31,337 research outputs found

    Femtosecond wavepacket interferometry using the rotational dynamics of a trapped cold molecular ion

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    A Ramsey-type interferometer is suggested, employing a cold trapped ion and two time-delayed off-resonant femtosecond laser pulses. The laser light couples to the molecular polarization anisotropy, inducing rotational wavepacket dynamics. An interferogram is obtained from the delay dependent populations of the final field-free rotational states. Current experimental capabilities for cooling and preparation of the initial state are found to yield an interferogram visibility of more than 80\%. The interferograms can be used to determine the polarizability anisotropy with an accuracy of about ±2%\pm 2\%, respectively ±5%\pm 5\%, provided the uncertainty in the initial populations and measurement errors are confined to within the same limits

    Charm production in deep inelastic and diffractive scattering

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    We consider the production of charm by real and virtual photons. Special attention is paid to diffractive charm production, which provides information on the gluonic content of the Pomeron. Our calculations are based on the gluon distributions of the CKMT-model, which is shown to lead to agreement with the data on open charm production in deep inelastic scattering. We compare predictions for diffractive charm production of different models for the distribution of gluons in the Pomeron. Experiments at HERA should be able to discriminate between them. Predictions for beauty production in diffractive and non-diffractive interactions of photons are also given.Comment: 14 pages REVTEX and 24 figures include

    Thermal Hadron Production in High Energy Heavy Ion Collisions

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    We provide a method to test if hadrons produced in high energy heavy ion collisions were emitted at freeze-out from an equilibrium hadron gas. Our considerations are based on an ideal gas at fixed temperature TfT_f, baryon number density nBn_B, and vanishing total strangeness. The constituents of this gas are all hadron resonances up to a mass of 2 GeV; they are taken to decay according to the experimentally observed branching ratios. The ratios of the various resulting hadron production rates are tabulated as functions of TfT_f and nBn_B. These tables can be used for the equilibration analysis of any heavy ion data; we illustrate this for some specific cases.Comment: 12 pages (not included :13 figures + tables) report CERN-TH 6523/92 and Bielefeld preprint BI-TP 92/0

    The 'gated-diode' configuration in MOSFET's, a sensitive tool for characterizing hot-carrier degradation

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    This paper describes a new measurement technique, the forward gated-diode current characterized at low drain voltages to be applied in MOSFET's for investigating hot-carrier stress-induced defects at high spatial resolution. The generation/recombination current in the drain-to-substrate diode as a function of gate voltage, combined with two-dimensional numerical simulation, provides a sensitive tool for detecting the spatial distribution and density of interface defects. In the case of strong accumulation, additional information is obtained from interband tunneling processes occurring via interface defects. The various mechanisms for generating interface defects and fixed charges at variable stress conditions are discussed, showing that information complementary to that available from other methods is obtaine

    Baryon number and strangeness: signals of a deconfined antecedent

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    The correlation between baryon number and strangeness is used to discern the nature of the deconfined matter produced at vanishing chemical potential in high-energy nuclear collisions at the BNL RHIC. Comparisons of results of various phenomenological models with correlations extracted from lattice QCD calculations suggest that a quasi-particle picture applies. At finite baryon densities, such as those encountered at the CERN SPS, it is demonstrated that the presence of a first-order phase transition and the accompanying development of spinodal decomposition would significantly enhance the number of strangeness carriers and the associated fluctuations.Comment: 10 pages, 4 figures, latex, to appear in the proceedings of the Workshop on Correlations and Fluctuations in Relativistic Nuclear collisions, (MIT, April 21-23,2005

    The GEMPAK Barnes objective analysis scheme

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    GEMPAK, an interactive computer software system developed for the purpose of assimilating, analyzing, and displaying various conventional and satellite meteorological data types is discussed. The objective map analysis scheme possesses certain characteristics that allowed it to be adapted to meet the analysis needs GEMPAK. Those characteristics and the specific adaptation of the scheme to GEMPAK are described. A step-by-step guide for using the GEMPAK Barnes scheme on an interactive computer (in real time) to analyze various types of meteorological datasets is also presented

    The chemical equilibration volume: measuring the degree of thermalization

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    We address the issue of the degree of equilibrium achieved in a high energy heavy-ion collision. Specifically, we explore the consequences of incomplete strangeness chemical equilibrium. This is achieved over a volume V of the order of the strangeness correlation length and is assumed to be smaller than the freeze-out volume. Probability distributions of strange hadrons emanating from the system are computed for varying sizes of V and simple experimental observables based on these are proposed. Measurements of such observables may be used to estimate V and as a result the degree of strangeness chemical equilibration achieved. This sets a lower bound on the degree of kinetic equilibrium. We also point out that a determination of two-body correlations or second moments of the distributions are not sufficient for this estimation.Comment: 16 pages, 15 figures, revtex

    A Two-Parameter Recursion Formula For Scalar Field Theory

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    We present a two-parameter family of recursion formulas for scalar field theory. The first parameter is the dimension (D)(D). The second parameter (ζ\zeta) allows one to continuously extrapolate between Wilson's approximate recursion formula and the recursion formula of Dyson's hierarchical model. We show numerically that at fixed DD, the critical exponent γ\gamma depends continuously on ζ\zeta. We suggest the use of the ζ\zeta -independence as a guide to construct improved recursion formulas.Comment: 7 pages, uses Revtex, one Postcript figur

    Uit de donkere dagen van voor linguistic turn oftewel wat J. M. Coetzee in de bekentenis van Willem Termeer zag en wat hij daarmee deed

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    The South African Nobel Prize winner, J. M. Coetzee has a particular connection to the Netherlands. For instance, he had reviewed Dutch literature for the New York Times (the reviews were later included in a book called Stranger Shores: essays 1986–1999) and he translated and compiled an anthology of Dutch poetry (Landscape with Rowers, 2004) for the English readership. Moreover, his books are frequently published in their Dutch translation prior to their official English releases. In 1976, Coetzee translated a novel by Marcelus Emants Een nagelaten bekentenis (1894), published in English as A Posthumous Confession. Parallel to this translation work, Coetzee also worked on his second novel In the Heart of the Country (1977). This paper is devoted to a detective-like tracing of reflections that Coetzee’s close reading of the Dutch novelist might have left in his own book. Why did Coetzee in the first place decide to translate Emants’ novel? What was its appeal that attracted him so much? What was Coetzee’s reading of Emants back in the 1970s? Article text in Afrikaans
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