Partenaires

Nos tutelles

Centre National de la Recherche Scientifique Université de Caen ENSICAEN Normandie Université

LPC CAEN
ENSICAEN
6, bd du Maréchal Juin
14050 CAEN Cedex
Tel : +033 (0) 231452500



Annuaire


Organigrammes


Contacts

Rechercher





Accueil > Recherche & Enseignement

Mme Francesca Gulminelli



Professeur UCBN


Groupe : Théorie et phénoménologie


gulminelli lpccaen.in2p3.fr


Tél : +33 2 31 45 25 44



PUBLICATIONS

[in2p3-01301860] Finite-size effects on the phase diagram of the thermodynamical cluster model

25 septembre 2017

The thermodynamical cluster model is known to present a first-order liquid-gas phase transition in the idealized case of an uncharged, infinitely extended medium. However, in most practical applications of this model, the system is finite and charged. In this paper we study how the phase (...)

Lire la suite

[in2p3-01366040] Examination of strangeness instabilities and effects of strange meson couplings in dense strange hadronic matter and compact stars

10 mars 2017

Background : The emergence of hyperon degrees of freedom in neutron star matter has been associated to first order phase transitions in some phenomenological models, but conclusions on the possible physical existence of an instability in the strangeness sector are strongly model dependent. (...)

Lire la suite

[in2p3-01408663] Stellar electron capture rates on neutron-rich nuclei and their impact on stellar core collapse

10 mars 2017

During the late stages of gravitational core-collapse of massive stars, extreme isospin asymmetries are reached within the core. Due to the lack of microscopic calculations of electron capture (EC) rates for all relevant nuclei, in general simple analytic parameterizations are employed. We (...)

Lire la suite

[in2p3-01269560] Hyperons in neutron stars and supernova cores

11 octobre 2016

The properties of compact stars and their formation processes depend on many physical ingredients. The composition and the thermodynamics of the involved matter is one of them. We will investigate here uniform strongly interacting matter at densities and temperatures, where potentially other (...)

Lire la suite

[in2p3-01301864] Neutron star radii and crusts: uncertainties and unified equations of state

6 octobre 2016

The uncertainties in neutron star (NS) radii and crust properties due to our limited knowledge of the equation of state (EOS) are quantitatively analysed. We first demonstrate the importance of a unified microscopic description for the different baryonic densities of the star. If the pressure (...)

Lire la suite

[in2p3-01293418] The 12C* Hoyle state in the inelastic 12C + 12C reaction and in 24Mg* decay

25 mars 2016

The reaction 12C + 12C at 95 MeV has been studied at the Legnaro Laboratories of INFN with the GARFIELD + RCo apparatus. Data have been analyzed in order to investigate the decay of the Hoyle state of 12C*. Two different data selections have been made. The first one corresponds to peripheral (...)

Lire la suite

[in2p3-01275770] Analytical mass formula and nuclear surface properties in the ETF approximation. Part I: symmetric nuclei

18 février 2016

The problem of the determination of the nuclear surface and surface symmetry energy is addressed in the framework of the Extended Thomas Fermi (ETF) approximation using Skyrme functionals. We propose an analytical model for the density profiles with variationally determined diffuseness (...)

Lire la suite

[in2p3-01213940] Liquid-gas phase transition in strange hadronic matter with relativistic models

16 février 2016

Background: The advent of new dedicated experimental programs on hyperon physics is rapidly boosting the field, and the possibility of synthetizing multiple strange hypernuclei requires the addition of the strangeness degree of freedom to the models dedicated to nuclear structure and nuclear (...)

Lire la suite

[in2p3-01226400] Modification of magicity toward the dripline and its impact on electron-capture rates for stellar core collapse

16 février 2016

The importance of microphysical inputs from laboratory nuclear experiments and theoretical nuclear structure calculations in the understanding of the core collapse dynamics, and the subsequent supernova explosion, is largely recognized in the recent literature. In this work, we analyze the (...)

Lire la suite

[in2p3-01243596] Finite-size effects on the phase diagram of the thermodynamical cluster model

16 décembre 2015

The thermodynamical cluster model is known to present a first-order liquid-gas phase transition in the idealized case of an uncharged, infinitely extended medium. However, in most practical applications of this model, the system is finite and charged. In this paper we study how the phase (...)

Lire la suite

[in2p3-01244049] Hyperons in neutron star matter within relativistic mean-field models

16 décembre 2015

Since the discovery of neutron stars with masses around 2M ⊙ the composition of matter in the central part of these massive stars has been intensively discussed. Within this paper we will (re)investigate the question of the appearance of hyperons. To that end we will perform parameter study (...)

Lire la suite

[in2p3-01163153] Unified treatment of subsaturation stellar matter at zero and finite temperature

24 novembre 2015

The standard variational derivation of stellar matter structure in the Wigner-Seitz approximation is generalized to the finite temperature situation where a wide distribution of different nuclear species can coexist in the same density and proton fraction condition, possibly out of (...)

Lire la suite

[in2p3-01226404] Heat capacity of the neutron star inner crust within an extended nuclear statistical equilibrium model

24 novembre 2015

Background: Superfluidity in the crust is a key ingredient for the cooling properties of proto-neutron stars. Present theoretical calculations employ the quasiparticle mean-field Hartree-Fock-Bogoliubov theory with temperature-dependent occupation numbers for the quasiparticle states. Purpose: (...)

Lire la suite

[in2p3-01158954] Microscopic evaluation of the hypernuclear chart with $\Lambda$ hyperons

28 octobre 2015

We calculate the comprehensive hypernuclear chart for even-even 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 (...)

Lire la suite

[in2p3-01102611] Hyperons in neutron star matter within relativistic mean-field models

22 juillet 2015

Since the discovery of neutron stars with masses around 2 solar masses the composition of matter in the central part of these massive stars has been intensively discussed. Within this paper we will (re)investigate the question of the appearance of hyperons. To that end we will perform an (...)

