As part of the FRATHEA project, the LNHB is tasked with developing primary absorbed-dose standards for very-high-energy electron beams (VHEE, > 50 MeV) delivered at ultra-high dose rates (FLASH), intended for applications in innovative radiotherapy.
The person appointed to this position will be involved in all stages of the development and transfer of these standards.
Postdoctoral open position at LNHB related to Dosimetry of VHEE beams for radiotherapy.
The position is based at DOSEO platform at the CEA Paris-Saclay site, France.
As part of an innovative radiotherapy project, FRATHEA, the laboratory is developing primary absorbed dose references for very high energy electron beams (VHEE, > 50 MeV) delivered at ultra-high dose rates (FLASH), for use in radiotherapy.
The dosimetry part of the project aims to ensure metrological traceability of dose measurements in these extreme beams by establishing primary standards and to achieve the transfer of these references to secondary standards (ionization chambers, diamond detectors, chemical or radiochromic dosimeters, etc.) adapted to the clinical environment.
The simulation of electromagnetic (EM) wave problems plays a key role in many fields, ranging from object characterization and inspection to radar stealth. A common approach consists in transforming the initial 3D volumetric problem into a 3D surface integral equation defined at material interfaces and discretizing it using a Boundary Element Method (BEM). High-order (HO) discretization schemes accelerate approximation convergence and thus provide a significant gain in accuracy for a given number of mesh elements, but complicates the assembly of the linear system. In particular, the calculation of singular and quasi-singular integrals becomes challenging, while the integration of HO methods into fast compression algorithms based on the hierarchical matrix formalism (HMAT) raises questions about the overall efficiency of the BEM. This postdoctoral position aims to address these in order to obtain a solution that is both efficient and robust for the targeted EM applications.
CEA-List is developing CIVA, a reference platform for non-destructive testing (NDT) simulations, particularly X-ray radiography using the Monte Carlo method.
The project aims to extend these capabilities to neutron imaging, which complements X-ray radiography due to its different sensitivity to chemical elements. The goal is to develop the necessary digital tools for industrial neutron imaging simulation, with an eventual link to an experimental platform.
The post-doctoral researcher will first work on implementing a simplified neutron imaging model for thermal and fast neutrons. Next, they will account for scattering effects using the Monte Carlo method, in collaboration with CEA DES. Finally, experimental validation will assess the model's ability to reproduce experimental observations, using existing data and data to be acquired on large instruments.
The project is cross-cutting across CEA-List/DRT, DES, and DRF, with exchanges focusing on the comparison of different neutron simulation codes.
This 12-month postdoctoral position focuses on X-ray metrology and spectrometry for medical imaging. The context is the need for beam-quality traceability, since current standards (IEC 61267) do not cover the new filtration combinations (silver, gold, tin) used in spectral computed tomography (sCT), a technique involved in over 60 million CT exams annually in Europe. The position comprises two independent strands. The first (tasks 1-3) covers drafting methodological guides, qualifying LNHB's two spectrometry benches (CdTe and HPGe), establishing new reference radiation conditions, on-site clinical measurements, and participation in an inter-laboratory comparison. The second strand (tasks 4-5) concerns an instrumented dosimeter dedicated to radiological imaging, stemming from a thesis currently being finalized: pre-series fabrication, calibration, full metrological characterization, clinical validation in a hospital setting, and building a demonstrator.
How do you predict a material's properties when the number of possible atomic configurations exceeds 2^2500? That is the bottleneck our IRESNE (nuclear fuel physics) and LIST (AI) teams have just cracked with PULSE, a generative (VAE) method published in Nature Scientific Reports, already cutting computational cost by more than two orders of magnitude (22,282 CPU hours down to 85 on a test case). With no known equivalent in the international literature, PULSE positions CEA as a pioneer in generative sampling of the configuration space of chemically disordered materials.
This 24-month postdoc gives you the opportunity to drive this method toward its next generation, leading three ambitious, parallel research axes: pushing model accuracy on systems of several thousand atoms with an IWAE architecture; equipping it with the ability to quantify its own uncertainty — a prerequisite for any use in nuclear safety; and, in the second year, tackling a high-value exploratory axis — generalizing PULSE to a continuous latent space, opening the door to any disordered crystal or alloy.
