Influence of hydrostatic pressure on the lifetimes of polymers

Under uniaxial tension, the lifetimes of polymers under hydrostatic pressure are longer than under atmospheric pressure. This effect is attributed to a change in the failure mechanism under pressure owing to retardation of the free-radical chain reaction of breakage of the macromolecules under omnidirectional compression.A. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 2, pp. 207–213, March–April, 1976.     

Exact theory of the (Einstein) gravitational field in an arbitrary background space-time

The Lagrangian based theory of the gravitational field and its sources at the arbitrary background space-time is developed. The equations of motion and the energy-momentum tensor of the gravitational field are derived by applying the variational principle. The gauge symmetries of the theory and the associated conservation laws are investigated. Some properties of the energymomentum tensor of the gravitational field are described in detail and the examples of its application are given. The desire to have the total energymomentum tensor as a source for the linear part of the gravitational field leads to the universal coupling of gravity with other fields (as well as to the self-interaction) and finally to the Einstein theory.     

Intensity measurement for Kβ η satellites in the radiative auger effect

Calculations have been performed on the integral shapes of the K lines, which are long-wave satellites of the K ₁ lines, for Cl, Ti, and Fe, where allowance has been made for interference between states in the 2p^–1 and 3p^–2p configurations. The calculations show that these satellites represent short-wave branches of the K lines strengthened by the 3p-1s transition with simultaneous M electron ejection. The strong interference between the amplitudes of these processes in the final state means that it is in principle quite impossible to speak of the intensities of the K satellites without stating how they are isolated from the measured spectrum.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 34–39, September, 1984.     

The theory of photorefractive resonance

A theory is proposed to describe holograms in thin photorefractive crystals and the self-diffraction of two writing laser beams, one of which is periodically modulated in phase. In linear approximation with respect to the amplitude of the phase modulation, expressions are derived for the AC component of the intensity of various diffraction orders. Oscillations in the intensity are observed having a well-defined resonance character connected with excitation of photorefraction waves, and the frequency position of the resonance peaks is related to the period of the grating by the dispersion law of these oscillations. The results obtained are in good agreement with available experimental data. Fiz. Tverd. Tela (St. Petersburg) 40, 1450–1459 (August 1998)     

New experimental data on the possibility of influencing fluctuational particle fluxes in a L-2M stellarator edge plasma

The results of an experiment show that in the edge plasma of a L-2M stellarator the radial electric field is one of the determining factors influencing the formation of spatial structures and fluctuational particle fluxes. A point where the poloidal velocity of the fluctuations reverses is observed in an experiment with a high neutral-gas flux from the chamber walls. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 7, 560–565 (10 October 1998)     

Electrically controlled diffraction of light by reflection holograms in an LiNbO3 crystal

A theoretical and experimental investigation is made of the electrical selectivity of reflection volume holograms recorded in a LiNbO₃ crystal using a near-optimum geometry. An analysis is made of the factors limiting electrical multiplexing. Fiz. Tverd. Tela (St. Petersburg) 40, 1038–1041 (June 1998)     

Thermal multifragmentation in p + Au interactions at 2.16, 3.6 and 8.1 GeV incident energies

Multiple emission of intermediate-mass fragments has been studied for the collisions p + Au at 2.16, 3.6 and 8.1 GeV with the FASA setup. The mean IMF multiplicities for events with at least one IMF are equal to 1.7, 1.9 and 2.1 (±0.2) respectively. The multiplicity, charge distributions and kinetic energy spectra of IMF are described in the framework of a intranuclear cascade model followed by the statistical multifragmentation model. However, between the two parts of the calculation the excitation energies and the residual masses and charges are modified to take into account the losses during expansion. The results support a scenario of true thermal multifragmentation of a hot and expanded target spectator. Received: 15 December 1997 / Revised version: 24 April 1998