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Improved titanium-44 purification process for establishing a high apparent molar activity titanium-44/scandium-44 generator
No full textInternational audience44Sc-radiopharmaceuticals are gaining more interest but still lack availability. The proof of principle of a44Ti/44Sc generator, which can produce 44Sc daily, has been established but with some limitations and drawbacks. Despite recent advances, separation of 44Ti from massive quantities of scandium target material is still cumbersome. In this work, the improved radiochemical separation of 44Ti from residual scandium target material was carried out by precipitation of Sc with fluoride ions. Furthermore, two approaches were used to set up a high apparent molar activity small-scale generator. The first method relied on extraction chromatography for fine purification using a DGA resin, followed by loading of the purified 44Ti onto a ZR resin column. In the second method, 44Ti was loaded on the ZR resin directly after the precipitation step. This second method was used to set up a generator of 370 kBq and evaluate by radiolabeling. An apparent molar activity of 2 MBq/nmol was obtained for the radiolabeling with DOTA, the most common and suitable chelate for scandium. This result is comparable with previously published data on 44 m/44Sc. •Improved radiochemical purification of 44Ti isotope.•High apparent molar activity of small-scale (Horwitz et al., 2008)Ti/44Sc generator tested.•Eluted Sc-44 radiolabeled with DOTA without additional treatment
XENONnT WIMP Search: Signal & Background Modeling and Statistical Inference
No full textInternational audienceThe XENONnT experiment searches for weakly-interacting massive particle (WIMP) dark matter scattering off a xenon nucleus. In particular, XENONnT uses a dual-phase time projection chamber with a 5.9-tonne liquid xenon target, detecting both scintillation and ionization signals to reconstruct the energy, position, and type of recoil. A blind search for nuclear recoil WIMPs with an exposure of 1.1 tonne-years yielded no signal excess over background expectations, from which competitive exclusion limits were derived on WIMP-nucleon elastic scatter cross sections, for WIMP masses ranging from 6 GeV/ up to the TeV/ scale. This work details the modeling and statistical methods employed in this search. By means of calibration data, we model the detector response, which is then used to derive background and signal models. The construction and validation of these models is discussed, alongside additional purely data-driven backgrounds. We also describe the statistical inference framework, including the definition of the likelihood function and the construction of confidence intervals
Microvolume analysis of 226Ra by inductively coupled plasma mass spectrometry: Environmental applications to high-resolution profile of wetland soil pore waters
No full textInternational audienceBackground: The release to the environment of natural radionuclides like 226Ra due to human activities haveraised concerns about human and ecosystem exposure. 226Ra’s resemblance to calcium and involvement inbiological processes accentuate the importance of understanding its geochemical behavior and migrationpathways. Soil and sediment pore waters provide valuable information but have proved to be challenging toanalyze, requiring to push the limits of current sample preparation and detection methods often not scaled forlow concentrated microvolumes of samples. A more efficient and accurate analytical method is therefore neededto get reliable data to support hydro-geochemical modeling.Results: We describe here a novel comprehensive approach for accurate 226Ra quantification in pore waters of awetland located downstream of the former Rophin uranium mine. In order to highlight the migration of 226Rabetween the different soil layers, microvolumes of soil pore waters were in situ sampled up to 50 cm depthemploying Diffusive Equilibrium in Thin-Films (DET) probes. The workflow included spiking DET extracts withan in-house 228Ra tracer, specific solid-phase extraction with 50 mg of AnaLig Ra-01® resin, and elution fractioncalcination. This process eliminated interferences and simplify the analysis matrix. Quantification relied onisotope dilution after measurement by ICP-MS hyphenated to a desolvator module and to a microsampler (150 µLinjection). The resulting 1 cm-high-resolution profile revealed unusual 226Ra enrichment with depth, signs of Ramobility from the solid contamination source. These elements are essential for assessing 226Ra distribution coefficients across soil horizons and subsequent wetland remobilization considerations.Significance and novelty: This first methodological advance for 226Ra constitutes a significant step to understand 226Ra behavior i.e., to quantify its activity level, fluxes inside of wetland soils or at the interface overlyingwaters/sediments. Its potential extension to studies involving other elements underscores its broader applicability in environmental research. The findings contribute to evidence-based decision-making for environmentalprotection and management, aiding in the preservation of ecological integrity and human health
ALICE upgrades during the LHC Long Shutdown 2
No full textInternational audienceA Large Ion Collider Experiment (ALICE) has been conceived and constructed as a heavy-ion experiment at the LHC. During LHC Runs 1 and 2, it has produced a wide range of physics results using all collision systems available at the LHC. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies, the experiment has undergone a major upgrade during the LHC Long Shutdown 2 (2019–2022). This comprises the move to continuous readout, the complete overhaul of core detectors, as well as a new online event processing farm with a redesigned online-offline software framework. These improvements will allow to record Pb-Pb collisions at rates up to 50 kHz, while ensuring sensitivity for signals without a triggerable signature
Cartan monopoles
No full textInternational audienceThe effective Hamiltonians for chiral supersymmetric gauge theories at small spatial volume are generalizations of the Hamiltonians describing the motion of a scalar or a spinor particle in a field of Dirac monopoles (we are dealing in fact with a certain lattice of monopoles supplemented with a periodic singular potential). The gauge fields in such Hamiltonians belong to the Cartan subalgebras of the corresponding gauge algebras. Such a construction exists for all groups admitting complex representations, i.e. for with and . We give explicit expressions for these Hamiltonians for , and for . The simplified version of such a Hamiltonian, deprived of fermion terms, of the extra scalar potential and when only one node of the lattice is taken into consideration, describe a -dimensional motion ( being the rank of the group) in the field what we call a {\it Cartan monopole}. As is the case for the ordinary monopole, the Lagrangian of this system enjoys gauge symmetry, rotational symmetry, and the parameter, generalizing the notion of magnetic charge for Cartan monopoles, is quantized
