According to standard inflationary theories, the origin of cosmological structures is explained by a period of exponential expansion of the Universe induced by the potential of a scalar field and its quantum fluctuations. In addition to these primordial densities, inflation also predicts the existence of a primordial gravitational waves background. The imprint of which would be visible on the...
The first gravitational waves signal was detected on the 14th september 2015 by the LIGO observatories. Since then many other detections have been made and especially in August 2017 with the detection in coincidence on both LIGO and Virgo detectors of the coalescence of two neutron stars which position in the sky was precise enough to identify the galaxy host and electromagnetic counterpart....
In the Standard Model of particle physics (SM), the lepton sector is composed of massive charged particles (electron, muon and tau) and neutral particles, neutrinos, which are massless by construction.
Nevertheless, observations of neutrino oscillations indicate that neutrinos are massive particles.
Given their neutral character, neutrinos can be either Dirac or Majorana particles.
Should...
The ATLAS electromagnectic calorimeter allows for a precise measurement of electron and photon energy produced during collisions at the LHC. To get an accurate measurement, the reconstructed energy is calibrated over several steps. One of these steps is the inter-calibration of the 3 layers of the calorimeter to correct for electronic cross-talk among cells and possible residual...
The top quark is the heaviest elementary particle we know. Therefore, it may play a special role in the Standard Model of particle physics. Its Yukawa coupling to
the Higgs boson is close to one, which makes this particle a key element of many theories beyond the Standard Model.
The Large Hadron Collider (LHC), located at CERN (Geneva, Switzerland) is a proton-proton collider with a...
Collective excitations are observed and analyzed in several many-body systems such as, for instance, atomic nuclei, trapped atomic gases or metallic clusters. A model which is widely used to describe collective excitations is the random-phase approximation (RPA), where the excited modes are superpositions of 1 particle-1 hole configurations only. The RPA allows in general for a satisfactory...
Économiste, Directeur de l'Observatoire Français des Conjonctures Économiques (OFCE)
Classical novae outbursts are the third most energetic explosions in the Universe after gamma-ray bursts and supernovae. During this explosive burning, nucleosynthesis takes place and the newly synthesized material is ejected into the interstellar medium. In order to understand these objects, the study of presolar grains and γ-ray emitters are of specific interest since they can give direct...
The CMS experiment implements a sophisticated two-level triggering system composed of a Level-1 trigger, instrumented by custom-design hardware boards, and a software High-Level-Trigger. A new Level-1 trigger architecture with improved performance is now being used, allowing complex correlations to be computed online. The implementation of the first dedicated Vector Boson Fusion trigger...
In the context of High Luminosity phase of LHC (Phase-2), envisaged to start in $\sim$2026, it's planned to increase the beam luminosity up to $7.5\cdot10^{34} cm^{-2}s^{-1}$ and collision energy up to 14 TeV in the center of mass to achieve the high-precision results in the project tasks. These conditions will lead to additional requirements especially on an inner part of the ATLAS detector...
Performances of superconducting accelerating cavities, in particular made of bulk Niobium, depend on the purity and crystallographic quality of the material exposed to an intense radio-frequency electromagnetic field. The preparation of the cavity walls has been and is still one of the major challenges in SRF accelerator technology. In order to avoid performance degradation, the damaged layer...
The ERC Advanced Grant COXINEL aims at demonstrating free electron laser amplification, at a resonant wavelength of 200 nm, based on a laser plasma acceleration source. To achieve the amplification, a 8 m long dedicated transport line was designed to manipulate the beam qualities. It starts with a triplet of permanent magnet with tunable gradient quadrupoles (QUAPEVA) that handles the highly...
The emittance is an essential feature to measure for an accelerator beam. It describes the behavior of the beam at each longitudinal position. For the time, the Alisson scanner is the most used system to qualify the emittance of a proton beam. However, this type of measurement has a default: it is a two-dimensions diagnostic. It means that it can only measure the position and angular...
During in-reactor operation, the nuclear fuel is subjected to simultaneous radiation sources induced by the slowing down of fission fragments, the alpha and beta decay, etc. In addition, fission products incorporation induce chemical effects in the matrix. At the atomic scale radiation, damage is produced by both low-energy particles, leading to the collision cascades formation and high-energy...
Understanding the baryonic processes taking place in the large scale structures of the Universe is essential both if we want to understand structure formation and the biases they may induce in cosmological studies (e.g. σ8 or ωm). Among those processes, turbulent motions that are induced at various scales, for instance by AGN jets or accretion of matter from intergalactic filaments, are...
Ion beams are currently used in numerous fields of material science. It is crucial to have powerful tools to characterize irradiated materials and to have a better understanding of the basic mechanisms of the ion/solid interactions through mastering the technical aspects of the use of ion beams.
The aim of the thesis work is to develop new approaches that combine experimental characterization...
