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Direct observation of the dead-cone effect in quantum chromodynamics
No full textInternational audienceThe direct measurement of the QCD dead cone in charm quark fragmentation is reported, using iterative declustering of jets tagged with a fully reconstructed charmed hadron
Transport model comparison studies of intermediate-energy heavy-ion collisions
No full textInternational audienceTransport models are the main method to obtain physics information on the nuclear equation of state and in-medium properties of particles from low to relativistic-energy heavy-ion collisions. The Transport Model Evaluation Project (TMEP) has been pursued to test the robustness of transport model predictions in reaching consistent conclusions from the same type of physical model. To this end, calculations under controlled conditions of physical input and set-up were performed with various participating codes. These included both calculations of nuclear matter in a box with periodic boundary conditions, which test separately selected ingredients of a transport code, and more realistic calculations of heavy-ion collisions. Over the years, six studies have been performed within this project. In this intermediate review, we summarize and discuss the present status of the project. We also provide condensed descriptions of the 26 participating codes, which contributed to some part of the project. These include the major codes in use today. After a compact description of the underlying transport approaches, we review the main results of the studies completed so far. They show, that in box calculations the differences between the codes can be well understood and a convergence of the results can be reached. These studies also highlight the systematic differences between the two families of transport codes, known under the names of Boltzmann–Uehling–Uhlenbeck (BUU) and Quantum Molecular Dynamics (QMD) type codes. However, when the codes were compared in full heavy-ion collisions using different physical models, as recently for pion production, they still yielded substantially different results. This calls for further comparisons of heavy-ion collisions with controlled models and of box comparisons of important ingredients, like momentum-dependent fields, which are currently underway. Our evaluation studies often indicate improved strategies in performing transport simulations and thus can provide guidance to code developers. Results of transport simulations of heavy-ion collisions from a given code will have more significance if the code can be validated against benchmark calculations such as the ones summarized in this review
The Double Chooz antineutrino detectors
No full textInternational audienceThis article describes the setup and performance of the near and far detectors in the Double Chooz experiment. The electron antineutrinos of the Chooz nuclear power plant were measured in two identically designed detectors with different average baselines of about 400 m and 1050 m from the two reactor cores. Over many years of data taking the neutrino signals were extracted from interactions in the detectors with the goal of measuring a fundamental parameter in the context of neutrino oscillation, the mixing angle . The central part of the Double Chooz detectors was a main detector comprising four cylindrical volumes filled with organic liquids. From the inside towards the outside there were volumes containing gadolinium-loaded scintillator, gadolinium-free scintillator, a buffer oil and, optically separated, another liquid scintillator acting as veto system. Above this main detector an additional outer veto system using plastic scintillator strips was installed. The technologies developed in Double Chooz were inspiration for several other antineutrino detectors in the field. The detector design allowed implementation of efficient background rejection techniques including use of pulse shape information provided by the data acquisition system. The Double Chooz detectors featured remarkable stability, in particular for the detected photons, as well as high radiopurity of the detector components
Altération des verres nucléaires en phase vapeur et effets des irradiations
No full textUnder the context of geological disposal of French high-level nuclear waste, glass vapor hydration is expected to occur prior to liquid alteration. A poorly understood phenomenon, hydration of nuclear glass in the unsaturated vapor phase as well as under radiations may eventually affect its chemical durability in the aqueous phase. This study investigates firstly the releases of boron (as a tracer of glass alteration) and iodine (as a problematic radionuclide for disposal safety) during glass vapor hydration and subsequent leaching tests. Glass samples of different surface states were hydrated and characterized by a wide range of techniques. The results show the preferential release of boron in the form of BO 3, revealing the important role of boron incontrolling the kinetics of glass vapor hydration. Discussions linking the modifications in mechanical properties and in chemical durability shed light on the understanding of the mechanisms of boron release,comprising the processes of hydrolysis, diffusion, and evaporation. Great retention of iodine in the hydrated layer and during subsequent leaching suggests the transport-limiting effect of the hydrated layer. Effect of alpha and gamma radiations were studied by irradiating the pre-hydrated glass samples or by hydrating the samples in the presence of gamma rays. No significant effect of radiation on the chemical durability of hydrated glass was demonstrated. Supplementary work aimed at generating a possible acceleration of the hydration of the glass in the presence of secondary phases has been carried out. The method developed in this study paves the way to a more general study on the effect of environmental materials on the alteration of glass in the vapor phase.Dans le cadre du stockage géologique des déchets nucléaires français de haute activité, l'hydratation des verres en phase vapeur est envisagée avant l'altération aqueuse. Phénomène mal connu, l'hydratation du verre nucléaire en phase vapeur insaturée ainsi que sous irradiations peut à terme affecter sa durabilité chimique en phase aqueuse. Cette thèse étudie d'abord les relâchements en bore (en tant que traceur de l'altération du verre) et en iode (en tant que radionucléide problématique pour la sécurité du stockage) du verre lors des tests