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Cluster and hypercluster production in relativistic heavy-ion collisions within the parton-hadron-quantum-molecular-dynamics approach
No full textInternational audienceWe study cluster and hypernuclei production in heavy-ion collisions at relativistic energies employing the parton-hadron-quantum-molecular-dynamics (PHQMD) approach, a microscopic n-body transport model based on the QMD propagation of the baryonic degrees of freedom with density dependent two-body potential interactions. All other ingredients of PHQMD, including the collision integral and the treatment of the quark-gluon plasma (QGP) phase, are adopted from the parton-hadron-string-dynamics (PHSD) approach. In PHQMD the cluster formation occurs dynamically, caused by the interactions. The clusters are recognized by the Minimum Spanning Tree (MST) algorithm. We present the PHQMD results for cluster and hypernuclei formation in comparison with the available experimental data at energies available at the Alternating Gradient Synchrotron, the Super Proton Synchrotron, and the Beam Energy Scan and fixed-target programs at the BNL Relativistic Heavy Ion Collider. We also provide predictions on cluster production for the upcoming experiments at the GSI Facility for Antiproton and Ion Research (FAIR) and the Nuclotron-based Ion Collider Facility (NICA). PHQMD allows one to study the time evolution of formed clusters and the origin of their production, which helps to understand how such weakly bound objects are formed and survive in the rather dense and hot environment created in heavy-ion collisions. It offers therefore an explanation of the “ice in the fire” puzzle
Subleading power corrections to heavy quarkonium production in QCD factorization approach
No full textInternational audienceWe report the current understanding of heavy quarkonium production at high transverse momentum () in hadronic collisions in terms of QCD factorization. In this presentation, we highlight the role of subleading power corrections to heavy quarkonium production, which are essential to describe the spectrum of quarkonium at a relatively lower . We also introduce prescription to match QCD factorization to fixed-order NRQCD factorization calculations for quarkonium production at low
Optimization of the JUNO liquid scintillator composition using a Daya Bay antineutrino detector
No full textInternational audienceTo maximize the light yield of the liquid scintillator (LS) for the Jiangmen Underground Neutrino Observatory (JUNO), a 20 t LS sample was produced in a pilot plant at Daya Bay. The optical properties of the new LS in various compositions were studied by replacing the gadolinium-loaded LS in one antineutrino detector. The concentrations of the fluor, PPO, and the wavelength shifter, bis-MSB, were increased in 12 steps from 0.5 g/L and <0.01 mg/L to 4 g/L and 13 mg/L, respectively. The numbers of total detected photoelectrons suggest that, with the optically purified solvent, the bis-MSB concentration does not need to be more than 4 mg/L. To bridge the one order of magnitude in the detector size difference between Daya Bay and JUNO, the Daya Bay data were used to tune the parameters of a newly developed optical model. Then, the model and tuned parameters were used in the JUNO simulation. This enabled to determine the optimal composition for the JUNO LS: purified solvent LAB with 2.5 g/L PPO, and 1 to 4 mg/L bis-MSB
ϒ production and nuclear modification at forward rapidity in Pb–Pb collisions at sNN=5.02TeV
No full textInternational audienceThe production of ϒ mesons in Pb–Pb collisions at a centre-of-mass energy per nucleon pair sNN=5.02 TeV is measured with the muon spectrometer of the ALICE detector at the LHC. The yields as well as the nuclear modification factors are determined in the forward rapidity region 2.5<y<4.0, as a function of rapidity, transverse momentum and collision centrality. The results show that the production of the ϒ(1S) meson is suppressed by a factor of about three with respect to the production in proton–proton collisions. For the first time, a significant signal for the ϒ(2S) meson is observed at forward rapidity, indicating a suppression stronger by about a factor 2–3 with respect to the ground state. The measurements are compared with transport, hydrodynamic, comover and statistical hadronisation model calculations
Calibration Strategy of the JUNO Experiment
No full textInternational audienceWe present the calibration strategy for the 20 kton liquid scintillator central detector of the Jiangmen Underground Neutrino Observatory (JUNO). By utilizing a comprehensive multiple-source and multiple-positional calibration program, in combination with a novel dual calorimetry technique exploiting two independent photosensors and readout systems, we demonstrate that the JUNO central detector can achieve a better than 1% energy linearity and a 3% effective energy resolution, required by the neutrino mass ordering determination.[graphic not available: see fulltext
Evaluation de glyco-saccharides dans une approche théranostique
