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Measurement of the Cm neutron capture cross section at the n_TOF facility at CERN
No full textInternational audienceAccurate neutron capture cross section data for minor actinides are essential for the safe and efficient management of high level radioactive waste produced during the operation of nuclear reactors. In particular, 244Cm, with a half-life of 18.11 years, dominates neutron emission in spent fuel and also contributes significantly to the decay heat and radiotoxicity. Furthermore, neutron capture on 244Cm opens the pathway for the formation of heavier isotopes such as Bk, Cf, and other Cm isotopes. Sensitivity studies for present and future nuclear reactors have highlighted the need to reduce the uncertainties in the 244Cm capture cross section. Experimental data on the capture cross section of this isotope are scarce due to the challenges associated with its measurements. Prior to the presented measurement and two recent measurements conducted at J-PARC, only one set of data for the 244Cm capture cross section existed, obtained in 1969 during an underground nuclear explosion experiment. The capture cross section of 244Cm has been measured at the n_TOF facility at CERN with three different experimental setups: one at Experimental Area 1 (EAR1) using the Total Absorption Calorimeter and two measurements at Experimental Area 2 (EAR2) with CD detectors, employing two different samples. The results from these three measurements were found to be compatible and then combined. In total, 17 resonances of 244Cm were measured at n_TOF below 300 eV. The radiative kernels obtained in this measurement are in good agreement with JENDL-4.0 for the majority of the resonances. Additionally, they are compatible with the recent JENDL-5 library below 50 eV, while at higher energies, the majority of radiative kernels from this evaluation based on the recent measurement by Kawase et al., are not compatible. Additionally, the 244Cm samples also contained 240Pu. Resonances of this isotope were analyzed in the energy range between 20 and 180 eV, and the results were found to be consistent with previous measurements and evaluations, that enhances confidence in the 244Cm results
Constraining capture cross sections using proton inelastic scattering as a surrogate reaction
No full textInternational audienceThe surrogate reaction method is an alternative to direct measurements of compound nuclear reaction cross sections. We introduce theory tools for extracting capture cross sections from experiments that use proton inelastic scattering as a surrogate reaction mechanism. This makes it possible to constrain compound nucleus decay models which are typically the largest source of uncertainty in capture cross section calculations. This letter describes the theory developments that were used to simultaneously infer Y and Zr cross sections from Zr surrogate measurements
Le spectromètre de neutrons à focalisation temporelle SHARP
No full textInternational audienceSHARP (Spectromètre Hybride Alpes Région Parisienne) is a new-generation time-of-flight neutron spectrometer installed at the Institut Laue-Langevin (ILL). It is designed to investigate dynamical processes in condensed matter with high energy resolution and broad experimental versatility. Developed as a complete upgrade of the former IN6 instrument, SHARP addresses key scientific challenges in soft matter, biology, energy materials, and solid-state physics, where precise measurements of atomic and molecular motions are essential. The main design objective is to achieve a higher counting rate while maintaining the IN6 strong neutron flux, by providing wide angular and energy coverage through multiple take-off angle geometries. Notable features include a fully vacuum-compatible secondary spectrometer, a retractable sample window allowing the detector tank to remain under vacuum while enabling experiments requiring controlled sample environments, and a bank of 240 position-sensitive 3 He detectors operating at 5 bar, ensuring enhanced spectral spatial definition. Compared to IN6, SHARP delivers a twofold increase in counting rate in the elastic region and a lower background. This paper outlines the scientific motivations behind the SHARP project, describes the main instrumental innovations, and demonstrates the instrument's performance through initial scientific results on molecular diffusion in zeolite, determinant of the selectivity of these materials for use in membrane-based gas separations.SHARP (Spectromètre Hybride Alpes Région Parisienne) est un spectromètre de neutrons à temps de vol de nouvelle génération installé à l’Institut Laue-Langevin (ILL). Il est conçu pour étudier les processus dynamiques dans la matière condensée avec une haute résolution en énergie et une grande polyvalence expérimentale. Développé comme une mise à niveau complète de l’ancien instrument IN6, SHARP répond à des défis scientifiques majeurs en matière de matière molle, biologie, matériaux pour l’énergie et physique du solide, où des mesures précises des mouvements atomiques et moléculaires sont essentielles.L’objectif principal de conception est d’obtenir un taux de comptage plus élevé tout en maintenant le fort flux de neutrons d’IN6, grâce à une large couverture angulaire et énergétique permise par plusieurs géométries d’angles de réflexion. Parmi les caractéristiques notables figurent un spectromètre secondaire entièrement compatible avec le vide, une fenêtre d’échantillon rétractable permettant de maintenir la cuve des détecteurs sous vide tout en réalisant des expériences nécessitant un environnement contrôlé autour de l’échantillon, ainsi qu’un ensemble de 240 détecteurs ³He sensibles à la position opérant à 5 bars, offrant une meilleure définition spatiale du spectre.Comparé à IN6, SHARP fournit un taux de comptage doublé dans la région élastique et un bruit de fond réduit. Cet article expose les motivations scientifiques du projet SHARP, décrit les principales innovations instrumentales, et démontre les performances de l’instrument à travers des premiers résultats scientifiques sur la diffusion moléculaire dans une zéolithe, déterminante pour la sélectivité de ces matériaux utilisés dans les séparations de gaz par membranes
Spectroscopy and complex-time correlations using minimally entangled typical thermal states
