Publications (129)280.58 Total impact

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ABSTRACT: Spinorbit coupling characterizes quantum systems such as atoms, nuclei, hypernuclei, quarkonia, etc., and is essential for understanding their spectroscopic properties. Depending on the system, the effect of spinorbit coupling on shell structure is large in nuclei, small in quarkonia, perturbative in atoms. In the standard nonrelativistic reduction of the singleparticle Dirac equation, we derive a universal rule for the relative magnitude of the spinorbit effect that applies to very different quantum systems, regardless of whether the spinorbit coupling originates from the strong or electromagnetic interaction. It is shown that in nuclei the near equality of the mass of the nucleon and the difference between the large repulsive and attractive potentials explains the fact that spinorbit splittings are comparable to the energy spacing between major shells. For a specific ratio between the particle mass and the effective potential whose gradient determines the spinorbit force, we predict the occurrence of giant spinorbit energy splittings that dominate the singleparticle excitation spectrum. 
Article: The hypernuclear chart
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ABSTRACT: We calculate the comprehensive hypernuclear chart for eveneven hypernuclei with magic numbers of $\Lambda$'s (for Z $\leq$ 120 and $\Lambda \leq$70) and estimate the number of bound systems, considering the present uncertainties in the $\Lambda$nucleon and $\Lambda\Lambda$ interactions. We consider a density functional approach adjusted to microscopic BrucknerHartreeFock calculations, where the $\Lambda\Lambda$ term is corrected in a phenomenological way, to reproduce present experimental constraints. Different models which strongly deviate at large densities, but giving the same bond energy, are generated in order to take into account the uncertainties related to the high density equation of state. The number of bound eveneveneven hypernuclei is estimated to 491680 $\pm$ 34400. This relatively low uncertainty is due to the fact that the well constrained low density and highly unconstrained high density behavior of the energy functional turn out to be largely decoupled. Results in hypernuclei appear to be almost independent of the choice for the highdensity part of the $\Lambda\Lambda$ interaction. The location of the hyperdriplines is also evaluated. Significant deviations from IronNickel elements can be found for hypernuclei with the largest binding energy per baryon. Proton, neutron and hyperon magicity evolution and triple magic hypernuclei are studied. Possible bubbles and haloes effect in hypernuclei are also discussed. The present results provide a first microscopic evaluation of the hypernuclear landscape. 
Dataset: ncomms7743supplementary information
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ABSTRACT: Excited states in $^{28}$Na have been studied using the $\beta$decay of implanted $^{28}$Ne ions at GANIL/LISE as well as the inbeam $\gamma$ray spectroscopy at the NSCL/S800 facility. New states of positive (J$^{\pi}$=3,4$^+$) and negative (J$^{\pi}$=15$^$) parity are proposed. The former arise from the coupling between 0d$\_{5/2}$ protons and a 0d$\_{3/2}$ neutron, while the latter are due to couplings with 1p$\_{3/2}$ or 0f$\_{7/2}$ neutrons. While the relative energies between the J$^{\pi}$=14$^+$ states are well reproduced with the USDA interaction in the N=17 isotones, a progressive shift in the ground state binding energy (by about 500 keV) is observed between $^{26}$F and $^{30}$Al. This points to a possible change in the protonneutron 0d$\_{5/2}$0d$\_{3/2}$ effective interaction when moving from stability to the drip line. The presence of J$^{\pi}$=14$^$ negative parity states around 1.5 MeV as well as of a candidate for a J$^{\pi}$=5$^$ state around 2.5 MeV give further support to the collapse of the N=20 gap and to the inversion between the 0f$\_{7/2}$ and 1p$\_{3/2}$ levels below Z=12. These features are discussed in the framework of Shell Model and EDF calculations, leading to predicted negative parity states in the low energy spectra of the $^{26}$F and $^{25}$O nuclei.  [Show abstract] [Hide abstract]
ABSTRACT: Giant resonances are collective excitation modes for manybody systems of fermions governed by a mean field, such as the atomic nuclei. The microscopic origin of such modes is the coherence among elementary particlehole excitations, where a particle is promoted from an occupied state below the Fermi level (hole) to an empty one above the Fermi level (particle). The same coherence is also predicted for the particle–particle and the hole–hole excitations, because of the basic quantum symmetry between particles and holes. In nuclear physics, the giant modes have been widely reported for the particle–hole sector but, despite several attempts, there is no precedent in the particle–particle and hole–hole ones, thus making questionable the aforementioned symmetry