Surface tension and equilibrium shape of crystals in a wide range of angles

We have found the angular dependence of the surface tension using simplified models including short-range interaction as well as long-range interaction. The shape of a rounded surface is found in total range of angles as well as sizes of rectilinear (smooth) faces depending on parameters of a model and the temperature. Some dimensionless ratios have occurred to be universal.     

Probing fission time scales with neutrons and GDR gamma rays

The time scales for nuclear fission have been explored using both pre-and postfission neutrons and GDR gamma rays. Four systems were investigated: 133-MeV ¹⁶O + ¹⁷⁶Yb and ²⁰⁸Pb and 104-MeV ⁴He + ¹⁸⁸Os and ²⁰⁹Bi. Fission fragments were measured in coincidence with PPACs. The neutrons were detected using eight detectors from the DEMON array, while gamma rays were measured using the US BaF2 array. The pre-and postfission gamma rays were determined using moving source fits parallel and perpendicular to the fission fragment emission directions. The time scales for fission for the neutrons were determined using the neutron clock technique. The gamma-ray data were fitted using a statistical model calculation based on the code CASCADE. The results of the fits from both data types were used to extract nuclear friction coefficients, γ, and fission time scales. The γ values ranged from 7 to 20, while the fission times were (31–105)×10^?21 s.     

Study of nuclear density effects on secondary hadrons many-particle correlations

The data obtained by the bubble chambers and nuclear photoemulsion in the interval of energies from 4 up to 400 GeV have been analysed in the quasirapidity scale with the purpose of secondary hadrons' clasterisation study. The new method of the multiparticle correlations, independing on the energy, quasirapidity interval chosen and models, has been proposed in this work. It is shown that the density correlations of different signs in the analysed events are observed. Among their the events with maximal densities, in which the correlations factor does not differ from background beyond a double statistical error, are not observed. However are bumps at 400 GeV the values of which require an affimation.     

Domain wall depinning in random media by ac fields

The viscous motion of an interface driven by an ac external field of frequency omega(0) in a random medium is considered here in the nonadiabatic regime. The velocity exhibits a smeared depinning transition showing a double hysteresis which is absent in the adiabatic case omega(0)-->0. Using scaling arguments and an approximate renormalization group calculation we explain the main characteristics of the hysteresis loop. In the low frequency limit these can be expressed in terms of the depinning threshold and the critical exponents of the adiabatic case.     

Fully relativistic theory of the ponderomotive force in an ultraintense standing wave

A relativistic field-gradient (ponderomotive) force in a laser standing wave ceases to exist in a familiar form; e.g., the adiabatic Hamiltonian is not separable into kinetic and potential energies for electrons moving in the antinode planes. We show that the force in the direction across the initial motion of an electron reverses its sign and makes the high-field areas attractive for electrons, opposite to a regular ponderomotive force. The reversal occurs at a relativistic-scale incident momentum, and represents the only effect known so far that pins down a distinct borderline between relativistic and nonrelativistic motion.     

On coulomb capture ratios of negative mesons in chemical compounds

An approach to reproduce the experimental Coulomb capture ratios of negative mesons in chemical compounds is proposed. An essential feature of this approach is the assumption that the decisive role in the capture process is played by not too strongly bound electrons.