Description du sujet de thèse

Subject : Behavior of Metallic and Superconducting Surfaces Under Electron Bombardment at Very Low Temperature: Implications for Particle Accelerators
Modern particle accelerators, such as the Large Hadron Collider (LHC) at CERN, use cryogenic technologies to enhance their performance. However, electron bombardment of metallic surfaces can lead to complex phenomena, such as secondary electron emission, gas desorption, and surface structure modifications, which remain poorly understood at very low temperatures. These effects can significantly influence the performance and lifespan of accelerator components.
Furthermore, superconducting materials such as niobium (Nb) and niobium nitride (NbN) play a key role in many technological applications, particularly in superconducting accelerating cavities. The interaction of electrons with these materials, especially through secondary electron emission, is a critical phenomenon that can affect device performance. Understanding how these emissions vary with temperature is essential for optimizing the use of superconducting materials under various conditions. This study will therefore focus on analyzing the microstructural and physical properties of these materials, with particular emphasis on their behavior under electron bombardment at different temperatures.
Internship Objectives :
1. Experimentally study the behavior of metallic and superconducting surfaces (for example, copper, niobium, niobium nitride thin films and FeSe thin films) under electron bombardment at room temperature and cryogenic temperatures (10 K).
2. Characterize secondary electron emission as a function of temperature and incident electron energy.
3. Analyze changes in surface structure and chemical composition resulting from electron bombardment as a function of temperature.
Methodology :
• Use of a multi-technique ultra-high vacuum setup equipped with an electron gun coupled with XPS analysis;
• Measurement of secondary electron emission;
• Surface characterization using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).

Contexte de travail

The Irène Joliot-Curie Physics Laboratory of 2 Infinities (IJCLab) is a UMR under the supervision of the CNRS (IN2P3), the University of Paris-Saclay and the University of Paris is located on the campus of the University of Paris -Saclay in Orsay. The laboratory is located on the campus of the Université Paris-Sud, Université Paris-Saclay in Orsay. The campus is located 20 km south of Paris and easily accessible by RER in 35 minutes. IJCLab was born in 2020 from the merger of five units (CSNSM, IMNC, IPN, LAL, LPT). The staff is made up of nearly 560 permanent (340 engineers, technicians and administrators and 220 researchers and teacher-researchers) and approximately 200 non-permanent including 120 doctoral students. The research themes of the laboratory are nuclear physics, high energy physics, theoretical physics, astroparticles, astrophysics and cosmology, particle accelerators, energy and the environment and health. IJCLab has very significant technical capacities (around 280 IT) in all the major fields required to design, develop / implement the experimental devices necessary for its scientific activity, as well as the design, development and use of instruments.
IJCLAB bases its recruitment policy on the promotion of equality, diversity and inclusion. Essential values, they allow the professional development of agents, who are real actors in a collective success, but also the development of the laboratory itself.
The PhD candidate will work under the supervision of Prof. Gaël Sattonnay within the MAVERICS team of the Accelerator Physics division at IJClab, with access to the equipment of the Vacuum & Surfaces platform.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

The PhD will be affiliated with the PHENIICS doctoral school.
Short trips within France and abroad are to be expected.

Informations complémentaires

The candidate must hold an engineering degree and/or a master's degree in Materials Science. The position requires:
-Strong knowledge of materials science;
-Experience in materials characterization;
-The ability to work both independently and as part of a team in an international research environment.
Experience with very low-temperature work acquired during an internship would be a plus.
Good oral and written communication skills in both French and English are required for presenting at conferences and writing articles in scientific journals.
Applications must include:
• A detailed CV, specifying at least two references (people who may be contacted);
• A one-page cover letter;
• Master's (M1 and M2) or engineering school transcripts.
As IJCLab is subjected to ZRR (Zone à Régime Restrictif) military regulation, hiring choices must be approved by the Haut Fonctionnaire Securité Défense (HFSD). Therefore, the date of employment written above should be understood as provisional, and may need to be delayed.