Parametric x-ray radiation in polycrystals

Parametric X-ray radiation produced during the interaction of charged particles with polycrystals is regarded. A review of the existing theories, perspectives of application and performed experiments is presented. The evolution of experimental capabilities as well as the progress in the process comprehension is illustrated. The state of the art of PXR in polycrystals is presente

Parametric x-ray radiation in the backward geometry

Parametric X-ray Radiation registered in the backward geometry is analysed. The main properties of the radiation for such geometry are discussed. The advantages of the backward geometry over other configurations regarding the intensity, the spectral width and the possibility to discriminate the contributions form different radiation mechanisms to the total radiation yield are presente

Parametric X-ray Radiation in the backward geometry

Parametric X-ray Radiation registered in the backward geometry is analysed. The main properties of the radiation for such geometry are discussed. The advantages of the backward geometry over other configurations regarding the intensity, the spectral width and the possibility to discriminate the contributions form different radiation mechanisms to the total radiation yield are presented.Аналізується параметричне рентгенівське випромінювання, зареєстроване в геометрії «строго назад». Обговорюються основні властивості випромінювання для такої геометрії. Представлено переваги геометрії «строго назад» у порівнянні з іншими геометріями в залежності від інтенсивності, спектральної ширини і можливості поділу внесків від різних механізмів випромінювання в загальний вихід випромінювання.Анализируется параметрическое рентгеновское излучение, зарегистрированное в геометрии «строго назад». Обсуждаются основные свойства излучения для такой геометрии. Представлены преимущества геометрии «строго назад» по сравнению с другими геометриями в зависимости от интенсивности, спектральной ширины и возможности разделения вкладов от различных механизмов излучения в общий выход излучения

Parametric X-ray radiation in polycrystals

Parametric X-ray radiation produced during the interaction of charged particles with polycrystals is regarded. A review of the existing theories, perspectives of application and performed experiments is presented. The evolution of experimental capabilities as well as the progress in the process comprehension is illustrated. The state of the art of PXR in polycrystals is presented.Розглянуто параметричне рентгенівське випромінювання (ПРВ), що виникає при взаємодії заряджених частинок з полікристалічними мішенями. Представлено огляд сучасного стану дослідження ПРВ в полікристалах: існуючих теорій, перспектив застосування і проведених експериментів з урахуванням розвитку експериментальних можливостей.Рассмотрено параметрическое рентгеновское излучение (ПРИ), возникающее при взаимодействии заряженных частиц с поликристаллическими мишенями. Представлен обзор современного состояния исследования ПРИ в поликристаллах: существующих теорий, перспектив применения и проведенных экспериментов с учетом развития экспериментальных возможностей

Geometry of WZW Orientifolds

We analyze unoriented Wess-Zumino-Witten models from a geometrical point of view. We show that the geometric interpretation of simple current crosscap states is as centre orientifold planes localized on conjugacy classes of the group manifold. We determine the locations and dimensions of these planes for arbitrary simply-connected groups and orbifolds thereof. The dimensions of the O-planes turn out to be given by the dimensions of symmetric coset manifolds based on regular embeddings. Furthermore, we give a geometrical interpretation of boundary conjugation in open unoriented WZW models; it yields D-branes together with their images under the orientifold projection. To find the agreement between O-planes and crosscap states, we find explicit answers for lattice extensions of Gaussian sums. These results allow us to express the modular P-matrix, which is directly related to the crosscap coefficient, in terms of characters of the horizontal subgroup of the affine Lie algebra. A corollary of this relation is that there exists a formal linear relation between the modular P- and the modular S-matrix.Comment: 35 pages LaTeX, 2 tables; Proof added for symmetric space relation; minor improvements; references adde

Slowly rotating charged black holes in anti-de Sitter third order Lovelock gravity

In this paper, we study slowly rotating black hole solutions in Lovelock gravity (n=3). These exact slowly rotating black hole solutions are obtained in uncharged and charged cases, respectively. Up to the linear order of the rotating parameter a, the mass, Hawking temperature and entropy of the uncharged black holes get no corrections from rotation. In charged case, we compute magnetic dipole moment and gyromagnetic ratio of the black holes. It is shown that the gyromagnetic ratio keeps invariant after introducing the Gauss-Bonnet and third order Lovelock interactions.Comment: 14 pages, no figur

Entropy and Quantum Kolmogorov Complexity: A Quantum Brudno's Theorem

In classical information theory, entropy rate and Kolmogorov complexity per symbol are related by a theorem of Brudno. In this paper, we prove a quantum version of this theorem, connecting the von Neumann entropy rate and two notions of quantum Kolmogorov complexity, both based on the shortest qubit descriptions of qubit strings that, run by a universal quantum Turing machine, reproduce them as outputs.Comment: 26 pages, no figures. Reference to publication added: published in the Communications in Mathematical Physics (http://www.springerlink.com/content/1432-0916/

Boundary States of c=1 and 3/2 Rational Conformal Field Theories

We study the boundary states for the rational points in the moduli spaces of c=1 conformal and c=3/2 superconformal field theories, including the isolated Ginsparg points. We use the orbifold and simple-current techniques to relate the boundary states of different theories and to obtain symmetry-breaking, non-Cardy boundary states. We show some interesting examples of fractional and twisted branes on orbifold spaces.Comment: Latex, 46 pages, 1 figur

Lebedev physical institute radiation complex – current status and new concepts

Multipurpose radiation complex is the result of long- term permanent development of new instrumentation at the Lebedev Physical Institute. This is stand-alone large facility designed for fundamental and applied research that had been started from the high current racetrack microtron project in the mid of seventies and has been completed by commissioning of far infrared FEL nowadays. Current status of the radiation complex including research as well as linac and FEL performance improvement is discussed in paper presented followed by new ideas in further facility development and application

Coherent information analysis of quantum channels in simple quantum systems

The coherent information concept is used to analyze a variety of simple quantum systems. Coherent information was calculated for the information decay in a two-level atom in the presence of an external resonant field, for the information exchange between two coupled two-level atoms, and for the information transfer from a two-level atom to another atom and to a photon field. The coherent information is shown to be equal to zero for all full-measurement procedures, but it completely retains its original value for quantum duplication. Transmission of information from one open subsystem to another one in the entire closed system is analyzed to learn quantum information about the forbidden atomic transition via a dipole active transition of the same atom. It is argued that coherent information can be used effectively to quantify the information channels in physical systems where quantum coherence plays an important role.Comment: 24 pages, 7 figs; Final versiob after minor changes, title changed; to be published in Phys. Rev. A, September 200