d'hydratation en phase vapeur suivis par une lixiviation sous eau. Des échantillons de verre présentant différents états de surface ont été hydratés et caractérisés par une large gamme de techniques. Les résultats montrent le relâchement préférentiel du bore sous forme BO3, révélant le rôle important de cet élément dans le contrôle de la cinétique d'hydratation de verre en phase vapeur. Les discussions reliant les modifications des propriétés mécaniques du verre à sa durabilité chimique permettent d'éclairer la compréhension des mécanismes de relâchement du bore, comprenant les processus d'hydrolyse, diffusion et évaporation. Une rétention importante d'iode dans la couche hydratée et qui perdure lors de la remise en en eau suggère l'effet barrière de la couche hydratée pour le transport des espèces aqueuses. L'effet des irradiations alpha et gamma a été étudié en irradiant les échantillons de verre pré-hydraté ou en hydratant les échantillons en présence de rayonnements gamma. Aucun effet significatif de l’irradiation sur la durabilité chimique du verre hydraté n’a été mis en évidence. Des travaux complémentaires visant à mettre en évidence une possible accélération de l'hydratation du verre en présence de phases secondaires ont été réalisés. La méthode développée dans cette étude ouvre la voie à une étude plus générale sur l’effet des matériaux d’environnement sur lors de l’altération du verre en phase vapeur
Therapeutic efficacy of 166Holmium siloxane in microbrachytherapy of induced glioblastoma in minipig tumor model
No full textInternational audienceGlioblastoma is considered the most common malignant primary tumor of central nervous system. In spite of the current standard and multimodal treatment, the prognosis of glioblastoma is poor. For this reason, new therapeutic approaches need to be developed to improve the survival time of the glioblastoma patient. In this study, we performed a preclinical experiment to evaluate therapeutic efficacy of 166 Ho microparticle suspension administered by microbrachytherapy on a minipig glioblastoma model. Twelve minipigs were divided in 3 groups. Minipigs had injections into the tumor, containing microparticle suspensions of either 166 Ho (group 1; n = 6) or 165 Ho (group 2; n = 3) and control group (group 3; n = 3). The survival time from treatment to euthanasia was 66 days with a good state of health of all minipigs in group 1. The median survival time from treatment to tumor related death were 8.6 and 7.3 days in groups 2 and control, respectively. Statistically, the prolonged life of group 1 was significantly different from the two other groups (p < 0.01), and no significant difference was observed between group 2 and control (p=0.09). Our trial on the therapeutic effect of the 166 Ho microparticle demonstrated an excellent efficacy in tumor control. The histological and immunohistochemical analysis showed that the efficacy was related to a severe 166 Ho induced necrosis combined with an immune response due to the presence of the radioactive microparticles inside the tumors. The absence of reflux following the injections confirms the safety of the injection device
Hydrogen peroxide formation to investigate the radiolytic ROS production mechanism under proton FLASH conditions
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Anomalous dimension of transverse momentum broadening in planar SYM
No full textInternational audienceThe typical transverse momentum (or "saturation" momentum) acquired by a hard particle propagating through a SYM plasma increases over time like , with an anomalous exponent characteristic of super-diffusion. This anomalous exponent is a function of the 't Hooft coupling . Recently, a method has been proposed to systematically compute the perturbative series of at weak coupling. This method relies on the traveling wave interpretation of the time evolution of and on the dominance of soft-collinear radiative corrections at large times. In this paper, we compute up to using the double logarithmic behaviour of the BFKL equation in planar SYM at three loops. This calculation allows us to discuss the transition towards the strong coupling regime where AdS/CFT calculations predict
Microdosimetry and radiolytic species production in UHDR proton beam using GATE and Geant4-DNA
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Exploration of the phase diagram within a transport approach
No full textInternational audienceWe study equilibrium as well as out-of-equilibrium properties of the strongly interacting QGP medium under extreme conditions of high temperature T and high baryon densities or baryon chemical potentials μB within a kinetic approach. We present the thermodynamic and transport properties of the QGP close to equilibrium in the framework of effective models with Nf=3 active quark flavours such as the Polyakov extended Nambu-Jona Lasinio (PNJL) and dynamical quasiparticle model with the CEP (DQPM-CP). Considering the transport coefficients and the EoS of the QGP phase, we compare our results with various results from the literature. Furthermore, out-of equilibrium properties of the QGP medium and in particular, the effect of a μB- dependence of thermodynamic and transport properties of the QGP are studied within the Parton-Hadron-String-Dynamics (PHSD) transport approach, which covers the full evolution of the system during HICs. We find that bulk observables and flow coefficients for strange hadrons as well as for antiprotons are more sensitive to the properties of the QGP, in particular to the μB - dependence of the QGP interactions
Sub-percent precision measurement of neutrino oscillation parameters with JUNO
No full textInternational audienceJUNO is a multi-purpose neutrino observatory under construction in the south of China. This publication presents new sensitivity estimates for the measurement of the , , , and oscillation parameters using reactor antineutrinos, which is one of the primary physics goals of the experiment. The sensitivities are obtained using the best knowledge available to date on the location and overburden of the experimental site, the nuclear reactors in the surrounding area and beyond, the detector response uncertainties, and the reactor antineutrino spectral shape constraints expected from the TAO satellite detector. It is found that the , , and oscillation parameters will be determined to better than 0.5% precision in six years of data collection, which represents approximately an order of magnitude improvement over existing constraints