Potential to Identify the Neutrino Mass Ordering with Reactor Antineutrinos in JUNO
No full textInternational audienceThe Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose neutrino experiment under construction in South of China. This paper presents an updated estimate of JUNO's sensitivity to the neutrino mass ordering using the reactor antineutrinos emitted from eight nuclear reactor cores in the Taishan and Yangjiang nuclear power plants. This measurement is planned by studying the fine interference pattern caused by quasi-vacuum oscillations in the oscillated antineutrino spectrum at a baseline of 52.5~km and is completely independent of the CP violating phase and the neutrino mixing angle . The sensitivity is obtained through a joint analysis of JUNO and TAO detectors utilizing the best available knowledge to date about the location and overburden of the JUNO experimental site, the local and global nuclear reactors, the JUNO and TAO detectors responses, the expected event rates and spectra of signal and backgrounds, and the systematic uncertainties of the analysis inputs. It is found that a 3 median sensitivity to reject the wrong mass ordering hypothesis can be reached with an exposure of about 6.5 years 26.6~GW thermal power
Probing strangeness hadronization with event-by-event production of multistrange hadrons
No full textInternational audienceThis Letter presents the first measurement of event-by-event fluctuations of the net number (difference between the particle and antiparticle multiplicities) of multistrange hadrons and and its correlation with the net-kaon number using the data collected by the ALICE Collaboration in pp, pPb, and PbPb collisions at a center-of-mass energy per nucleon pair . The statistical hadronization model with a correlation over three units of rapidity between hadrons having the same and opposite strangeness content successfully describes the results. On the other hand, string-fragmentation models that mainly correlate strange hadrons with opposite strange quark content over a small rapidity range fail to describe the data
From Nuclear Waste to Hydrogen Production: From Past Consequences to Future Prospect
No full textInternational audienceNuclear wastes may not be considered as unusable materials in the sense that they deliver a free source of energyunder the form of ionizing radiations that can be used to produce hydrogen (H2) through water radiolysis. Thecurrent paradigm that define these nuclear wastes as troublesome by-products which no one uses nowadays mustbe shifted into a new opportunity for pure H2 production with no CO2 emission. Here, we propose a low-techmethod to boost H2 production by water radiolysis thanks to the catalytic effect of a suspension of TiO2 nano-particles. We also demonstrate the relevance of this concept by scaling up our laboratory results. From ourcalculations, this radiocatalytic process can supply until 60% of the actual global demand in hydrogen (42.9MtH2.y-1) and open the door, together with the green and white hydrogen productions, to the “Hydrogencentury
Femtoscopic correlations of identical charged pions and kaons in pp collisions at TeV with event-shape selection
No full textInternational audienceCollective behavior has been observed in high-energy heavy-ion collisions for several decades. Collectivity is driven by the high particle multiplicities that are produced in these collisions. At the Large Hadron Collider (LHC), features of collectivity have also been seen in high-multiplicity proton-proton collisions that can attain particle multiplicities comparable to peripheral Pb-Pb collisions. One of the possible signatures of collective behavior is the decrease of femtoscopic radii extracted from pion and kaon pairs emitted from high-multiplicity collisions with increasing pair transverse momentum. This decrease can be described in terms of an approximate transverse mass scaling. In the present work, femtoscopic analyses are carried out by the ALICE collaboration on charged pion and kaon pairs produced in pp collisions at TeV from the LHC to study possible collectivity in pp collisions. The event-shape analysis method based on transverse sphericity is used to select for spherical versus jet-like events, and the effects of this selection on the femtoscopic radii for both charged pion and kaon pairs are studied. This is the first time this selection method has been applied to charged kaon pairs. An approximate transverse-mass scaling of the radii is found in all multiplicity ranges studied when the difference in the Lorentz boost for pions and kaons is taken into account. This observation does not support the hypothesis of collective expansion of hot and dense matter that should only occur in high-multiplicity events. A possible alternate explanation of the present results is based on a scenario of common emission conditions for pions and kaons in pp collisions for the multiplicity ranges studied
Higgs interference effects in top-quark pair production in the 1HSM
No full textInternational audienceWe present a next-to-leading-order (NLO) study of the process in the 1-Higgs-singlet extension of the Standard Model with an additional heavy Higgs boson that mixes with the light Higgs boson . This process is subject to large interference effects between loop-induced Higgs-mediated amplitudes and the QCD continuum background which tend to overcompensate any resonance contributions. A reliable modelling of the resulting top-pair invariant mass shapes requires the inclusion of higher-order QCD corrections, which are presented here. The computation of these NLO corrections is exact in all contributions but in the class of non-factorisable two-loop diagrams which are included in an approximate way such that all infrared singular limits are preserved. We present numerical results for several benchmark points with heavy Higgs masses in the range -- GeV considering the production of stable top quarks. We find that the interference effects dominate the BSM signal yielding sharp dip structures instead of resonance peaks. The significance and excludability of the BSM effect is explored for the LHC Run 2, Run 3 and HL-LHC