3,947 research outputs found

    Incoherent pion photoproduction on the deuteron in the first resonance region

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    Incoherent pion photoproduction on the deuteron is studied in the first resonance region. The unpolarized cross section, the beam asymmetry, and the vector and tensor target asymmetries are calculated in the framework of a diagrammatic approach. Pole diagrams and one-loop diagrams with NNNN scattering in the final state are taken into account. An elementary operator for pion photoproduction on the nucleon is taken in various on-shell forms and calculated using the SAID and MAID multipole analyses. Model dependence of the obtained results is discussed in some detail. A comparison with predictions of other works is given. Although a reasonable description of many available experimental data on the unpolarized total and differential cross sections and photon asymmetry has been achieved, in some cases a significant disagreement between the theory and experiment has been found. Invoking known information on the reactions γdπ0d\gamma d\to\pi^0 d and γdnp\gamma d\to np we predict the total photoabsorption cross section for deuterium. We find that our values strongly overestimate experimental data in the vicinity of the Δ\Delta peak.Comment: 22 pages, 23 figure

    An Analysis of the Chemical Composition of the Atmosphere of Venus on an AMS of the Venera-12 Using a Gas Chromatograph

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    Eight analyses of the atmosphere of Venus were made beginning at an altitude of 42 km right down to the surface of the planet. The following were detected in the atmosphere of Venus: nitrogen in concentrations of 2.5 plus or minus 0.5 volumetric %, argon ir concentrations (4 plus or minus 2) x 10 to the minus 3 power volumetric %, CO--(2.8 plus or minus 1.4) x 10 to the minus 3 power volumetric % and SO2 in concentrations (1.3 plus or minus 0.6) x 10 to the minus 2 power volumetric %. The upper limits were estimated for the content of oxygen and water equal to 2 x 10 to the minus 3 power and 10 to the minus 2 power volumetric %, respectively

    Neurohumoral markers that predict the efficiency of pharmacologic therapy of depressive disorders

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    We present a comprehensive clinical and biological study of 46 patients with depressive disorder (F32-F33: depressive episode and recurrent depressive disorder) during pharmacotherapy. Neurohumoral factors (cortisol, brain-derived neurotrophic factor, serotonin, DHEA and its sulfated form) were determined in serum by ELISA. The severity of the current depressive episode was evaluated using the 17-point Hamilton Depression Rating Scale (HDRS-17); the pharmacotherapy efficacy was evaluated using the scale of the Clinical Global Impression (CGI Scale). We showed that before prescription of pharmacotherapy peripheral blood neurohumoral markers that characterize the state of stress-realizing and stress-limiting systems of the body may be considered as biological predictors of the effective pharmacotherapy of a current depressive episode and used as additional paraclinical examination methods. At higher concentrations of cortisol and serotonin associated with a decrease in the content of neurosteroid dehydroepiandrosterone, the high efficiency of the pharmacotherapy of depressive episode is predicted

    Homogeneous Focusing Field for Short Relativistic Electron Bunches in Plasma

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    Plasma wake lens in which all short relativistic electron bunches of sequence are focused identically and uniformly is studied analytically and by numerical simulation. For two types of lenses necessary parameters of focused sequence of relativistic electron bunches are formulated. Verification of these parameters is performed by numerical simulation

    Control of Characteristics of Self-injected and Accelerated Electron Bunch in Plasma by Laser Pulse Shaping on Radius, Intensity and Shape

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    At the laser acceleration of self-injected electron bunch by plasma wakefield it is important to form bunch with small energy spread and small size. It has been shown that laser-pulse shaping on radius, intensity and shape controls characteristics of the self-injected electron bunch and provides at certain shaping small energy spread and small size of self-injected and accelerated electron bunch.Comment: 4 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:2001.01246, arXiv:2007.1298

    Neutron polarizabilities investigated by quasi-free Compton scattering from the deuteron

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    Measuring Compton scattered photons and recoil neutrons in coincidence, quasi-free Compton scattering by the neutron has been investigated at MAMI (Mainz) at thetaγlab=136otheta^{lab}_\gamma=136^o in an energy range from 200 to 400 MeV. From the data a polarizability difference of αnβn=9.8±3.6(stat)1.1+2.1(syst)±2.2(model)\alpha_n - \beta_n = 9.8 \pm 3.6(stat)^{+2.1}_{-1.1}(syst)\pm 2.2(model) in units of 104fm310^{-4}fm^3 has been determined. In combination with the polarizability sum αn+βn=15.2±0.5\alpha_n+\beta_n= 15.2\pm 0.5 deduced from photo absorption data, the neutron electric and magnetic polarizabilities, αn=12.5±1.8(stat)0.6+1.1(syst)±1.1(model)\alpha_n=12.5\pm 1.8(stat)^{+1.1}_{-0.6}(syst)\pm 1.1(model) and βn=2.71.8(stat)1.1+0.6(syst)1.1(model)\beta_n = 2.7\mp 1.8(stat)^{+0.6}_{-1.1}(syst)\mp 1.1(model), are obtained

    Spatial datasets of radionuclide contamination in the Ukrainian Chernobyl Exclusion Zone

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    The dataset “Spatial datasets of radionuclide contamination in the Ukrainian Chernobyl Exclusion Zone” was developed to enable data collected between May 1986 (immediately after Chernobyl) and 2014 by the Ukrainian Institute of Agricultural Radiology (UIAR) after the Chernobyl accident to be made publicly available. The dataset includes results from comprehensive soil sampling across the Chernobyl Exclusion Zone (CEZ). Analyses include radiocaesium (134Cs and 134Cs) 90Sr, 154Eu and soil property data; plutonium isotope activity concentrations in soil (including distribution in the soil profile); analyses of “hot” (or fuel) particles from the CEZ (data from Poland and across Europe are also included); and results of monitoring in the Ivankov district, a region adjacent to the exclusion zone. The purpose of this paper is to describe the available data and methodology used to obtain them. The data will be valuable to those conducting studies within the CEZ in a number of ways, for instance (i) for helping to perform robust exposure estimates to wildlife, (ii) for predicting comparative activity concentrations of different key radionuclides, (iii) for providing a baseline against which future surveys in the CEZ can be compared, (iv) as a source of information on the behaviour of fuel particles (FPs), (v) for performing retrospective dose assessments and (vi) for assessing natural background dose rates in the CEZ. The CEZ has been proposed as a “radioecological observatory” (i.e. a radioactively contaminated site that will provide a focus for long-term, radioecological collaborative international research). Key to the future success of this concept is open access to data for the CEZ. The data presented here are a first step in this process. The data and supporting documentation are freely available from the Environmental Information Data Centre (EIDC) under the terms and conditions of the Open Government Licence: https://doi.org/10.5285/782ec845-2135-4698-8881-b38823e533bf
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