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Definition and characterization of refueling equilibrium for batch-operated molten salt reactors
No full textInternational audienceThis paper presents a definition of the refueling equilibrium for batch-operated molten salt reactors (MSR). Batch-operated MSR are molten salt reactors for which the refueling option considered is not continuous but batch-wise. In the present work, the molten salt reactor considered is the ARAMIS-A burner reactor, developed within the ISAC (Innovative System for Actinide Conversion) project. This project involves the main contributors of the French nuclear field: CEA, CNRS, EDF, Framatome and Orano. The study of the equilibrium cycle is relevant to evaluate a certain loading strategy for a specific reactor design, notably in terms of fuel fabrication, operating costs, fuel cycle analysis and waste management. Refueling equilibrium is reached when, for a fixed feed-salt, full end of cycle (EOC) in-salt atomic compositions do not vary one from another. In this paper, it is demonstrated that equilibrium compositions depend only on feed-salt properties and a direct method for equilibrium computation is studied. Last, data-sets of equilibrium composition are generated and deep learning models (multilayer perceptrons, a.k.a MLP) are trained so as to provide satisfactory estimation of the equilibrium associated to the fuel composition in the feed-salt. Such MLP models provide precise estimations for dynamic fuel cycle simulation analysis
Proton beam monitoring through water scintillation in radiobiology experiments
No full textInternational audienceNon-invasive methods based on the detection of secondary particles generated in the irradiated medium are being investigated to monitor ion beams without disturbing the beam. This study investigates the use of water scintillation as a beam monitoring tool, taking into account the challenges posed by the radiobiology experiment constraints. An experimental setup has been designed to measure the depth deposited energy profile produced by protons of (67.5 ± 0.4) MeV entering a water tank, through the water scintillation detected with a photomultiplier. The beam current during the experiment was around 100 pA, and beam intensity fluctuations were monitored using a parallel plate ionization chamber and a Faraday cup. The experiment was repeated with a second ionization chamber as a reference detector placed inside the water tank, and simulated with the GATE Monte Carlo code. The position of the Bragg peak, measured with the water scintillation, shows significant agreement (deviation of 0.5 mm) with the positions obtained from the ionization chamber and the Monte Carlo simulation within a submillimeter uncertainty. The ionization quenching effect was also observed and corrected using the Birks and Chou models. A new value of the key parameter for these models (k · B = (8.0 ± 4.0) × 10−3 g/MeV.cm2) has been determined for water, which is in good agreement with the data available in the literature for organic scintillators. This study demonstrated the feasibility of using water scintillation measured with a collimated photomultiplier as a tool for monitoring the depth deposited energy profile in water. •Water scintillation is used to monitor proton beams in radiobiological experiment.•The Bragg peak is localized with submillimeter uncertainty.•The Chou model allows for correction of ionization quenching for water.•The Birks and Chou parameters were determined for water
The Three-Body Limit Cycle: Universal Form for General Regulators
No full textInternational audienceThe Efimov effect, a remarkable realization of discrete scale invariance, emerges in the three-body problem with short-range interactions and is understood as a renormalization group (RG) limit cycle within Short-Range Effective Field Theory (SREFT). While the analytic form of the three-body renormalization relation has been established for a sharp cutoff regulator, its universality for other regulators remains underexplored. In this letter, we derive the universal functional form of the three-body renormalization relation for general separable regulators through a detailed analysis of the Skorniakov-Ter-Martirosian and Faddeev equations. We find that the relation is characterized by three parameters. This universality is verified numerically for various regulators. Although the functional form remains the same, the parameters characterizing the limit cycle exhibit regulator dependence. These findings broaden the class of RG limit cycles in SREFT and offer a more complete understanding of three-body renormalization
On the contribution from the light quarks to
No full textInternational audienceThis Letter addresses the contribution from the light quarks to the amplitudes for the decay modes of the Brout-Englert-Higgs scalar boson into two photons () or to a photon and a neutral weak gauge boson (), taking into account the non-perturbative aspects of QCD. Contrary to a recent claim, the contribution from the light quarks does not vanish. Rather, it is shown that, in contrast to the perturbative evaluations usually considered in the literature, this contribution to the amplitudes starts with a term that is linear, and not quadratic, in the masses of the light quarks, thus pointing toward a sizeable enhancement of their contribution to
