Dependence of the temperature of stochastically heated electrons on the flux density of pulsed laser radiation on a target

Electron dynamics in the field of focused picosecond multimode laser radiation was considered by numerical methods. It was found that the electron energy during stochastic perturbation of its trajectory can exceed the energy of oscillatory motion in a plane wave by several orders of magnitude. The electron distribution function was studied based on 2D numerical simulation. An analytical expression for the distribution function of relativistic electrons as ideal gas was derived. The distribution function in the radiation flux density range of 10¹⁴–10¹⁷ W/cm² was compared with an analytical expression of the equilibrium distribution; a temperature characteristic for electrons stochastically heated by the laser field was introduced. The dependence of the electron temperature on the radiation flux density was determined.     

Transfer measurements for the Ti+Ni systems at near barrier energies

Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies. Coupled channel calculations incorporating couplings to 2⁺ and 3⁻ states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer were carried out for ^46,48Ti+⁶¹Ni systems. The present paper gives the results of these studies.     

Fractality of materials based on silica gel

Based on the analysis of the isotherms of N₂ adsorption, the fractal dimension and other texture geometric parameters were determined for silica gel, modified silica gel, and relevant composite materials. The correlations between the texture parameters were found. A criterion for the estimation of the efficiency of using the composite adsorbent volume was proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 781–785, May, 2000.     

Dispersive power and crossover temperature,TCO, of two polar nematic liquid crystals in the visible spectral region

Refractive index studies are carried out on two highly polar liquid crystals: 1. N-(p-n-methoxy benzylidene)-p-amino benzonitrile, PmBAB, 2. N-(p-n-ethoxy benzylidene)-p-amino benzonitrile, PeBAB. The experimental investigations are carried out in the visible region at four different wavelengths, namely, 633, 589, 546 and 436 nm. The two compounds exhibit only the nematic liquid crystalline phase in between the isotropic and crystalline solid. The dispersive power ω is estimated for two consecutive wavelengths for the case of <n>, n_e and n_o for different wavelengths and found to be constant with temperature. Further the temperature gradients of n_e and n_o are estimated, and the crossover temperature is obtained using dn_o/dT for all the wavelengths.     

Steering in computational science: Mesoscale modelling and simulation

This paper outlines the benefits of computational steering for high performance computing applications. Lattice-Boltzmann mesoscale fluid simulations of binary and ternary amphiphilic fluids in two and three dimensions are used to illustrate the substantial improvements which computational steering offers in terms of resource efficiency and time to discover new physics. We discuss details of our current steering implementations and describe their future outlook with the advent of computational grids.     

Structure of a laser field of various polarizations in the focal region of an ideal focusing lens. Calculation by methods of scalar diffraction theory

Within the framework of the scalar diffraction theory, we elaborate the method of calculating the electromagnetic-field structure in the ideal-lens focal plane. Using the method of quaternions for describing the rotation in three-dimensional space and diffraction integrals, we derive analytic formulas for the intensity distribution in the fields in the vicinity of the lens focal plane. We generalize the Debye method for an arbitrary polarization of the incident laser beam, in particular, for the linear, radial, and azimuthal polarizations. Such an approach, in view of the analytic formulas obtained, allows us to decrease the processing speed by an order. We show that the algorithm elaborated allows us to calculate the field amplitude?Cphase structure in the case of multimode laser radiation with a random phase.     

Isolobal analogy between trivalent boron and divalent silicon

Singlet organosilylenes with a lone pair and an emptyp orbital are isolobal to trivalent borane if a B-H is equated to the lone pair on Si. Using this analogy, a particular isomer of CSi₂H₂ (24) is predicted to be a stable structure. MNDO calculations on24 and many of its possible isomers suggest that24 is at global minimum on the potential energy surface of CSi₂H₂.Ab initio calculations using a, minimal STO-3G basis set, on some selected structures also support these results.     

Measurement of the ground state 2n pickup probability for 28Si+68Zn and its role in sub-barrier fusion enhancement

The ground state and excited state transfer yields for the 2-neutron pickup channel in the ²⁸Si+⁶⁸Zn system have been measured explicitly. The recoil mass separator at the nuclear Science Centre, New Delhi was used for the measurement. A NaI(T1) detector was used for detecting the deexcitation γ’s from the transfer products. The kinematic coincidence technique was employed for the transfer measurement. Simplified coupled channels calculations show that out of all transfer channels the major contribution to the sub-barrier enhancement comes from the ground state 2 neutron pickup channel with a ground state Q-value of+1.83 MeV.