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Virus-to-prokaryote ratio in spring waters along a gradient of natural radioactivity
No full textInternational audienceAlthough a strong link between viruses and prokaryotes is commonly known to exist in aquatic systems, few studies have investigated their relationship in spring waters. In the French Massif Central, certain springs are known to exhibit varying levels of naturally occurring radioactivity. Therefore, the aim of this study was to examine the standing stock of viruses together with prokaryotes, and determine the potential environmental factors influencing them in springs characterized by contrasted radioactivity gradient. Among the investigated 15 spring habitats, flow cytometry analyses indicated that both viral (VA) and prokaryotic abundances (PA) varied by an order of magnitude accompanied by virus-to-prokaryote ratio ranging between 8 and 144.2. Significant differences in VA was evident among springs where low abundances (mean ± SD: 21.3 ± 7.0 x 107 VLP l-1) corresponded to high (mean ± SD: 1911 ± 814.0 nGy.h-1) gamma (γ) dose radiation (222Rn) and vice versa. Adverse effect of water radioactivity (222Rn) on VA could perhaps corroborate our hypothesis of drastic effect of ionizing radiations on viruses, which might explain for lack of significant relationship between PA and VA. In such a scenario of prevailing low VA, the adopted phage life strategies could define their existence in these specialized ecosystems
Digitalisation for nuclear waste management: predisposal and disposal
No full textInternational audienceData science (digitalisation and artificial intelligence) became more than an important facilitator for many domains in fundamental and applied sciences as well as industry and is disrupting the way of research already to a large extent. Originally, data sciences were viewed to be well-suited, especially, for data-intensive applications such as image processing, pattern recognition, etc. In the recent past, particularly, data-driven and physics-inspired machine learning methods have been developed to an extent that they accelerate numerical simulations and became directly usable for applications related to the nuclear waste management cycle. In addition to process-based approaches for creating surrogate models, other disciplines such as virtual reality methods and high-performance computing are leveraging the potential of data sciences more and more. The present challenge is utilising the best models, input data and monitoring information to integrate multi-chemical-physical, coupled processes, multi-scale and probabilistic simulations in Digital Twins (DTw) able to mirror or predict the performance of its corresponding physical twins. Therefore, the main target of the Topical Collection is exploring how the development of DTw can benefit the development of safe, efficient solutions for the pre-disposal and disposal of radioactive waste. A particular challenge for DTw in radioactive waste management is the combination of concepts from geological modelling and underground construction which will be addressed by linking structural and multi-physics/chemistry process models to building or tunnel information models. As for technical systems, engineered structures a variety of DTw approaches already exist, the development of DTw concepts for geological systems poses a particular challenge when taking the complexities (structures and processes) and uncertainties at extremely varying time and spatial scales of subsurface environments into account
Ultrahigh-Dose-Rate Proton Irradiation Elicits Reduced Toxicity in Zebrafish Embryos
No full textInternational audiencePurposeRecently, ultrahigh-dose-rate radiation therapy (UHDR-RT) has emerged as a promising strategy to increase the benefit/risk ratio of external RT. Extensive work is on the way to characterize the physical and biological parameters that control the so-called “Flash” effect. However, this healthy/tumor differential effect is observable in in vivo models, which thereby drastically limits the amount of work that is achievable in a timely manner.Methods and MaterialsIn this study, zebrafish embryos were used to compare the effect of UHDR irradiation (8-9 kGy/s) to conventional RT dose rate (0.2 Gy/s) with a 68 MeV proton beam. Viability, body length, spine curvature, and pericardial edema were measured 4 days postirradiation.ResultsWe show that body length is significantly greater after UHDR-RT compared with conventional RT by 180 µm at 30 Gy and 90 µm at 40 Gy, while pericardial edema is only reduced at 30 Gy. No differences were obtained in terms of survival or spine curvature.ConclusionsZebrafish embryo length appears as a robust endpoint, and we anticipate that this model will substantially fasten the study of UHDR proton-beam parameters necessary for “Flash.