No full text15 pages, 15 figuresInternational audienceTensor network states have enjoyed great success in capturing aspects of strong correlation physics. However, obtaining dynamical correlators at nonzero temperatures is generically hard even using these methods. Here, we introduce a practical approach to computing such correlators using minimally entangled typical thermal states (METTS). While our primary method directly computes dynamical correlators of physical operators in real time, we propose extensions where correlations are evaluated in the complex-time plane. The imaginary time component bounds the rate of entanglement growth and strongly alleviates the computational difficulty allowing the study of larger system sizes. To extract the physical correlators, one must take the limit of purely real-time evolution. We present two routes for obtaining this information: (i) via an analytic correlation function in complex time combined with a stochastic analytic continuation method to obtain the real-time limit and (ii) a Hermitian correlation function that asymptotically captures the desired correlation function quantitatively. We show that these numerical techniques capture the finite-temperature dynamics of the Shastry-Sutherland model—a model of interacting spins one-half in two spatial dimensions
Using thin AZO layers coupled with SiNx:H as a way to decrease Indium consumption in SHJ cells and modules
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TCT-based monitoring of LGAD radiation hardness for ATLAS-HGTD production
No full textInternational audienceProduction of the High Granularity Timing Detector for the ATLAS experiment at High Luminosity LHC requires over 21000 silicon sensors based on Low Gain Avalanche Diode (LGAD) technology. Their radiation hardness is monitored as a part of the production quality control. Dedicated test structures from each wafer are irradiated with neutrons and a fast and comprehensive characterization is required. We introduce a new test method based on Transient Current Technique (TCT) performed in the interface region of two LGAD devices. The measurement enables extraction of numerous sensor performance parameters, such as LGAD gain layer depletion voltage, LGAD gain dependence on bias voltage, sensor leakage current and effective interpad distance. Complementary capacitance-voltage measurements and charge collection measurements with 90Sr on the same samples have been performed to calibrate the TCT results in terms of charge collection and define acceptance criteria for wafer radiation hardness in the ATLAS-HGTD project
A model-independent measurement of the CKM angle in the decays and ()
No full textInternational audienceA model-independent determination of the CKM angle is presented, using the and decays, with . This measurement is the first phase-space-binned study of these decay modes, and uses a sample of proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of fb. The phase-space bins are optimised for sensitivity to , and in each bin external inputs from the BESIII experiment are used to constrain the charm strong-phase parameters. The result of this binned analysis is , where the uncertainty includes both statistical and systematic contributions. Furthermore, when combining with existing phase-space-integrated measurements of the same decay modes, a value of is obtained, which is one of the most precise determinations of to date
Observation of production in collisions at = 13 TeV with the ATLAS detector and constraints on anomalous quartic gauge-boson couplings
No full textInternational audienceThis Letter reports the observation of triboson production in 140 fb of data collected by the ATLAS detector from proton-proton collisions at a centre-of-mass energy of = 13 TeV at the LHC. Events with an opposite-charge pair, a high transverse-momentum photon, and significant missing transverse momentum are considered. The observed (expected) significance of the signal is 5.9 (6.0) standard deviations. The measured fiducial cross-section, defined for the final state is 6.2 0.8 (stat.) 0.6 (sys.) fb, in good agreement with the Standard Model prediction of 6.1 fb. Constraints on the Wilson coefficients of 13 dimension-8 operators describing physics beyond the Standard Model through anomalous quartic gauge-boson couplings are derived using the effective field theory framework
Decay spectroscopy of heavy and superheavy nuclei
No full textInternational audienceAfter more than half a century afte the first predictions of the so-called {\it "island of stability of superheavy nuclei"}, exploring the limits of nuclear stability at highest atomic numbers is still one of the most prominent challenges in low-energy nuclear physics. These exotic nuclear species reveal their character and details of some of their properties by their induced or spontaneous disintegration. The achievements in the field superheavy nuclei (SHN) research have been reported in a number of review papers throughout the decades. This review is an attempt to summarize the progress that has been made in recent years by employing the versatile tool park of Decay Spectroscopy After Separation (DSAS) for the heaviest isotopes from =99 (einsteinium) to =118 (oganesson). In addition, references to earlier reviews and the relevant papers, together with the major decay properties of all these isotopes are given
The Online Data Filter for the KM3NeT Neutrino Telescopes
No full textInternational audienceThe KM3NeT research infrastructure comprises two neutrino telescopes located in the deep waters of the Mediterranean Sea, namely ORCA and ARCA. KM3NeT/ORCA is designed for the measurement of neutrino properties and KM3NeT/ARCA for the detection of high\nobreakdashes-energy neutrinos from the cosmos. Neutrinos are indirectly detected using three\nobreakdashes-dimensional arrays of photo\nobreakdashes-sensors which detect the Cherenkov light that is produced when relativistic charged particles emerge from a neutrino interaction. The analogue pulses from the photo\nobreakdashes-sensors are digitised offshore and all digital data are sent to a station on shore where they are processed in real time using a farm of commodity servers and custom software. In this paper, the design and performance of the software that is used to filter the data are presented. The performance of the data filter is evaluated in terms of its purity, capacity and efficiency. The purity is measured by a comparison of the event rate caused by muons produced by cosmic ray interactions in the Earth's atmosphere with the event rate caused by the background from decays of radioactive elements in the sea water and bioluminescence. The capacity is measured by the minimal number of servers that is needed to sustain the rate of incoming data. The efficiency is measured by the effective volumes of the sensor arrays