architecture for embedded system of Automated and Reliable Mapping of indoor installations
The research focuses on the 3D localization of data from measurements inside buildings, where satellite location systems, such as GPS, are not operational. Different solutions exist in the literature, they rely in particular on the use of SLAM (Simultaneous Localization And Mapping) algorithms, but the 3D reconstruction is generally carried out a posteriori. In order to be able to propose this type of approach for embedded systems, a first thesis was carried out and led to a choice of algorithms to embed and a draft of the electronic architecture. A first proof of concept was also realized. Continuing this work, the thesis will have to propose a method allowing the localization device to be easily embedded on a wide range of nuclear measuring equipment (diameter, contamination meter, portable spectrometry, etc.). The work is not limited to a simple integration phase; it requires an architectural exploration, which will be based on adequacy between algorithm and architecture. These approaches will make it possible to respect different criteria, such as weight and small size so as not to compromise ergonomics for the operators carrying out the maps and quality of the reconstruction to ensure the reliability of the input data for the Digital Twin models.
Development of a transportable and high sensibility gamma/neutron spectro-imager to reconstruct and identify radioactive hotspots during decomissioning and dismantling operations
Radioactive hotspots reconstruction is a significant challenge when characterising radioelements in environments that have been impacted by radiological or nuclear activity. A thesis proposal aims to address this issue by developing a compact, highly sensitive multimodal instrument for assessing and characterising gamma-ray and neutron contributions. This system will help to meet the encountered challenges, during decommissioning and dismantling (D&D) operations, in nuclear industry sites. To do this, it will incorporate spectro-imaging specifications to ensure the identification and location of present radioelements. The state of art has already demonstrated the advantages and benefits of combining ionising radiations spectrometry and imaging. However, the suggested solutions show difficulties in deploying measurement systems (size, weight), as well as a sensitivity incompatible with the ground constraints. Results obtained in the frame of thesis works, carried out at SIMRI (Service Instrumentation et Métrologie des Rayonnements Ionisants), have led to the development of a gamma and neutron spectro-imager prototype.
Development of the Compton-TDCR Method for Scintillator Metrology
The objectives of this PhD thesis lie upstream of the applied domain, specifically in the field of radionuclide metrology. The research aims to obtain essential information for a deeper understanding of scintillation mechanisms. This topic represents a new discipline within the national metrology laboratory, currently nonexistent in other laboratories, and focuses specifically on scintillator metrology. The work will be centered on instrumentation and data analysis, enabling a refined understanding of the underlying physical phenomena. The PhD will be co-supervised by Benoit Sabot (expert in radioactivity metrology) and Christophe Dujardin (expert in scintillation).
One of the primary experimental objectives of this PhD is the development and implementation of the new Compton-TDCR setup [7], designed for the absolute measurement of scintillation yield as a function of electron energy. This system will be designed using 3D printing technology and will integrate high-purity germanium (GeHP) detectors to enhance measurement precision. After characterizing these detectors in terms of energy resolution and efficiency, they will be integrated into the final experimental setup. The PhD candidate will be responsible for signal processing using a digital module generating List-Mode files. The data will then be analyzed using an existing Rust-based software with a Python interface, which is currently limited to four channels. Given that the new setup will incorporate up to three GeHP detectors in addition to three photomultiplier channels, the software must be adapted to ensure optimal processing of the acquired data. Following fine-tuning of the electronics and a series of experimental tests, the required software modifications will be implemented to enable full data exploitation from the platform.
Once this initial phase is completed and the platform is fully operational, the candidate will focus on investigating scintillation phenomena. The first studies will examine standard scintillating materials, such as organic (liquid or plastic) and inorganic scintillators. Subsequently, the research will extend to less explored materials, such as porous scintillators. This phase will involve close collaboration with the University of Lyon, particularly with the Institut Lumière Matière, where complementary measurements will be performed to refine the analysis of scintillation phenomena, complete the laboratory findings, and develop simulations that integrate various experimental approaches.
The ultimate goal of this setup is to establish a metrology methodology for scintillators, enabling access to the response curve of these materials as a function of the energy of electrons interacting within them, as well as their temporal properties. This work will pave the way for new ionizing radiation measurement techniques and will make a significant contribution to the scientific community in this field.
Diamond Beam Monitor for FLASH Therapy
Optimizing tumor dose delivery requires advanced treatment techniques. One promising approach focuses on refining beam delivery through ultra-high dose rate irradiation (UHDR), with temporal optimization being a key strategy. Recent studies highlight the effectiveness of FLASH irradiation using electrons, demonstrating similar tumor inhibition capabilities as gamma rays but with reduced damage to healthy tissue. To fully harness this potential, we are exploring innovative beams, such as high energy electron beams, which offer instantaneous dose rates and per-pulse doses many times higher than those produced by conventional radiation sources. However, accurately monitoring and measuring these beams remains a significant challenge, primarily due to the high dose rate.
The Sensors and Instrumentation Laboratory (CEA-List) will collaborate with the Institut Curie as part of the FRATHEA project. We propose the development of a novel diamond-based monitor, connected to associated electronics, to achieve precise measurements of dose and beam shape for high-rate electron and proton beams. Interdisciplinary experimental techniques, including diamond growth, device microfabrication, device characterization under radioactive sources, and final evaluation with electron beam, will be used for prototyping and testing the diamond beam monitor.
