Institute Of Physique Nucleaire

Orsay, France

Institute Of Physique Nucleaire

Orsay, France
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Yekken R.,University of Science and Technology Houari Boumediene | Lombard R.J.,Institute Of Physique Nucleaire
Journal of Physics A: Mathematical and Theoretical | Year: 2010

The properties of the wave equation are studied in the case of energy-dependent potentials for bound sates. The nonlinearity induced by the energy dependence requires modification of the standard rules of quantum mechanics. These modifications are briefly recalled. Analytical and numerical solutions are given in the three-dimensional space for power-law radial shape potentials with a linear energy dependence. This last is chosen since it allows the construction of a coherent theory. Among the results, we stress the saturation of the spectrum observed for confining potentials: as the quantum numbers increase, the eigenvalues reach an upper limit. Finally, the problem of the equivalent local potential is discussed. The existence of analytical solutions presents a good opportunity to tackle this problem in detail. © 2010 IOP Publishing Ltd.

Rowley N.,Institute Of Physique Nucleaire | Hagino K.,Tohoku University | Hagino K.,Japan National Astronomical Observatory
Physical Review C - Nuclear Physics | Year: 2015

We re-examine the well-known Wong formula for heavy-ion fusion cross sections. Although this celebrated formula yields almost-exact results for single-channel calculations for relatively heavy systems such as O16+Sm144, it tends to overestimate the cross section for light systems such as C12+C12. We generalize the formula to take account of the energy dependence of the barrier parameters and show that the energy-dependent version gives results practically indistinguishable from a full quantal calculation. We then examine the deviations arising from the discrete nature of the intervening angular momenta, whose effect can lead to an oscillatory contribution to the excitation function. We recall some compact, analytic expressions for these oscillations and highlight the important physical parameters that give rise to them. Oscillations in symmetric systems are discussed, as are systems where the target and projectile identities can be exchanged via a strong transfer channel. © 2015 American Physical Society.

Balbutsev E.B.,Joint Institute for Nuclear Research | Molodtsova I.V.,Joint Institute for Nuclear Research | Schuck P.,Institute Of Physique Nucleaire | Schuck P.,CNRS Physics and Models in Condensed Media Laboratory
Nuclear Physics A | Year: 2011

The coupled dynamics of low lying modes, including the scissors mode, and various giant quadrupole resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom. Equations of motion for collective variables are derived on the basis of Time Dependent Hartree-Fock equations in the harmonic oscillator model including spin-orbit potential plus quadrupole-quadrupole residual interaction. Introducing spin allows one to consider new types of nuclear collective motion where the nucleons with spin 'up' oscillate against nucleons with spin 'down'. © 2011 Elsevier B.V.

Verkhoturov S.V.,Texas A&M University | Eller M.J.,Texas A&M University | Rickman R.D.,Halliburton Co. | Della-Negra S.,Institute Of Physique Nucleaire | Schweikert E.A.,Texas A&M University
Journal of Physical Chemistry C | Year: 2010

We report on the co-emission of secondary ions and electrons resulting from 15 keV C60 + and 30 keV C60 2 + impacts on targets of Al, Si, Au, CsI, glycine, and guanine. The study has been performed by the combination of an electron emission microscope and a time-of-flight (ToF) mass spectrometer. The electron emission occurs near the kinetic emission threshold, yet yields are notable (>3) for all investigated targets. A key observation for the projectile-target combinations studied is the absence of correlation between the electron emission and the number and type of co-emitted secondary ions for flat and homogeneous samples. This observation validates a novel concept of "positional mass spectrometry". In this approach a surface is probed in the event-by-event bombardment detection mode. Impacts of an individual C60 projectile are localized via electron emission. The location combined with the corresponding secondary ion information allows to map the distribution of surface molecules. The unique feature of positional mass spectrometry is the ability to identify co-emitted ions from a single projectile impact. To test the concept an electron emission microscope has been combined with a ToF mass spectrometer; the device operates with synchronized detection of electrons and ions. The spatial resolution of the method depends on the kinetic energy and angular distribution of the secondary electrons and the aberrations of the electron optics. Initial tests of positional mass spectrometry showed a spatial resolution of 1.2 μm. Progress is anticipated with improvements in the electron optics used and application of projectiles generating more prolific electron emission. © 2010 American Chemical Society.