No full textOsteosarcoma is the most common primary malignant bone tumor in children and young adults. It is a very aggressive type of cancer with a low prognosis; but molecular mechanism of metastases have been identified for designing new therapeutic strategies in the frame of personalized medicine. Among the biomarkers considered, glycoaminoglycans (GAGs) are a hallmark related with cancer growth and spread. GAGs could be employed in new drug delivery systems to deliver active compounds for therapeutic uses. A theranostics approach, i.e. combination of apredictive biomarker with a therapeutic agent, has been developed in this work. Firstly, because GAGs have antimetastatic properties and especially exopolysaccharides produced by a marine bacteria Alteromonas infernus. Additionally, a true theranostic pair of radionuclides has been considered, namely the scandium isotopes 44Sc/47Sc. Thus, GAGscould act in synergy with radionuclides of interest for NuclearMedicine and the goal of this work was to evaluate the feasibility of coupling EPS with Sc. The characteristics related to the applicability of these EPS in theranostics have been studied, for example the rheological behavior of the polymers. This stability depends on the chemical composition of the suspensions, but also on the size and size distribution of the molecules and their surface charge. This work presents the characterization tools that allow studying these properties. The methodology developed has been used to ensure the control of the composition, size, shape and surface characteristics of the EPS for further potential in vivo injections. The second objectiveof this work is to reach to the most comprehensive description of the interaction of these EPS with scandium. However, each metal is unique and is defined by its oxidation state, coordination number, hard‐soft characteristics, kinetic inertness or lability, and redox stability. Therefore, the particular coordination chemistry of scandium to these EPS has been accurately studied. Finally, the biological behavior of these EPS has been assessed on different cancer cell lines, being coupled or not with scandium to further evaluate their potency for Nuclear Medicine.L’ostéosarcome est la tumeur osseuse maligne primaire la plus courante chez les enfants et les jeunes adultes. C’est un type de cancer très agressif avec un pronostic faible ; mais le mécanisme moléculaire des métastases a été identifié permettant de concevoir de nouvelles stratégies thérapeutiques dans le cadre de la médecine personnalisée. Parmi les biomarqueurs considérés, les glycoaminoglycanes (GAGs) sont un biomarqueur de croissance et de propagation du cancer. Les GAG pourraient être utilisés dans de nouveaux systèmes d’administration de médicaments pour fournir des composés actifs à des fins thérapeutiques. Une approche théranostique, c’est‐à‐dire la combinaison d’un biomarqueur prédictif avec un agent thérapeutique, a été développée dans ce travail. Tout d’abord, parce que les GAGs ont des propriétés antimétastatiques et notamment des exopolysaccharides produits par une bactérie marine Alteromonas infernus. évalués sur différentes lignées de cellules cancéreuses, étant couplé ou non avec du scandium pour évaluer davantage leur efficacité en médecine nucléaire. De plus, une véritable paire théranostique de radionucléides a été envisagée, à savoir les isotopes du scandium 44Sc/47Sc. Ainsi, les GAGs pourraient agir en synergie avec les radionucléides d’intérêt pour la médecine nucléaire et l’objectif de ces travaux était d’évaluer la faisabilité du couplage EPS avec le scandium. Les caractéristiques liées à l’applicabilité de ces EPS en théranostique ont été étudiées, par exemple le comportement rhéologique des polymères. Cette stabilité dépend de la composition chimique des suspensions, mais aussi de la taille et de la distribution en taille des molécules ainsi que leur charge de surface. Ce travail présente les outils de caractérisation qui permettent d’étudier ces propriétés. La méthodologie mise au point a été utilisée pour assurer le contrôle de la composition, de la taille, de la forme et des caractéristiques de surface des EPS en vue pour de leurs injections in vivo. Le deuxième objectif de ce travail est de décrire et de quantifier le plus complètement possible l’interaction de ces EPS avec le scandium. Mais chaque métal est unique et est défini par son état d’oxydation, son nombre de coordination, ses caractéristiques (dures /molles), son inertie cinétique ou sa labilité, et sa stabilité redox. Par conséquent, la chimie de coordination particulière du scandium avec ces EPS a été étudiée avec précision. Enfin, le comportement biologique de ces EPS a été évalué sur différentes lignées de cellules cancéreuses, couplées ou non au scandium pour évaluer leur potentialité en médecine nucléaire
First measurements of N-subjettiness in central Pb-Pb collisions at = 2.76 TeV
