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Réduction de la radiotoxicité par hadronthérapie à ultra-haut débit de dose
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Classical vs quantum corrections to jet broadening in a weakly-coupled Quark-Gluon Plasma
No full textInternational audienceThe transverse momentum broadening coefficient receives both soft, classical and radiative, quantum corrections. The former are responsible for a large O(g) correction, whereas the latter enter at relative order , but are enhanced by a double logarithm of the length of the medium over the thermal wavelength. We analyze radiative corrections for a weakly-coupled quark-gluon plasma. We find that a thermal population of dynamical gluons changes the boundaries and reduces the size of the double-logarithmic phase space. It also provides new subdominant logarithmic corrections. We also show how the quantum, double-logarithmic and classical, soft phase spaces are smoothly connected once the radiated gluon becomes soft enough. Finally, we discuss a pathway to a determination of radiative corrections beyond the harmonic-oscillator approximation
Research on Emerging Medical radionuclides from the X-sections (REMIX): The Accelerator-based Production of Sc, Tb, Tb, Tb and Tb
No full textInternational audienceThe REMIX project is focused on the cyclotron-based production of Sc, Tb, Tb, Tb and Tb radionuclides, whose decay characteristics make them suitable for medical applications. This work will outline the main results achieved withing the REMIX collaboration, that is organized in the following Work Packages (WP): WP1. Target manufacturing (Ti, Ti and GdO) and characterization; WP2. Nuclear cross section (XS) measurements with Ti and Ti targets for Sc production; WP3. Nuclear XS measurements with Dy, Tb and Eu targets for Tb production; WP4. Nuclear XS modeling for Sc and Tb production; WP5. Dosimetric calculations for Sc- and Tb-labelled radiopharmaceuticals; WP6. Tb Thick Target Yield (TTY) measurements; WP7. Apparatus design and realization for irradiation tests with the LARAMED beamline. Since the LARAMED bunkers and ancillary laboratories are currently under completion at the INFN-LNL, the nuclear XS experiments are carried out in collaboration with the GIP ARRONAX facility (Saint-Herblain, France) and the Thick Target Yield (TTY) measurements are performed at the Sacro Cuore Don Calabria hospital (SCDCh, Negrar, Verona, Italy)
Recherche de désintégration double beta sans émission de neutrinos avec XENONnT
No full textIn the field of particle physics, the search for rare phenomena by means of low background experiments occupies a fundamental place. The nature of dark matter and neutrinos are among the major remaining unknowns in particle physics today. Their understanding is the subject of intense effort by the scientific community and relies on the observation of extremely rare physical processes, such as the direct interaction of dark matter candidates with a detector target and the search for neutrinoless double beta decays. To this end, the XENON collaboration has been developing for several years multiple low background experiments, based on the xenon dual-phase time projection chamber technology having as main objective the direct detection of the interaction of weakly interacting massive particle (WIMP) candidate with a xenon target nucleus. The XENONnT experiment, currently operating in the underground INFN Laboratori Nazionali del Gran Sasso in Italy, is the fourth generation of experiment from the XENON collaboration. Thanks to its unprecedented low level of background and its large target mass of xenon, XENONnT is sensitive to other rare processes, including the search for neutrinoless double beta decay of 136Xe. In this thesis I will present a first analysis of XENONnT calibration data used to monitor the detector stability during the first scientific run between July and November 2021 and a sensitivity study on the projection for neutrinoless double beta decay search in XENONnT.Dans le domaine de la physique des particules, la recherche de phénomènes rares par des expériences à bas bruit de fond occupe une place fondamentale. La nature de la Matière Noire et des neutrinos figurent parmi les principales inconnues subsistantes en physique des particules de nos jours. Leurs compréhensions sont l’objet d’efforts intenses de la part de la communauté scientifique et repose sur l’observation de processus physiques extrêmement rares, tel que l’interaction directe de particules candidates au rôle de Matière Noire avec la cible d’un détecteur et la recherche de désintégration double bêta sans émissions de neutrinos. Dans cette optique la collaboration XENON développe depuis plusieurs années de multiples expériences à bas bruit de fond, basées sur la technologie de détection de chambre à projection temporelle double phase au xénon et ayant pour objectif principal la détection directe de l’interaction d’une particule massive interagissant faiblement (WIMP) avec un noyau cible de xénon. L’expérience XENONnT, actuellement en activité au sein du laboratoire souterrain de l’INFN Laboratori Nazionali del Gran Sasso en Italie, est la quatrième génération d’expérience de la collaboration XENON. Grâce à son environnement de bas bruit de fond sans précédent et à sa grande masse cible de xénon, XENONnT est sensible à d’autres processus rares, dont la recherche de désintégration double bêta sans émissions de neutrinos du 136Xe. Dans cette thèse, je présenterai une première analyse des données de calibration de XENONnT utilisées pour surveiller la stabilité du détecteur lors de la première période d’acquisition de données scientifiques entre juillet et novembre 2021 et une étude de la sensibilité pour la recherche de désintégration double bêta sans neutrinos attendues dans XENONnT
JUNO physics and detector
