4,504 research outputs found

    Multiphoton inner-shell ionization of the carbon atom

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    We apply time-dependent R-matrix theory to study inner-shell ionization of C atoms in ultra-short high-frequency light fields with a photon energy between 170 and 245 eV. At an intensity of 1017^{17} W/cm2^2, ionization is dominated by single-photon emission of a 2â„“2\ell electron, with two-photon emission of a 1s electron accounting for about 2-3\% of all emission processes, and two-photon emission of 2â„“2\ell contributing about 0.5-1\%. Three-photon emission of a 1s electron is estimated to contribute about 0.01-0.03\%. Around a photon energy of 225 eV, two-photon emission of a 1s electron, leaving C+^+ in either 1s2s2p3^3 or 1s2p4^4 is resonantly enhanced by intermediate 1s2s2^22p3^3 states. The results demonstrate the capability of time-dependent R-matrix theory to describe inner-shell ionization processes including rearrangement of the outer electrons.Comment: 7 pages, 2 figures, 2 table

    Angular distributions in two-colour two-photon ionization of He

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    We present R-Matrix with time dependence (RMT) calculations for the photoionization of helium irradiated by an EUV laser pulse and an overlapping IR pulse with an emphasis on the anisotropy parameters of the sidebands generated by the dressing laser field. We investigate how these parameters depend on the amount of atomic structure included in the theoretical model for two-photon ionization. To verify the accuracy of the RMT approach, our theoretical results are compared with experiment.Comment: 8 pages, 4 figures, 1 tabl

    Electron dynamics in the carbon atom induced by spin-orbit interaction

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    We use R-Matrix theory with Time dependence (RMT) to investigate multiphoton ionization of ground-state atomic carbon with initial orbital magnetic quantum number MLM_L=0 and MLM_L=1 at a laser wavelength of 390 nm and peak intensity of 1014^{14} W cm−2^{-2}. Significant differences in ionization yield and ejected-electron momentum distribution are observed between the two values for MLM_L. We use our theoretical results to model how the spin-orbit interaction affects electron emission along the laser polarization axis. Under the assumption that an initial C atom is prepared at zero time delay with ML=0M_L=0, the dynamics with respect to time delay of an ionizing probe pulse modelled using RMT theory is found to be in good agreement with available experimental data.Comment: 8 pages, 5 figure

    An Extension of the Fluctuation Theorem

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    Heat fluctuations are studied in a dissipative system with both mechanical and stochastic components for a simple model: a Brownian particle dragged through water by a moving potential. An extended stationary state fluctuation theorem is derived. For infinite time, this reduces to the conventional fluctuation theorem only for small fluctuations; for large fluctuations, it gives a much larger ratio of the probabilities of the particle to absorb rather than supply heat. This persists for finite times and should be observable in experiments similar to a recent one of Wang et al.Comment: 12 pages, 1 eps figure in color (though intelligible in black and white

    Analytical approach to soliton ratchets in asymmetric potentials

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    We use soliton perturbation theory and collective coordinate ansatz to investigate the mechanism of soliton ratchets in a driven and damped asymmetric double sine-Gordon equation. We show that, at the second order of the perturbation scheme, the soliton internal vibrations can couple {\it effectively}, in presence of damping, to the motion of the center of mass, giving rise to transport. An analytical expression for the mean velocity of the soliton is derived. The results of our analysis confirm the internal mode mechanism of soliton ratchets proposed in [Phys. Rev. E {\bf 65} 025602(R) (2002)].Comment: 9 figures. Submitted to Phys. Rev.

    Search for universality in one-dimensional ballistic annihilation kinetics

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    We study the kinetics of ballistic annihilation for a one-dimensional ideal gas with continuous velocity distribution. A dynamical scaling theory for the long time behavior of the system is derived. Its validity is supported by extensive numerical simulations for several velocity distributions. This leads us to the conjecture that all the continuous velocity distributions \phi(v) which are symmetric, regular and such that \phi(0) does not vanish, are attracted in the long time regime towards the same Gaussian distribution and thus belong to the same universality class. Moreover, it is found that the particle density decays as n(t)~t^{-\alpha}, with \alpha=0.785 +/- 0.005.Comment: 8 pages, needs multicol, epsf and revtex. 8 postscript figures included. Submitted to Phys. Rev. E. Also avaiable at http://mykonos.unige.ch/~rey/publi.html#Secon

    Analisis Spasial Pengaruh Dinamika Suhu Muka Laut Terhadap Distribusi Curah Hujan Di Sulawesi Utara

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    Telah dilakukan analisis terhadap distribusi curah hujan yang dipengaruhi oleh dinamika suhu muka laut untuk mengetahui hubungan distribusi curah hujan dan dinamika suhu muka laut di Sulawesi Utara, serta telah dibuat peta spasial hubungan distribusi curah hujan dengan dinamika suhu muka laut menggunakan ArcMap 9.3. Analisis yang dilakukan menggunakan data curah hujan bulanan selama 10 tahun dari 5 stasiun BMKG dan 10 pos hujan kerjasama di Sulawesi Utara, dan data dinamika suhu muka laut berdasarkan nilai Indeks Osilasi Selatan dengan metode korelasi. Hasil penelitian diperoleh nilai korelasi positif antara 0,50 hingga 0,90 terjadi pada periode tiga bulanan yaitu Agustus-September-Oktober pada seluruh wilayah pengamatan.Analysis of the precipitation that caused by the dynamics of sea surface temperature has been made to find the correlation between the precipitation and the dynamics of sea surface temperature, with its spatial map of the correlation between precipitation and the dynamics of sea surface temperature using ArcMap 9.3. The analysis use the monthly rainfall data for 10 years from 5 BMKG Stations and 10 rain-gauge network in North Sulawesi, and Southern Oscillation Index monthly value using correlation method. The result of this research is the positive correlation between 1,50 to 0,90 occur in the period of August-September-October

    Supersymetry on the Noncommutative Lattice

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    Built upon the proposal of Kaplan et.al. [hep-lat/0206109], we construct noncommutative lattice gauge theory with manifest supersymmetry. We show that such theory is naturally implementable via orbifold conditions generalizing those used by Kaplan {\sl et.al.} We present the prescription in detail and illustrate it for noncommutative gauge theories latticized partially in two dimensions. We point out a deformation freedom in the defining theory by a complex-parameter, reminiscent of discrete torsion in string theory. We show that, in the continuum limit, the supersymmetry is enhanced only at a particular value of the deformation parameter, determined solely by the size of the noncommutativity.Comment: JHEP style, 1+22 pages, no figure, v2: two references added, v3: three more references adde

    Conformal regularization of Einstein's field equations

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    To study asymptotic structures, we regularize Einstein's field equations by means of conformal transformations. The conformal factor is chosen so that it carries a dimensional scale that captures crucial asymptotic features. By choosing a conformal orthonormal frame we obtain a coupled system of differential equations for a set of dimensionless variables, associated with the conformal dimensionless metric, where the variables describe ratios with respect to the chosen asymptotic scale structure. As examples, we describe some explicit choices of conformal factors and coordinates appropriate for the situation of a timelike congruence approaching a singularity. One choice is shown to just slightly modify the so-called Hubble-normalized approach, and one leads to dimensionless first order symmetric hyperbolic equations. We also discuss differences and similarities with other conformal approaches in the literature, as regards, e.g., isotropic singularities.Comment: New title plus corrections and text added. To appear in CQ
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