Ultra-sensitive radon assay using an electrostatic chamber in a recirculating system

International audienceRare event searches such as neutrinoless double beta decay and Weakly Interacting Massive Particle detection require ultra-low background detectors. Radon contamination is a significant challenge for these experiments, which employ highly sensitive radon assay techniques to identify and select low-emission materials. This work presents the development of ultra-sensitive electrostatic chamber (ESC) instruments designed to measure radon emanation in a recirculating gas loop, for future lower background experiments. Unlike traditional methods that separate emanation and detection steps, this system allows continuous radon transport and detection. This is made possible with a custom-built recirculation pump. A Python-based analysis framework, PyDAn, was developed to process and fit time-dependent radon decay data. Radon emanation rates are given for various materials measured with this instrument. A radon source of known activity provides an absolute calibration, enabling statistically-limited minimal detectable activities of 20 $\mu$Bq. These devices are powerful tools for screening materials in the development of low-background particle physics experiments

Dataset of artefacts for machine learning applications in astronomy

International audienceAccurate photometry in astronomical surveys is challenged by image artefacts, which affect measurements and degrade data quality. Due to the large amount of available data, this task is increasingly handled using machine learning algorithms, which often require a labelled training set to learn data patterns. We present an expert-labelled dataset of 1127 artefacts with 1213 labels from 26 fields in ZTF DR3, along with a complementary set of nominal objects. The artefact dataset was compiled using the active anomaly detection algorithm PineForest, developed by the SNAD team. These datasets can serve as valuable resources for real-bogus classification, catalogue cleaning, anomaly detection, and educational purposes. Both artefacts and nominal images are provided in FITS format in two sizes (28 x 28 and 63 x 63 pixels). The datasets are publicly available for further scientific applications

Simulation of irradiated hybrid planar pixels modules at fluences expected at HL-LHC

International audienceSignal loss is the main limitation on tracking/vertexing performance due to radiation damage effect to hybrid pixel detectors when irradiated at fluences expected at High Luminosity LHC (HL-LHC). It is important to have reliable predictions on the charge collection performance after irradiation in order to predict operational voltage values and test tracking algorithms robustness. In this paper the validation of combined TCAD and Monte Carlo simulations of hybrid silicon planar pixels sensors will be presented. In particular different trapping models will be compared to identify the one giving the best predictions. Eventually predictions on the collected charge performance of planar pixels modules at HL-LHC will be discussed

Definition and characterization of refueling equilibrium for batch-operated molten salt reactors

International 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

Search for Magnetic Monopoles with the Complete ANTARES Dataset

International audienceThis study presents a novel search for magnetic monopoles using data collected over a 14 year period (2008-2022) by the ANTARES neutrino telescope. The interaction of magnetic monopoles with matter was modeled according to Kazama, Yang, and Goldhaber cross-section. Upper limits on the flux of magnetic monopoles are obtained for velocities both above and below the Cherenkov threshold. No events consistent with the passage of magnetic monopoles were detected, enabling the setting of an upper flux limit for relativistic magnetic monopoles of the order of $10^{-18} \mathrm{cm}^{-2} \mathrm{s}^{-1} \mathrm{sr}^{-1}$

Development of the Range Counter for the COMET Phase-α\alpha Experiment

International audienceThe COMET Phase-$\alpha$ experiment aims to evaluate the novel muon transport beamline for the muon-to-electron conversion search at J-PARC, Japan. A dedicated Range Counter (RC) was developed to measure the momentum spectrum of transported negative muons with momenta of 30--100 MeV/$c$. The RC consists of graphite momentum degraders, a muon absorber, and plastic scintillation counters ($\rm T_0$, $\rm T_1$, and $\rm T_2$) to detect decay-in-orbit (DIO) electrons from stopped muons. The number of muons stopped in the absorber is reconstructed from the decay time distribution. A copper absorber was selected due to the short lifetime of muonic atoms in copper, which enhances signal separation. The counters' performance was evaluated experimentally. The $\rm T_0$ Counter, made of a $200\times 200\times 0.5~{\rm mm^3}$ scintillator plate, achieved a muon-trigger efficiency exceeding 99.9%. The $\rm T_1$ and $\rm T_2$ Counters also demonstrated high electron-detection efficiencies of $>99$%. Based on these results, simulation studies estimate the acceptance for reconstructing the number of DIO electrons from the absorber to be approximately 47% with a corresponding signal purity of 60% against muon capture-induced backgrounds

