Thee + e −→¯nn cross section predicted remarkably larger than thee + e −→¯pp one

It is shown that all global analyses of nucleon electromagnetic form factor data predict the electron-positron annihilation into neutron-antineutron cross section (for which there are no data till now) to be in a finite energy region substantially larger than the electron-positron annihilation into the proton-antiproton one.Dedicated to the memory of M. Gmitro.     

Screw dislocation in spherical particle

The elastic fields generated by a straight-line screw dislocation axially arranged in a spherical particle have been calculated and analyzed. Some features of the distribution of elastic fields in this case and in the case of a screw dislocation lying along the axis of a cylindrical whisker are similar. The elastic energies per unit dislocation length differ slightly in the two cases. This corroborates the validity of application of some of the results obtained for screw dislocations in elastic cylinders to the study of properties of screw dislocations in equiaxed particles.Authors are very indebted to dr. A. B. Lebedev for his kind support.     

Determination of the rate of nonradiative relaxation,processes on excitation of electronic states in YAG:Nd3+

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 2, pp. 229–233, February, 1991.     

Anisotropic field of background internal waves on a sea shelf and its effect on low-frequency sound propagation

The space-time spectral characteristics of the field of background internal waves (IW) are obtained for two oceanic shelf regions (the Atlantic shelf of the United States and the Kamchatka shelf) and analyzed. Within the framework of a numerical experiment, it is shown that the observed anisotropy of the IW field may considerably affect the low-frequency sound fluctuations in the aforementioned regions and, in particular, may change the interference invariant of the sound field.     

Mathematical modeling of random coupling between polarization modes in single-mode optical fibers: XIII. Conditions of applicability of the ergodic hypothesis for fiber ring interferometers

Some additional conditions of applicability of the ergodic hypothesis to fiber ring interferometers (FRIs) with a loop consisting of a single-mode optical fiber (SMOF) with random inhomogeneities are considered. It is shown by mathematical modeling that the change in the phase difference of counterpropagating waves at the FRI output with the SMOF temperature is not a stationary random process. However, in a fairly narrow temperature range, this dependence can be assumed to be locally stationary. The conditions determining this temperature range are formulated. It is shown for a fairly large ensemble of independent realizations of random inhomogeneities in an SMOF that, even when all conditions of ergodicity are satisfied with a large margin, there will always be at least one realization violating strict ergodicity. Thus, only conditional (approximate) ergodicity occurs in this case. Nevertheless, in calculation of the FRI zero drift in this situation, averaging over an ensemble of independent realizations of random inhomogeneities in the SMOF of an FRI loop can be performed with sufficient accuracy. As a result, calculations are simplified significantly. In the general case, when at least one of the conditions of ergodicity is not satisfied, averaging over temperature for each realization with subsequent averaging over the entire ensemble should be performed. It is shown also that, within this problem, we can speak only about quasi-ergodicity or emulation of ergodicity, since a change in the temperature of the SMOF of an FRI loop and successive enumeration of independent realizations of random inhomogeneities in the SMOF loop are radically different random processes. The parameters characterizing quasiperiodic temperature changes in the phase difference of counterpropagating waves at the FRI output are refined.     

Cyclotron resonance for electrons over helium in a resonator

The cyclotron resonance (CR) problem for electrons over a helium film occupying the lower part of a resonator is solved. This problem is shown to represent an example of the well-known problem on the behavior of a system of coupled oscillators. For such oscillators, the coupling constant is determined as a function of the problem parameters with its minimal value in zero magnetic field and its maximal value at resonance conditions, when the cyclotron frequency coincides with one of the resonator modes. The details of the CR absorption of microwave energy by the coupled system formed by 2D electrons and a resonator are calculated. The results are discussed in application to the known CR experiments with electrons over helium.