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Prognostic Factors of Mandibular Osteoradionecrosis Including Accurate Colocalization of Avulsions and Dosimetric Dental Mapping Software, a Case-control Study
No full textInternational audiencePurpose: Osteoradionecrosis (ORN) of the mandible remains a significant complication in the intensity modulated radiationtherapy (IMRT) era. Dental dose cannot be predicted from heterogeneous IMRT dose distributions; mandibular dose metricscannot guide dentist avulsion decisions in high-risk ORN situations. Using a mapping tool to report dental root dose, avul-sions, and ORN sites, we re-examined ORN risk factors in a case-control study.Methods and Materials: From 2008 to 2019, 897 consecutive patients with oral cavity/oropharynx or unknown primary cancerundergoing IMRT were analyzed to identify ORN cases. These were matched (1 ORN/2 controls) retrospectively for tumor location,surgery, and tobacco consumption in a monocentric case-control study. Univariate and multivariate analyses integrated ORN factorsand accurate dental dose data (grouped into 4 mandibular sectors). Generalizability was investigated in a simulated population database.Results: A total of 171 patients were included. The median follow-up was 5.2 and 4.5 years in the ORN and control groups,respectively. The median time to ORN was 12 months. In univariate analysis, post-IMRT avulsions at the ORN site (hazardratio [HR] = 3.6; 95% confidence interval [CI] = 1.5-8.9; P = .005), tumor laterality (HR, 4.4; 95% CI, = 1.4-14, P = .01), meanmandibular dose (HR, 1.1; 95% CI, = 1.01-1.1; P = .018) and mean dose to the ORN site (HR, 1.1; 95% CI, = 1.1-1.2; P < .001)correlated with higher ORN risk. In multivariate analysis, mean dose to the ORN site (HR, 1.1; 95% CI, = 1.1-1.2; P < .001)and post-IMRT avulsions at the ORN site (HR, 4.6; 95% CI, = 1.5-14.7; P = .009) were associated with ORN. For each increasein gray in dental dose, the ORN risk increased by 12%. Simulations confirmed study observations.Conclusions: Dental dose and avulsions are associated with ORN, with a 12% increase in risk with each additional gray. Accu-rate dose information can help dentists in their decisions after IMR
Measurement of baryon production and branching-fraction ratio in pp collisions at = 13 TeV
No full textInternational audienceThe inclusive production of the charm-strange baryon is measured for the first time via its semileptonic decay into at midrapidity () in protonproton (pp) collisions at the centre-of-mass energy TeV with the ALICE detector at the LHC. The transverse momentum () differential cross section multiplied by the branching ratio is presented in the interval . The branching-fraction ratio is measured to be 1.12 0.22 (stat.) 0.27 (syst.). Comparisons with other experimental measurements, as well as with theoretical calculations, are presented
Atmospheric muons measured with the KM3NeT detectors in comparison with updated numeric predictions
No full textInternational audienceThe measurement of the flux of muons produced in cosmic ray air showers is essential for the study of primary cosmic rays. Such measurements are important in extensive air shower detectors to assess the energy spectrum and the chemical composition of the cosmic ray flux, complementary to the information provided by fluorescence detectors. Detailed simulations of the cosmic ray air showers are carried out, using codes such as CORSIKA, to estimate the muon flux at sea level. These simulations are based on the choice of hadronic interaction models, for which improvements have been implemented in the post-LHC era. In this work, a deficit in simulations that use state-of-the-art QCD models with respect to the measurement deep underwater with the KM3NeT neutrino detectors is reported. The KM3NeT/ARCA and KM3NeT/ORCA neutrino telescopes are sensitive to TeV muons originating mostly from primary cosmic rays with energies around 10 TeV. The predictions of state-of-the-art QCD models show that the deficit with respect to the data is constant in zenith angle; no dependency on the water overburden is observed. The observed deficit at a depth of several kilometres is compatible with the deficit seen in the comparison of the simulations and measurements at sea level
Chapter 5 - France
No full textSecond Edition https://doi.org/10.1016/C2022-0-02667-2International audienceSince the ORNL experiments and projects on MSR, various studies on this kind of reactors were resumed in the 1980s in the world, including in France, with studies on the MSBR by EDF and the CEA. In the 1990s, the concept was taken up again with a view to burning nuclear wastes in subcritical reactors such as the TIER-1 project or in critical reactors such as the CEA TASSE project or the EDF AMSTER project
Heavy flavor production under a strong magnetic field
No full textInternational audienceThe magnetic field created in high energy nuclear collisions will affect the dynamical processes in the QCD medium, especially the heavy quark production that happens in the initial stage of the collisions. We calculate in a strong magnetic field the heavy quark production cross section for the elementary process gg → Q{Q̅} at leading order and the corresponding transverse momentum distribution in nucleus-nucleus collisions. In comparison to the QED process, the heavy quark production is dominated by the unique QCD channel with gluon self-interaction. Due to the dimension reduction of quark phase space in a strong magnetic field, the production is concentrated in a very narrow energy region above the threshold. Since the translation invariance is broken, the production becomes anisotropic in magnetic field
<math display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></mrow></math> Suppression in Pb-Pb Collisions at the LHC
