9 research outputs found
Global Superdiffusion of Weak Chaos
A class of kicked rotors is introduced, exhibiting accelerator-mode islands
(AIs) and {\em global} superdiffusion for {\em arbitrarily weak} chaos. The
corresponding standard maps are shown to be exactly related to generalized web
maps taken modulo an ``oblique cylinder''. Then, in a case that the web-map
orbit structure is periodic in the phase plane, the AIs are essentially {\em
normal} web islands folded back into the cylinder. As a consequence, chaotic
orbits sticking around the AI boundary are accelerated {\em only} when they
traverse tiny {\em ``acceleration spots''}. This leads to chaotic flights
having a quasiregular {\em steplike} structure. The global weak-chaos
superdiffusion is thus basically different in nature from the strong-chaos one
in the usual standard and web maps.Comment: REVTEX, 4 Figures: fig1.jpg, fig2.ps, fig3.ps, fig4.p
Chaos and flights in the atom-photon interaction in cavity QED
We study dynamics of the atom-photon interaction in cavity quantum
electrodynamics (QED), considering a cold two-level atom in a single-mode
high-finesse standing-wave cavity as a nonlinear Hamiltonian system with three
coupled degrees of freedom: translational, internal atomic, and the field. The
system proves to have different types of motion including L\'{e}vy flights and
chaotic walkings of an atom in a cavity. It is shown that the translational
motion, related to the atom recoils, is governed by an equation of a parametric
nonlinear pendulum with a frequency modulated by the Rabi oscillations. This
type of dynamics is chaotic with some width of the stochastic layer that is
estimated analytically. The width is fairly small for realistic values of the
control parameters, the normalized detuning and atomic recoil
frequency . It is demonstrated how the atom-photon dynamics with a
given value of depends on the values of and initial
conditions. Two types of L\'{e}vy flights, one corresponding to the ballistic
motion of the atom and another one corresponding to small oscillations in a
potential well, are found. These flights influence statistical properties of
the atom-photon interaction such as distribution of Poincar\'{e} recurrences
and moments of the atom position . The simulation shows different regimes of
motion, from slightly abnormal diffusion with at to a superdiffusion with at that
corresponds to a superballistic motion of the atom with an acceleration. The
obtained results can be used to find new ways to manipulate atoms, to cool and
trap them by adjusting the detuning .Comment: 16 pages, 7 figures. To be published in Phys. Rev.
Breakdown of correspondence in chaotic systems: Ehrenfest versus localization times
Breakdown of quantum-classical correspondence is studied on an experimentally
realizable example of one-dimensional periodically driven system. Two relevant
time scales are identified in this system: the short Ehrenfest time t_h and the
typically much longer localization time scale T_L. It is shown that
surprisingly weak modification of the Hamiltonian may eliminate the more
dramatic symptoms of localization without effecting the more subtle but
ubiquitous and rapid loss of correspondence at t_h.Comment: 4 pages, 5 figures, replaced with a version submitted to PR
Granulation as a method for preparation of alkali halide salts for the growth of scintillation single crystals
Described is a granulation method for high-purity alkali halide salts by spraying the melt into liquid nitrogen, as well as the design of the apparatus for realization of this process. Thermochemical treatment of the melt carried out directly in the apparatus allows to process the wastes of the manufacture of scintillation detectors (crystal cuttings and fragments or chips) for obtaining products suitable for repeated utilization as a starting material for crystal growth.Описан метод гранулирования щелочногалоидных солей особой чистоты путем рас-пыливания расплава в жидкий азот, а также конструкция аппарата для осуществления процесса. Термохимическая обработка расплава непосредственно в аппарате позволяет перерабатывать отходы производства сцинтилляционных детекторов (обрезков, осколков кристаллов и стружку) в продукт, пригодный для повторного использования в качестве сырья для выращивания кристаллов.Описано метод гранулювання лужногалоїдних солей особливої чистоти шляхом розпилювання розплаву у рідкий азот, а також конструкція апарату для здійснєння процесу. Термохімічна обробка розплава безпосередньо в апараті дозволяє переробляти відходи виробництва сцинтиляційних детекторів (обрізків, осколків кристалів і стружку) у продукт, придатний для повторного використання як сировину для вирощування кристалів
