Positron-electron annihilation in the field of a fixed electric dipole

Positron annihilation from a dipole Ps state caused by simultaneous localization of the positron and electron in the field of a fixed electrical dipole is considered. The angular correlation curve of annihilation -quanta is calculated. For a fixed value of dipole moment the half width of the correlation curve decreases with decrease in dipole charge. With increase in dipole moment the correlation curve narrows. In a number of cases the given annihilation mechanism may be responsible for the appearance of the characteristic narrow component in the angular correlation spectrum. This component is usually ascribed to decay of a positronium atom. It is stressed that in interpreting the narrow component one must be careful in choosing the corresponding annihilation mechanism. Experimental results are analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 74–78, August, 1989.     

The bauschinger effect in transition from rolling to bending

It is found that suppression of the Bauschinger effect is responsible for the sharp growth in resistance to small plastic deformations in bending in low-temperature annealing of material previously deformed by rolling.     

Results of T2K and NOvA Neutrino Experiments: Neutrino Mass Ordering and CP Symmetry

Journal of Experimental and Theoretical Physics - New data concerning neutrino oscillations as obtained in the T2K and NOvA accelerator neutrino experiments are considered. Both collaborations...     

Characteristics of laser applications in precision analytical measurements (review)

Conclusion Analytical laser spectroscopy is undergoing a great deal of progress and a large number of original and review work is published in which the development of different aspects of analytical laser spectroscopy is discussed (see [2, 82-102]). In practical analytical measurements, nontraditional methods find increasing acceptance based on the well-known physical models of the process of measurement and the indirect relation of the measured values with a standard which reproduces principal units in terms of fundamental, atomic and molecular constants. Development of absolute methods for the measurement of components of materials is a very relevant task when one is concerned with such a small number of probes or with trace concentrations that the making or using of standard gas mixture is practically not feasible. On the other hand, obtaining and saving the given gas mixtures for later use, as usual, introduces significant systematic error especially when we are concerned with unstable and corrosive gaseous components or ultra-microconcentrations. The universal method for the measurement of component concentration in the atmosphere is the direct absorption method. In order to determine the concentration of the component under measurement, it is necessary to know its coefficient of absorption under similar conditions. High sensitivity and accuracy as determined by the accuracy in the measurement of the absorption coefficient may be attained when laser radiation sources with a radiation power stabilization system are used.Translated from Zhurnal Prikladnoi Spectroskopii, Vol. 49, No. 2, pp. 183–201, August, 1988.The authors thank A. P. Voitovich for a discussion of the work and for valuable remarks     

Ultra-high energy neutrino-nucleon and neutrino-electron cross-sections in the standard model,in supersymmetric and superstring models

The neutrino-nucleon cross-section is calculated for energies up to 10¹⁵ GeV in the framework of the standard model assuming that the nucleon structure functionF ₂(x, Q ²) goes like ln²(a/x) asx→0. The cross-sections forv _μ e ^?(v _e e ^?)-interactions rise linearly with energy up toE _ν～10⁷ GeV and amount at this energy to ～10% of the neutrino-nucleon cross-section. The νN-cross-sections with production of supersymmetric particles in the framework of a supersymmetric model with minimal particle content are estimated. Photino-nucleon and photino-electron interactions are considered for masses of the squarks and sleptons in the range of 80–300 GeV. In superstring inspired unified models an estimation is made of the νN-interaction with an exchange of light leptoquarks.     

Methods for the synthesis of derivatives of 3-aminothietane (Review)

Methods for the production of derivatives of 3-aminothietane and 3-aminothietan-2-one are reviewed. Dedicated to Prof. Ivars Kalvinsh on the occasion of his 60^th birthday. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 655–682, May, 2007.     

Nitration of Pyrrolo[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrazines

We have synthesized nitro derivatives of pyrrolo[1,2-a]pyrazines using a nitrating mixture and acetyl nitrate. We have obtained the products of oxidation of the side chain of 1,6-substituted pyrrolo[1,2-a]-pyrazines. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1579–1586, October, 2005.