Lire la suite

[hal-00345772] Bimodal behavior of the heaviest fragment distribution in projectile fragmentation

3 juillet 2015

The charge distribution of the heaviest fragment detected in the decay of quasi-projectiles produced in intermediate energy heavy-ion collisions has been observed to be bimodal. This feature is expected as a generic signal of phase transition in non-extensive systems. In this paper we present (...)

Lire la suite

[in2p3-00084674] Transition from participant to spectator fragmentation in Au+Au reactions between 60A and 150A MeV

3 juillet 2015

Using the quantum molecular dynamics approach, we analyze the results of the recent INDRA Au+Au experiments at GSI in the energy range between 60 AMeV and 150 AMeV. It turns out that in this energy region the transition toward a participant-spectator scenario takes place. The large Au+Au system (...)

Lire la suite

4h3>[in2p3-00118535] Comparisons of statistical multifragmentation and evaporation models for heavy-ion collisions

3 juillet 2015

The results from ten statistical multifragmentation models have been compared with each other using selected experimental observables. Even though details in any single observable may differ, the general trends among models are similar. Thus, these models and similar ones are very good in (...)

Lire la suite

[in2p3-00025576] Bimodality: a possible experimental signature of the liquid-gas phase transition of nuclear matter

3 juillet 2015

We have observed a bimodal behaviour of the distribution of the asymmetry between the charges of the two heaviest products resulting from the decay of the quasi-projectile released in binary Xe+Sn and Au+Au collisions from 60 to 100 MeV/u. Event sorting has been achieved through the transverse (...)

Lire la suite

[in2p3-00171092] Yield scaling, size hierarchy and fluctuations of observables in fragmentation of excited heavy nuclei

3 juillet 2015

Multifragmentation properties measured with INDRA are studied for single sources produced in Xe+Sn reactions in the incident energy range 32-50 A MeV and quasiprojectiles from Au+Au collisions at 80 A MeV. A comparison for both types of sources is presented concerning Fisher scaling, Zipf law, (...)

Lire la suite

[in2p3-01133570] Thermal properties of light nuclei from $^{12}$C+$^{12}$C fusion-evaporation reactions

2 juillet 2015

The $^12$C+$^12$C reaction at 95 MeV has been studied through the complete charge identification of its products by means of the GARFIELD+RCo experimental set-up at INFN Laboratori Nazionali di Legnaro (LNL). In this paper, the first of a series of two, a comparison to a dedicated (...)

Lire la suite

[hal-00119539] Isospin-dependent clusterization of Neutron-Star Matter

1er juillet 2015

Because of the presence of a liquid-gas phase transition in nuclear matter, compact-star matter can present a region of instability against the formation of clusters. We investigate this phase separation in a matter composed of neutrons, protons and electrons, within a Skyrme-Lyon mean-field (...)

Lire la suite

[hal-00080648] Isospin fractionation : equilibrium versus spinodal decomposition

1er juillet 2015

This paper focuses on the isospin properties of the asymmetric nuclear-matter liquid-gas phase transition analyzed in a mean-field approach, using Skyrme effective interactions. We compare two different mechanisms of phase separation for low-density matter: equilibrium and spinodal (...)

Lire la suite

[in2p3-00118547] Fluctuations of fragment observables

1er juillet 2015

This contribution presents a review of our present theoretical as well as experimental knowledge of different fluctuation observables relevant to nuclear multifragmentation. The possible connection between the presence of a fluctuation peak and the occurrence of a phase transition or a critical (...)

Lire la suite

[in2p3-00117123] Challenges in nuclear dynamics and thermodynamics

1er juillet 2015

The purpose and contents of this topical issue, Dynamics and Thermodynamics with Nuclear Degrees of Freedom, which grew out of a series of workshops in the years 2004 and 2005, are introduced. The central topics are the nuclear density functional, nuclear multi-fragmentation, and nuclear phase (...)

Lire la suite

[in2p3-00117125] The challenges of finite-system statistical mechanics

1er juillet 2015

In this paper, we review the main challenges associated with the statistical mechanics of finite systems, with a particular emphasis on the present understanding of phase transitions in the framework of information theory. We show that this is a very powerful formalism allowing to treat in a (...)

Lire la suite

[in2p3-00023474] Generalized Gibbs ensembles for time dependent processes

1er juillet 2015

An information theory description of finite systems explicitly evolving in time is presented for classical as well as quantum mechanics. We impose a variational principle on the Shannon entropy at a given time while the constraints are set at a former time. The resulting density matrix deviates (...)

Lire la suite

[in2p3-00125783] Looking for bimodal distributions in multi-fragmentation reactions

1er juillet 2015

The presence of a phase transition in a finite system can be deduced, together with its order, from the shape of the distribution of the order parameter. This issue has been extensively studied in multifragmentation experiments, with results that do not appear fully consistent. In this paper we (...)

Lire la suite

[in2p3-00025297] Tracking energy fluctuations from fragment partitions in the lattice gas model

1er juillet 2015

Partial energy fluctuations are known tools to reconstruct microcanonical heat capacities. For experimental applications, approximations have been developed to infer fluctuations at freeze-out from the observed fragment partitions. The accuracy of this procedure as well as the underlying (...)

Lire la suite

[in2p3-00025400] Phase coexistence in nuclei

1er juillet 2015

In this work the general theory of first order phase transitions in finite systems is discussed, with a special emphasis to the conceptual problems linked to a thermodynamic description for small, short-lived systems de-exciting in the vacuum as nuclear samples coming from heavy ion collisions. (...)

Lire la suite

[in2p3-00024440] Anomalous thermodynamics and phase transitions of neutron-star matter

1er juillet 2015

In this letter we show that the presence of the long-range Coulomb force in dense stellar matter implies that the total charge cannot be associated with a chemical potential, even if it is a conserved quantity. As a further consequence, the analytical properties of the partition sum are (...)

Lire la suite

[in2p3-00025179] Role of isospin in the nuclear liquid-gas phase transition

1er juillet 2015

We study the thermodynamics of asymmetric nuclear matter using a mean field approximation with a Skyrme effective interaction, in order to establish its phase diagram and more particularly the influence of isospin on the order of the transition. A new statistical method is introduced to study (...)

