6,978 research outputs found
Fine structure of Vavilov-Cherenkov radiation near the Cherenkov threshold
We analyze the Vavilov-Cherenkov radiation (VCR) in a dispersive
nontransparent dielectric air-like medium both below and above the Cherenkov
threshold, in the framework of classical electrodynamics. It is shown that the
transition to the subthreshold energies leads to the destruction of
electromagnetic shock waves and to the sharp reduction of the frequency domain
where VCR is emitted. The fine wake-like structure of the Vavilov-Cherenkov
radiation survives and manifests the existence of the subthreshold radiation in
the domain of anomalous dispersion. These domains can approximately be defined
by the two phenomenological parameters of the medium, namely, the effective
frequency of oscillators and the damping describing an interaction with the
other degrees of freedom.Comment: 9 pages, 6 figure
Pension Reform in Russia: First Year of Implementing
From January 1, 2002 Russian embarked on a pension reform to set up a three-pillar pension system and introduce funded principles of retirement pensions to be accumulated for "younger" workers. The new pension includes the flat-rate basic part which is paid to ensure a certain guaranteed minimum income, and the insured and funded parts both of which depend on amounts of insurance contributions and the resulting pension assets registered on an individual basis through the working life. The reform is aimed at improving the pension provision standards in the Russian Federation through ensuring long-term financial stability of the pension system.
Evolution of the concept of Quark Matter: the Ianus face of the heavy ion collisions
Since the beginning of the efforts to produce and understand quark matter
large changes developed in the ideas of description of this matter. In the
present paper we summarize some aspects of this development.Comment: Talk given at 18th International Conference on Ultrarelativistic
Nucleus-Nucleus Collisions: Quark Matter 2005 (QM 2005), Budapest, Hungary,
4-9 Aug 2005. 10 pages, 7 figure
Xi- and Xi+ production in central Pb+Pb collisions at 158 GeV/c per nucleon
Results of the production of Xi and Xi-bar hyperons in central Pb+Pb interactions at 158 GeV/c per nucleon are presented. This analysis utilises a global reconstruction procedure, which allows a measurement of 4pi integrated yields to be made for the first time. Inverse slope paramters, which are determined from an exponential fit to the transverse mass spectra, are shown. Central rapidity densities are found to be 1.49 +- 0.08 and 0.33 +- 0.04 per event per unit of rapidity for Xi and Xi-bar respectively. Yields integrated to full phase space are 4.12 +- 0.02 and 0.77 +- 0.04 for Xi and Xi-bar. The ratio of Xi-bar/Xi at mid-rapidity is 0.22 +- 0.03
Age and metallicity of the bulges in lenticular galaxies
Panoramic spectroscopic data of the sample of 80 nearby lenticular galaxies
obtained with the Multi-Pupil Fiber Spectrograph of the 6-m telescope are
presented. The SSP-equivalent ages, [Z/H], and [Mg/Fe] are determined through
the Lick indices H-beta, Mgb, and separately for the nuclei and for the
bulges. About a half of the sample contain chemically distinct nuclei, more
metal-rich and younger than the bulges. The correlations of the stellar
population properties for the nearby S0s are discussed.Comment: 5 pages, 2 figures. To appear in the Proceedings of the IAU Symposium
245, "Formation and Evolution of Galaxy Bulges", held at Oxford, U.K., July
2007, Eds. M. Bureau, E. Athanassoula, B. Barbu
Event-by-event fluctuations of the kaon to pion ratio in central Pb+Pb collisions at 158 GeV per Nucleon
We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine non-statistical fluctuations, perhaps related to a first or second order QCD phase transition. Such fluctuations are shown to be very small
Bose-Einstein correlations of charged kaons in central Pb+Pb collisions at E_beam = 158 AGeV
Bose-Einstein correlations of charged kaons were measured near mid-rapidity in central Pb+Pb collisions at 158 A GeV by the NA49 experiment at the CERN SPS. Source radii were extracted using the Yano-Koonin-Podgoretsky and Bertsch-Pratt parameterizations. The results are compared to published pion data. The measured m_perp dependence for kaons and pions is consistent with collective transverse expansion of the source and a freeze-out time of about 9.5 fm
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