The effect of oxygen-containing anions on luminescent properties of CsI
It has been found that from the series of oxygen-containing impurities CO₃²⁻, SO₄²⁻, HCO₃–, OH–, IO₃–, NO₃–, NO₂–, CNO–, BO₂– only the bivalent ions stimulate an intensive blue luminescence in CsI crystals at UV- or gamma-excitation. The blue luminescence intensity is higher in CsI(CO₃) than in CsI(SO₄) crystals. The nature of blue luminescence components has been considered and two types of centres have been suggested: the impurity type – CO₃²⁻-Va⁺ (395 nm) and the structural one – Va⁺-Vc⁻ (435 nm). A method of deep purification of the melt from oxygen-containing anions during the growth process has been proposed
Effect of CO₃²⁻ and OH⁻ impurities on thermal growing conditions of large-size NaI:Tl crystals and their quality
25 Years of Self-Organized Criticality: Solar and Astrophysics
Shortly after the seminal paper “Self-Organized Criticality: An explanation of 1/fnoise” by Bak et al. (1987), the idea has been applied to solar physics, in “Avalanches and the Distribution of Solar Flares” by Lu and Hamilton (1991). In the following years, an inspiring cross-fertilization from complexity theory to solar and astrophysics took place, where the SOC concept was initially applied to solar flares, stellar flares, and magnetospheric substorms, and later extended to the radiation belt, the heliosphere, lunar craters, the asteroid belt, the Saturn ring, pulsar glitches, soft X-ray repeaters, blazars, black-hole objects, cosmic rays, and boson clouds. The application of SOC concepts has been performed by numerical cellular automaton simulations, by analytical calculations of statistical (powerlaw-like) distributions based on physical scaling laws, and by observational tests of theoretically predicted size distributions and waiting time distributions. Attempts have been undertaken to import physical models into the numerical SOC toy models, such as the discretization of magneto-hydrodynamics (MHD) processes. The novel applications stimulated also vigorous debates about the discrimination between SOC models, SOC-like, and non-SOC processes, such as phase transitions, turbulence, random-walk diffusion, percolation, branching processes, network theory, chaos theory, fractality, multi-scale, and other complexity phenomena. We review SOC studies from the last 25 years and highlight new trends, open questions, and future challenges, as discussed during two recent ISSI workshops on this theme.Fil: Aschwanden, Markus J.. Lockheed Martin Corporation; Estados UnidosFil: Crosby, Norma B.. Belgian Institute For Space Aeronomy; BélgicaFil: Dimitropoulou, Michaila. University Of Athens; GreciaFil: Georgoulis, Manolis K.. Academy Of Athens; GreciaFil: Hergarten, Stefan. Universitat Freiburg Im Breisgau; AlemaniaFil: McAteer, James. University Of New Mexico; Estados UnidosFil: Milovanov, Alexander V.. Max Planck Institute For The Physics Of Complex Systems; Alemania. Russian Academy Of Sciences. Space Research Institute; Rusia. Enea Centro Ricerche Frascati; ItaliaFil: Mineshige, Shin. Kyoto University; JapónFil: Morales, Laura Fernanda. Canadian Space Agency; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nishizuka, Naoto. Japan National Institute Of Information And Communications Technology; JapónFil: Pruessner, Gunnar. Imperial College London; Reino UnidoFil: Sanchez, Raul. Universidad Carlos Iii de Madrid. Instituto de Salud; EspañaFil: Sharma, A. Surja. University Of Maryland; Estados UnidosFil: Strugarek, Antoine. University Of Montreal; CanadáFil: Uritsky, Vadim. Nasa Goddard Space Flight Center; Estados Unido