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The Equation of State with EPOS model
No full textInternational audienceTransitions between different states of matter and their thermodynamical properties are described by the Equation of State (EoS). A universal representation of the equation of state of QCD for the whole phase diagram has not yet been determined. Expectation of the systems to undergo various types of transitions depending on the temperature, the chemical potential and other theromodymnamical features makes that puzzle even more challenging to solve. Furthermore, it is not apparent which experimentally measurable observables could provide the useful information for the determination of EoS. The application of different EoS for hydrodynamical evolution was introduced in the EPOS generator, what allowed to study the effect of its changing on the final observables. The family of EoS proposed by the BEST Collaboration was implemented. The Critical Point position and the strength of criticality variations were investigated with particle yield, transverse momentum spectra, flow, and moments of the net-proton distributions
Monopole harmonics on
No full textInternational audienceWe find the spectra and eigenfunctions of both ordinary and supersymmetric quantum-mechanical models describing the motion of a charged particle over the manifold in the presence of a background monopole-like gauge field. The states form degenerate multiplets and their wave functions acquire a very simple form being expressed via homogeneous coordinates. Their relationship to multidimensional orthogonal polynomials of a special kind is discussed. By the well-known isomorphism between the twisted Dolbeault and Dirac complexes, our construction also gives the eigenfunctions and eigenvalues of the Dirac operator on complex projective spaces in a monopole background
Baryon and meson masses in the Nambu–Jona-Lasinio model: a Bayesian approach
No full textInternational audienceWe investigate the capabilities of the Nambu--Jona-Lasinio model to describe and reproduce fundamental vacuum properties of Quantum Chromodynamics, notably the hadronic spectrum. Mesons are described as quark-antiquark bound states at the level of the random phase approximation of the Bethe-Salpeter equation, while baryons are characterized as quark-diquark bound states within the static approximation of the Fadeev equation. Within a Bayesian framework, we constrain the model by phenomenologically known quantities and study the implications on its parameters and predictions in vacuum, as well as the correlations between the two. We find that within our framework, the vacuum masses of mesons and baryons can be reasonably well reproduced. Scalar diquarks need to be significantly bound in order to correctly reproduce the masses of the baryon octet, therefore enforcing values of the scalar diquark coupling larger than what is suggested by the canonical Fierz values. These findings could have important implications on the phenomenology of strongly-interacting matter at high temperature and density as well as of compact star physics
Experimental study of isospin transport with Ca+ Ca reactions at 35 MeV/nucleon
No full textInternational audienceWe investigate the isospin transport with 40,48 Ca+ 40,48 Ca reactions at 35 MeV/nucleon, measured with the coupling of the VAMOS high acceptance spectrometer and the INDRA charged particle multidetector. Using the quasi-projectile remnant measured with VAMOS and carefully selected light-charged-particles measured in coincidence with INDRA, a reconstruction method is applied to estimate the excited quasi-projectile (QP) on an event-by-event basis. The isospin diffusion is investigated using the isospin transport ratio with the asymmetry δ = (N − Z)/A of the projectile as an isospin-sensitive observable and the total transverse energy of Z ≤ 2 nuclei for experimental centrality sorting. The experimental isospin transport ratios present, for both the reconstructed QP and its remnant, a clear evolution towards isospin equilibration with increasing dissipation of the collision while the full equilibration is not reached. A smoother evolution with less discrepancies between the two mixed systems in the case of the reconstructed QP is also observed. The isospin migration is investigated using the neutron-to-proton ratio of the light-charged-clusters and the velocity of the QP remnant as a sorting parameter. More particularly, we focused on an angular region centered around the mid-rapidity of the reaction so as to characterize the low-density neck emissions. A systematic neutron-enrichment is observed and interpreted as a consequence of isospin migration, more particularly for the symmetric systems which present no isospin gradient between the projectile and the target. We also noticed that the ^{2}H and ^{4}He particles exhibit very close multiplicities independently of the sorting variable for the symmetric systems
Integrating the Rivet analysis tool into EPOS 4
No full textInternational audienceEPOS 4 is the last version of the high-energy collision event generator EPOS, released publicly in 2022. It was delivered with improvements on several aspects, whether about the theoretical bases on which it relies, how they are handled technically, or regarding user’s interface and data compatibility.This last point is especially important, as part of a commitment to provide the widest possible use. In this regard, a new output data format have been implemented, based on the HepMC standard libraries. This feature enables in particular the analysis of EPOS simulations with Rivet , an analysis and validation toolkit for Monte Carlo event generators, with recent major upgrades on concerning heavy-ion analysis methods. In order to take advantage of this, the use of Rivet has been implemented directly in the EPOS analysis machinery, ensuring an easy and fast solution for comparison with experimental data, beneficial for both developers and users. We will hence present here the details of this implementation and the results obtained thanks to it
Is 70Zn(d,x)67Cu the best way to produce 67Cu for medical applications?
