644 research outputs found

    Anomalous population of 10^{10}He states in reactions with 11^{11}Li

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    Structure with the lowest energy observed in the 10^{10}He spectrum populated in the proton knockout reaction with 11^{11}Li beam has a peak at 1.21.51.2-1.5 MeV. This peak is usually interpreted as a resonant 0+0^+ ground state of 10^{10}He. Our theoretical calculations indicate that this peak is likely to be a pileup of 11^-, 0+0^+, and 2+2^+ excitations with very similar shapes. %We predict a very specific nature of the 11^- excitation in 10^{10}He. Moreover, the ``soft'' 11^- excitation appears to be the lowest one in energy. Such an anomalous continuum response is traced to the halo structure of 11^{11}Li providing extreme low energy shift to all the expected continuum excitations. Competitions of the initial state structure (ISS) and the final state interaction (FSI) effects on the spectrum and three-body correlations in 10^{10}He are discussed. Analogous effect of the extreme low-energy shift could also be expected in other cases of 2n2n emitters populated in reactions with halo nuclei. Simplified example of the 10^{10}He spectrum in α\alpha knockout from 14^{14}Be, is given. We also discuss limits on the properties of 9^{9}He stemming from the observed 10^{10}He spectrum.Comment: 10 pages, 13 figure

    On UHECR energy estimation algorithms based on the measurement of electromagnetic component parameters in EAS

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    Model calculations are performed of extensive air shower (EAS) component energies using a variety of hadronic interaction parameters. A conversion factor from electromagnetic component energy to the energy of ultra-high energy cosmic rays (UHECRs) and its model and primary mass dependence is studied. It is shown that model dependence of the factor minimizes under the necessary condition of the same maximum position and muon content of simulated showers.Comment: contracted version is accepted for publication in Doklady Physic

    Long-Time Asymptotics of Perturbed Finite-Gap Korteweg-de Vries Solutions

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    We apply the method of nonlinear steepest descent to compute the long-time asymptotics of solutions of the Korteweg--de Vries equation which are decaying perturbations of a quasi-periodic finite-gap background solution. We compute a nonlinear dispersion relation and show that the x/tx/t plane splits into g+1g+1 soliton regions which are interlaced by g+1g+1 oscillatory regions, where g+1g+1 is the number of spectral gaps. In the soliton regions the solution is asymptotically given by a number of solitons travelling on top of finite-gap solutions which are in the same isospectral class as the background solution. In the oscillatory region the solution can be described by a modulated finite-gap solution plus a decaying dispersive tail. The modulation is given by phase transition on the isospectral torus and is, together with the dispersive tail, explicitly characterized in terms of Abelian integrals on the underlying hyperelliptic curve.Comment: 45 pages. arXiv admin note: substantial text overlap with arXiv:0705.034

    Azimuthal modulation of the event rate of cosmic ray extensive air showers by the geomagnetic field

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    The Earth's magnetic field effect on the azimuthal distribution of extensive air showers (EAS) of cosmic rays has been evaluated using a bulk of the Yakutsk array data. The uniform azimuthal distribution of the EAS event rate is rejected at the significance level 10^(-14). Amplitude of the first harmonics of observed distribution depends on zenith angle as A1=0.2*sin^2(theta) and is almost independent of the primary energy; the phase coincides with the magnetic meridian. Basing upon the value of measured effect, the correction factor has been derived for the particle density depending on a geomagnetic parameter of a shower.Comment: 4 pages, 3 figures in ps file

    Spectrum of cosmic rays, produced in supernova remnants

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    Nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants is employed to calculate CR spectra. The magnetic field in SNRs is assumed to be significantly amplified by the efficiently accelerating nuclear CR component. It is shown that the calculated CR spectra agree in a satisfactory way with the existing measurements up to the energy 101710^{17} eV. The power law spectrum of protons extends up to the energy 3×10153\times 10^{15} eV with a subsequent exponential cutoff. It gives a natural explanation for the observed knee in the Galactic CR spectrum. The maximum energy of the accelerated nuclei is proportional to their charge number ZZ. Therefore the break in the Galactic CR spectrum is the result of the contribution of progressively heavier species in the overall CR spectrum so that at 101710^{17} eV the CR spectrum is dominated by iron group nuclei. It is shown that this component plus a suitably chosen extragalactic CR component can give a consistent description for the entire Galactic CR spectrum.Comment: 4 pages with emulateapj, 3 figures, accepted for publication in the Astrophysical Journal Letter

    Conduction mechanism of metal-TiO2-Si structures

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    The influence of annealing of titanium oxide films on the currents of metal-TiO2-n-Si structures was investigated. It has been shown that regardless of the annealing temperature the conductivity of structures at positive potentials on the gate is determined by currents limited by the space charge in the dielectric with traps exponentially distributed on energy. At negative potentials the main contribution to the current is the thermal generation of charge carriers in the space charge region in the silicon. Interface properties of TiO2-n-Si depend on the structural and phase state of the titanium oxide film which are determined by the annealing temperature

    Conduction mechanism of metal-TiO2–Si structures

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    The conduction model has been proposed for the metal-TiO2–Si (MIS) structures. Rutile films have been prepared on Si substrates by magnetron sputtering of TiO2 target and annealing in the air at temperatures T = 800 and 1050 K. The current-voltage (CVC) and capacitance-voltage characteristics of the structures have been measured over the range of T = 283–363 K. At positive potentials on the gate, the conductivity of the MIS structures is determined by the space charge-limited current in the dielectric layer
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