You will work at the heart of an all-CEA consortium bringing together two complementary strengths — atomistic nuclear fuel physics at IRESNE and state-of-the-art generative AI at LIST — with access to CEA supercomputers, the freedom to publish in top-tier journals, and the prospect of seeing your results feed directly into reactor safety analyses through the PLEIADES platform. A position built for a curious mind who wants to combine cutting-edge generative AI research with concrete impact on a strategic nuclear-energy challenge.
This postdoctoral position is offered by CEA List as part of the European UrbaQuantum project ("A novel, Integrated Approach to Urban Water Quality Monitoring, Management and Valorisation"), part of the HORIZON-CL6-2024-ZEROPOLLUTION-02 call for projects. The main objective of this project is to develop, in response to climate change, sensors, models, and protocols for better management of the water cycle in urban environments.
At the Sensors and Instrumentation for Measurement Laboratory (LCIM)of CEA List the postdoctoral fellow will contribute to the development of electrochemical sensors based on synthetic diamond and associated measurement protocols for the detection of pollutants such as pharmaceuticals, heavy metals, PFAS, and pesticides. These sensors will be miniaturized and integrated into a microfluidic cell, in partnership with CEA-Leti, then tested under real-world field conditions.
Cable faults are generally detected when communication is interrupted, resulting in significant repair costs and downtime. Additionally, data integrity becomes a major concern due to the increased threats of attacks and intrusions on electrical networks, which can disrupt communication. Being able to distinguish between disruptions caused by the degradation of the physical layer of an electrical network and an ongoing attack on the energy network will help guide decision-making regarding corrective operations, particularly network reconfiguration and predictive maintenance, to ensure network resilience. This study proposes to investigate the relationship between incipient faults in cables and their impact on data integrity in the context of Power Line Communication (PLC). The work will be based on deploying instrumentation using electrical reflectometry, combining distributed sensors and AI algorithms for online diagnosis of incipient faults in electrical networks. In the presence of certain faults, advanced AI methods will be applied to correct the state of the health of the electrical network's physical layer, thereby ensuring its reliability.
Ultra-flash beams are pulsed beams of high-energy electrons (over a hundred MeV) with pulse durations in the femto-second range. The IRAMIS facility (CEA Saclay) uses laser acceleration to produce this type of beam, with a view to their application in radiotherapy. The LNHB is in charge of establishing dosimetric traceability for the IRAMIS facility, and to do this it has to calibrate the facility's monitor. Current radiotherapy facilities are based on medical linear accelerators operating at energies of up to 18 MeV in electron mode. LNHB has such equipment. It is used to establish national references in terms of absorbed dose to water, under the conditions of the IAEA protocol TRS 398.
Establishing dosimetric traceability involves choosing the measurement conditions, knowing the transfer dosimeter characteristics used and any corrections to be applied to the measurements taking into account the differences between the IRAMIS Facility and those of LNHB.
The Laboratoire national Henri Becquerel (LNE-LNHB) at CEA/Saclay is the laboratory responsible for French references in the field of ionizing radiations. For several years now, it has been involved in the development of an automatic analysis tool for low-statistics gamma spectra, based on the spectral unmixing technique. This approach makes it possible to respond to metrological constraints such as robust decision-making and unbiased estimation of counts associated with identified radionuclides. To extend this technique to field measurements, and in particular to the deformation of spectra due to interactions in the environment of a radioactive source, a hybrid spectral unmixing model combining statistical and automatic learning methods is currently being developed. The aim of this mathematical solution is to implement a joint estimation of the spectra measured and the counts associated with the radionuclides identified. The next step will be to quantify the uncertainties of the quantities estimated from the hybrid model. The aim is also to investigate the technique of spectral unmixing in the case of neutron detection with a NaIL detector. The future candidate will contribute to these various studies in collaboration with the Laboratoire d'ingénierie logicielle pour les applications scientifiques (CEA/DRF).