As part of the FRATHEA project, the PhD student will work on the following tasks:
• Growth of optimized single-crystal chemical vapor-deposited (scCVD) diamond structures
• Characterization of the electronic properties of the synthesized diamond materials
• Estimation of the dose response characteristics of a simplified prototypes
• Fabrication of a pixelated beam monitor
• Participation in beam times at the Institut Curie (an other institutes) for devices testing in clinical beams
Required Skills:
• Strong background in semiconductor physics and instrumentation
• Knowledge of radiation detectors and radiation-matter interactions
• Ability to work effectively in a team and demonstrate technical rigor in measurements
Additional Skills:
• Knowledge of electronics, including signal processing, amplifiers, oscilloscopes, etc.
• Familiarity with device fabrication and microelectronics
• Previous experience working with diamond materials
Profile:
• Master's level (M2) or engineering school, with a specialization in physical measurements
• Adherence to radiation protection regulations (category B classification required)
PhD Duration: 3 years
Start Date: Last semester of 2025
Contact:
Michal Pomorski : michal.pomorski@cea.fr
Guillaume Boissonnat: guillaume.boissonnat@cea.fr
Towards a multimodal photon irradiation platform: foundations and conceptualization
Photonic irradiation techniques exploit the interactions between a beam of high-energy photons and matter to carry out non-destructive measurements. By inducing photonuclear reactions such as photonic activation, nuclear resonance fluorescence (NRF) and photofission, these irradiation techniques enable deep probing of matter. Combining these different nuclear measurement techniques within a single irradiation platform would enable precise, quantitative identification of a wide variety of elements, probing the volume of the materials or objects under study. The high-energy photon beam is generally produced by the Bremsstrahlung phenomenon within a conversion target of a linear electron accelerator. An innovative alternative is to exploit the high-energy electrons delivered by a laser-plasma source, converted by Bremsstrahlung radiation or inverse Compton scattering. A platform based on such a source would open up new possibilities, as laser-plasma sources can reach significantly higher energies, enabling access to new advanced imaging techniques and applications. The aim of this thesis is to establish the foundations and conceptualize a multimodal photonic irradiation platform. Such a device would aim to be based on a laser-plasma source and would enable the combination of photonic activation, nuclear resonance fluorescence (NRF) and photofission techniques. By pushing back the limits of non-destructive nuclear measurements, this platform would offer innovative solutions to major challenges in strategic sectors such as security and border control, radioactive waste package management, and the recycling industry.
3D ultrasound imaging using orthogonal row and column addressing of the matrix array for ultrasonic NDT
This thesis is part of the activities of the Digital Instrumentation Department (DIN) in Non-Destructive Testing (NDT), and aims to design a new, fast and advanced 3D ultrasound imaging method using matrix arrays. The aim will be to produce three-dimensional ultrasound images of the internal volume of a structure that may contain defects (e.g. cracks), as realistically as possible, with improved performance in terms of data acquisition and 3D image computation time. The proposed method will be based on an approach developed in medical imaging based on Row and Column Addressed (RCA) arrays. The first part will focus on the development of new data acquisition strategies for matrix arrays and associated ultrafast 3D imaging using RCA approach in order to deal with conventional NDT inspection configurations. In the second part, developed methods will be validated on simulated data and evaluated on experimental data acquired with a conventional matrix array of 16x16 elements operating in RCA mode. Finally, a real-time proof of concept will be demonstrated by implementing the new 3D imaging methods in a laboratory acquisition system.
Development of a multiphysics stochastic modelling for liquid scintillation measurements
The Bureau international des poids et mesures (BIPM) is developing a new transfer instrument named the "Extension of the International Reference System" (ESIR), based on the Triple-to-Double Coincidence Ratio (TDCR) method of liquid scintillation counting with a specific instrumentation comprising three photomultipliers. The aim is to enable international comparisons of pure beta radionuclides, certain radionuclides that decay by electron capture, and to facilitate international comparisons of alpha emitting radionuclides.
The TDCR method is a primary activity measurement technique used in national laboratories. For the activity determination, its application relies on the construction of a model of light emission requiring knowledge of the energy deposited in the liquid scintillator. Depending on the decay scheme, the combination of different deposited energies can be complex, particularly when it results from electronic rearrangement following electron capture decay. The stochastic approach of the RCTD model is applied by randomly sampling the different ionizing radiation emissions following a radioactive decay. The recent addition of modules for automatically reading nuclear data (such as those available in the Table des Radionucléides) in radiation/matter simulation codes (PENELOPE, GEANT4), means that all possible combinations can be rigorously taken into account. The stochastic approach makes it possible to consider the actual energy deposited in the liquid scintillation vial, taking into account interactions in the instrumentation as a whole.
The aim of this thesis is to develop a multiphysics stochastic approach using the GEANT4 radiation/matter simulation code, to be applied in particular to the BIPM's ESIR system. The choice of the Geant4 code offers the possibility of integrating the transport of ionizing particles and scintillation photons. This development is of great interest for radioactivity metrology, with the aim of ensuring metrological traceability to a larger number of radionuclides with the BIPM's ESIR system. The thesis will be carried out in collaboration with the Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), which already has experience in developing a stochastic model with the GEANT4 code for its instrumentation dedicated to the TDCR method at the Laboratoire National Henri Becquerel (LNE-LNHB).