121 research outputs found

    Elaboration of a computer system for determining the energy of laser pulse

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    This work investigates the neutron-induced fission of U-234 and the fission-fragment properties for neutron energies between E-n = 0.2 and 5.0 MeV with a special highlight on the prominent vibrational resonance at E-n = 0.77 MeV. Angular, energy, and mass distributions were determined based on the double-energy technique by means of a twin Frisch-grid ionization chamber. The experimental data are parametrized in terms of fission modes based on the multimodal random neck-rupture model. The main results are a verified strong angular anisotropy and fluctuations in the energy release as a function of incident-neutron energy

    String model description of polarisation and angular distributions in pbar p -> Lambdabar Lambda at low energies

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    The observed polarisation of Lambda hyperons from the inclusive pA -> Lambda X reaction at high energies has previously been well described within the Lund string model through polarised ss quark pair production in the string breaking hadronisation process. This model is here applied to the exclusive pbar p -> Lambdabar Lambda reaction at low energies and compared to available data sets down to an incident beam momentum of 1.835 GeV/c. This required an extension of the diquark scattering model to involve three components: an isotropic part relevant close to threshold, a spectator part and a forward scattering part as in pA -> Lambda X at high energies. The observed angular distributions are then reproduced and, for momentum transfers above |t'| = 0.2 GeV^2, agreement with the measured polarisation is also obtained.Comment: 12 pages, 4 figures, submitted to Eur. Phys. J.

    Analysis of segregated boundary-domain integral equations for variable-coefficient problems with cracks

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    This is the pre-print version of the article. The official published version can be obtained from the link below - Copyright @ 2011 Wiley-BlackwellSegregated direct boundary-domain integral equation (BDIE) systems associated with mixed, Dirichlet and Neumann boundary value problems (BVPs) for a scalar “Laplace” PDE with variable coefficient are formulated and analyzed for domains with interior cuts (cracks). The main results established in the paper are the BDIE equivalence to the original BVPs and invertibility of the BDIE operators in the corresponding Sobolev spaces.This work was supported by the International Joint Project Grant - 2005/R4 ”Boundary- Domain Integral Equations: Formulation, Analysis, Localisation” of the Royal Society, UK, and the grant ”Mathematical analysis of localised boundary-domain integral equations for BVPs with variable coefficients” of the EPSRC, UK

    L’Etat et la profession universitaire en France et en Allemagne

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    Cet article repose sur une analyse des relations entre la profession universitaire et l'administration de tutelle en France et en Allemagne et de l'autonomie respective des disciplines et des gestionnaires de l'enseignement supérieur. En France, les relations sont fortes et fréquentes entre la tutelle parisienne et certains représentants de la profession universitaire qui influencent les décisions prises à travers de multiples mécanismes (consultations, expertises, groupes de réflexion,...) Dans les trois ministères de Land étudiés en Allemagne, en revanche, les relations avec la profession académique sont rares. Les ajustements entre les disciplines obéissent à des mécanismes plus locaux (sans régulation fédérale) qui contribuent à modifier leur poids relatif au sein de chaque Land. Cette comparaison nous permettra de conclure sur la nature des relations entre la profession universitaire et l'Etat dans les deux pays