Lire la suite

[in2p3-00023736] Distribution of the largest fragment in the Lattice Gas Model

1er juillet 2015

The distribution of the largest fragment is studied in different regions of the Lattice Gas model phase diagram. We show that first and second order transitions can be clearly distinguished in the grancanonical ensemble, while signals typical of a continuous transition are seen inside the (...)

Lire la suite

[hal-00628137] Boundary conditions for star matter and other periodic fermionic systems

1er juillet 2015

Bulk fermionic matter, as it can be notably found in supernova matter and neutrons stars, is subject to correlations of infinite range due to the antisymmetrisation of the N-body wave function, which cannot be explicitly accounted for in a practical simulation. This problem is usually addressed (...)

Lire la suite

[in2p3-00098157] Ising analogue to compact-star matter

1er juillet 2015

By constructing an Ising analogue of compact-star matter at sub-saturation density we explored the effect of Coulomb frustration on the nuclear liquid-gas phase transition. Our conclusions is twofold. First, the range of temperatures where inhomogeneous phases form expands with increasing (...)

Lire la suite

[hal-00000847] Exact pairing correlations in one-dimensionally trapped fermions with stochastic mean-field wave-functions

1er juillet 2015

The canonical thermodynamic properties of a one-dimensional system of interacting spin-1/2 fermions with an attractive zero-range pseudo-potential are investigated within an exact approach. The density operator is evaluated as the statistical average of dyadics formed from a stochastic (...)

Lire la suite

[hal-00974520] Non-statistical decay and $\alpha$-correlations in the $^{12}$C+$^{12}$C fusion-evaporation reaction at 95 MeV

1er juillet 2015

Multiple alpha coincidence and correlations are studied in the reaction $^12$C+$^12$C at 95 MeV for fusion-evaporation events completely detected in charge. Two specific channels with Carbon and Oxygen residues in coincidence with $\alpha$-particles are addressed, which are associated with (...)

Lire la suite

[in2p3-00020106] Transient backbending behavior in the Ising model with fixed magnetization

1er juillet 2015

The physical origin of the backbendings in the equations of state of finite but not necessarily small systems is studied in the Ising model with fixed magnetization (IMFM) by means of the topological properties of the observable distributions and the analysis of the largest cluster with (...)

Lire la suite

[in2p3-00024070] Comment on "Negative heat capacities and first order phase transitions in nuclei

1er juillet 2015

In a recent paper Moretto et al. [ Phys. Rev. C 66, 041601 (2002) ] claim that the negative heat capacities presented in our previously published paper [ Chomaz, Duflot, and Gulminelli, Phys. Rev. Lett. 85, 3587 (2000) ] are "artifacts" coming from the use of periodic boundary (...)

Lire la suite

Thermal properties of light nuclei from $^{12}$C+$^{12}$C fusion-evaporation reactions

2 juillet 2014

The $^12$C+$^12$C reaction at 95 MeV has been studied through the complete charge identification of its products by means of the GARFIELD+RCo experimental set-up at INFN Laboratori Nazionali di Legnaro (LNL). In this paper, the first of a series of two, a comparison to a dedicated (...)

Lire la suite

Non-statistical decay and $\alpha$-correlations in the $^{12}$C+$^{12}$C fusion-evaporation reaction at 95 MeV

2 juillet 2014

Multiple alpha coincidence and correlations are studied in the reaction $^12$C+$^12$C at 95 MeV for fusion-evaporation events completely detected in charge. Two specific channels with Carbon and Oxygen residues in coincidence with $\alpha$-particles are addressed, which are associated with (...)

Lire la suite

Thermodynamics of baryonic matter with strangeness within non-relativistic energy density functional model

2 juillet 2014

The phase diagram of dense baryonic matter is investigated in the non-relativistic mean-field framework including the full baryonic octet. It is shown that, depending on the thermodynamic conditions, up to three strangeness-driven phase transitions may occur, such that a huge fraction of the (...)

Lire la suite

[in2p3-00978296] In-medium nuclear cluster energies within the Extended Thomas-Fermi approach

14 avril 2014

A recently introduced analytical model for the nuclear density profile[1] is implemented in the Extended Thomas-Fermi (ETF) energy density functional. This allows to (i) shed a new light on the issue of the sign of surface symmetry energy in nuclear mass formulas, which is strongly related to (...)

Lire la suite

Non-statistical decay and alpha-correlations in the 12C+12C fusion-evaporation reaction at 95 MeV

8 avril 2014

Multiple alpha coincidence and correlations are studied in the reaction 12C+12C at 95 MeV for fusion-evaporation events completely detected in charge. Two specific channels with Carbon and Oxygen residues in coincidence with alpha−particles are addressed, which are associated with anomalously (...)

Lire la suite

Thermal properties of light nuclei from 12C+12C fusion-evaporation reactions

7 avril 2014

The 12C+12C reaction at 95 MeV has been studied through the complete charge identification of its products by means of the GARFIELD+RCo experimental set-up at INFN Laboratori Nazionali di Legnaro (LNL). In this paper, the first of a series of two, a comparison to a dedicated Hauser-Feshbach (...)

Lire la suite

[in2p3-00857485] Clusterized nuclear matter in the (proto-)neutron star crust and the symmetry energy

3 septembre 2013

Though generally agreed that the symmetry energy plays a dramatic role in determining the structure of neutron stars and the evolution of core-collapsing supernovae, little is known in what concerns its value away from normal nuclear matter density and, even more important, the correct (...)

Lire la suite

Probing the statistical decay and alpha-clustering effects in 12c+12c and 14n+10b reactions

3 septembre 2013

An experimental campaign has been undertaken at INFN Laboratori Nazionali di Legnaro, Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation (...)

Lire la suite

[in2p3-00839915] Equivalence between fractional exclusion statistics and Fermi liquid theory in interacting particle systems

1er juillet 2013

We explore the connections between the description of interacting particles systems in terms of fractional exclusion statistics (FES) and other many-body methods used for the same purpose. We consider a system of particles with generic, particle-particle interaction in the quasi-classical limit (...)