Observational strategies for ultrahigh-energy neutrinos: the importance of deep sensitivity for detection and astronomy
No full textInternational audienceDetecting ultrahigh-energy neutrinos can take two complementary approaches with different trade-offs. 1)~Wide and shallow: aim for the largest effective volume, and to be cost-effective, go for wide field-of-view but at the cost of a shallow instantaneous sensitivity -- this is less complex conceptually, and has strong discovery potential for serendipitous events. However, it is unclear if any source can be identified, following detection. And 2)~Deep and narrow: here one uses astrophysical and multi-messenger information to target the most likely sources and populations that could emit neutrinos -- these instruments have deep instantaneous sensitivity albeit a narrow field of view. Such an astrophysically-motivated approach provides higher chances for detection of known/observed source classes, and ensures multi-messenger astronomy. However, it has less potential for serendipitous discoveries. In light of the recent progress in multi-messenger and time-domain astronomy, we assess the power of the deep and narrow instruments, and contrast the strengths and complementarities of the two detection strategies. We update the science goals and associated instrumental performances that envisioned projects can include in their design in order to optimize discovery potential
Synchrotron-based infrared microspectroscopy study on the biomolecular impact of carbon minibeam radiation therapy on a mouse osteosarcoma cell line
No full textInternational audienceCarbon minibeam radiation therapy (CMBRT) is a novel oncology treatment modality that combines the superior radiobiological properties of carbon ions with the remarkable tissue-sparing effects of spatial dose fractionation. Nevertheless, the differential biological mechanisms that CMBRT activates are not fully understood. To shed further light on such biomolecular processes, this study analysed the impact of CMBRT on LM8 osteosarcoma cells using synchrotron-based infrared microspectroscopy (SR-FTIRM). Samples were subjected to conventional carbon RT (CBB) and CMBRT at GSI (Germany). RT-treated cells underwent SR-FTIRM evaluations at ALBA Synchrotron (Spain) at 24 h post-RT. Principal component analysis (PCA) uncovered the main spectral differences between the treatment modalities, revealing that the IR signatures of CMBRT-treated samples were the most dissimilar from Control cells. Modifications of IR peaks attributed to -helical and -sheet protein sub-structures were consistent with the alterations of the Amide I spectral band due to CMBRT (assessed via curve-fitting analysis), suggesting enhanced protein oxidation. Conformational alterations in the sugar-phosphate backbone of nucleic acids might also have resulted from further oxidative damage due to CMBRT. Additionally, CMBRT led to greater alterations of methylene and methyl bands compared to CBB, which may have been caused by free radical attacks. Spectral signatures in the CMBRT valleys differed from those in the CMBRT peaks, suggesting distinct biomolecular mechanisms involved in these two dose regions. Comparison with proton and neon irradiations revealed common IR features affected by MBRT modalities
Radiobiology Contributions and Perspectives in Hadron Therapy, with a focus on carbon ions: Report from the workshop Hadron therapy for life, Caen, March 2025
No full textISTCTInternational audienceThe "Hadrontherapy for Life" symposium in Caen, France highlighted that a new era of radiobiology is fundamental for advancing particle therapy to the next level. A radiobiology capable of integrating molecular biology and omics technologies is needed to deeply analyze treatment responses and underlying mechanisms.Key challenges discussed at the symposium included tumor hypoxia, which remains only partially mitigated by high-LET radiation, and the specificity of carbon ions, or more broadly, high LET particles, considered as "new drugs" capable of providing systemic benefits beyond local tumor control, including their potential to promote immunogenicity. Moreover, emerging modalities, such as Ultra High Dose Rate irradiation, and spatial fractionated beam were also discussed, with consensus that all require dedicated and coordinated radiobiological investigations.Infrastructure presentations highlighted the international capabilities of leading centers in Europe and Asia, emphasizing the importance of integrating radiobiology into clinical programs, advancing multi-ion experimentation, and adopting innovative experimental models, such as organoids and/or 3D cell cultures. Participants also stressed the need for greater access to animal experimentation facilities, which are essential for accelerating progress in the field. Furthermore, the meeting underscored translational endpoints such as biomarker development, a hot topic in current radiotherapy. The C400 accelerator enables Caen to incorporate radiobiology from its very inception, establishing a European hub for collaborative research. Round-table discussions emphasized the importance of harmonized protocols, dedicated in vivo irradiation rooms, international training programs with exchange of students and researchers, and comprehensive patient biobanking.In summary, the symposium reinforced the essential role of radiobiology in advancing hadrontherapy (HT), providing strategic directions for translational research, infrastructure development, and international collaborations to accelerate personalized and effective particle therapy
