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The evolution of the transverse-momentum dependent gluon distribution at small
No full textInternational audienceUsing the colour dipole picture for photon-nucleus interactions at small together with the Color Glass Condensate (CGC) effective theory, we demonstrate that the next-to-leading (NLO) order corrections to the cross-section for the inclusive production of a pair of hard jets encode not only the JIMWLK evolution with decreasing , but also the DGLAP evolution of the gluon distribution function and the CSS evolution of the gluon transverse momentum dependent (TMD) distribution. The emergent CSS equation takes the form of a rate equation describing the evolution of the dijet distribution in the transverse momentum imbalance when increasing the dijet relative momentum . All three types of evolution become important when both and are much larger than the nuclear saturation momentum and we propose a framework which encompasses all of them. The solution to the JIMWLK equation provides the source term for the DGLAP evolution with increasing , which in turn generates the initial condition for the CSS evolution with increasing
Model validation and interpretation of the interaction between glass and cement in an integrated glass dissolution experiment
No full textInternational audienceThis article presents the modeling results from the interaction between simulated nuclear waste glasses and ordinary Portland cement (OPC). In general, the modeling results are in good agreement with the experimental results. A diffusion-based glass dissolution model well describes the release of B and Li from the glass, and a reactive transport model well describes the profiles of dissolved glass elements in the cement. It is found that the effective diffusion coefficient of Li in the cement is much larger than that of B. Sorption of both Li and B onto the cement is required to better fit their measured diffusion profiles. For B profiles in the cement, one spatially uniform distribution coefficient is needed, while for Li, sorption needs to be linked to the gel-like secondary phase at the surface of the cement. The effective diffusion coefficients for both Li and B are relatively low and can be linked to the pore-filling effects of the gel-like secondary phase. Even though it is generally believed that nuclear waste glass will dissolve faster in cementitious environments, the results show that the gel-like secondary phase can both seal the cement and act as a strong sorbent for dissolved glass species, thus inhibiting the migration of dissolved glass species
Measurement of the impact-parameter dependent azimuthal anisotropy in coherent photoproduction in PbPb collisions at = 5.02 TeV
No full textInternational audienceThe first measurement of the impact-parameter dependent angular anisotropy in the decay of coherently photoproduced mesons is presented. The mesons are reconstructed through their decay into a pion pair. The measured anisotropy corresponds to the amplitude of the modulation, where is the angle between the two vectors formed by the sum and the difference of the transverse momenta of the pions, respectively. The measurement was performed by the ALICE Collaboration at the LHC using data from ultraperipheral PbPb collisions at a center-of-mass energy of TeV per nucleon pair. Different impact-parameter regions are selected by classifying the events in nuclear-breakup classes. The amplitude of the modulation is found to increase by about one order of magnitude from large to small impact parameters. Theoretical calculations, which describe the measurement, explain the anisotropy as the result of a quantum interference effect at the femtometer scale that arises from the ambiguity as to which of the nuclei is the source of the photon in the interaction
Prompt Gamma Energy Integration : a new method for online-range verification in proton therapy with pulsed-beams
No full textInternational audienceWe propose a method for prompt-gamma verification of proton range during particle therapy. This method, called Prompt-Gamma Energy Integration (PGEI), is based on the measurement of the total energy deposited in a set of detectors located around a patient. It is particularly suited in the case of high-instantaneous beam intensities, like for pulsed beams extracted from a synchro-cyclotron. GATE simulations show that millimetric range shifts can be measured at a beam-spot scale. The sensitivity is slightly degraded as compared to the Prompt-Gamma Peak Integration Method, for which Time-of-Flight can be employed to reduce the background in single-photon detection conditions at cyclotron accelerators. Experimentally, lead tungstate scintillators have shown to cope with the high instantaneous gamma count rates for PGEI at synchro-cyclotrons
Neutrinoless Double Beta Decay Sensitivity of the XLZD Rare Event Observatory
No full textInternational audienceThe XLZD collaboration is developing a two-phase xenon time projection chamber with an active mass of 60 to 80 t capable of probing the remaining WIMP-nucleon interaction parameter space down to the so-called neutrino fog. In this work we show that, based on the performance of currently operating detectors using the same technology and a realistic reduction of radioactivity in detector materials, such an experiment will also be able to competitively search for neutrinoless double beta decay in Xe using a natural-abundance xenon target. XLZD can reach a 3 discovery potential half-life of 5.710 yr (and a 90% CL exclusion of 1.310 yr) with 10 years of data taking, corresponding to a Majorana mass range of 7.3-31.3 meV (4.8-20.5 meV). XLZD will thus exclude the inverted neutrino mass ordering parameter space and will start to probe the normal ordering region for most of the nuclear matrix elements commonly considered by the community