Classical vs Quantum Corrections to Jet Broadening in a Weakly Coupled Quark-Gluon Plasma
No full textInternational audienceThe transverse momentum broadening coefficient, serves as a key ingredient in characterising the quenching of a jet as it propagates through the Quark-Gluon Plasma (QGP). While its lead- ing order value was calculated in the early 2000’s, it has since been realised to receive quantum, radiative corrections featuring potentially large logarithmic enhancements at relative order g^2. It is still not clear how these corrections compare quantitatively with their classical counterparts, i.e, those coming from the exchange of thermal gluons with large occupation number, present at relative order g and higher.During the course of the talk, I plan to first motivate the need for a more careful calculation of the aforementioned logarithmic corrections in the case of a weakly coupled QGP. I will then sketch how the argument of the leading logarithm is altered with respect to earlier calculations and furthermore, how the phase space giving rise to these logarithmic corrections is smoothly connected to that from which the classical corrections emerge. Finally, I will conclude by discussing how these findings, detailed in our own work are relevant with respect to the overall goal of determining which class of corrections are quantitatively more important
JUNO sensitivity to Be, , and CNO solar neutrinos
No full textInternational audienceThe Jiangmen Underground Neutrino Observatory (JUNO), the first multi-kton liquid scintillator detector, which is under construction in China, will have a unique potential to perform a real-time measurement of solar neutrinos well below the few MeV threshold typical for Water Cherenkov detectors. JUNO's large target mass and excellent energy resolution are prerequisites for reaching unprecedented levels of precision. In this paper, we provide estimation of the JUNO sensitivity to 7Be, pep, and CNO solar neutrinos that can be obtained via a spectral analysis above the 0.45 MeV threshold. This study is performed assuming different scenarios of the liquid scintillator radiopurity, ranging from the most opti mistic one corresponding to the radiopurity levels obtained by the Borexino experiment, up to the minimum requirements needed to perform the neutrino mass ordering determination with reactor antineutrinos - the main goal of JUNO. Our study shows that in most scenarios, JUNO will be able to improve the current best measurements on 7Be, pep, and CNO solar neutrino fluxes. We also perform a study on the JUNO capability to detect periodical time variations in the solar neutrino flux, such as the day-night modulation induced by neutrino flavor regeneration in Earth, and the modulations induced by temperature changes driven by helioseismic waves
Cosmic decoherence: primordial power spectra and non-Gaussianities
No full textInternational audienceWe study the effect of quantum decoherence on the inflationary cosmological perturbations. This process might imprint specific observational signatures revealing the quantum nature of the inflationary mechanism being related to the longstanding issue of the quantum-to-classical transition of inflationary fluctuations. Several works have investigated the effect of quantum decoherence on the statistical properties of primordial fluctuations. In particular, it has been shown that cosmic decoherence leads to corrections to the curvature power spectrum predicted by standard slow-roll inflation. Equally interesting, a non zero curvature trispectrum has been shown to be purely induced by cosmic decoherence, but surprisingly, decoherence seems not to generate any bispectrum. We further develop such an analysis by adopting a generalized form of the pointer observable, showing that decoherence does induce a non vanishing curvature bispectrum and providing a specific underlying concrete physical process. Present constraints on primordial bispectra allow to put an upper bound on the strength of the environment-system interaction. In full generality, the decoherence-induced bispectrum can be scale dependent provided one imposes the corresponding correction to the power spectrum to be scale independent. Such scale dependence on the largest cosmological scales might represent a distinctive imprint of the quantum decoherence process taking place during inflation. We also provide a criterion that allows to understand when cosmic decoherence induces scale independent corrections, independently of the type of environment considered. As a final result, we study the effect of cosmic decoherence on tensor perturbations and we derive the decoherence corrected tensor-to-scalar perturbation ratio. In specific cases, decoherence induces a blue tilted correction to the standard tensor power spectrum
New insights into Monte Carlo simulation of borosilicate glass aqueous alteration
