959 research outputs found

    Elastic hadron scattering and optical theorem

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    All contemporary phenomenological models of elastic hadronic scattering have been based in principle on the assumption of optical theorem validity that has been overtaken from optics. It will be shown that the given theorem which has not been actually proved in particle physics cannot be applied to short-ranged strong interactions. The analysis of corresponding collision experiments is to be done under new basic assumptions. The actual progress in description of hadronic collision processes might then exist only if the initial states are specified on the basis of impact parameter values of colliding particles and probability dependence on this parameter is established, without limiting corresponding conclusion by optical theorem validity.Comment: 11 pages, improved text to emphasize invalidity of optical theorem in short-ranged hadronic collisions and the necessity of looking for some new description of elastic hadronic scattering which would not be based on this theore

    Evolution of structure and local magnetic fields during crystallization of HITPERM glassy alloys studied by in situ diffraction and nuclear forward scattering of synchrotron radiation

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    Evolution of structure and local magnetic fields in Fe1 xCox 76Mo8Cu1B15 HITPERM metallic glass ribbons with various amounts of Co x 0, 0.25, 0.5 were studied in situ using diffraction and nuclear forward scattering of synchrotron radiation. It was found that crystallization for all three glasses proceeds in two stages. In the first stage, bcc Fe,Co nanocrystals are formed, while in the second stage additional crystalline phases evolve. For all three glasses, the crystallization temperatures at the wheel side were found to be lower than at the air side of the ribbon. The crystallization temperatures were found to decrease with increasing Co content. The lattice parameters of the bcc nanocrystals decrease up to about 550 C and then increase pointing to squeezing Mo atoms out of the nanograins or to interface effects between the nanocrystals and the glassy matrix. Nuclear forward scattering enabled separate evaluation of the contributions that stem from structurally different regions within the investigated samples including the newly formed nanocrystals and the residual amorphous matrix. Even minor Co content x 0.25 has a substantial effect not only upon the magnetic behaviour of the alloy but also upon its structure. Making use of hyperfine magnetic fields, it was possible to unveil structurally diverse positions of Fe atoms that reside in a nanocrystalline lattice with different number of Co nearest neighbour

    Atopic conditions and brain tumor risk in children and adolescents—an international case-control study (CEFALO)

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    In this study, atopic conditions were not associated with risk of brain tumors in children and adolescents or of glioma in particular. Results are not consistent with findings for adult glioma, possibly explained by a different distribution of histological subtypes. Only a few studies on atopic conditions and pediatric brain tumors are currently available, and the evidence is conflictin

    First Results from the TOTEM Experiment

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    The first physics results from the TOTEM experiment are here reported, concerning the measurements of the total, differential elastic, elastic and inelastic pp cross-section at the LHC energy of s\sqrt{s} = 7 TeV, obtained using the luminosity measurement from CMS. A preliminary measurement of the forward charged particle η\eta distribution is also shown.Comment: Conference Proceeding. MPI@LHC 2010: 2nd International Workshop on Multiple Partonic Interactions at the LHC. Glasgow (UK), 29th of November to the 3rd of December 201
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