No full textInternational audienceThe production of the ψ(2S) charmonium state was measured with ALICE in Pb-Pb collisions at sNN=5.02 TeV, in the dimuon decay channel. A significant signal was observed for the first time at LHC energies down to zero transverse momentum, at forward rapidity (2.5<y<4). The measurement of the ratio of the inclusive production cross sections of the ψ(2S) and J/ψ resonances is reported as a function of the centrality of the collisions and of transverse momentum, in the region pT<12 GeV/c. The results are compared with the corresponding measurements in pp collisions, by forming the double ratio [σψ(2S)/σJ/ψ]Pb-Pb/[σψ(2S)/σJ/ψ]pp. It is found that in Pb-Pb collisions the ψ(2S) is suppressed by a factor of ∼2 with respect to the J/ψ. The ψ(2S) nuclear modification factor RAA was also obtained as a function of both centrality and pT. The results show that the ψ(2S) resonance yield is strongly suppressed in Pb-Pb collisions, by a factor of up to ∼3 with respect to pp. Comparisons of cross section ratios with previous Super Proton Synchrotron findings by the NA50 experiment and of RAA with higher-pT results at LHC energy are also reported. These results and the corresponding comparisons with calculations of transport and statistical models address questions on the presence and properties of charmonium states in the quark-gluon plasma formed in nuclear collisions at the LHC
Atomistic Computer Simulations of Uranyl Adsorption on Hydrated Illite and Smectite Surfaces
No full textInternational audienceA quantitative understanding of the molecular-scale mechanisms of radionuclide sorption on different clay minerals is crucial for the development and safe implementation of geological nuclear waste disposal technologies. We apply classical molecular dynamics (MD) computer simulations to study the adsorption of uranyl on the external basal surfaces of two typical clay models. In the illite model, negative charge is primarily localized in the tetrahedral sheets, while in the lower-charge smectite model, the isomorphic substitutions are introduced in the octahedral sheet. The comparison of atomic density distributions at the clay surfaces and adsorption-free energies profiles as a function of distance from these surfaces demonstrates that overall U behavior at the basal clay surface is quite similar for illite and smectite. Uranyl is sorbed as a mixture of outer-sphere aqua complexes [UO2(H2O)5]2+ and hydrolyzed aqua complexes [UO2(H2O)4–5OH]+ on both surfaces. The structural and compositional differences between the models do not greatly affect the uranyl’s nearest coordination environment and are mainly reflected in the specific localization and orientation of the uranyl ions at both surfaces and in the magnitude of the adsorption-free energies. The observed quantitative characteristics of uranyl interactions with illite and smectite surfaces will help to better understand U behavior during the sorption process on clay minerals for the entire range of mixed-layer illite–smectite structures. A comparison of two versions of the ClayFF force field in the simulations made it possible to more accurately and quantitatively evaluate some subtle features of the uranyl–clay interactions and to obtain a more precise composition of uranyl complex with the modified ClayFF force field (ClayFF-MOH).</jats:p
Virtual Photons Shed Light on the Early Temperature of Dense QCD Matter
No full textInternational audienceDileptons produced during heavy-ion collisions represent a unique probe of the QCD phase diagram, and convey information about the state of the strongly interacting system at the moment their preceding off-shell photon is created. In this study, we compute thermal dilepton yields from Au+Au collisions performed at different beam energies, employing a (3+1)-dimensional dynamic framework combined with emission rates accurate at next-to-leading order in perturbation theory and which include baryon chemical potential dependencies. By comparing the effective temperature extracted from the thermal dilepton invariant mass spectrum with the average temperature of the fluid, we offer a robust quantitative validation of dileptons as effective probe of the early quark-gluon plasma stage
Confirmation of the spectral excess in DAMIC at SNOLAB with skipper CCDs
No full textInternational audienceWe present results from a 3.1 kg-day target exposure of two charge-coupled devices (CCDs), each with 24 megapixels and skipper readout, deployed in the DAMIC (DArk Matter In CCDs) setup at SNOLAB. With a reduction in pixel readout noise of a factor of 10 relative to the previous detector, we investigate the excess population of low-energy bulk events previously observed above expected backgrounds. We address the dominant systematic uncertainty of the previous analysis through a depth fiducialization designed to reject surface backgrounds on the CCDs. The measured bulk ionization spectrum confirms with higher significance the presence of an excess population of low-energy events in the CCD target with characteristic rate of events per kg-day and electron-equivalent energies of eV, whose origin remains unknown
The ALICE experiment: a journey through QCD
No full textCERN-EP-2022-227International audienceThe ALICE experiment was proposed in 1993, to study strongly-interacting matter at extreme energy densities and temperatures. This proposal entailed a comprehensive investigation of nuclear collisions at the LHC. Its physics programme initially focused on the determination of the properties of the quark–gluon plasma (QGP), a deconfined state of quarks and gluons, created in such collisions. The ALICE physics programme has been extended to cover a broader ensemble of observables related to Quantum Chromodynamics (QCD), the theory of strong interactions. The experiment has studied Pb–Pb, Xe–Xe, p–Pb and pp collisions in the multi-TeV centre of mass energy range, during the Run 1–2 data-taking periods at the LHC (2009–2018). The aim of this review is to summarise the key ALICE physics results in this endeavor, and to discuss their implications on the current understanding of the macroscopic and microscopic properties of strongly-interacting matter at the highest temperatures reached in the laboratory. It will review the latest findings on the properties of the QGP created by heavy-ion collisions at LHC energies, and describe the surprising QGP-like effects in pp and p–Pb collisions. Measurements of few-body QCD interactions, and their impact in unraveling the structure of hadrons and hadronic interactions, will be discussed. ALICE results relevant for physics topics outside the realm of QCD will also be touched upon. Finally, prospects for future measurements with the ALICE detector in the context of its planned upgrades will also be briefly described