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Non-intrusive and reliable speciation of organically bound tritium in environmental matrices
No full textInternational audienceMeasurements of tritium in its various forms within the environment and especially in organic matter are keys to improving the current understanding of its environmental behavior and distribution. Validated or standardized analytical procedures for tritium determination methods have now been developed for several forms of tritium in environmental samples, yet an analytical lack remains regarding the quantifications of exchangeable and non-exchangeable forms of organically bound tritium (OBT) fractions. The present work therefore aims to provide a means of developing a standardized method for OBT fraction determination by evaluating the robustness and relevance of two methods (intrusive and non-intrusive methods) developed for non-exchangeable OBT quantification on a broad panel of pertinent environmental matrices. The validity and reliability of a non-intrusive method has thus been confirmed through a robust comparative study. Moreover, its relevance for standardization purposes is discussed, while the fundamental weakness of the conventional and most widespread method is highlighted and directly quantified for the first time in relying on many demonstrated biases
Long- and short-range correlations and their event-scale dependence in high-multiplicity pp collisions at TeV
No full textInternational audienceTwo-particle angular correlations are measured in high-multiplicity proton-proton collisions at = 13 TeV by the ALICE Collaboration. The yields of particle pairs at short-(∆η ∼ 0) and long-range (1.6 < |∆η| < 1.8) in pseudorapidity are extracted on the near-side (∆φ ∼ 0). They are reported as a function of transverse momentum (p) in the range 1 < p< 4 GeV/c. Furthermore, the event-scale dependence is studied for the first time by requiring the presence of high-p leading particles or jets for varying p thresholds. The results demonstrate that the long-range “ridge” yield, possibly related to the collective behavior of the system, is present in events with high-p processes as well. The magnitudes of the short- and long-range yields are found to grow with the event scale. The results are compared to EPOS LHC and PYTHIA 8 calculations, with and without string-shoving interactions. It is found that while both models describe the qualitative trends in the data, calculations from EPOS LHC show a better quantitative agreement for the p dependency, while overestimating the event-scale dependency.[graphic not available: see fulltext
Recent Developments in EPOS: Core–Corona Effects in Air Showers?
No full textInternational audienceEPOS-LHC is the public EPOS version, heavily used by experimental groups in high energy and cosmic ray physics. It is based on an S-matrix approach, being the ideal framework for multiple scattering in small systems. However, factorization and binary scaling do not come for free, it is a very complex issue, and in the current model it is simply not properly done. Another topic concerns flow, which is only implemented as ‘‘parameterized,’’ with is quite a limited applications. There was substantial progress during the past few years, referred to as ‘‘EPOS4 project,’’ to develop a consistent formalism, which accommodates a multiple scattering S-matrix approach, factorization, and saturation, all of these topics being closely related to each other. In addition, secondary interactions are considered, most importantly a full hydrodynamic evolution. In this talk, we will report about the status of the EPOS4 project
Structural and vibrational properties of ettringite from classical atomistic simulations
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Production of Sc with natural vanadium targets: results of the PASTA project
No full textInternational audienceThe goal of PASTA project (acronym for production with accelerator ofSc for theranostic applications) is the determination of excitation functions associated to several nuclear reactions, aimed at yielding the theranostic radionuclideSc. This work reports the main results obtained by irradiating natural vanadium targets with proton beams up to 70 MeV. Particular care is also given to the co-production ofSc, the only isotopic contaminant with half-life longer thanSc. Experimental results are compared with theoretical studies by means of known nuclear reaction software tools that are publicly available
Hadronic resonance production and interaction in p-Pb collisions at LHC energies in EPOS3
No full textInternational audienceUsing the EPOS3 model with the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model to describe the hadronic phase, we study the production of short-lived hadronic resonances and the modification of their yields and pT spectra in p-Pb collisions at sNN= 5.02 TeV. High-multiplicity p-Pb collisions exhibit similar behavior to midperipheral Pb-Pb collisions at LHC energies, and we find indications of a short-lived hadronic phase in p-Pb collisions that can modify resonance yields and pT spectra through scattering processes. The evolution of resonance production is investigated as a function of the system size, which is related to the lifetime of the hadronic phase in order to study the onset and evolution of scattering effects in p-Pb collisions. We also study hadron production separately in the core and corona parts of these collisions and explore how this division affects the total particle yields as the system size increases
Synthèse de matrices vitreuses en conditions extrêmes dopées en iode : Application au stockage sous pression des radioisotopes produits de l'industrie nucléaire.
No full textThe 129I isotope is a long-lived isotope, radiotoxic and highly mobile by-product of fission reactors. Its disposal in geological repositories requires matrix at least as durable as current nuclear waste glasses. The volatility of iodine at high temperature is a concern for nuclear waste glass processing, because its evaporation prior to vitrification, results in a low retention rate in the final glass.The present study investigates the use of vitrification under high pressure for the conditioning of iodine in nuclear waste glasses. Simulants of nuclear waste glasses were held in extreme conditions (0.5-2 GPa) to assess the solubility of iodine in various compositions and thermodynamic conditions.Pressure, boron content and non-network forming cations content are key parameters to dissolve iodine in borosilicate glasses. Polymerized glasses like the International Simple Glass incorporates ~1 mol.% I while depolymerized glasses, such as Low Activity Waste glasses can incorporate ~2 mol.% I.Iodine is incorporated in the vicinity of the non-network forming cations, and induce changes in the polymerization state of the network. Polymerized glasses (like ISG) tends to depolymerize with the addition of iodine in the structure, while the opposite occurs for depolymerized glasses. Iodine solubility is also strongly dependent with its oxidation state, the I5+ is more soluble in glasses than the I- specie.L’129I est un produit de fission de l’uranium dans les centrales nucléaires. Il est radiotoxique, très mobile dans l’environnement, et a une demi-vie longue (15.6 Ma). Le conditionnement de l’129I dans les verres nucléaires pour un stockage géologique est compliqué par sa forte volatilité à haute température. La vitrification des verres nucléaires sous pression est une solution qui peut pallier ce problème, car la solubilité des éléments volatils dans les liquides augmente avec la pression.Des analogues de verres nucléaires ont été vitrifiés sous haute pression (0.5-2 GPa) pour déterminer la solubilité de l’iode dans les verres, en fonction de paramètres thermodynamiques et compositionnels.La solubilité de l’iode dans les verres dépend de la pression, de la teneur en bore, mais également de la teneur en cations non formateurs de réseau. Les verres borosilicatés polymérisés comme le simulant de verre nucléaire ISG incorporent ~1 mol.% d’iode, tandis que les verres dépolymérisés comme les “Low Activity Waste Glass” en incorporent ~2 mol.%. L’iode s’incorpore dans les verres au voisinage des cations non formateurs de réseau. Ce faisant, il modifie l’état de polymérisation duréseau. L’iode a un effet dépolymérisant sur les verres polymérisés, et inversement pour les verres dépolymérisés. La solubilité de l’iodeest également fortement influencée par son état d’oxydation, l’espèce I5+ état bien plus soluble dans les verres que l’espèce I-