Lire la suite

[in2p3-00825301] Transformation between statistical ensembles in the modelling of nuclear fragmentation

23 mai 2013

We explore the conditions under which the particle number conservation constraint deforms the predictions of fragmentation observables as calculated in the grand canonical ensemble. We derive an analytical formula allowing to extract canonical results from a grand canonical calculation and vice (...)

Lire la suite

[in2p3-00824193] Densities and energies of nuclei in dilute matter at zero temperature

21 mai 2013

We explore the ground-state properties of nuclear clusters embedded in a gas of nucleons with the help of Skyrme-Hartree-Fock microscopic calculations. Two alternative representations of clusters are introduced, namely coordinate-space and energy-space clusters. We parameterize their density (...)

Lire la suite

Thermal properties of nuclear systems : from neutron stars to finite nuclei

16 mai 2013

Thermal and phase properties of nuclear systems are briefly reviewed within an information theory approach. Such theory allows treating on the same ground extended systems at the thermodynamic limit, as nuclear matter in the inner crust of neutron stars, and finite size, short-lived systems, as (...)

Lire la suite

Phase diagram of neutron-rich nuclear matter and its impact on astrophysics

7 mai 2013

Dense matter as it can be found in core-collapse supernovae and neutron stars is expected to exhibit different phase transitions which impact the matter composition and equation of state, with important consequences on the dynamics of core-collapse supernova explosion and on the structure of (...)

Lire la suite

Some aspects of the phase diagram of nuclear matter relevant to compact stars

15 février 2013

Dense matter as it can be found in core-collapse supernovae and neutron stars is expected to exhibit different phase transitions which impact the matter composition and the equation of state, with important consequences on the dynamics of core-collapse supernova explosion and on the structure (...)

Lire la suite

Ensemble in-equivalence in supernova matter within a simple model

6 février 2013

A simple, exactly solvable statistical model is presented for the description of baryonic matter in the thermodynamic conditions associated to the evolution of core-collapsing supernova. It is shown that the model presents a first order phase transition in the grandcanonical ensemble which is (...)

Lire la suite

[in2p3-00785506] Phase transition towards strange matter

6 février 2013

The phase diagram of a system constituted of neutrons and $\Lambda$-hyperons in thermal equilibrium is evaluated in the mean-field approximation. It is shown that this simple system exhibits a complex phase diagram with first and second order phase transitions. Due to the generic presence of (...)

Lire la suite

[in2p3-00785502] alpha-clustering effects in dissipative 12C+12C reactions at 95 MeV

6 février 2013

Dissipative 12C+12C reactions at 95 MeV are fully detected in charge with the GARFIELD and RCo apparatuses at LNL. A comparison to a dedicated Hauser-Feshbach calculation allows to select events which correspond, to a large extent, to the statistical evaporation of highly excited 24Mg, as well (...)

Lire la suite

Neutron-rich nuclei and the equation of state of stellar matter

29 janvier 2013

In this contribution we will review our present understanding of the matter equation of state in the density and temperature conditions where it can be described by nucleonic degrees of freedom. At zero temperature, all the information is contained in the nuclear energy functional in its (...)

Lire la suite

[in2p3-00776595] Strangeness-driven phase transition in star matter

15 janvier 2013

The phase diagram of a system constituted of neutrons, protons, $\Lambda$-hyperons and electrons is evaluated in the mean-field approximation in the complete three-dimensional space given by the baryon, lepton and strange charge. It is shown that the phase diagram at sub-saturation densities is (...)

Lire la suite

Phase diagram of neutron-rich nuclear matter and its impact on astrophysics

7 décembre 2012

Dense matter as it can be found in core-collapse supernovae and neutron stars is expected to exhibit different phase transitions which impact the matter composition and equation of state, with important consequences on the dynamics of core-collapse supernova explosion and on the structure of (...)

Lire la suite

Phase diagram of neutron-rich nuclear matter and its impact on astrophysics

10 octobre 2012

Dense matter as it can be found in core-collapse supernovae and neutron stars is expected to exhibit different phase transitions which impact the matter composition and equation of state, with important consequences on the dynamics of core-collapse supernova explosion and on the structure of (...)

Lire la suite

Staggering in S+Ni collisions

11 septembre 2012

Odd-even effects in fragment production have been studied since a long time and never quantitatively understood. The odd-even anomaly was reported in the literature [1,2] to be more pronounced in reactions involving Ni projectile and targets, in particular in n-poor systems. In some experiments (...)

Lire la suite

Statistical (?) decay of light hot nuclei

11 septembre 2012

The reaction 12C+12C at 95 MeV beam energy has been measured using the GARFIELD+RCo apparatuses at Laboratori Nazionali di Legnaro LNL - INFN, Italy, in the framework of an experimental campaign proposed by the NUCL-EX collaboration. The aim is to progress in the understanding of statistical (...)

Lire la suite

Fragmentation and clustering in star matter

11 septembre 2012

The specificity of the crust-core phase transition in neutron star at zero and finite temperature will be discussed. It will be shown that, as a consequence of the presence of long range Coulomb interactions, the equivalence of statistical ensembles is violated and a clusterised phase is (...)

Lire la suite

An interpretation of staggering effects by correlation observables

11 septembre 2012

The reactions 32S+58,64Ni are studied at 14.5 A MeV. Evidence is found for odd-even effects in isotopic observables of the decay of a projectile-like source. The influence of secondary decays on the staggering is studied with a correlation function technique, showing that odd-even effects are (...)

Lire la suite

Phase transition toward strange matter

10 septembre 2012

The phase diagram of a system constituted of neutrons and Λ hyperons in thermal equilibrium is evaluated in the mean-field approximation. It is shown that this simple system exhibits a complex phase diagram with first- and second-order phase transitions. Due to the generic presence of attractive (...)

Lire la suite

Transition from participant to spectator fragmentation in Au+Au reactions between 60A and 150A MeV

2 juillet 2012

Using the quantum molecular dynamics approach, we analyzed the results of the recent INDRA Collaboration Au+Au experiments at GSI in the energy range between 60A and 150A MeV. It turns out that in this energy region, the transition toward a participant-spectator scenario takes place. The large (...)

