Fission yield measurements for decay heat evaluation of used nuclear fuel
The fission process involves the violent splitting of a heavy nucleus into two fission fragments, resulting in over 300 different isotopes. Understanding the distribution and production of these fragments, known as fission yields, is essential for grasping the underlying mechanisms of fission, which are influenced by nuclear structure and dynamics. Accurate measurements of fission yields are crucial for advancing nuclear energy applications, particularly in developing Generation IV reactors and recycling spent nuclear fuel. The VAMOS magnetic spectrometer enables precise fission yield measurements due to its large acceptance and identification capabilities for various isotopes. An experimental campaign at VAMOS in 2024 utilized beams of (^{238})U and (^{232})Th on a carbon target to produce fissioning actinides. The combination of VAMOS with a new Silicon telescope (PISTA) enhances data quality significantly. The candidate will analyze VAMOS data to produce high-resolution fission yields and study uncerta
Conceptual lessons of indefinite causality
Recent developments have recognized that quantum causal structures introduce a new non-classical resource known as causal indefiniteness, opening up novel perspectives in quantum information. Despite theoretical advancements and several experimental realizations, the conceptual implications of indefinite causality remain poorly understood. Concurrently, quantum causality has emerged as a crucial foundation for elucidating the discrepancies between operational approaches and spacetime physics. It has already facilitated a novel or enhanced understanding of fundamental concepts such as events (Vilasini and Renner, Phys. Rev. Lett. 133, 080201), facts (Brukner, Nature Phys. 16, 1172–1174, 2020), inputs/outputs (Chiribella and Liu, Comm. Phys. 5, 190, 2022), systems (Grinbaum, Stud. Hist. Phil. Mod. Phys. 58, 22-30, 2017), and computation (Araujo et al., Phys. Rev. A 96, 052315, 2017).
In this PhD project, the candidate will develop a systematic understanding of the conceptual lessons of indefinite causality within the classical, quantum, and generalized probabilistic theory (GPT) frameworks. They will examine the foundational significance of bipartite and multipartite settings, including their spatiotemporal and computational capacities. To make significant progress in quantum foundations, the candidate will seek to extract insights from indefinite causality to deepen our understanding of standard quantum theory, quantum information, and quantum interpretations.
Specific research questions include:
• Establishing conceptual grounds for the identification of systems and events across time, particularly in relation to indefinite causal orders and to "Wigner's friend" scenarios.
• Placing this emerging foundational discussion within a broader philosophical and metaphysical framework.
• Addressing the notion of the agent/observer as a theoretical rather than a metatheoretical entity.
Publications are expected in physics journals (PRL, PRA, NJP, Quantum) and/or philosophy of physics journals (Philosophy of physics, BJPS, Found. Phys., SHPMP). Collaborations are expected with groups in France, Austria, Belgium, and Canada.
Optimization of gamma radiation detectors for medical imaging. Time-of-flight positron emission tomography
Positron emission tomography (PET) is a nuclear medical imaging technique widely used in oncology and neurobiology.
We're proposing you to contribute to the development of an ambitious, patented technology: ClearMind. This gamma photon detector uses a monolithic PbWO4 crystal, in which Cherenkov and scintillation photons are produced. These optical photons are converted into electrons by a photoelectric layer and multiplied in a MicroChannel plate. The induced electrical signals are amplified by gigahertz amplifiers and digitized by SAMPIC fast acquisition modules. The opposite side of the crystal will be fitted with a matrix of silicon photomultiplier (SiPM).
You will work in an advanced instrumentation laboratory in a particle physics environment .
The first step will be to optimize the "components" of ClearMind detectors, in order to achieve nominal performance. We'll be working on scintillating crystals, optical interfaces, photoelectric layers and associated fast photodetectors, and readout electronics.
We will then characterize the performance of the prototype detectors on our measurement benches.
The data acquired will be interpreted using in-house analysis software written in C++ and/or Python.
Finally, we will compare the physical behavior of our detectors to Monté-Carlo simulation software (Geant4/Gate).
A particular effort will be devoted to the development of ultra-fast scintillating crystals in the context of a European collaboration.
MEASUREMENT OF THE W-BOSON MASS WITH THE ATLAS DETECTOR AT THE LHC
The objective of the thesis is a precise measurement of the mass and width of the W boson, by studying its leptonic decays with the ATLAS detector at the LHC. The analysis will be based on data from Run 2 of the LHC, and aims for an precision on the mass of 10 MeV.
The candidate will be involved in the study of the alignment and calibration of the ATLAS muon spectrometer. IRFU played a leading role in the design and construction of this instrument and is heavily involved in its scientific exploitation. This will involve optimally combining the measurement given by the spectrometer with that of the ATLAS inner detector, using a precise model of the magnetic field and the relative positioning of these systems, in order to reconstruct the muon kinematics with the precision required for measurement.
The second phase of the project consists of improving the modeling of the W-boson production and decay process and optimizing the analysis itself in order to minimize the final uncertainty of the measurement. The measurement result will be combined with other existing measurements, and interpreted in terms of compatibility with the Standard Model prediction or as an indication of the presence of new physics.