assumption. Here we provide experimental indications of the Giant Pairing Vibration, which is the leading particle–particle giant mode. An immediate implication of it is the validation of the particle–hole symmetry.Nature Communications 03/2015; 6. DOI:10.1038/ncomms7743 · 11.47 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Nuclear states are often described as quantum liquid states. Using the localisation parameter, it is possible to understand cluster states in nuclei as hybrid states between quantum liquid and crystal states. Recent calculations discussing the effect of the depth of the confining potential, as well as various lengthscales ratios, are presented in order to provide a complementary view on the cluster phenomenon in nuclei.Journal of Physics Conference Series 12/2014; 569(1). DOI:10.1088/17426596/569/1/012006  [Show abstract] [Hide abstract]
ABSTRACT: Nuclear Energy Density Functionals (EDFs) are a microscopic tool of choice extensively used over the whole chart to successfully describe the properties of atomic nuclei ensuing from their quantum liquid nature. In the last decade, they also have proved their ability to deal with the cluster phenomenon, shedding a new light on its fundamental understanding by treating on an equal footing both quantum liquid and cluster aspects of nuclei. Such a unified microscopic description based on nucleonic degrees of freedom enables to tackle the question pertaining to the origin of the cluster phenomenon and emphasizes intrinsic mechanisms leading to the emergence of clusters in nuclei.Journal of Physics Conference Series 12/2014; 569(1). DOI:10.1088/17426596/569/1/012028  [Show abstract] [Hide abstract]
ABSTRACT: We study the finite temperature HartreeFockBCS approximation for selected stable Sn nuclei with zerorange Skyrme forces. Hartree Fock BCS approximation allows for a straightforward interpretation of the results since it involves $u$ and $v$'s which are not matrices as in HFB. Pairing transitions from superfluid to the normal state are studied with respect to the temperature. The temperature dependence of the nuclear radii and neutron skin are also analyzed. An increase of proton and neutron radii is obtained in neutron rich nuclei especially above the critical temperature. Using different Skyrme energy functionals, it is found that the correlation between the effective mass in symmetric nuclear matter and the critical temperature depends on the pairing prescription. The temperature dependence of the nucleon effective mass is also investigated, showing that proton and neutron effective masses display different behavior below and above the critical temperature, due to the small temperature dependence of the density.European Physical Journal A 10/2014; 50(10):160. DOI:10.1140/epja/i2014141604 · 2.74 Impact Factor 
Article: Pairing properties of hot nuclei within the finite temperature Hartree Fock+BCS approximation
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ABSTRACT: In this work, finite temperature Hartree Fock BCS (FT+HFBCS) calculations are performed in Sn isotopes with the zerorange Skyrme type interactions. Vanishing of pairing correlations due to the increase in temperature are investigated with various types of Skyrme interactions. In addition, dependence of the critical temperature with respect to the several properties of these energy density functionals are analysed.Journal of Physics Conference Series 09/2014; 533(1):012019. DOI:10.1088/17426596/533/1/012019  Physical Review Letters 07/2014; 113(5). DOI:10.1103/PhysRevLett.113.059902 · 7.51 Impact Factor
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ABSTRACT: The isoscalar monopole response has been measured in the unstable nucleus ^{68}Ni using inelastic alpha scattering at 50A MeV in inverse kinematics with the active target MAYA at GANIL. The isoscalar giant monopole resonance (ISGMR) centroid was determined to be 21.1±1.9 MeV and indications for a soft monopole mode are provided for the first time at 12.9±1.0 MeV. Analysis of the corresponding angular distributions using distortedwaveborn approximation with randomphase approximation transition densities indicates that the L=0 multipolarity dominates the cross section for the ISGMR and significantly contributes to the lowenergy mode. The L=0 part of this lowenergy mode, the soft monopole mode, is dominated by neutron excitations. This demonstrates the relevance of inelastic alpha scattering in inverse kinematics in order to probe both the ISGMR and isoscalar soft modes in neutronrich nuclei.Physical Review Letters 07/2014; 113(3):032504. DOI:10.1103/PhysRevLett.113.032504 · 7.51 Impact Factor 
Article: Study of new resonances at high excitation energy by the 120 Sn(p,t) 118 Sn reaction at 35 MeV
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ABSTRACT: The 120Sn(p,t)118Sn reaction was investigated at 35 MeV incident energy. The 118Sn excitation energy spectrum was reconstructed up to about 16 MeV. Preliminary results show the presence of a broad resonance at high excitation energy, compatible with the predicted population of the Giant Pairing Vibration (GPV).Izvestiya Akademii Nauk. Ser. Fizicheskaya 07/2014; 78(7):802804. DOI:10.7868/S0367676514070199 