Lire la suite

[in2p3-00691845] Towards an understanding of staggering effects in dissipative binary collisions

27 avril 2012

The reactions S32+58,64Ni are studied at 14.5 A MeV. Evidence is found for important odd-even effects in isotopic observables of selected peripheral collisions corresponding to the decay of a projectile-like source. The influence of secondary decays on the staggering is studied with a (...)

Lire la suite

Ensemble in-equivalence in supernova matter within a simple model

29 février 2012

A simple, exactly solvable statistical model is presented for the description of baryonic matter in the thermodynamic conditions associated to the evolution of core-collapsing supernova. It is shown that the model presents a first order phase transition in the grandcanonical ensemble which is (...)

Lire la suite

[in2p3-00674988] Ensemble inequivalence in supernova matter within a simple model

28 février 2012

A simple, exactly solvable statistical model is presented for the description of baryonic matter in the thermodynamic conditions associated to the evolution of core-collapsing supernova. It is shown that the model presents a first-order phase transition in the grand-canonical ensemble which is (...)

Lire la suite

Boundary conditions for star matter and other periodic fermionic systems

3 octobre 2011

Bulk fermionic matter, as it can be notably found in supernova matter and neutrons stars, is subject to correlations of infinite range due to the antisymmetrisation of the N-body wave function, which cannot be explicitly accounted for in a practical simulation. This problem is usually addressed (...)

Lire la suite

Boundary conditions for star matter and other periodic fermionic systems

3 octobre 2011

Bulk fermionic matter, as it can be notably found in supernova matter and neutrons stars, is subject to correlations of infinite range due to the antisymmetrisation of the N-body wave function, which cannot be explicitly accounted for in a practical simulation. This problem is usually addressed (...)

Lire la suite

Reaction mechanisms and staggering in S+Ni collisions

6 juillet 2011

The reactions 32S + 58Ni and 32S + 64Ni are studied at 14.5 A MeV. After a selection of the collision mechanism, we show that important even-odd effects are present in the isotopic fragment distributions when the excitation energy is small. Close to the multifragmentation threshold this (...)

Lire la suite

[in2p3-00606217] Reaction mechanisms and staggering in S+Ni collisions

6 juillet 2011

The reactions 32S + 58Ni and 32S + 64Ni are studied at 14.5 A MeV. After a selection of the collision mechanism, we show that important even-odd effects are present in the isotopic fragment distributions when the excitation energy is small. Close to the multifragmentation threshold this (...)

Lire la suite

Statistical description of complex nuclear phases in supernovae and proto-neutron stars

25 novembre 2010

We develop a phenomenological statistical model for dilute star matter at finite temperature, in which free nucleons are treated within a mean-field approximation and nuclei are considered to form a loosely interacting cluster gas. Its domain of applicability, that is baryonic densities ranging (...)

Lire la suite

[in2p3-00539882] Statistical description of complex nuclear phases in supernovae and proto-neutron stars

25 novembre 2010

We develop a phenomenological statistical model for dilute star matter at finite temperature, in which free nucleons are treated within a mean-field approximation and nuclei are considered to form a loosely interacting cluster gas. Its domain of applicability, that is baryonic densities ranging (...)

Lire la suite

Monopole oscillations in light nuclei with a molecular dynamics approach

30 août 2010

Collective monopole vibrations are studied in the framework of antisymmetrized version of molecular dynamics as a function of the vibration amplitude. The giant monopole resonance energy in $^40Ca$ is sensitive to the incompressibility of the effective interaction, in good agreement with (...)

Lire la suite

[in2p3-00512379] Monopole oscillations in light nuclei with a molecular dynamics approach

30 août 2010

Collective monopole vibrations are studied in the framework of antisymmetrized version of molecular dynamics as a function of the vibration amplitude. The giant monopole resonance energy in $^40Ca$ is sensitive to the incompressibility of the effective interaction, in good agreement with (...)

Lire la suite

Phase diagram of the charged lattice-gas model with two types of particles

17 juin 2010

A lattice-gas model with two types of particles, a particle-dependent short-range coupling and a long-range repulsive Coulombic interaction, is introduced. The phase diagram of an isolated finite system of 129 particles is constructed using the bimodality properties of the observables' (...)

Lire la suite

[in2p3-00492917] Phase diagram of the charged lattice-gas model with two types of particles

17 juin 2010

A lattice-gas model with two types of particles, a particle-dependent short-range coupling and a long-range repulsive Coulombic interaction, is introduced. The phase diagram of an isolated finite system of 129 particles is constructed using the bimodality properties of the observables' (...)

Lire la suite

Advancement in the understanding of multifragmentation and phase transition for hot nuclei

5 mars 2010

Recent advancement on the knowledge of multifragmentation and phase transition for hot nuclei is reported. It concerns i) the influence of radial collective energy on fragment partitions and the derivation of general properties of partitions in presence of such a collective energy, ii) a better (...)

Lire la suite

Advancement in the understanding of multifragmentation and phase transition for hot nuclei

5 mars 2010

Recent advancement on the knowledge of multifragmentation and phase transition for hot nuclei is reported. It concerns i) the influence of radial collective energy on fragment partitions and the derivation of general properties of partitions in presence of such a collective energy, ii) a better (...)

Lire la suite

Multifragmentation and phase transition for hot nuclei

5 mars 2010

Recent important progress on the knowledge of multifragmentation and phase transition for hot nuclei, thanks to the high detection quality of the INDRA array, is reported. It concerns i) the radial collective energies involved in hot fragmenting nuclei/sources produced in central and semi- (...)

Lire la suite

Multifragmentation and phase transition for hot nuclei

5 mars 2010

Recent important progress on the knowledge of multifragmentation and phase transition for hot nuclei, thanks to the high detection quality of the INDRA array, is reported. It concerns i) the radial collective energies involved in hot fragmenting nuclei/sources produced in central and semi- (...)

Lire la suite

THE PROMINENT ROLE OF THE HEAVIEST FRAGMENT IN MULTIFRAGMENTATION AND PHASE TRANSITION FOR HOT NUCLEI

5 mars 2010

The role played by the heaviest fragment in partitions of multifragmenting hot nuclei is emphasized. Its size/charge distribution (mean value, fluctuations and shape) gives information on properties of fragmenting nuclei and on the associated phase (...)