Statistical approach to describe the properties of nanoporous carbons from lignin by chemical activation
No full textInternational audienceBlack liquor (BL), being a residue of pulp and paper industries, composed of lignin, sulphides and carbonates of alkaline metals. BL valorisation into activated carbon is one of the possible solutions to manage waste from the mentioned industry sectors. A number of studies from the literature reported the preparation of activated carbon from lignin through metallic salt and hydroxide activation. Relying on the existing massive experimental data set, this paper proposes regression models that describe the variation of the textural properties of lignin-derived activated carbon as a function of operation conditions, such as temperature, activation time and impregnation ratio for different activators (KOH, NaOH). Statistical significance of model parameters was verified by relying on results of t-test. Using the proposed models, it was highlighted that activation temperature and impregnation ratio parameters are the principal factors controlling the activation process, while activation time has less significant effect on the development of porous structure. Carbons produced by lignin activation in the presence of KOH exhibit higher specific surface area (SSA) and micropore volume (MPV) than NaOH-activated carbons and require shorter activation time to reach high porosity. KOH activation of lignin-derived char requires lower activation temperature in comparison with a direct KOH-activation of lignin
Model-independent searches of new physics in DARWIN with a semi-supervised deep learning pipeline
No full textInternational audienceWe present a novel deep learning pipeline to perform a model-independent, likelihood-free search for anomalous (i.e., non-background) events in the proposed next generation multi-ton scale liquid Xenon-based direct detection experiment, DARWIN. We train an anomaly detector comprising a variational autoencoder and a classifier on extensive, high-dimensional simulated detector response data and construct a one-dimensional anomaly score optimised to reject the background only hypothesis in the presence of an excess of non-background-like events. We benchmark the procedure with a sensitivity study that determines its power to reject the background-only hypothesis in the presence of an injected WIMP dark matter signal, outperforming the classical, likelihood-based background rejection test. We show that our neural networks learn relevant energy features of the events from low-level, high-dimensional detector outputs, without the need to compress this data into lower-dimensional observables, thus reducing computational effort and information loss. For the future, our approach lays the foundation for an efficient end-to-end pipeline that eliminates the need for many of the corrections and cuts that are traditionally part of the analysis chain, with the potential of achieving higher accuracy and significant reduction of analysis time
PRODUCTION OF PB-203: PATHWAY FROM TARGET MANUFACTURING TO CHEMICAL SEPARATION WTTC19 1
No full textInternational audienceLead-212 (t1/2 = 10.6 h) and lead-203 (t1/2 = 51.9 h), can be used as a pair of isotopes for theranostic applications in nuclear medicine. Pb-212 can be obtained from ageing 232Th and is used for targeting alpha-therapy [1] whereas Pb-203 can be produced by proton or deuteron irradiation of a thallium target and allows for single photon emission computed tomography (SPECT) thanks to its 279.2 keV (80.9%) photons. Current production of Pb-203 uses natural Tl, Tl-203, or Tl-205 bombarded by a proton beam. In this work, we consider alternative production routes using enriched Tl-205 and a deuteron beam in order to limit the level of Pb-201 (t1/2 = 9.33h) impurities and to avoid the production of Pb-200 (t1/2 = 21.5h). Cross section measurements were conducted to determine the optimal production parameters for achieving high purity Pb-203. Our specification for Pb-203 has been created. Furthermore, radiolabelling was tested with the DOTAM chelate and DOTATATE peptide.The electrodeposition technique is used to prepare enriched Tl targets for both cross section measurements and mass production. A pulse reverse potential is used to reduce Tl+ to Tl on gold substrate. The temperature and pH of the solution are fixed respectively at 20°C and 8. The solution contains EDTA as a complexing agent, hydrazine to prevent Tl+ from oxidation to Tl3+ and Brig-35 as a surfactant [3]. A Pb resin from Triskem is used to separate Tl and Pb yielding a high purity Pb-203 solution in ammonium acetate solution at 1 mol/l at pH 5. For the study of Pb-203 production cross sections and its impurities, thin deposits of Tl-205 (thicknesses ranging from 10 µm and 15 µm) with a circular shape (4 cm2) were made. Experiments were done with a deuteron beam whose energy is ranging from 22 MeV and 34 MeV. The production yields of Pb-203 and Pb-201 in the range of irradiation