The electromagnetic calorimeter is one of the key elements of the ATLAS detector at the Large Hadron Collider at CERN. In combination with the inner tracker the calorimeter allows to measure the energy and the momentum of electrons and photons coming out of the interaction point of the detector.
In order to properly reconstruct the physical processes happening after the collision it is...
Minibeam radiation therapy (MBRT) is a promising cancer treatment method that can help increase the sparing of healthy tissue while simultaneously allowing for higher doses to be administered, thereby making new types of cancers (hypoxic tumors) accessible to this type of treatment. While MBRT with x-rays is already being put to use in hospitals, the advantages of irradiating with protons and...
The NEWS-G collaboration utilises the novel technology of the Spherical Proportional Counter (SPC) to conduct a direct search for low mass Dark Matter (DM) candidates. The SPC comprises a grounded metallic spherical vessel with a central spherical readout anode. In the ideal geometry, the radial electric field within the detector varies as 1/r$^{2}$, however, the details of the support...
Les simulations Particle-in-Cell sont utilisées dans une large variété de problèmes liés à la physique des plasmas. Dans plusieurs cas, une description précise et fiable des effets cinétiques qui se produisent en 3D est requise. Néanmoins, ce type de simulations est très couteux et nécessite beaucoup de ressources de calcul. Ceci est principalement dû à la haute résolution que nécessite les...
Laser Plasma Acceleration (LPA) enables to generate up to several GeV electron beam with short bunch length and high peak current within centimeters scale via different schemes. However, the generated beam quality (energy spread, divergence) is not sufficient to drive a Free Electron Laser (FEL) and a beam control is required. The COXINEL manipulation line is composed of high gradient variable...
The top quark mass ($m_t$) is a key parameter of the Standard Model (SM). Its large size, of the order of the electroweak scale, is associated with a Yukawa coupling of order 1, that gives important contributions, via radiative corrections, to SM observables. After the Higgs boson discovery and the accurate measurement of its mass, the allowed values of the W boson and top quark masses have...
In the Standard Model (SM) of Particle Physics, the electroweak (EW) symmetry breaking pattern is the less known and understood. With the discovery of a Higgs-like boson by the Large Hadron Collider (LHC) experiment in 2012, the Brout-Englert-Higgs (BEH) mechanism, which involves a new scalar field to break the EW gauge symmetry, seems to be at work in Nature. Nevertheless, the origin of the...
• Intro
- Intro sujet MYRRHA 600 MeV avec réacteur nucléaire
- Nécessité d’avoir un système fiable avec peu d’arrêt de fonctionnement
- Sûreté d’un pilotage par accélérateur, k$_{eff}$<1
• Dynamique faisceau
- Commissioning et test de fiabilité à 100 MeV
- Photo dynamique faisceau, photo quadupole, dipole
- Mon travail sur la définition du kicker-septum nécessaire et sur le design...
The High Luminosity LHC (HL-LHC) is an upgrade of the LHC to achieve instantaneous luminosities a factor of five larger than the LHC nominal value. The Future Circular Collider (FCC) study is developing designs for a higher performance particle collider to extend the research currently being conducted by present colliders. For these two project, the investigation of beam interactions with the...
Methods to solve the N-body Schroedinger equation must cope with two specific attributes of inter-nucleon interactions that are responsible for the non-perturbative character of the nuclear many-body problem. These elements of non-perturbative physics are of ultra-violet and infra-red natures and can be tamed down by pre-processing the nuclear Hamiltonian via Similarity Renormalization Group...
Oxide dispersion strengthened (ODS) ferritic/ martensitic FeCr steels are reinforced by dense and stable metallic (Y,Ti) nano-oxide particles. These ODS steels are known to have very good creep and radiation resistance as well as improved mechanical properties at high temperatures, making them ideal candidates to be used as structural materials for future generation IV (Gen IV) fission and...
In spite of intensive international research on Oxide Dispersed Strengthened (ODS) steels in the last decade, many fundamental issues concerning modification of steel properties under fusion environment are still under debate. The main objective of this research project is to demonstrate the role of the different microstructural components in radiation resistance of ODS steel under high...
Protactinium, as a $^{235}$U decay product, is naturally present in the environment as $^{231}$Pa isotope (alpha emitter with a half-life of 32,400 years). Over the years, this isotope is accumulated in uranium tailings and stocks of yellow cake. Modelling the behavior of this element in the geosphere requires thermodynamic and structural data relevant to environmental conditions. The present...
Targeted radionuclide therapy is the most used treatment modality against malign and benign diseases of thyroid. The large heterogeneity of therapeutic doses in patients and the range of effects observed state that an individualized dosimetry is essential for optimizing this therapy. The goal of the project is to strengthen the control of the doses delivered to thyroid during treatment of...
Cosmic strings are topological defects which can be formed in GUT-scale phase transitions in
the early universe. They are also predicted to form in the context of string theory. I will present the analysis conducted to specifically search for gravitational-wave bursts from cosmic string loops in the data of Advanced LIGO 2015-2016 observing run (O1).