Slug flow boiling in microchannels at high vapour volume fraction
No full textInternational audienceIn this work, we experimentally study the thermal performance and bubbly flow characteristicsof convective boiling inside a multi-microchannel exchanger operated in slug flow regime at highvapour volume fraction with CO2 as the working fluid. To that purpose, flow regime and heattransfer are characterised for a silicon/pyrex heat exchanger containing 16 parallel microchannelsof hydraulic diameter 183 μm, for saturation temperatures close to −35◦C, mass fluxes between258 kg/(m2s) and 537 kg/(m2s), heat fluxes range 12.7 − 69 kW/m2 and inlet vapour volumefraction ranging from 68% up to 85%. The investigated boiling flow is characterised by a laminarregime, a high confinement, a small Capillary number (Ca < 0.036) and a Jakob number rangeof 0.1 ≤ Ja ≤ 1. At high vapour volume fraction, the heat transfer is found to be monitored bythe heat transport in the liquid film forms between bubbles and the wall because the contact timewith bubbles (and liquid film) is much larger than the contact time with liquid slugs. In addition,since at wall the film velocity vanishes because of adherence, experimental Nusselt numbers arefound to be close to the one predicted by the pure heat conduction problem in the liquid film. Thisbehaviour explains why the experimental heat transfer coefficient is systematically degraded whenthe flow velocity and the liquid film thickness increase together. This study represents the firstmeasurement of heat transfer coefficients for CO2 boiling flow below −30◦C and for an hydraulicdiameter below 200 μm. Such a silicon exchanger design can be useful for the direct cooling ofCMOS sensors at negative temperatures without thermal interface between the refrigerant and thesubstrate
Can galactic magnetic fields diffuse into the voids?
No full textInternational audienceCosmic voids are magnetized at the level of at least G on Mpc scales, as implied by blazar observations. We show that an electrically conducting plasma is present in the voids, and that, because of the plasma, \emph{diffusion} into the voids of galactic fields generated by a mean-field dynamo is far too slow to explain the present-day void magnetization. Indeed, we show that even in the presence of turbulence in the voids, dynamo-generated galactic fields diffuse out to a galactocentric radius of only 200-400 kpc. Therefore, it is challenging to meet the required volume filling-factor of the void magnetic field. We conclude that a primordial origin remains the most natural explanation to the space-filling weak fields in voids
Probing Cosmic Expansion and Early Universe with Einstein Telescope
No full textInternational audienceOver the next two decades, gravitational-wave (GW) observations are expected to evolve from a discovery-driven endeavour into a precision tool for astrophysics, cosmology, and fundamental physics. Current second-generation ground-based detectors have established the existence of compact-binary mergers and enabled GW multi-messenger astronomy, but they remain limited in sensitivity, redshift reach, frequency coverage, and duty cycle. These limitations prevent them from addressing many fundamental open questions in cosmology. By the 2040s, wide-field electromagnetic surveys will have mapped the luminous Universe with unprecedented depth and accuracy. Nevertheless, key problems including the nature of dark matter, the physical origin of cosmic acceleration, the properties of gravity on cosmological scales, and the physical conditions of the earliest moments after the Big Bang will remain only partially constrained by electromagnetic observations alone. Progress on these fronts requires access to physical processes and epochs that do not emit light. Gravitational waves provide a unique and complementary observational channel: they propagate over cosmological distances largely unaffected by intervening matter, probe extreme astrophysical environments, and respond directly to the geometry of spacetime. In this context, next-generation GW observatories such as the Einstein Telescope (ET) will be transformative for European astronomy. Operating at sensitivities and frequencies beyond existing detectors, ET will observe binary black holes and neutron stars out to previously inaccessible redshifts, enable continuous high signal-to-noise monitoring of compact sources, and detect gravitational-wave backgrounds of astrophysical and cosmological origin. Together with space-based detectors, ET will play a central role in advancing our understanding of cosmic evolution and fundamental physics