energy between 28.5 MeV – 31 MeV gives 52.4 MBq/µAh and 0.7 MBq/µAh, respectively [2]. The yield ratio of 1.4% for Pb-201 and Pb-203 at EOB (End Of Bombardment) is low, implying that Pb-203 purity will be greater than 99% several hours after cooling.For mass production, a large deposit of enriched Tl is needed (14 cm2 area) to reduce the heat deposition density. To this end, we are using our rabbit system that accommodates a 15° tilted angle target. A 40 µm thick deposit was successfully obtained with a smooth deposit and good adhesion on gold backing. Two columns containing Pb resin were required to prevent Tl from being detected by ICP-OES. Since September 2023, a monthly production has been held for 1 hour with 60 µA irradiation. At Calibration Time (CT - 2 days after EOB) Pb-203, radiopurity exceeded 99.5%, and all impurities were below the detection limit of γ-spectrometry, with the exception of Pb-201 (less than 0.5%). Furthermore, at CT, an average of 1500 MBq of Pb-203 activity was produced. Pb recovery ranged from 80% to 90%, with all impurities (Tl, Fe, Ni, and Au) in the Pb-containing solution falling below the detection limit. In parallel, the yield Tl recovery topped 90%, allowing it to be recycled.A comparison of the production yield ratios of Pb-203 or Pb-201 anticipated by cross section measurement and those measured since September 2023 shows a difference of 1% to 10%. These low numbers demonstrate that our computations can accurately estimate Pb-203 and Pb-201 activity outputs. A radiolabelling test using 250 MBq of Pb-203 per 100 µg of peptide, comparable to clinical trial conditions has been performed. The initial results showed that the radiochemical purity at the end of the synthesis was 99%. The stability of the reactive environment after 12 hours, 24 hours, and 96 hours are being conducted.All of these values show promise for large-scale manufacturing of high purity Pb-203, and the results will be discussed during my presentation.[1]E. Delpassand, I. Tworowska, R. Esfandiari, J. Torgue, J. D. Hurt, and R. Nunez, “Phase I dose-escalation study of AlphaMedix for targeted-alpha-emitter therapy of PRRT-naive neuroendocrine patients.,” JCO, vol. 39, no. 15_suppl, pp. 4117–4117, May 2021, doi: 10.1200/JCO.2021.39.15_suppl.4117.[2]T. Sounalet, A. Guertin, F. Haddad, K. Kamalakannan, and E. Nigron, “Production of 203Pb from enriched 205Tl using deuteron beams,” Applied Radiation and Isotopes, p. 111190, Jan. 2024, doi: 10.1016/j.apradiso.2024.111190.[3]T. Sounalet et al., “Manufacture of Tl targets by electrodeposition for the study of excitation functions of 203Pb,” EPJ Web Conf., vol. 285, p. 09001, 2023, doi: 10.1051/epjconf/202328509001
Methodology for small animals targeted irradiations at conventional and ultra-high dose rates 65 MeV proton beam
No full textInternational audienceAs part of translational research projects, mice may be irradiated on radiobiology platforms such as the one at the ARRONAX cyclotron. Generally, these platforms do not feature an integrated imaging system. Moreover, in the context of ultra-high dose-rate radiotherapy (FLASH-RT), treatment planning should consider potential changes in the beam characteristics and internal movements in the animal. A patient-like set-up and methodology has been implemented to ensure target coverage during conformal irradiations of the brain, lungs and intestines. In addition, respiratory cycle amplitudes were quantified by fluoroscopic acquisitions on a mouse, to ensure organ coverage and to assess the impact of respiration during FLASH-RT using the 4D digital phantom MOBY. Furthermore, beam incidence direction was studied from mice µCBCT and Monte Carlo simulations. Finally,in vivo dosimetry with dose-rate independent radiochromic films (OC-1) and their LET dependency were investigated. The immobilization system ensures that the animal is held in a safe and suitable position. The geometrical evaluation of organ coverage, after the addition of the margins around the organs, was satisfactory. Moreover, no measured differences were found between CONV and FLASH beams enabling a single model of the beamline for all planning studies. Finally, the LET-dependency of the OC-1 film was determined and experimentally verified with phantoms, as well as the feasibility of using these filmsin vivoto validate the targeting. The methodology developed ensures accurate and reproducible preclinical irradiations in CONV and FLASH-RT without in-room image guidance in terms of positioning, dose calculation and in vivo dosimetry
Exclusive four pion photoproduction in ultraperipheral Pb-Pb collisions at TeV
No full textInternational audienceThe intense photon fluxes from relativistic nuclei provide an opportunity to study photonuclear interactions in ultraperipheral collisions. The measurement of coherently photoproduced final states in ultraperipheral Pb-Pb collisions at TeV is presented for the first time. The cross section, d/d, times the branching ratio () is found to be mb in the rapidity interval . The invariant mass distribution is not well described with a single Breit-Wigner resonance. The production of two interfering resonances, and , provides a good description of the data. The values of the masses () and widths () of the resonances extracted from the fit are MeV/, MeV/, MeV/ and MeV/, respectively. The measured cross sections times the branching ratios are compared to recent theoretical predictions