Article: Effects of the tensor force on the ground and first $2^{+}$ states of the magic $^{54}$Ca nucleus
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ABSTRACT: The magic nature of the $^{54}$Ca nucleus is investigated in the light of the recent experimental results. We employ both HFB and HF+BCS methods using Skyrmetype SLy5, SLy5+T and T44 interactions. The evolution of the singleparticle spectra is studied for the N=34 isotones: $^{60}$Fe, $^{58}$Cr, $^{56}$Ti and $^{54}$Ca. An increase is obtained in the neutron spinorbit splittings of $p$ and $f$ states due to the effect of the tensor force which also makes $^{54}$Ca a magic nucleus candidate. QRPA calculations on top of HF+BCS are performed to investigate the first $J^{\pi}$=$2^{+}$ states of the calcium isotopic chain. A good agreement for excitation energies is obtained when we include the tensor force in the meanfield part of the calculations. The first $2^{+}$ states indicate a subshell closure for both $^{52}$Ca and $^{54}$Ca nuclei. We confirm that the tensor part of the interaction is quite essential in explaining the neutron subshell closure in $^{52}$Ca and $^{54}$Ca nuclei.Physical Review C 06/2014; 89(6):064322. DOI:10.1103/PhysRevC.89.064322 · 3.73 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The framework of nuclear energy density functionals is applied to a study of the formation and evolution of cluster states in nuclei. The relativistic functional DDME2 is used in triaxial and reflectionasymmetric relativistic HartreeBogoliubov calculations of relatively light $N = Z$ and neutronrich nuclei. The role of deformation and degeneracy of singlenucleon states in the formation of clusters is analysed, and interesting cluster structures are predicted in excited configurations of Be, C, O, Ne, Mg, Si, S, Ar and Ca $N = Z$ nuclei. Cluster phenomena in neutronrich nuclei are discussed, and it is shown that in neutronrich Be and C nuclei cluster states occur as a result of molecular bonding of $\alpha$particles by the excess neutrons, and also that proton covalent bonding can occur in $^{10}$C.Physical Review C 06/2014; 90(5). DOI:10.1103/PhysRevC.90.054329 · 3.73 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Expérience GANIL/LISE/MAYA  [Show abstract] [Hide abstract]
ABSTRACT: Recent results obtained with energy density functional (EDF) based methods are presented, focused on the nuclear phenomenology. EDF approaches aim for an universal description of the nuclear phenomena over the nuclear chart. Achievements from large to small nuclear systems are depicted: equation of state of nuclear matter, heavy and light nuclei. Dynamical aspects such as nuclear excitations, decay and reactions are also presented. EDF methods are progressing towards an unified and systematic description of the rich variety of the nuclear phenomena such as quantum liquid and cluster states, or nuclear structure and reactions.The European Physical Journal Conferences 02/2014; 66. DOI:10.1051/epjconf/20146601009  [Show abstract] [Hide abstract]
ABSTRACT: The role of superfluidity on the symmetry energy and on the incompressibility is studied in nuclear matter and finite nuclei employing HartreeFockBogoliubov modeling based on several types of pairing interactions (surface, mixed and isovectordensity dependent). It is observed that, while pairing has only a marginal effect on the symmetry energy and on the incompressibility at saturation density, the effects are significantly larger at lower densities.European Physical Journal A 01/2014; 50(2). DOI:10.1140/epja/i2014140189 · 2.74 Impact Factor  Acta Physica Polonica Series B 01/2014; 45(2):437. DOI:10.5506/APhysPolB.45.437 · 0.85 Impact Factor
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ABSTRACT: The isoscalar monopole response is studied in doubly magic 208Pb, 100,132Sn nuclei using the Skyrme HF+RPA model. A lowenergy strength is predicted and corresponds to almost pure singleparticle excitations. These pure singleparticle excitations allow to analyse the splitting of the corresponding spinorbit partners. A good agreement with the spinorbit splitting data is found in the case of 208Pb. The experimental width of the giant monopole resonance may hinder the measurement of the soft monopole mode.European Physical Journal A 10/2013; 49(124):18. DOI:10.1140/epja/i2013131246 · 2.74 Impact Factor
Publication Stats
1k  Citations  
280.58  Total Impact Points  
Top Journals
Institutions

2004–2014

Université ParisSud 11
 Institut de Physique Nucléaire (IPN)
Orsay, ÎledeFrance, France


2013

Yildiz Technical University
 Department of Physics
İstanbul, Istanbul, Turkey


2000–2012

Institut de Physique Nucléaire de Lyon
Lyons, RhôneAlpes, France


2000–2010

French National Centre for Scientific Research
Lutetia Parisorum, ÎledeFrance, France


1998

Orsay Physics
Fuveau, ProvenceAlpesCôte d'Azur, France