Eller M.J.,Texas A&M University | Verkhoturov S.V.,Texas A&M University | Della-Negra S.,Institute Of Physique Nucleaire | Schweikert E.A.,Texas A&M University
Journal of Physical Chemistry C | Year: 2010

Secondary ion mass spectrometry (SIMS) performed in the event-by-event bombardment detection mode when coupled to an electron emission microscope allows one to investigate individual nano-objects. Two groups of Au and Al oxide nano-objects were compared with their bulk counterparts based on their secondary ion and electron emission from individual C60 impacts at 15 and 30 keV total impact energy. Our results show that electron yields depend on the size and surroundings of the nano-object, and at higher impact energies, these differences in electron emission are more pronounced. A second key observation for systems of similar chemical makeup but different surface topography and size is that the emission of secondary ions and electrons is independent of each other. © 2010 American Chemical Society.

Mirea M.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Tassan-Got L.,Institute Of Physique Nucleaire
Central European Journal of Physics | Year: 2011

Fission barriers of actinides are calculated in the framework of the macroscopic-microscopic method. The single particle energies are obtained within a new version of the Woods-Saxon two-center shell model. A nuclear shape parametrization characterized by five degrees of freedom is used. The barriers are calculated along the minimal action trajectory in the configuration space and the inertia is evaluated within the cranking formalism. The reliability of the model is tested by comparing the theoretical results with values deduced from experimental data. © 2010 Versita Warsaw and Springer-Verlag Berlin Heidelberg.

Da Silveira R.,Institute Of Physique Nucleaire | Leclercq-Willain C.,Free University of Colombia
Physical Review C - Nuclear Physics | Year: 2011

We present a qualitative analysis of the effects of the Coulomb force on the edge scattering produced in elastic nuclear collisions occurring under strong absorption conditions. This analysis is illustrated with several examples of nucleus-nucleus and antiproton-nucleus elastic scattering. © 2011 American Physical Society.

Munoz Camacho C.,Institute Of Physique Nucleaire
EPJ Web of Conferences | Year: 2014

The understanding of Quantum Chromodynamics (QCD) at large distances still remains one of the main outstanding problems of nuclear physics. Studying the internal structure of hadrons provides a way to probe QCD in the non-perturbative domain and can help us unravel the internal structure of the most elementary blocks of matter. Jefferson Lab (JLab) has already delivered results on how elementary quarks and gluons create nucleon structure and properties. The upgrade of JLab to 12 GeV will allow the full exploration of the valence-quark structure of nucleons and the extraction of real threedimensional pictures. I will present recent results and review the future experimental program at JLab. © Owned by the authors, published by EDP Sciences, 2014.

Sokhan D.,Institute Of Physique Nucleaire
AIP Conference Proceedings | Year: 2011

The recent breakthroughs in the technology of polarised targets have enabled a new generation of meson photo-production experiments to be carried out. A measurement of a full set of polarisation observables off both polarised proton and neutron targets and in a large number of meson-production channels has come within sight. Such a measurement would very significantly reduce model-dependence in the analysis of the data and thus has the potential to resolve long-standing issues, such as the "missing resonance" problem, and shed new light on the nucleon excitation spectrum. This has formed the motivation for the recent N* experimental programme of CLAS. © 2011 American Institute of Physics.

Lombard R.J.,Institute Of Physique Nucleaire
Journal of Physics: Conference Series | Year: 2013

The earlier attempts to construct a density functional for nuclear systems are shortly reviewed. Some results obtained with the functional derived by Beiner, Mas and myself are then recalled, as well as the extension to excited states. The universality of the functional is discussed. A way to improve the efficiency of the functional is proposed, in which the parameters of the functional are allowed to vary according to the underlying shell structure of each nucleus.

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