Equilibrium constants of hydrogen and helium isotopes at low nuclear densities

Bougault, R.; Bonnet, É.; Borderie, B.; Chbihi, A.; Frankland, J.D.; Galichet, E.; Gruyer, D.; Henri, M.; Commara, M. La; Neindre, N. Le; Lombardo, I.; Lopez, O.; Manduci, L.; Pârlog, M.; Roy, R.; Verde, G.; Vigilante, M.

doi:10.1088/1361-6471/ab56ba

Cited by 20 publications

(65 citation statements)

References 28 publications

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“…This suggests that the momentum distribution of the cluster f * C (p) in the nuclear medium differs from those in vacuum f C (p). Similar conclusions have been drawn in [40] where the question of the binding energies of the clusters is raised.…”

Section: B In-medium Ac = 3 Clusters Characteristicssupporting

confidence: 78%

In-medium effects in central heavy ion collisions at intermediate energies

Henri¹,

Lopez²,

Durand³

et al. 2020

Phys. Rev. C

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Energy dissipation and cluster production in central nuclear collisions in the Fermi energy range have been investigated using the large INDRA database. A study of the in-medium nucleon-nucleon cross section, σ * N N , has been performed by comparing the results of a model with the measured isotropy ratio of the kinetic energy distributions of the detected protons. This analysis has been done for a large variety of systems at various incident energies from 20 to 100 MeV/nucleon and confirms nicely previous results with enhanced statistics in a full Monte Carlo treatment. Most importantly, it is found that σ * N N is drastically reduced as compared to the vacuum values, due partly to Pauli blocking but also to in-medium effects for which mean values and uncertainties are given. Concerning the cluster production, a coalescence model has been developed to study the parallel and perpendicular velocity distributions of the light clusters (A ≤ 4). For the AC = 3 (3 H, 3 He), it is found that the mean internal kinetic energy of the nucleons in the cluster is reduced as compared to the vacuum value. These two results shows that any comparison between experimental and theoretical predictions in heavy-ions induced reactions around and above Fermi energy must take into account these in-medium effects.

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Section: B In-medium Ac = 3 Clusters Characteristicssupporting

confidence: 78%

In-medium effects in central heavy ion collisions at intermediate energies

Henri¹,

Lopez²,

Durand³

et al. 2020

Phys. Rev. C

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“…So far we had only one constraint from experimental data [13]. Recently, the same analysis was applied by the INDRA collaboration on different sets of data [14]. These data confirm the low density values as obtained in Ref.…”

Section: Introductionsupporting

confidence: 81%

“…[13], because the measured temperatures are not the same. However, it was pointed out in [14] that in the analysis of Ref. [13] an ideal gas partition sum is supposed in order to extract the system density, which is not consistent with the fact that the experimental chemical constants are not reproduced by the ideal gas hypothesis.…”

Section: Introductionmentioning

confidence: 99%

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Improved method for the experimental determination of in-medium effects from heavy-ion collisions

Pais,

Bougault,

Gulminelli

et al. 2020

Preprint

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The equation of state with light clusters for nuclear and stellar matter is determined using chemical equilibrium constants evaluated from the analysis of the recently published (Xe+Sn) heavy ion data, corresponding to three reactions with different isotopic contents of the emission source. The measured multiplicities are used to extract the thermodynamic properties, and an in-medium correction to the ideal gas internal partition function of the clusters is included in the analysis. This in-medium correction and its respective uncertainty are calculated via a Bayesian analysis, with the unique hypothesis that the different nuclear species in a given sample must correspond to a unique common value for the density of the expanding source. Different parameter sets for the correction are tested, and the effect of the radius of the clusters on the thermodynamics and on the chemical equilibrium constants is also addressed. It is shown that the equilibrium constants obtained are almost independent of the isospin content of the analysed systems. Finally, a comparison with a relativistic mean field model proves that data are consistent with a universal in-medium correction of the scalar σ-meson coupling for nucleons bound in clusters. The obtained value, g s /g 0 s = 0.92 ± 0.02, is larger than that obtained in a previous study not including in-medium effects in the data analysis. This result implies a smaller effect on the binding energy of the clusters and, as a consequence, larger melting densities, and an increased cluster contribution in supernova matter.

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“…where n AZ , n g,p and n g,n are the densities of the specific cluster of mass A and charge Z, free protons and free neutrons respectively. The thermodynamic variables (T, n B , y p ) are extracted from the experimentally measured multiplicities for different surface velocity bins in 124 Xe on 124 Sn central collision reactions at 32 AMeV performed by INDRA collaboration [12,21], and used as input for the NSE model calculation. The baryonic density dependence of chemical equilibrium constant for 2 H, 3 H, 3 He, 4 He and 6 He is initially investigated from the NSE model without in-medium correction, that is ∆E = 0 in Eq.…”

Section: Resultsmentioning

confidence: 99%

Binding energy shifts from heavy-ion experiments in a nuclear statistical equilibrium model

Mallik¹,

Pais²,

Gulminelli³

2021

Preprint

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Chemical constants extracted from 124 Xe+ 124 Sn collisions at 32 AMeV are compared to the predictions of an extended Nuclear Statistical Equilibrium model including mean-field interactions and in-medium binding energy shifts for the light (Z ≤ 2) clusters. The ion species and density dependence of the in-medium modification is directly extracted from the experimental data. We show that the shift increases with the mass of the cluster and the density of the medium, and we provide a simple linear fit for future use in astrophysical simulations in the framework of the CompOSE data base. The resulting mass fractions are computed in representative thermodynamic conditions relevant for supernova and neutron star mergers. A comparison to the results of a similar analysis of the same data performed in the framework of a relativistic mean-field model shows a good agreement at low density, but significant discrepancies close to the Mott dissolution of clusters in the dense medium.

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Equilibrium constants of hydrogen and helium isotopes at low nuclear densities

Cited by 20 publications

References 28 publications

In-medium effects in central heavy ion collisions at intermediate energies

In-medium effects in central heavy ion collisions at intermediate energies

Improved method for the experimental determination of in-medium effects from heavy-ion collisions

Binding energy shifts from heavy-ion experiments in a nuclear statistical equilibrium model

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