No full textInternational audienceThe ALICE Collaboration reports the first fully-corrected measurements of the N-subjettiness observable for track-based jets in heavy-ion collisions. This study is performed using data recorded in pp and Pb-Pb collisions at centre-of-mass energies of = 7 TeV and = 2.76 TeV, respectively. In particular the ratio of 2-subjettiness to 1-subjettiness, τ/τ, which is sensitive to the rate of two-pronged jet substructure, is presented. Energy loss of jets traversing the strongly interacting medium in heavy-ion collisions is expected to change the rate of two-pronged substructure relative to vacuum. The results are presented for jets with a resolution parameter of R = 0.4 and charged jet transverse momentum of 40 ≤ p ≤ 60 GeV/c, which constitute a larger jet resolution and lower jet transverse momentum interval than previous measurements in heavy-ion collisions. This has been achieved by utilising a semi-inclusive hadron-jet coincidence technique to suppress the larger jet combinatorial background in this kinematic region. No significant modification of the τ/τ observable for track-based jets in Pb-Pb collisions is observed relative to vacuum PYTHIA6 and PYTHIA8 references at the same collision energy. The measurements of τ/τ, together with the splitting aperture angle ∆R, are also performed in pp collisions at = 7 TeV for inclusive jets. These results are compared with PYTHIA calculations at = 7 TeV, in order to validate the model as a vacuum reference for the Pb-Pb centre-of-mass energy. The PYTHIA references for τ/τ are shifted to larger values compared to the measurement in pp collisions. This hints at a reduction in the rate of two-pronged jets in Pb-Pb collisions compared to pp collisions.[graphic not available: see fulltext
Benign ghosts in higher-derivative systems
No full textInternational audienceA brief review of the physics of systems including higher derivatives in the Lagrangian is given. All such systems involve ghosts, i.e. the spectrum of the Hamiltonian is not bounded from below and the vacuum ground state is absent. Usually this leads to collapse and loss of unitarity. In certain special cases, this does not happen, however: ghosts are benign. This happens, in particular, in exactly solvable higher-derivative theories, but exact solvability seems to be a sufficient but not a necessary condition for the benign nature of the ghosts. We speculate that the Theory of Everything is a higher-derivative field theory, characterized by the presence of such benign ghosts and defined in a higher-dimensional bulk. Our Universe represents then a classical solution in this theory, having the form of a 3-brane embedded in the bulk
Marine Exopolysaccharide Complexed With Scandium Aimed as Theranostic Agents
No full textInternational audienceBackground: Exopolysaccharide (EPS) derivatives, produced by Alteromonas infernus bacterium, showed anti-metastatic properties. They may represent a new class of ligands to be combined with theranostic radionuclides, such as 47Sc/44Sc. The goal of this work was to investigate the feasibility of such coupling.Methods: EPSs, as well as heparin used as a drug reference, were characterized in terms of molar mass and dispersity using Asymmetrical Flow Field-Flow Fractionation coupled to Multi-Angle Light Scattering (AF4-MALS). The intrinsic viscosity of EPSs at different ionic strengths were measured in order to establish the conformation. To determine the stability constants of Sc with EPS and heparin, a Free-ion selective radiotracer extraction (FISRE) method has been used.Results: AF4-MALS showed that radical depolymerization produces monodisperse EPSs, suitable for therapeutic use. EPS conformation exhibited a lower hydrodynamic volume for the highest ionic strengths. The resulting random-coiled conformation could affect the complexation with metal for high concentration. The LogK of Sc-EPS complexes have been determined and showing that they are comparable to the Sc-Hep.Conclusions: EPSs are very promising to be coupled with the theranostic pair of scandium for Nuclear Medicin
Automated selection of nuclides and reactions of interest in a depletion simulation. Precision loss estimation for multiple outputs
No full textInternational audienceTo accelerate depletion calculations, it is common to only consider a selection of isotopes. Simulating only a limited number of nuclides leads inevitably to some bias on the outputs of the depletion simulation. Most methods used are either implicit or dedicated to specific cases. This paper presents a new method, based on physics consideration and an explicit algorithm, that automatically selects isotopes and reactions for a depletion calculation. This method uses the creation and simplification of a nucleus tree gathering and linking together all nuclides that can possibly be created during the depletion process. This is performed by recursively adding nuclides possibly created from nuclides previously in the tree through decay or nuclear reaction. After the creation of the tree, it can be simplified by automatically cutting nuclides and reaction out through 3 processes: half-life threshold, cross-section threshold and reaction type cut. Using these simplification processes, the presented method leads to important calculation cost reduction (up to 40%) with effect on outputs lower than 3 times their stochastic standard deviation