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Debrecen, Hungary

Jull A.J.T.,University of Arizona | Jull A.J.T.,Institute for Nuclear Research | Panyushkina I.P.,University of Arizona | Lange T.E.,University of Arizona | And 7 more authors.
Geophysical Research Letters

The calibration of radiocarbon dates by means of a master calibration curve has been invaluable to Earth, environmental and archeological sciences, but the fundamental reason for calibration is that atmospheric radiocarbon content varies because of changes in upper atmosphere production and global carbon cycling. Improved instrumentation has contributed to high-resolution (interannual) radiocarbon activity measurements, which have revealed sudden and anomalous activity shifts previously not observed at the common resolution of 5-10years of most of the calibration scale. One such spike has been recently reported from tree rings from Japan and then again in Europe at A.D. 774-775, for which we report here our efforts to both replicate its existence and determine its spatial extent using tree rings from larch at high latitude (northern Siberia) and bristlecone pine from lower latitude (the White Mountains of California). Our results confirm an abrupt ~15‰ 14C activity increase from A.D. 774 to 776, the size and now the hemispheric extent of which suggest that an extraterrestrial influence on radiocarbon production is most likely responsible. Key Points Excursion in 774-776 A.D. due to a rapid change in 14C production Event must be global and uniform in scale Phenomenon is reproduced in two new locations, making a total of five ©2014. American Geophysical Union. All Rights Reserved. Source

Garcia Gallardo J.A.,Bariloche Atomic Center | Gervasoni J.L.,Bariloche Atomic Center | Gervasoni J.L.,CONICET | Kover L.,Institute for Nuclear Research

In this work we study the surface plasmon generation by a suddenly created electron-hole pair in nanoparticles of spherical shape. We use a previously developed model based on the Hamiltonian formulation for plasmon field. © 2014 Elsevier Ltd. All rights reserved. Source

Trunov M.L.,Uzhgorod National University | Lytvyn P.M.,V Lashkaryov Institute Of Semiconductors Nas Ukraine | Nagy P.M.,Research Center for Natural science | Csik A.,Institute for Nuclear Research | Kokenyesi S.,Debrecen University
Physica Status Solidi (B) Basic Research

Two types of amorphous functional materials, based on light-sensitive inorganic compounds like Se and As20Se80 chalcogenide glass (ChG) were investigated with the aim to establish the influence of plasmonic fields, excited by the recording light in nanocomposite layers made of these compounds and gold nanoparticles on their photomechanical response. Both these basic materials are characterized by pronounced photoplastic effect and used for real-time optical recording of optoelectronic elements (based mainly on surface relief gratings) due to high photofluidity and polarization-dependent mass-transport. We have established that mass-transport processes in these ChG can be enhanced in the presence of localized plasmonic fields generated by light if the condition of surface plasmon resonance (SPR) is fulfilled. The subjects of special interest are the mass-transport processes at nano-scale stimulated in the nano-composite layers either by uniform or periodically distributed optical fields. It was found that irradiation by light in the presence of SPR really enhanced the efficiency of mass-transport and produced surface nanostructurizations. The variation in the topography follows closely and permanently the underlying near field intensity pattern. Nanostructurization of photosensitive amorphous As20Se80 film by surface plasmon near field irradiation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Garcia Gallardo J.,Comision Nacional de la Energia Atomica | Gervasoni J.L.,Bariloche Atomic Center | Kover L.,Institute for Nuclear Research
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

In this work we study the surface plasmon generation by electron-hole interaction in an aluminum spherical nano-particle due to the Auger electron-hole interaction by means of the Hamiltonian formalism. © 2015 Elsevier B.V. All rights reserved. Source

Kolesnichenko Y.I.,Institute for Nuclear Research | Konies A.,Max Planck Institute for Plasma Physics (Greifswald) | Lutsenko V.V.,Institute for Nuclear Research | Yakovenko Yu.V.,Institute for Nuclear Research
Plasma Physics and Controlled Fusion

Most of the published theoretical works on plasma instabilities driven by energetic (superthermal) ions are relevant to tokamaks. However, these instabilities play an important role not only in tokamaks but also in stellarators. That is why it is of importance to analyse the limits of applicability of theoretical results obtained for tokamaks and understand in which cases using these results for the description of similar phenomena in stellarators is justified and, if so, to what extent. On the other hand, stellarator theory incorporating effects of 3D geometry in some cases can be useful for understanding instabilities in tokamaks. Therefore, comparative analysis of instabilities in various types of toroidal systems is of interest for both stellarator and tokamak communities. Such an analysis based on an overview of energetic-ion-driven instabilities in tokamaks and stellarators is carried out in this paper. Instabilities in wide frequency range, from the ion/electron diamagnetic frequency to high frequencies of specific stellarator modes, are considered. Effects of the instabilities on the confinement of both the energetic ions and the bulk plasma are described. Numerical tools available for simulation of instabilities driven by the energetic ions are reviewed. © 2011 IOP Publishing Ltd. Source

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