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Experimental cross-section measurement of the nuclear reactions induced by protons on Tb: Evaluation of theDy/Tb precursor system
No full textInternational audience149,152,155,161Tb have recently been under the lens of research in nuclear medicine due to their physical characteristics, which allow them to be used in various applications in both diagnosis and therapy. Performing the optimization of the production methods of these terbium radioisotopes is of great research interest. In this work, the viability of the production of 155Tb (T1/2=5.32 d) via the 155Dy/155Tb precursor system was studied and discussed from a theoretical point of view. The production of 155Dy, alongside its contaminants, was accomplished through the 159Tb(p,x) nuclear reactions. The cross-sections of these reactions were studied in the 37.5–62 MeV energy range using the stacked-foils technique. The study of the yield of the indirectly produced 155Tb give promising estimations for an implementation of the 155Dy/155Tb precursor system. •Determination of the cross-section of the 159Tb(p,x) nuclear reactions up to 62 MeV.•Indirect production of Terbium-155 starting from natural terbium targets.•Thick-target yield calculation of the precursor system Dy-155/Tb-155.•Promising results for large scale production of the theranostic Tb-155
Radioactivity as a driver of bacterial community composition in naturally radioactive mineral springs in the French Massif Central
No full textInternational audienceSome natural environments on Earth are characterised by high levels of radiation, including naturally radioelement enriched mineral springs in the French Massif Central. Therefore, naturally radioactive mineral springs are interesting ecosystems for understanding how bacterial populations in these springs have adapted to high levels of natural and chronic radioactivity over the very long term. The aim of this study was to analyse the bacterial communities of sediments from five naturally radioactive mineral springs in the French Massif Central, sampled in autumn 2019 and spring 2020, and to observe whether radionuclides, compared to other physicochemical parameters, are drivers of the bacterial community structuring in these extreme environments. Physicochemical measurements showed that two springs, Dourioux and Montagne had high radioelement concentrations/activities (uranium, thorium and radon). Analysis of the structure of the bacterial communities, by next generation sequencing based on 16S rRNA gene sequencing, showed that the presence of radionuclides in Dourioux and Montagne, did not lead to a reduction in bacterial diversity and richness compared to the other springs. However, Dourioux and Montagne were characterised by specific bacterial populations, whose presence correlates with the radioelement concentrations/activities measured in these springs. This suggests that radioelements could partly explain the structuring of bacterial communities in these springs. In addition, several of these operational taxonomic units (OTUs) specific to Dourioux and Montagne, mainly affiliated to Proteobacteria, Firmicutes, Acidobacteria, Actinobacteria, and Bacteroidetes, could be involved in the biogeochemistry of radionuclides through different mechanisms (biosorption, biomineralisation, bioaccumulation, and bioreduction), which would allow the development of other bacterial species sensitive to these metals/radioelements. In particular, the co-occurrence of sulphate and/or iron-reducing bacteria, capable of bioreducing uranium, with fermentative bacteria, releasing sources of organic carbons, reflects associations of bacteria with complementary functions that allow them to grow in this peculiar environment and maintain a high diversity in these extreme environments. This study has provided a better understanding of the structuring of bacterial communities exposed to ionising radiation for thousands of years in naturally radioactive environments.</jats:p
Search for light dark matter with NEWS-G at the LSM using a methane target
No full textInternational audienceThe NEWS-G direct detection experiment uses spherical proportional counters to search for light dark matter candidates. New results from a 10 day physics run with a in diameter spherical proportional counter at the Laboratoire Souterrain de Modane are reported. The target consists of of methane, providing sensitivity to dark matter spin-dependent coupling to protons. New constraints are presented in the mass range to , with a 90% confidence level cross-section upper limit of for a mass of
Measurement of the inclusive isolated-photon production cross section in pp collisions at = 13 TeV
No full textInternational audienceThe production cross section of inclusive isolated photons has been measured by the ALICE experiment at the CERN LHC in pp collisions at centre-of-momentum energy of TeV collected during the LHC Run 2 data-taking period. The measurement is performed by combining the measurements of the electromagnetic calorimeter EMCal and the central tracking detectors ITS and TPC, covering a pseudorapidity range of and a transverse momentum range of GeV/. The result extends to lower and ranges, the lowest of any isolated photon measurements to date, extending significantly those measured by the ATLAS and CMS experiments towards lower at the same collision energy with a small overlap between the measurements. The measurement is compared with next-to-leading order perturbative QCD calculations and the results from the ATLAS and CMS experiments as well as with measurements at other collision energies. The measurement and theory prediction are in agreement with each other within the experimental and theoretical uncertainties
High-Resolution Modeling Without Computation Slowdown for PETALE in CROCUS