Lire la suite

The prominent role of the heaviest fragment in multifragmentation and phase transition for hot nuclei

5 mars 2010

The role played by the heaviest fragment in partitions of multifragmenting hot nuclei is emphasized. Its size/charge distribution (mean value, fluctuations and shape) gives information on properties of fragmenting nuclei and on the associated phase (...)

Lire la suite

Fermionic Molecular Dynamics for nuclear dynamics and thermodynamics

1er mars 2010

A new Fermionic Molecular Dynamics (FMD) model based on a Skyrme functional is proposed in this paper. After introducing the basic formalism, an application to nuclear thermodynamics is presented.

Lire la suite

Fermionic Molecular Dynamics for nuclear dynamics and thermodynamics

1er mars 2010

A new Fermionic Molecular Dynamics (FMD) model based on a Skyrme functional is proposed in this paper. After introducing the basic formalism, an application to nuclear thermodynamics is presented.

Lire la suite

Multifragmentation and phase transition for hot nuclei: recent progress

23 février 2010

Recent important progress on the knowledge of multifragmentation and phase transition for hot nuclei, thanks to the high detection quality of the INDRA array, is reported. It concerns i) the radial collective energies involved in hot fragmenting nuclei/sources produced in central and (...)

Lire la suite

Multifragmentation and phase transition for hot nuclei: recent progress

23 février 2010

Recent important progress on the knowledge of multifragmentation and phase transition for hot nuclei, thanks to the high detection quality of the INDRA array, is reported. It concerns i) the radial collective energies involved in hot fragmenting nuclei/sources produced in central and (...)

Lire la suite

Probing the nuclear equation of state in heavy-ion collisions at Fermi energy in isospin-sensitive exclusive experiments

8 février 2010

In order to guide the study of the form of the density dependence of the symmetry energy in the nuclear equation of state, robust observables are searched within the Stochastic Mean Field model coupled to a secondary decay treatment. We propose a few selected experimental approaches to show (...)

Lire la suite

[in2p3-00454242] Probing the nuclear equation of state in heavy-ion collisions at Fermi energy in isospin-sensitive exclusive experiments

8 février 2010

In order to guide the study of the form of the density dependence of the symmetry energy in the nuclear equation of state, robust observables are searched within the Stochastic Mean Field model coupled to a secondary decay treatment. We propose a few selected experimental approaches to show (...)

Lire la suite

From fission to multifragmentation and back

21 janvier 2010

Multifragmentation, defined as the decay of a highly excited nuclear source into more than two fragments, is generally considered in the nuclear physics community as a completely different phenomenon than nuclear fission, and tentatively interpreted as the finite system counterpart of the (...)

Lire la suite

From fission to multifragmentation and back

21 janvier 2010

Multifragmentation, defined as the decay of a highly excited nuclear source into more than two fragments, is generally considered in the nuclear physics community as a completely different phenomenon than nuclear fission, and tentatively interpreted as the finite system counterpart of the (...)

Lire la suite

Isospin dependent thermodynamics of fragmentation

27 novembre 2009

The thermal and phase properties of a multifragmentation model that uses clusters as degrees of freedom are explored as a function of isospin. Good qualitative agreement is found with the phase diagram of asymmetric nuclear matter as established by different mean-field models. In particular, (...)

Lire la suite

[in2p3-00142537] Isospin dependent thermodynamics of fragmentation

27 novembre 2009

The thermal and phase properties of a multifragmentation model that uses clusters as degrees of freedom are explored as a function of isospin. Good qualitative agreement is found with the phase diagram of asymmetric nuclear matter as established by different mean-field models. In particular, (...)

Lire la suite

Extended Gibbs ensembles with flow

27 novembre 2009

A recently proposed [Ph. Chomaz, F. Gulminelli, and O. Juillet, Ann. Phys. (Paris) 320, 135 (2005)] statistical treatment of finite unbound systems in the presence of collective motions is applied to a classical Lennard-Jones system, numerically simulated through molecular dynamics. In the (...)

Lire la suite

[in2p3-00337203] Extended Gibbs ensembles with flow

27 novembre 2009

A recently proposed [Ph. Chomaz, F. Gulminelli, and O. Juillet, Ann. Phys. (Paris) 320, 135 (2005)] statistical treatment of finite unbound systems in the presence of collective motions is applied to a classical Lennard-Jones system, numerically simulated through molecular dynamics. In the (...)

Lire la suite

Expansion dynamics of Lennard-Jones systems

27 novembre 2009

The dynamics of the expansion of a Lennard-Jones system, initially confined at high density and subsequently expanding freely in a vacuum, is compared with an expanding statistical ensemble derived in the diluted quasi-ideal Boltzmann approximation. The description proves to be fairly accurate (...)

Lire la suite

[in2p3-00337187] Expansion dynamics of Lennard-Jones systems

27 novembre 2009

The dynamics of the expansion of a Lennard-Jones system, initially confined at high density and subsequently expanding freely in a vacuum, is compared with an expanding statistical ensemble derived in the diluted quasi-ideal Boltzmann approximation. The description proves to be fairly accurate (...)

Lire la suite

Bimodality and Coulomb effects with a canonical thermodynamic model

27 novembre 2009

The effect of the Coulomb interaction on the phase diagram of finite nuclei is studied within the Canonical Thermodynamic Model. If Coulomb effects are artificially switched off, this model shows a phenomenology consistent with the liquid–gas phase transition. The inclusion of Coulomb does not (...)

Lire la suite

[in2p3-00350387] Bimodality and Coulomb effects with a canonical thermodynamic model

27 novembre 2009

The effect of the Coulomb interaction on the phase diagram of finite nuclei is studied within the Canonical Thermodynamic Model. If Coulomb effects are artificially switched off, this model shows a phenomenology consistent with the liquid–gas phase transition. The inclusion of Coulomb does not (...)

