Anisotropy of Thermal Dileptons

The meaningful specific anisotropy in the angle distribution of leptons with respect to the three-momentum of pair is predicted as a feasibility signature of synchrotron-like mechanism resulting from the quarks interacting with a collective confining color field in the heavy ion collisions. The lepton pair production rate and the spectrum of pair invariant mass are presented for this new dilepton source that is apparently not taken into consideration in the available phenomenological estimates.     

HYDJET++ model of relativistic heavy-ion collisions

The HYDJET++ event generator intended for simulating multiparticle hadron production in relativistic heavy-ion collisions over a broad energy range ($ \sqrt s \sim 10 - 10 000 GeV $ \sqrt s \sim 10 - 10 000 GeV per nucleon pair) is described in the present article. Within HYDJET++, the final state of a nuclear reaction is a superposition of two independent components: a soft, hydrodynamic, part (processes involving the production of low-transverse-momentum hadrons) and a hard, multiparton, state (processes involving the production of high-transverse-momentum hadrons via the fragmentation of quark-gluon jets). Some results of a simulation of nucleus-nucleus interactions on the basis of the HYDJET++ event generator at the energies of the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC) are discussed.     

Magnetic properties of ultrathin Ni films

The magnetic properties of Au/Ni/Si(100) films with Ni thicknesses of 8–200 Å are studied at T=77 K using a scanning magnetic microscope with a thin-film high-temperature dc SQUID. It is found that the Ni films, with an area of 0.6×0.6 mm, which are thicker than 26 Å have a single-domain structure with the magnetic moment oriented in the plane of the film and a saturation magnetization close to 0.17 MA/m. For films less than 26 Å thick, the magnetization of the film is found to drop sharply.     

Extracting the jet azimuthal anisotropy from higher order cumulants

We derive model-independent constraints on four-fermion contact interaction-type dynamics from the published preliminary LEP2 experimental data on e ⁺ e ^- annihilation into and pairs, measured at different energies between 130 and 207 GeV. The basic observables are chosen to be the total cross section and the forward-backward asymmetry, and the analysis realistically takes into account data uncertainties and correlations among measurements at the various energies. The combination of data from different energy points plays an important role in the determination of regions allowed for the contact interaction coupling constants. In contrast to the more common one-parameter analyses, we only obtain constraints on pairs of parameters rather than limits on individual ones. Received: 18 December 2002 / Revised version: 19 March 2003 / Published online: 13 May 2003     

Quark interaction with an instanton liquid

The effect of quarks on an instanton liquid through the excitation of adiabatic phonon-like modes in it is considered. An effective Lagrangian that includes a scalar color-singlet field interacting with quarks is derived, and the relevant generating functional is estimated in the tadpole approximation. The nature of this dynamical field as a mediator of interaction at soft momenta and its possible relationship with unusual properties of the sigma meson are discussed.     

Azimuthal anisotropy of jet quenching at LHC

We analyze the azimuthal anisotropy of jet spectra due to energy loss of hard partons in quark-gluon plasma, created initially in nuclear overlap zone in collisions with non-zero impact parameter. The calculations are performed for semi-central Pb-Pb collisions at LHC energy.     

Spatial structure of a focused X‐ray beam diffracted from crystals

The spatial structure of a beam focused by a planar refractive lens and Bragg diffracted from perfect silicon crystals was experimentally studied at the focal plane using a knife‐edge scan and a high‐resolution CCD camera. The use of refractive lenses allowed for a detailed comparison with theory. It was shown that diffraction leads to broadening of the focused beam owing to the extinction effect and, for a sufficiently thin crystal, to the appearance of a second peak owing to reflection from the back surface. It was found that the spatial structure of the diffracted beam depends on whether the crystal diffracts strongly (dynamically) or weakly (kinematically). The results help to understand the physical origin of the diffracted intensity recorded in a typical microbeam diffraction experiment.     

Effect of Praestol Cationic and Anionic Flocculants on the Efficiency of Water Pretreatment at Heat and Electric Power Plants

The efficiency of water purification at simultaneous use of Praestol macromolecular flocculants, iron(II) sulfate coagulant, and calcium hydroxide alkalizing agent was studied as influenced by the nature (cationic and anionic), chemical composition, and conformational state of the flocculant macromolecules in solution and by the concentrations of the flocculant and coagulant.     

Propagation of an X‐ray beam modified by a photonic crystal

A method of calculating the transmission of hard X‐ray radiation through a perfect and well oriented photonic crystal and the propagation of the X‐ray beam modified by a photonic crystal in free space is developed. The method is based on the approximate solution of the paraxial equation at short distances, from which the recurrent formula for X‐ray propagation at longer distances is derived. A computer program for numerical simulation of images of photonic crystals at distances just beyond the crystal up to several millimetres was created. Calculations were performed for Ni inverted photonic crystals with the [111] axis of the face‐centred‐cubic structure for distances up to 0.4 mm with a step size of 4 µm. Since the transverse periods of the X‐ray wave modulation are of several hundred nanometres, the intensity distribution of such a wave is changed significantly over the distance of several micrometres. This effect is investigated for the first time.