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Assessing radiation dosimetry for microorganisms in naturally radioactive mineral springs using GATE and Geant4-DNA Monte Carlo simulations
No full textInternational audienceMineral springs in Massif Central, France can be characterized by higher levels of natural radioactivity in comparison to the background. The biota in these waters is constantly under radiation exposure mainly from the α-emitters of the natural decay chains. This study proposes to apply for the first time micro- and nanodosimetric approaches and tools to evaluate the dose received by microorganisms living in naturally radioactive ecosystems. We focus on the impact of the dominant radioelements, 226Ra in the sediments and 222Rn dissolved in the water of the mineral springs, and on diatoms, microalgae displaying an exceptional abundance of teratological forms in the most radioactive springs studied in Auvergne. Our results show that the dose rates are significant and comparable to the threshold suggested for the protection of the ecosystems. They also offer a first evaluation of the radiation induced DNA damage on these species. Our study confirms the significant mutational pressure from natural radioactivity to which microbial biodiversity has been exposed since Earth origin in hydrothermal springs
Witten index in 4d supersymmetric gauge theories
No full textInternational audienceWe present a review of Witten index calculations in different supersymmetric gauge theories in four dimensions: supersymmetric electrodynamics, pure N=1 supersymmetric Yang-Mills theories and also SYM theories including matter multiplets -- both with chirally symmetric and asymmetric content
Performance of the ALICE Electromagnetic Calorimeter
No full textInternational audienceThe performance of the electromagnetic calorimeter of theALICE experiment during operation in 2010–2018 at the Large HadronCollider is presented. After a short introduction into the design,readout, and trigger capabilities of the detector, the proceduresfor data taking, reconstruction, and validation are explained. Themethods used for the calibration and various derived corrections arepresented in detail. Subsequently, the capabilities of thecalorimeter to reconstruct and measure photons, light mesons,electrons and jets are discussed. The performance of thecalorimeter is illustrated mainly with data obtained with test beamsat the Proton Synchrotron and Super Proton Synchrotron or inproton-proton collisions at √s = 13 TeV, and compared tosimulations
Enhanced Deuteron Coalescence Probability in Jets
No full textInternational audienceThe transverse-momentum (pT) spectra and coalescence parameters B2 of (anti)deuterons are measured in p-p collisions at s=13 TeV for the first time in and out of jets. In this measurement, the direction of the leading particle with the highest pT in the event (pTlead>5 GeV/c) is used as an approximation for the jet axis. The event is consequently divided into three azimuthal regions, and the jet signal is obtained as the difference between the toward region, that contains jet fragmentation products in addition to the underlying event (UE), and the transverse region, which is dominated by the UE. The coalescence parameter in the jet is found to be approximately a factor of 10 larger than that in the underlying event. This experimental observation is consistent with the coalescence picture and can be attributed to the smaller average phase-space distance between nucleons in the jet cone as compared with the underlying event. The results presented in this Letter are compared to predictions from a simple nucleon coalescence model, where the phase-space distributions of nucleons are generated using pythia8 with the Monash 2013 tuning, and to predictions from a deuteron production model based on ordinary nuclear reactions with parametrized energy-dependent cross sections tuned on data. The latter model is implemented in pythia8.3. Both models reproduce the observed large difference between in-jet and out-of-jet coalescence parameters, although the almost flat trend of the B2Jet is not reproduced by the models, which instead give a decreasing trend
Toward a better understanding of radium lability in wetland soils
No full textInternational audienceRadium is a naturally occurring radioactive element and could in certain cases poses environmental and health risks due to its involvement in biological processes and subsequent release of radon gas from its radioactive decay. Interest in the environmental behavior of radium follows from its ubiquitous presence in the context of TE-NORM (Technologically Enhanced Naturally Occurring Radioactive Material) related activities, which mainly originate from uranium mining/milling, fossil fuels, etc… As such, the main scientific challenge calls for identifying its mobility, transport and bioavailability in the environment. The former uranium mining site of Rophin (Lachaux, France) is characterized at the downstream by a wetland area with high concentrations of 238U and its decay products, such as 226Ra [1]. In particular, an inherited layer of soil found at a depth of approximately 15 cm is recording radium concentrations up to 74 kBq.kg-1 of dry mass of soil. The overall adopted scientific approach is then to propose a mechanistic description of the mobility of radium in Rophin wetland soils by coupling laboratory experiments and field investigations with DET (Diffusive Equilibrium in Thin-Films) samplers. The objective was to determine which fraction is labile, i.e. the fraction that is adsorbed on soils and whose resupply in solution is rapid. This was assessed by desorption experiments under representative site conditions by an original methodology involving different solid/liquid ratios. This extensive lab methodology is based on a distribution coefficient (Kd) model allowing to assess the labile fraction of radium and Kd values in soils. DET probes field deployment followed to monitor radium concentrations in pore waters down to a depth of 50 cm. A centimetric-scale Ra profile was obtained from an original analytical strategy developed in Boudias (2022) [2] (see Boudias et al.’s abstract to this conference). Field data were then implemented into the Kd model to evaluate and improve the representativeness of the laboratory results on labile parameters of radium compared to the in natura equilibrium between soils and pore waters [3]. Overall, the labile fraction of radium was found to be very low (from 5 to 12 % for the inherited layer) and was characterized by Kd values of the order of 100 L.kg-1.This study provides access to valuable data essentials for a more detailed description of radium behavior and interactions in wetland soils. To go a step further, a combined DET-DGT (Diffusive Gradients in Thin-Films) approach will be implemented in the Rophin site in order to determine both labile and dissolved fractions from large soil profiles [3]. The ambition of this work will therefore be to directly access to in natura Kd values and associated kinetic parameters for a more accurate characterization of Ra lability and fate in soil layers
Measuring 226Ra concentration in soil pore waters by means of Diffusive Equilibrium in Thin-films: is it still an analytical challenge?