Lire la suite

Isoscaling as a Measure of Symmetry Energy in the Lattice Gas Model

27 novembre 2009

The energetic properties of nuclear clusters inside a low-density, finite-temperature medium are studied with a lattice gas model including isospin dependence and Coulomb forces. Important deviations are observed with respect to the Fisher approximation of an ideal gas of noninteracting (...)

Lire la suite

[in2p3-00378550] Isoscaling as a Measure of Symmetry Energy in the Lattice Gas Model

27 novembre 2009

The energetic properties of nuclear clusters inside a low-density, finite-temperature medium are studied with a lattice gas model including isospin dependence and Coulomb forces. Important deviations are observed with respect to the Fisher approximation of an ideal gas of noninteracting (...)

Lire la suite

Thermodynamics of clusterized matter

27 novembre 2009

Thermodynamics of clusterized matter is studied in the framework of statistical models with noninteracting cluster degrees of freedom. At variance with the analytical Fisher model, exact Metropolis simulation results indicate that the transition from homogeneous to clusterized matter lies along (...)

Lire la suite

[in2p3-00410921] Thermodynamics of clusterized matter

27 novembre 2009

Thermodynamics of clusterized matter is studied in the framework of statistical models with noninteracting cluster degrees of freedom. At variance with the analytical Fisher model, exact Metropolis simulation results indicate that the transition from homogeneous to clusterized matter lies along (...)

Lire la suite

Symmetry energy from fragment observables in the canonical thermodynamic model

27 novembre 2009

Different formulas relating measurable fragment isotopic observables to the symmetry energy of excited nuclei were proposed and applied to the analysis of heavy ion collision data in the recent literature. In this article, we examine the quality of the different expressions in the framework of (...)

Lire la suite

[in2p3-00435479] Symmetry energy from fragment observables in the canonical thermodynamic model

27 novembre 2009

Different formulas relating measurable fragment isotopic observables to the symmetry energy of excited nuclei were proposed and applied to the analysis of heavy ion collision data in the recent literature. In this article, we examine the quality of the different expressions in the framework of (...)

Lire la suite

Bimodal behavior of the heaviest fragment distribution in projectile fragmentation

9 juillet 2009

The charge distribution of the heaviest fragment detected in the decay of quasi-projectiles produced in intermediate energy heavy-ion collisions has been observed to be bimodal. This feature is expected as a generic signal of phase transition in non-extensive systems. In this paper we present (...)

Lire la suite

Bimodal behavior of the heaviest fragment distribution in projectile fragmentation

9 juillet 2009

The charge distribution of the heaviest fragment detected in the decay of quasi-projectiles produced in intermediate energy heavy-ion collisions has been observed to be bimodal. This feature is expected as a generic signal of phase transition in non-extensive systems. In this paper we present (...)

Lire la suite

Fermionic Molecular Dynamics for nuclear dynamics and thermodynamics

6 décembre 2008

A new Fermionic Molecular Dynamics (FMD) model based on a Skyrme functional is proposed in this paper. After introducing the basic formalism, some first applications to nuclear structure and nuclear thermodynamics are presented

Lire la suite

Fermionic Molecular Dynamics for nuclear dynamics and thermodynamics

6 décembre 2008

A new Fermionic Molecular Dynamics (FMD) model based on a Skyrme functional is proposed in this paper. After introducing the basic formalism, some first applications to nuclear structure and nuclear thermodynamics are presented

Lire la suite

Signals of bimodality in the fragmentation of Au quasi-projectiles

10 novembre 2008

Signals of bimodality have been investigated in experimental data of quasi-projectile decay produced in Au+Au collisions at 35 AMeV. This same data set was already shown to provide several signals characteristic of a first order, liquid-gas-like phase transition. Different event sortings (...)

Lire la suite

[in2p3-00337913] Signals of bimodality in the fragmentation of Au quasi-projectiles

10 novembre 2008

Signals of bimodality have been investigated in experimental data of quasi-projectile decay produced in Au+Au collisions at 35 AMeV. This same data set was already shown to provide several signals characteristic of a first order, liquid-gas-like phase transition. Different event sortings (...)

Lire la suite

Critical Behavior in the Coexistence Region of Finite Systems

19 août 2008

The liquid-gas phase transition in finite systems is studied within a lattice gas model in the canonical ensemble. In the coexistence region, the existence of conservation laws is shown to result in anomalies in the associated equation of state leading, for example, to negative compressibility (...)

Lire la suite

Critical Behavior in the Coexistence Region of Finite Systems

19 août 2008

The liquid-gas phase transition in finite systems is studied within a lattice gas model in the canonical ensemble. In the coexistence region, the existence of conservation laws is shown to result in anomalies in the associated equation of state leading, for example, to negative compressibility (...)

Lire la suite

Caloric Curves and Energy Fluctuations in the Microcanonical Liquid-Gas Phase Transition

19 août 2008

In this paper we study a microcanonical lattice gas model with a constrained average volume. We show that the caloric curve explicitly depends on the considered transformation of the volume with the excitation energy and so does not bear direct information on the characteristics of the phase (...)

Lire la suite

Caloric Curves and Energy Fluctuations in the Microcanonical Liquid-Gas Phase Transition

19 août 2008

In this paper we study a microcanonical lattice gas model with a constrained average volume. We show that the caloric curve explicitly depends on the considered transformation of the volume with the excitation energy and so does not bear direct information on the characteristics of the phase (...)

Lire la suite

Phase Transitions in Finite Systems using Information Theory

6 décembre 2007

(abridged) In this paper, we present the issues we consider as essential as far as the statistical mechanics of finite systems is concerned. In particular, we emphasis our present understanding of phase transitions in the framework of information theory. Information theory provides a (...)

Lire la suite

Phase Transitions in Finite Systems using Information Theory

6 décembre 2007

(abridged) In this paper, we present the issues we consider as essential as far as the statistical mechanics of finite systems is concerned. In particular, we emphasis our present understanding of phase transitions in the framework of information theory. Information theory provides a (...)

Lire la suite

Yield scaling, size hierarchy and fluctuations of observables in fragmentation of excited heavy nuclei

13 septembre 2007

Multifragmentation properties measured with INDRA are studied for single sources produced in Xe+Sn reactions in the incident energy range 32-50 A MeV and quasiprojectiles from Au+Au collisions at 80 A MeV. A comparison for both types of sources is presented concerning Fisher scaling, Zipf law, (...)