No full textInternational audienceIn a collaboration between Ecole Polytechnique F & eacute;d & eacute;rale de Lausanne (EPFL) and CEA, in the fall of 2020, the experimental Programme d'& Eacute;tude en Transmission de l'Acier Lourd et ses El & eacute;ments (PETALE) was successfully carried out in the CROCUS reactor of EPFL. This article presents and compares the methods tested in the modeling of the experiments, specifically focusing on the metal reflectors installed at the periphery of CROCUS. A basic design model consisting of a few cuboids was refined to a fully detailed version, without impacting the run time of simulations. Notably, each reflector sheet of PETALE was segmented into 121 voxels based on topological measurements. This detailed voxelization did not affect calculation times, thanks to the use of three-dimensional lattices as available in Serpent 2. Profiling of the simulations revealed the high computational surface transformations associated with Serpent 2 and highlighted the efficiency benefits of factorizing these into universe transformations. As the CROCUS simulations were carried out using a modified build of Serpent 2, additional simulations were also performed using a standard version of Serpent 2 with a GODIVA model as a neutron source to ensure that the findings are generalizable. These additional tests confirmed the initial results, with significant performance variations observed between the models, particularly larger in surface-tracking mode than in delta-tracking mode. Consequently, the modeling method may therefore be applied to future high-fidelity modeling of neutron transmission and shielding experiments
Prediction of Energy Resolution in the JUNO Experiment
No full textInternational audienceThis paper presents the energy resolution study in the JUNO experiment, incorporating the latest knowledge acquired during the detector construction phase. The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV. To achieve this ambitious goal, significant efforts have been undertaken in the design and production of the key components of the JUNO detector. Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution, extending beyond the statistical fluctuations of the detected number of photons, such as the properties of liquid scintillator, performance of photomultiplier tubes, and the energy reconstruction algorithm. To account for these effects, a full JUNO simulation and reconstruction approach is employed. This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution. The study reveals an energy resolution of 2.95% at 1 MeV. Furthermore, the study assesses the contribution of major effects to the overall energy resolution budget. This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data taking. Moreover, it provides a guideline in comprehending the energy resolution characteristics of liquid scintillator-based detectors
Euclid. I. Overview of the Euclid mission
No full textInternational audienceThe current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Euclid is a medium-class mission in the Cosmic Vision 2015-2025 programme of the European Space Agency (ESA) that will provide high-resolution optical imaging, as well as near-infrared imaging and spectroscopy, over about 14,000 deg^2 of extragalactic sky. In addition to accurate weak lensing and clustering measurements that probe structure formation over half of the age of the Universe, its primary probes for cosmology, these exquisite data will enable a wide range of science. This paper provides a high-level overview of the mission, summarising the survey characteristics, the various data-processing steps, and data products. We also highlight the main science objectives and expected performance
Probing the path-length dependence of parton energy loss via scaling properties in heavy ion collisions
No full textInternational audienceThe scaling property of large- hadron suppression, , measured in heavy ion collisions at RHIC and LHC leads to the determination of the average parton energy loss in quark-gluon plasma produced in a variety of collision systems and centrality classes. Relating to the particle multiplicity and collision geometry allows for probing the dependence of parton energy loss on the path-length . We find that with , consistent with the pQCD expectation of parton energy loss in a longitudinally expanding quark-gluon plasma. We then demonstrate that the azimuthal anisotropy coefficient divided by the collision eccentricity, , follows the same scaling property as . This scaling is observed in data, which are reproduced by the model at large . Finally, a linear relationship between and the logarithmic derivative of is found and confirmed in data, offering an additional way to probe the dependence of parton energy loss using coming measurements from LHC Run 3
Investigating the nature of the K state with K correlations at the LHC
No full textInternational audienceThe first measurements of femtoscopic correlations with the particle pair combinations K in pp collisions at TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a K pair. The extracted mass and Breit-Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K. The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K resonance
Measurements of chemical potentials in Pb-Pb collisions at TeV
No full textInternational audienceThis Letter presents the most precise measurement to date of the matter/antimatter imbalance at midrapidity in Pb-Pb collisions at a center-of-mass energy per nucleon pair TeV. Using the Statistical Hadronization framework, it is possible to obtain the value of the electric charge and baryon chemical potentials, MeV and MeV, with unprecedented precision. A centrality-differential study of the antiparticle-to-particle yield ratios of charged pions, protons, -baryons, and light (hyper)nuclei is performed. These results indicate that the system created in Pb-Pb collisions at the LHC is on average baryon-free and electrically neutral at midrapidity