – 230.0; and in Japan (1920) – 234 cases respectively. Having undergone colossal socio-economic catastrophes like no other country, Russia achieved significant success in the fight against tuberculosis: in 1913, tuberculosis incidence was 733.0 per 100,000 population, tuberculosis mortality was 276.8; while in 2021 these made 31.1 and 4.3 respectively. In 2021, WHO excluded Russia from the list of countries with a high burden of tuberculosis. However, in Russia as well as in the other BRICS countries, the burden of MDR TB and TB/HIV co-infection still remains high, which requires allocation of resources to reduce their spread.На основе анализа архивных материалов, научных публикаций и официальных статистических данных, полученных из 56 источников, выполнена оценка глобального бремени туберкулеза. В 1918 году смертность от туберкулеза в России составляла 360 случаев на 100 тыс. населения, превышая таковую в других индустриальных странах: в Англии этот показатель составлял – 113,0; в США – 148,0; в Швейцарии – 201,0; в Италии – 209,0; во Франции – 226,0; в Германии – 230,0; в Японии (1920г.) – 234 случая соответственно. Претерпев колоссальные, несоизмеримые с другими странами социально-экономические катастрофы, Россия добилась значительных успехов в борьбе с туберкулезом: в 1913 году заболеваемость туберкулезом составляла 733,0 на 100 тыс. населения, смертность от него – 276,8; в 2021 году эти показатели составили уже 31,1 и 4,3 соответственно. ВОЗ в 2021 году исключила Россию из списка стран с высоким бременем туберкулеза. Тем не менее, в России, наряду с другими государствами БРИКС, сохраняется высокое бремя МЛУ-ТБ и сочетания туберкулеза с ВИЧ-инфекцией, требующее ресурсных вложений для снижения их распространения

    Объемные показатели офтальмогемодинамики при миопии и сопутствующей глаукоме с «нормализованным» давлением

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    PURPOSE: To study volumetric measurements of ocular hemodynamics in patients with myopia and primary open-angle glaucoma with statistically normal IOP on hypotensive medication. METHODS: The study included 326 eyes (206 patients) with myopia and glaucoma with IOP 25 мм в сравнении с аналогичным показателем у пациентов с ПЗ

    Effects of Transmitters and Amyloid-Beta Peptide on Calcium Signals in Rat Cortical Astrocytes: Fura-2AM Measurements and Stochastic Model Simulations

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    BACKGROUND: To better understand the complex molecular level interactions seen in the pathogenesis of Alzheimer's disease, the results of the wet-lab and clinical studies can be complemented by mathematical models. Astrocytes are known to become reactive in Alzheimer's disease and their ionic equilibrium can be disturbed by interaction of the released and accumulated transmitters, such as serotonin, and peptides, including amyloid- peptides (A). We have here studied the effects of small amounts of A25-35 fragments on the transmitter-induced calcium signals in astrocytes by Fura-2AM fluorescence measurements and running simulations of the detected calcium signals. METHODOLOGY/PRINCIPAL FINDINGS: Intracellular calcium signals were measured in cultured rat cortical astrocytes following additions of serotonin and glutamate, or either of these transmitters together with A25-35. A25-35 increased the number of astrocytes responding to glutamate and exceedingly increased the magnitude of the serotonin-induced calcium signals. In addition to A25-35-induced effects, the contribution of intracellular calcium stores to calcium signaling was tested. When using higher stimulus frequency, the subsequent calcium peaks after the initial peak were of lower amplitude. This may indicate inadequate filling of the intracellular calcium stores between the stimuli. In order to reproduce the experimental findings, a stochastic computational model was introduced. The model takes into account the major mechanisms known to be involved in calcium signaling in astrocytes. Model simulations confirm the principal experimental findings and show the variability typical for experimental measurements. CONCLUSIONS/SIGNIFICANCE: Nanomolar A25-35 alone does not cause persistent change in the basal level of calcium in astrocytes. However, even small amounts of A25-35, together with transmitters, can have substantial synergistic effects on intracellular calcium signals. Computational modeling further helps in understanding the mechanisms associated with intracellular calcium oscillations. Modeling the mechanisms is important, as astrocytes have an essential role in regulating the neuronal microenvironment of the central nervous system

    Feasibility studies for the measurement of time-like proton electromagnetic form factors from p¯ p→ μ+μ- at P ¯ ANDA at FAIR

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    This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, | GE| and | GM| , using the p¯ p→ μ+μ- reaction at P ¯ ANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at P ¯ ANDA , using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is p¯ p→ π+π-, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented

    Physics Performance Report for PANDA: Strong Interaction Studies with Antiprotons

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    To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with nucleons and nuclei, the universal PANDA detector will be built. Gluonic excitations, the physics of strange and charm quarks and nucleon structure studies will be performed with unprecedented accuracy thereby allowing high-precision tests of the strong interaction. The proposed PANDA detector is a state-of-the art internal target detector at the HESR at FAIR allowing the detection and identification of neutral and charged particles generated within the relevant angular and energy range. This report presents a summary of the physics accessible at PANDA and what performance can be expected.Comment: 216 page
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