The High Voltage Splitter board for the JUNO SPMT system

International audienceThe Jiangmen Underground Neutrino Observatory (JUNO) in southern China is designed to study neutrinos from nuclear reactors and natural sources to address fundamental questions in neutrino physics. Achieving its goals requires continuous operation over a 20-year period. The small photomultiplier tube (small PMT or SPMT) system is a subsystem within the experiment composed of 25600 3-inch PMTs and their associated readout electronics. The High Voltage Splitter (HVS) is the first board on the readout chain of the SPMT system and services the PMTs by providing high voltage for biasing and by decoupling the generated physics signal from the high-voltage bias for readout, which is then fed to the front-end board. The necessity to handle high voltage, manage a large channel count, and operate stably for 20 years imposes significant constraints on the physical design of the HVS. This paper serves as a comprehensive documentation of the HVS board: its role in the SPMT readout system, the challenges in its design, performance and reliability metrics, and the methods employed for production and quality control

Strongly interacting matter in extreme magnetic fields

International audienceMagnetic fields are ubiquitous across different physical systems of current interest; from the early Universe, compact astrophysical objects and heavy-ion collisions to condensed matter systems. A proper treatment of the effects produced by magnetic fields during the dynamical evolution of these systems, can help to understand observables that otherwise show a puzzling behavior. Furthermore, when these fields are comparable to or stronger than Λ_QCD, they serve as excellent probes to help elucidate the physics of strongly interacting matter under extreme conditions of temperature and density. In this work we provide a comprehensive review of recent developments on the description of QED and QCD systems where magnetic field driven effects are important. These include the modification of meson static properties such as masses and form factors, the chiral magnetic effect, the description of anomalous transport coefficients, superconductivity in extreme magnetic fields, the properties of neutron stars, the evolution of heavy-ion collisions, as well as effects on the QCD phase diagram. We describe recent theory and phenomenological developments using effective models as well as LQCD methods. The work represents a state-of-the-art review of the field, motivated by presentations and discussions during the "Workshop on Strongly Interacting Matter in Strong Electromagnetic Fields" that took place in the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*) in the city of Trento, Italy, September 25-29, 2023

Do penguins care about on-paper boundaries? Conservation implications of spatio-temporal winter consistency in an Antarctic sentinel species

International audienceUnderstanding the spatial and temporal at-sea distribution of marine predators throughout their annual cycle is crucial for identifying priority areas for conservation in the Southern Ocean. However, the delimitation of boundaries of the proposed East Antarctic Marine Protected Area (EAMPA) is largely based on species' breeding distributions, overlooking seasonal and annual shifts driven by sea ice variability. We studied the non-breeding distribution and space use of a key Antarctic eco-indicator species, the Adélie penguin, by tracking 62 individuals from Terre Adélie over five years using geolocators. Moulting occurred in areas of low sea ice concentration (SIC), whereas during winter, penguins migrated on average 1550 km westward from the colony to areas along the sea ice edge with high SIC (75 %). The inter-annual overlap of wintering grounds revealed high spatiotemporal consistency, indicating productive regions. Despite variability across years, tracked individuals moulted predominantly outside the proposed EAMPA, and only 16.3 % of winter locations fell within its boundaries. These findings provide new insights into the non-breeding ecology of Adélie penguins, and highlight a relevant gap in spatial coverage of critical moulting and wintering areas of this highly mobile species in the current EAMPA proposal

Proton beam monitoring through water scintillation in radiobiology experiments

International 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