No full textInternational audienceThe Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton LS detector at 700-m underground. An excellent energy resolution and a large fiducial volume offer exciting opportunities for addressing many important topics in neutrino and astro-particle physics. With 6 years of data, the neutrino mass ordering can be determined at 3-4 sigma and three oscillation parameters can be measured to a precision of 0.6% or better by detecting reactor antineutrinos. With 10 years of data, DSNB could be observed at 3-sigma; a lower limit of the proton lifetime of 8.34e33 years (90% C.L.) can be set by searching for p->nu_bar K^+; detection of solar neutrinos would shed new light on the solar metallicity problem and examine the vacuum-matter transition region. A core-collapse supernova at 10 kpc would lead to ~5000 IBD and ~2000 (300) all-flavor neutrino-proton (electron) scattering events. Geo-neutrinos can be detected with a rate of ~400 events/year. We also summarize the final design of the JUNO detector and the key R&D achievements. All 20-inch PMTs have been tested. The average photon detection efficiency is 28.9% for the 15,000 MCP PMTs and 28.1% for the 5,000 dynode PMTs, higher than the JUNO requirement of 27%. Together with the >20 m attenuation length of LS, we expect a yield of 1345 p.e. per MeV and an effective energy resolution of 3.02%/\sqrt{E (MeV)}$ in simulations. The underwater electronics is designed to have a loss rate <0.5% in 6 years. With degassing membranes and a micro-bubble system, the radon concentration in the 35-kton water pool could be lowered to <10 mBq/m^3. Acrylic panels of radiopurity <0.5 ppt U/Th are produced. The 20-kton LS will be purified onsite. Singles in the fiducial volume can be controlled to ~10 Hz. The JUNO experiment also features a double calorimeter system with 25,600 3-inch PMTs, a LS testing facility OSIRIS, and a near detector TAO
Prompt and non-prompt J/ψ production cross sections at midrapidity in proton-proton collisions at = 5.02 and 13 TeV
No full textInternational audienceThe production of J/ψ is measured at midrapidity (|y| < 0.9) in proton-proton collisions at = 5.02 and 13 TeV, through the dielectron decay channel, using the ALICE detector at the Large Hadron Collider. The data sets used for the analyses correspond to integrated luminosities of = 19.4 ± 0.4 nb and = 32.2 ± 0.5 nb at = 5.02 and 13 TeV, respectively. The fraction of non-prompt J/ψ mesons, i.e. those originating from the decay of beauty hadrons, is measured down to a transverse momentum p = 2 GeV/c (1 GeV/c) at = 5.02 TeV (13 TeV). The p and rapidity (y) differential cross sections, as well as the corresponding values integrated over p and y, are carried out separately for prompt and non-prompt J/ψ mesons. The results are compared with measurements from other experiments and theoretical calculations based on quantum chromodynamics (QCD). The shapes of the p and y distributions of beauty quarks predicted by state-of-the-art perturbative QCD models are used to extrapolate an estimate of the pair cross section at midrapidity and in the total phase space. The total cross sections are found to be = 541 ± 45 (stat.) ± 69 (extr.) μb and = 218±37 (stat.)±31 (extr.) μb at = 13 and 5.02 TeV, respectively. The value obtained from the combination of ALICE and LHCb measurements in pp collisions at = 13 TeV is also provided.[graphic not available: see fulltext
Hypertriton Production in p-Pb Collisions at =5.02 TeV
No full textInternational audienceThe study of nuclei and antinuclei production has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. The first measurement of the production of HΛ3 in p-Pb collisions at sNN=5.02 TeV is presented in this Letter. Its production yield measured in the rapidity interval -1<y<0 for the 40% highest-multiplicity p-Pb collisions is dN/dy=[6.3±1.8(stat)±1.2(syst)]×10−7. The measurement is compared with the expectations of statistical hadronization and coalescence models, which describe the nucleosynthesis in hadronic collisions. These two models predict very different yields of the hypertriton in charged particle multiplicity environments relevant to small collision systems such as p-Pb, and therefore the measurement of dN/dy is crucial to distinguish between them. The precision of this measurement leads to the exclusion with a significance larger than 6.9σ of some configurations of the statistical hadronization model, thus constraining the theory behind the production of loosely bound states at hadron colliders
Volatilization of BC control rods in Fukushima Daiichi nuclear reactors during meltdown: B–Li isotopic signatures in cesium-rich microparticles
No full textInternational audienceBoron carbide control rods remain in the fuel debris of the damaged reactors in the Fukushima Daiichi Nuclear Power Plant, potentially preventing re-criticality; however, the state and stability of the control rods remain unknown. Sensitive high-resolution ion microprobe analyses have revealed B–Li isotopic signatures in radioactive Cs-rich microparticles (CsMPs) that formed by volatilization and condensation of Si-oxides during the meltdowns. The CsMPs contain 1518–6733 mg kg–1 of 10+11B and 11.99–1213 mg kg–1 of 7Li. The 11B/10B (4.15–4.21) and 7Li/6Li (213−406) isotopic ratios are greater than natural abundances (~4.05 and ~12.5, respectively), indicating that 10B(n,α)7Li reactions occurred in B4C prior to the meltdowns. The total amount of B released with CsMPs was estimated to be 0.024–62 g, suggesting that essentially all B remains in reactor Units 2 and/or 3 and is enough to prevent re-criticality; however, the heterogeneous distribution of B needs to be considered during decommissioning
Measurement of beauty production via non-prompt mesons in Pb-Pb collisions at = 5.02 TeV
No full textInternational audienceThe production of non-prompt mesons from beauty-hadron decays was measured at midrapidity ( in the % central Pb-Pb collisions. The data are described by models that include both collisional and radiative processes in the calculation of beauty-quark energy loss in the quark-gluon plasma, and quark recombination in addition to fragmentation as a hadronization mechanism. The ratio of the non-prompt to prompt -meson is larger than unity for in the % central Pb-Pb collisions, as predicted by models in which beauty quarks lose less energy than charm quarks in the quark-gluon plasma because of their larger mass