No full textInternational audienceTo elucidate the residual rate in the realm of glass alteration, the underlying mechanisms remain a subject of ongoing debate, as they potentially encompass multiple channels that collectively result in a decrease by several orders of magnitude of the initial alteration rate [1].The Monte-Carlo (MC) method is an effective method for studying complex scientific problems. For studying the glass dissolution by the Monte-Carlo method, early attempts were made in the late 20th century by Aerstens and Van Iseghem followed by Devreux [2] and in the near past by Sebastian Kerisit and his coworkers [3]. The major limitations of the models developed was that it had no way to explain the residual rate and the evolution of gel maturation. In my thesis, we investigate glass alteration using a new Monte-Carlo code described below to explore the role of the different elements. In parallel, classical force fields for molecular dynamics (MD) simulation are developed to simulate boron diffusion in water within a model alteration gel. Additionally, experiments are performed with glasses containing different Al2O3 quantities. The MD simulations and the experiments will help to determine the Monte Carlo parameters. At the end, we plan to obtain a better description of the role of the different elements on glass alteration in the so called residual rate regime.This poster is dedicated to the Monte Carlo method. The algorithm has been developed by J.-M. Delaye and coworkers. It differs from the previous algorithm in the fact that the diffusion of water inside the solid is taken into account, using two intricated networks to represent the glass on one side, and the solution on the other side. The MC code is able to reproduce the formation of an alteration layer in glasses containing Si, B, Na and Al. Even if the current version of the code is quite slow, which imposes limitations on the number of calculations that can be executed, we have simulated the alteration of three distinct glass compositions each characterized by varying quantities of Al2O3. The Monte Carlo parameters have been fitted to reproduce at the best the experiments, in particular the quantity of Si and B released in solution. Our findings will demonstrate that two different types of passivating layers can form depending on the way Si is released in solution. When a large quantity of Si atoms is rapidly released in solution, it can lead to the formation of an external layer characterized by a notable enrichment of Si. Conversely, when the release of Si into the solution occurs in a more continuous manner, no layer enriched in Si is observed but the external part of the gel undergoes a progressive reticulation process. These two distinct mechanisms offers a plausible explanation for the alteration behavior change observed with an increase in Al2O3 content. [4]
Towards the understanding of the genuine three-body interaction for p–p–p and p–p–
No full textInternational audienceThree-body nuclear forces play an important role in the structure of nuclei and hypernuclei and are also incorporated in models to describe the dynamics of dense baryonic matter, such as in neutron stars. So far, only indirect measurements anchored to the binding energies of nuclei can be used to constrain the three-nucleon force, and if hyperons are considered, the scarce data on hypernuclei impose only weak constraints on the three-body forces. In this work, we present the first direct measurement of the p–p–p and p–p– systems in terms of three-particle correlation functions carried out for pp collisions at TeV. Three-particle cumulants are extracted from the correlation functions by applying the Kubo formalism, where the three-particle interaction contribution to these correlations can be isolated after subtracting the known two-body interaction terms. A negative cumulant is found for the p–p–p system, hinting to the presence of a residual three-body effect while for p–p– the cumulant is consistent with zero. This measurement demonstrates the accessibility of three-baryon correlations at the LHC
JUNO sensitivity to the annihilation of MeV dark matter in the galactic halo
No full textInternational audienceWe discuss JUNO sensitivity to the annihilation of MeV dark matter in the galactic halo via detecting inverse beta decay reactions of electron anti-neutrinos resulting from the annihilation. We study possible backgrounds to the signature, including the reactor neutrinos, diffuse supernova neutrino background, charged- and neutral-current interactions of atmospheric neutrinos, backgrounds from muon-induced fast neutrons and cosmogenic isotopes. A fiducial volume cut, as well as the pulse shape discrimination and the muon veto are applied to suppress the above backgrounds. It is shown that JUNO sensitivity to the thermally averaged dark matter annihilation rate in 10 years of exposure would be significantly better than the present-day best limit set by Super-Kamiokande and would be comparable to that expected by Hyper-Kamiokande
Pseudorapidity densities of charged particles with transverse momentum thresholds in pp collisions at <math display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>5.02</mn></mrow></math> and 13 TeV
No full textInternational audienceThe pseudorapidity density of charged particles with minimum transverse momentum (pT) thresholds of 0.15, 0.5, 1, and 2 GeV/c is measured in pp collisions at the center of mass energies of s=5.02 and 13 TeV with the ALICE detector. The study is carried out for inelastic collisions with at least one primary charged particle having a pseudorapidity (η) within ±0.8 and pT larger than the corresponding threshold. In addition, measurements without pT-thresholds are performed for inelastic and nonsingle-diffractive events as well as for inelastic events with at least one charged particle having |η|<1 in pp collisions at s=5.02 TeV for the first time at the LHC. These measurements are compared to the pythia 6, pythia 8, and epos-lhc models. In general, the models describe the η dependence of particle production well. However, discrepancies are observed for the highest transverse momentum threshold (pT>2 GeV/c), highlighting the importance of such measurements for tuning event generators. The new measurements agree within uncertainties with results from the ATLAS and CMS experiments obtained at s=13 TeV