HAL Mines Nantes
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Some impacts of advanced fuel cycle options on waste management and long term disposal safety
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When heavy ions meet cosmic rays: potential impact of QGP formation on the muon puzzle
No full textInternational audienceThe deficit of muons in the simulation of extensive air showers is a long-standing problem and the origin of large uncertainties in the reconstruction of the mass of the high energy primary cosmic rays. Hadronic interaction models, re-tuned after early LHC data, have a more consistent description of the muon content among them but still disagree with data. Collective hadronization due to the formation of a quark gluon plasma (QGP) has already been studied as a possible cause for a larger production of muons under extreme conditions (rare, very central nuclear interactions), but without real success. However, in the view of the most recent LHC data, a collective hadronization phase might not only be limited to such extreme conditions. And because of its different ratio of electromagnetic to hadronic energy, a QGP may have the properties to solve the muon puzzle. This hypothesis is demonstrated using a theoretical approach and tested in a proper way by the modification of hadronic model spectra in CONEX to mimic the production of a QGP also in less extreme conditions with a possible large impact on air shower physics
Characterization of Uranyl Coordinated by Equatorial Oxygen: Oxo in UO versus Oxyl in UO
No full textInternational audienceUranium trioxide, UO3, has a T-shaped structure with bent uranyl, UO22+, coordinated by an equatorial oxo, O2-. The structure of cation UO3+ is similar but with an equatorial oxyl, O center dot-. Neutral and cationic uranium trioxide coordinated by nitrates were characterized by collision induced dissociation (CID), infrared multiple-photon dissociation (IRMPD) spectroscopy, and density functional theory. CID of uranyl nitrate, [UO2 (NO3)(3)](-) (complex A1), eliminates NO2 to produce nitrate-coordinated UO3+, [UO2 (O-center dot)(NO3)(2)](-) (BI), which ejects NO3 to yield UO3 in [UO2 (O)(NO3)](-) (C1). Finally, C1 associates with H2O to afford uranyl hydroxide in [UO2(OH)(2) (NO3)](-) (D1). IRMPD of B1, C1, and D1 confirms uranyl equatorially coordinated by nitrate(s) along with the following ligands: (B1) radical oxyl O center dot-; (C1) oxo O2-; and (D1) two hydroxyls, OH- . As the nitrates are bidentate, the equatorial coordination is six in A1, five in B1, four in D1, and three in C1. Ligand congestion in low-coordinate C1 suggests orbital-directed bonding. Hydrolysis of the equatorial oxo in C1 epitomizes the inverse trans influence in UO3, which is uranyl with inert axial oxos and a reactive equatorial oxo. The uranyl nu(3) IR frequencies indicate the following donor ordering: O2- [best donor] >> O center dot- > OH-> NO3
IsZn(d,x)Cu the Best Way to Produce Cu for Medical Applications?
No full textInternational audienceThe pair of copper radionuclides 64Cu/67Cu (T1/2 = 12. 7 h/61.8 h) allows, respectively, PET imaging and targeted beta therapy. An analysis of the different production routes of 67Cu with charged particles was performed and the reaction 70Zn(d,x) route was identified as a promising one. It may allow the production of 67Cu without 64Cu. The production cross section has been measured up to 28.7 MeV. Measurements were done using the well-known stacked-foils technique using 97.5% enriched 70Zn homemade electroplated targets. These measurements complement at higher incident energies the only set of data available in nuclear databases. The results show that using a 26 MeV deuteron beam and a highly enriched 70Zn target, it is possible to produce high purity 67Cu comparable to that obtained using photoproduction. This production route can be of interest for future linear accelerators under development where mA deuteron beams can be available if adequate targetry is developed.</jats:p
QCD factorization for hadronic quarkonium production at high
No full textInternational audienceHeavy quarkonium production at high transverse momentum () in hadronic collisions is explored in the QCD factorization approach. We find that the leading power in the expansion is responsible for high regime, while the next-to-leading power contribution is necessary for the low region. We present the first numerical analysis of the scale evolution of coupled twist-2 and twist-4 fragmentation functions (FFs) for heavy quarkonium production and demonstrate that the QCD factorization approach is capable of describing the spectrum of hadronic production at the LHC
Experience with RIVET from a user/"analyser" (an event generator user point-of-view)
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Influence of temperature and relative humidity on vapor hydration of an AVM nuclear waste glass
No full textInternational audience• The vapor hydration rate, calculated from the thickness of the homogeneous altered layer, follows Arrhenius law for temperature dependence between the temperature range 50°C-90°C. • Network-hydrolysis is the predominant rate controlling mechanism for the studied duration. • Nature/identity of secondary phases vary as function of both temperature and relative humidity and the nature of the altered surface varies as a function of relative humidity. • XRD patterns indicated the presence of precipitates containing rare-earth elements and transition metals only on the samples altered at lower relative humidity values (50% and 76%)
Production of muons from heavy-flavour hadron decays at high transverse momentum in Pb–Pb collisions at sNN=5.02 and 2.76 TeV
No full textInternational audienceMeasurements of the production of muons from heavy-flavour hadron decays in Pb–Pb collisions at sNN=5.02 and 2.76 TeV using the ALICE detector at the LHC are reported. The nuclear modification factor RAA at sNN=5.02 TeV is measured at forward rapidity (2.5<y<4) as a function of transverse momentum pT in central, semi-central, and peripheral collisions over a wide pT interval, 3<pT<20 GeV/c, in which muons from beauty-hadron decays are expected to take over from charm as the dominant source at high pT (pT>7 GeV/c). The RAA shows an increase of the suppression of the yields of muons from heavy-flavour hadron decays with increasing centrality. A suppression by a factor of about three is observed in the 10% most central collisions. The RAA at sNN=5.02 TeV is similar to that at sNN=2.76 TeV. The precise RAA measurements have the potential to distinguish between model predictions implementing different mechanisms of parton energy loss in the high-density medium formed in heavy-ion collisions. They place important constraints for the understanding of the heavy-quark interaction with the hot and dense QCD medium
EXCESS workshop: Descriptions of rising low-energy spectra
No full textInternational audienceMany low-threshold experiments observe sharply rising event rates of yet unknown origins below a few hundred eV, and larger than expected from known backgrounds. Due to the significant impact of this excess on the dark matter or neutrino sensitivity of these experiments, a collective effort has been started to share the knowledge about the individual observations. For this, the EXCESS Workshop was initiated. In its first iteration in June 2021, ten rare event search collaborations contributed to this initiative via talks and discussions. The contributing collaborations were CONNIE, CRESST, DAMIC, EDELWEISS, MINER, NEWS-G, NUCLEUS, RICOCHET, SENSEI and SuperCDMS. They presented data about their observed energy spectra and known backgrounds together with details about the respective measurements. In this paper, we summarize the presented information and give a comprehensive overview of the similarities and differences between the distinct measurements. The provided data is furthermore publicly available on the workshop’s data repository together with a plotting tool for visualization