Lire la suite

Yield scaling, size hierarchy and fluctuations of observables in fragmentation of excited heavy nuclei

13 septembre 2007

Multifragmentation properties measured with INDRA are studied for single sources produced in Xe+Sn reactions in the incident energy range 32-50 A MeV and quasiprojectiles from Au+Au collisions at 80 A MeV. A comparison for both types of sources is presented concerning Fisher scaling, Zipf law, (...)

Lire la suite

Instability against cluster formation in nuclear and compact-star matter

10 juillet 2007

Nuclear matter is known to present a phase transition of the liquid-gas type : this implies that homogeneous matter at sub-saturation density can be unstable against finite-size density fluctuations, leading to the formation of clusters. This is also true for asymmetric matter, concerning a (...)

Lire la suite

Instability against cluster formation in nuclear and compact-star matter

10 juillet 2007

Nuclear matter is known to present a phase transition of the liquid-gas type : this implies that homogeneous matter at sub-saturation density can be unstable against finite-size density fluctuations, leading to the formation of clusters. This is also true for asymmetric matter, concerning a (...)

Lire la suite

Anomalous thermodynamics and phase transitions of neutron-star matter

20 juin 2007

In this letter we show that the presence of the long-range Coulomb force in dense stellar matter implies that the total charge cannot be associated with a chemical potential, even if it is a conserved quantity. As a further consequence, the analytical properties of the partition sum are (...)

Lire la suite

Anomalous thermodynamics and phase transitions of neutron-star matter

20 juin 2007

In this letter we show that the presence of the long-range Coulomb force in dense stellar matter implies that the total charge cannot be associated with a chemical potential, even if it is a conserved quantity. As a further consequence, the analytical properties of the partition sum are (...)

Lire la suite

Instability against cluster formation in nuclear and compact-star matter

12 juin 2007

Nuclear matter is known to present a phase transition of the liquid-gas type : this implies that homogeneous matter at sub-saturation density can be unstable against finite-size density fluctuations, leading to the formation of clusters. This is also true for asymmetric matter, concerning a (...)

Lire la suite

Instability against cluster formation in nuclear and compact-star matter

12 juin 2007

Nuclear matter is known to present a phase transition of the liquid-gas type : this implies that homogeneous matter at sub-saturation density can be unstable against finite-size density fluctuations, leading to the formation of clusters. This is also true for asymmetric matter, concerning a (...)

Lire la suite

Thermodynamics of compact-star matter within an ising approach

12 juin 2007

In the formation and evolution of compact stars, nuclear matter explores high thermal excursions and is the site of intense neutrino emission. Neutrino transport as well as structural properties of this matter depend on the presence of inhomogeneous \u201cpasta\u201d phases, which are the (...)

Lire la suite

Thermodynamics of compact-star matter within an ising approach

12 juin 2007

In the formation and evolution of compact stars, nuclear matter explores high thermal excursions and is the site of intense neutrino emission. Neutrino transport as well as structural properties of this matter depend on the presence of inhomogeneous \u201cpasta\u201d phases, which are the (...)

Lire la suite

Transition liquide-gaz nucléaire : multifragmentation et matière d'étoile

12 juin 2007

Déterminer l'équation d'état de la matière nucléaire est l'un des enjeux majeurs des études de collisions d'ions lourds, notamment en raison de ses implications pour les propriétés des étoiles compactes. La matière nucléaire est un modèle de matière infinie et homogène, formée de nucléons liés par (...)

Lire la suite

Transition liquide-gaz nucléaire : multifragmentation et matière d'étoile

12 juin 2007

Déterminer l'équation d'état de la matière nucléaire est l'un des enjeux majeurs des études de collisions d'ions lourds, notamment en raison de ses implications pour les propriétés des étoiles compactes. La matière nucléaire est un modèle de matière infinie et homogène, formée de nucléons liés par (...)

Lire la suite

Multifragmentation and the symmetry term of the nuclear equation of state

10 mai 2007

We investigate the possibility of extracting the symmetry energy from multifragmentation data. The applicability of the grandcanonical formula earlier proposed by Ono et al. [Phys. Rev. C 68, 051601(R) (2003)] in the case of finite excited nuclei is tested within a microcanonical framework. (...)

Lire la suite

[in2p3-00141867] Multifragmentation and the symmetry term of the nuclear equation of state

10 mai 2007

We investigate the possibility of extracting the symmetry energy from multifragmentation data. The applicability of the grandcanonical formula earlier proposed by Ono et al. [Phys. Rev. C 68, 051601(R) (2003)] in the case of finite excited nuclei is tested within a microcanonical framework. (...)

Lire la suite

Isospin-dependent clusterization of Neutron-Star Matter

19 avril 2007

Because of the presence of a liquid-gas phase transition in nuclear matter, compact-star matter can present a region of instability against the formation of clusters. We investigate this phase separation in a matter composed of neutrons, protons and electrons, within a Skyrme-Lyon mean-field (...)

Lire la suite

What Can Be Learned Studying The Distribution Of The Biggest Fragment ?

11 avril 2007

In the canonical formalism of statistical physics, a signature of a first order phase transition for finite systems is the bimodal distribution of an order parameter. Previous thermodynamical studies of nuclear sources produced in heavy-ion collisions provide information which support the (...)

Lire la suite

Looking for bimodal distributions in multi-fragmentation reactions

22 janvier 2007

The presence of a phase transition in a finite system can be deduced, together with its order, from the shape of the distribution of the order parameter. This issue has been extensively studied in multifragmentation experiments, with results that do not appear fully consistent. In this paper we (...)

Lire la suite

Isospin fractionation : equilibrium versus spinodal decomposition

21 décembre 2006

This paper focuses on the isospin properties of the asymmetric nuclear-matter liquid-gas phase transition analyzed in a mean-field approach, using Skyrme effective interactions. We compare two different mechanisms of phase separation for low-density matter: equilibrium and spinodal (...)

Lire la suite