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Design and optimization of a Chloride Molten Salt Fast Reactor
No full textInternational audienceThis paper presents several studies for the design and optimization of a 3GWth breeder Molten Salt Fast Reactor using chloride salts and the uranium cycle (Cl-MSFR). Results lead to a configuration of 45m3 of NaCl-depUCl3-(spent UOX fuel TRUs)Cl3 for the fuel salt, along with a fertile blanket of 80cm of width filled with NaCl-depUCl3 in which a small amount of spent MOX fuel TRUs is dissolved for spent MOX reuse and proliferation resistance. A reprocessing scheme dedicated to the cleaning of these chloride salts is proposed. Finally, preliminary studies on Cl-MSFR deployment don't show any constraints on matter availability and present a good synergy with PWRs
High Resolution Modelling without Computation Slowdown for PETALE in CROCUS
No full textInternational audienceThe PETALE experimental program was successfully carried out in the CROCUS reactor of EPFL in the fall of 2020, in a collaboration between EPFL and CEA. It consists of criticality and transmission experiments with four distinct metallic reflectors made of 304L stainless steel, iron, nickel, and chromium, to study the nuclear data of stainless steel. In addition to the experimental results, one of its outcomes is the production of C/E and their covariance matrices for the reaction rates of the dosimeters used in the transmission experiments, with the aim of allowing to constrain future nuclear data evaluations. For this purpose, the chosen methodology for uncertainty propagation is the computationally expensive Total Monte-Carlo method. A modified build of the Serpent2 Monte Carlo transport code is used to perform Variance Reduction and correlated sampling. In addition, high resolution modelling of the experiments is used to limit the presence of bias in the analysis, and to pave the way toward the submission of a high-quality benchmark to an NEA database. This paper presents advances in the modelling of the experiments, focusing on the metal reflectors, as installed at the periphery of CROCUS. It was possible to refine from a simple design model made of a few cuboids, to a fully detailed model, while keeping the loss in computational efficiency below 15%. Notably, all reflector sheets of PETALE were detailed into 121 voxels each, based on topological measurements, without impact on the calculation time, thanks to the use of Serpent2 3D lattices
Development of a high pressure single-anode radial TPC for the search of 2β0ν decays
No full textInternational audienceThe objective of R&D R2D2 is to develop a very simple TPC filled with pressurized xenon for the search of neutrinoless double beta decays (2β0ν). We tested several chamber concepts (spherical (SPC) or cylindrical (CPC) geometries) with an argon-methane gas mixture at pressures up to 8 bars. We report the results obtained in ionization and proportional modes, especially in terms of signal shape and energy resolution. Furthermore, based on both an in-house simulation for the signal formation and our experimental observations, we have studied the possibilities of localization and discrimination of the interaction tracks within these detectors. Future developments will also be presented
Tool developments in the OpenMC code: Correlated Sampling and Transient Fission Matrix approach using OpenFOAM CFD mesh
No full textInternational audienceThis article presents the developments performed to enlarge the application of the OpenMC neutron transport code for thermohydraulics coupling and nuclear data uncertainty propagation. These developments rely firstly on the addition of the Correlated Sampling (CS) technique, which allows to propagate the impact of thermal feedback or cross section sampling on the neutronic calculations thanks to neutron weight modifications. The Correlated Sampling technique is associated here to Computer Aided Design (CAD) based mesh and to the Transient Fission Matrix (TFM) approach. These three elements are used together to allow a global handling of the neutronics-thermohydraulics coupling: the TFM approach deals with the neutron kinetics using a pre-calculation of the neutron transport stored in matrices, the Correlated Sampling technique provides the impact of the thermal feedbacks on the matrices, and the CAD mesh is used to define the volumes associated to each bin of the matrices in order to get the results on the same format as the Computational Fluid Dynamics (CFD) code to be coupled to neutronics, here the OpenFOAM code. Both the implementations and the verifications done are detailed in the article, together with a discussion on the current limitations