No full textInternational audienceThe release of natural radionuclides into the environment as a result of anthropogenic activities has raised concerns about potential chronic exposures of humans and ecosystems. 226Ra, alpha emitter coming from the 238U decay chain, is of particular concern due to its similarity to calcium and involvement in biological processes. Understanding the geochemical behavior and migration processes of 226Ra across the different compartments of the biosphere (i.e., accumulation and transport areas) is thus essential for assessing its impact. However, quantifying 226Ra in transport zones, such as soil or sediment pore waters sampled by Diffusive Equilibrium in Thin-Films (DET) probe, poses several analytical challenges including the handling of small sample volumes (i.e., agarose hydrogel piece of about 25 µL), complex matrices potential sources of ICP-MS signal suppression and/or polyatomic interferences, but also the elution procedure diluting the initial 226Ra concentration thus leading to difficult ICP-MS detection.A new full analytical strategy was developed to quantify 226Ra in pore waters that overcomes all the obstacles previously described. A wetland soil downstream the former uranium mine of Rophin (Allier, France) was selected for a field application. Being that the wetland soil particles contains significant amount level of 238U-decay chain radionuclides1, 2, we were sure to detect 226Ra signal in the pore waters. The strategy involved the deployment of DET probes to sample soil pore waters down to a depth of 50 cm. To obtain a centimetric depth profile, DET extracts were spiked with an in-house 228Ra tracer and subjected to purification and preconcentration by solid-phase extraction using the specific AnaLig Ra-01® resin3. Nitriloacetic acid agent was employed to elute Ra and was removed by a calcination treatment to prevent any matrix effects and fouling of the ICP-MS introduction system during analysis. The 200 µL preconcentrated samples were analyzed with an automatic sample changer dedicated to micro-volumes hyphenated with a desolvating nebulizer and ICP-MS. 226Ra was finally quantified by isotope dilution based on linear regression slopes applied on the obtained transient signals. The resulting drawn profile revealed an enrichment of 226Ra with depth, concentrations ranging from 24 to 90 fmol L-1 (i.e., activities from 0.2 to 8.1 Bq L-1).This comprehensive strategy represents a significant step forward for further understanding the behavior of 226Ra in continental systems and could be extended to studies involving other elements, such as Pb or U
Resonant screening in dense and magnetized QCD matter
No full textInternational audienceWe calculate the Debye screening mass in thermal, dense and magnetized QCD matter in the frame of resummed perturbation theory. In the limit of zero temperature, when the Landau energy level and Fermi surface of quarks match each other , where , and are respectively the quark electric charge, chemical potential and external magnetic field, the screening mass diverges and the system is in the state of weakly interacting parton gas, which is very different from the known result of strongly interacting quark-gluon plasma at high temperature. The divergence disappears in thermal medium, but the screening mass oscillates with clear peaks at the matched magnetic field
An integrated online radioassay data storage and analytics tool for nEXO
No full textInternational audienceLarge-scale low-background detectors are increasingly used in rare-event searches as experimental collaborations push for enhanced sensitivity. However, building such detectors, in practice, creates an abundance of radioassay data especially during the conceptual phase of an experiment when hundreds of materials are screened for radiopurity. A tool is needed to manage and make use of the radioassay screening data to quantitatively assess detector design options. We have developed a Materials Database Application for the nEXO experiment to serve this purpose. This paper describes this database application, explains how it functions, and discusses how it streamlines the design of the experiment
Environmental sustainability in basic research: a perspective from HECAP+
No full textInternational audienceThe climate crisis and the degradation of the world's ecosystems require humanity to take immediate action. The international scientific community has a responsibility to limit the negative environmental impacts of basic research. The HECAP+ communities (High Energy Physics, Cosmology, Astroparticle Physics, and Hadron and Nuclear Physics) make use of common and similar experimental infrastructure, such as accelerators and observatories, and rely similarly on the processing of big data. Our communities therefore face similar challenges to improving the sustainability of our research. This document aims to reflect on the environmental impacts of our work practices and research infrastructure, to highlight best practice, to make recommendations for positive changes, and to identify the opportunities and challenges that such changes present for wider aspects of social responsibility
Constraining the coupled channel dynamics using femtoscopic correlations at the LHC
No full textInternational audienceThe interaction of with protons is characterised by the presence of several coupled channels, systems like n and \uppi \Sigma with a similar mass and the same quantum numbers as the p state. The strengths of these couplings to the p system are of crucial importance for the understanding of the nature of the resonance and of the attractive p strong interaction. In this article, we present measurements of the p correlation functions in relative momentum space obtained in pp collisions at Te, in p–Pb collisions at Te, and (semi)peripheral Pb–Pb collisions at Te. The emitting source size, composed of a core radius anchored to the p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the n and \uppi \Sigma inelastic channels on the measured p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights , necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured p interaction indicates that, while the \uppi \Sigma –p dynamics is well reproduced by the model, the coupling to the n channel in the model is currently underestimated