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San Carlos de Bariloche, Argentina

Alessi M.,INVAP SE | Focke P.,Bariloche Atomic Center | Otranto S.,National University of the South
Journal of Physics: Conference Series | Year: 2015

Electron capture reactions for 3He2+ collisions on He at impact energies in the range 40 keV-300 keV have been studied using the Cold Target Recoil-Ion Momentum Spectroscopy setup which has recently became operational at the Centro Atomico Bariloche. State-selective charge exchange cross sections were obtained and in this work we present recoil-ion transverse momentum distributions. For targets with residual thermal motion, we show that the implementation of a back-projection algorithm based on the transverse momentum distribution component along a direction perpendicular to the jet direction provides results in agreement with those obtained by using previously cooled targets. Present results nicely fit the gaps in the datasets already published by other laboratories and are found to be in good agreement with classical trajectory Monte Carlo simulations. © Published under licence by IOP Publishing Ltd. Source


Ruderman A.,National University of Cordoba | Ruderman A.,University of Ulm | Dente A.D.,INVAP SE | Santos E.,National University of Cordoba | And 2 more authors.
Journal of Physics Condensed Matter | Year: 2015

In this work we show that molecular chemical bond formation and dissociation in the presence of the d-band of a metal catalyst can be described as a quantum dynamical phase transition (QDPT). This agrees with DFT calculations that predict sudden jumps in some observables as the molecule breaks. According to our model this phenomenon emerges because the catalyst provides for a non-Hermitian Hamiltonian. We show that when the molecule approaches the surface, as occurs in the Heyrovsky reaction of H2, the bonding H2 orbital has a smooth crossover into a bonding molecular orbital built with the closest H orbital and the surface metal d-states. The same occurs for the antibonding state. Meanwhile, two resonances appear within the continuous spectrum of the d-band, which are associated with bonding and antibonding orbitals between the furthest H atom and the d-states at the second metallic layer. These move toward the band center, where they collapse into a pure metallic resonance and an almost isolated H orbital. This phenomenon constitutes a striking example of the non-trivial physics enabled when one deals with non-Hermitian Hamiltonian beyond the usual wide band approximation. © 2015 IOP Publishing Ltd. Source


Srinivasan V.S.,Indira Gandhi Center for Atomic Research | Ibanez A.R.,INVAP SE | Saxena A.,University of Arkansas
Transactions of the Indian Institute of Metals | Year: 2010

In the present study, fracture toughness and creep crack growth behavior of directionally solidified Ni-base superalloy was investigated at elevated temperatures. Creep crack growth rate was correlated to the parameter C t. Change in fracture toughness as a function of temperature followed the same trend as the variation of yield strength of Ni3 Al with temperature. © 2010 TIIM, India. Source


Toscano R.G.,SIM Inc | Goldschmit M.B.,SIM Inc | Tempone S.,INVAP SE | Dvorkin E.N.,SIM Inc
PANACM 2015 - 1st Pan-American Congress on Computational Mechanics, in conjunction with the 11th Argentine Congress on Computational Mechanics, MECOM 2015 | Year: 2015

The scientific-technological development is essential for the sustained growth of our regions; the production of quality goods with high added value is an important step forward when compared with the production of raw materials. Computational Mechanics is an essential tool for the development of new technologies and for the optimization of the existing ones [1]. The industry faces technological problems increasingly more complex, and the numerical simulation of those technological problems induces scientists to computational developments of greater complexity. Since technological decisions are reached based on the results provided by numerical models, it is evident that these models have to be highly reliable. Therefore, it is essential that sophisticated modeling techniques are used; that highly qualified engineers develop models and that the results are validated experimentally using industrial or laboratory determinations [2]. The examples used to illustrate this article are taken from real applications developed for industry: the structural verification of the communications satellite ARSAT-1 and the modeling of rock fracturing processes. Source


Mochi I.,INVAP SE
Science and Technology of Nuclear Installations | Year: 2011

Since its origins in 1976, INVAP has been on continuous development of the calculation system used for design and optimization of nuclear reactors. The calculation codes have been polished and enhanced with new capabilities as they were needed or useful for the new challenges that the market imposed. The actual state of the code packages enables INVAP to design nuclear installations with complex geometries using a set of easy-to-use input files that minimize user errors due to confusion or misinterpretation. A set of intuitive graphic postprocessors have also been developed providing a fast and complete visualization tool for the parameters obtained in the calculations. The capabilities and general characteristics of this deterministic software package are presented throughout the paper including several examples of its recent application. Copyright © 2011 Ignacio Mochi. Source

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