Description du sujet de thèse

The objective of this PhD thesis is to measure the entry distribution in the energy and spin (H, K) plane in order to determine the fission barrier and its spin dependence in 253No, employing gamma-ray tracking for the first time. This study is critical because the existence of superheavy nuclei (SHN) relies predominantly on the fission barrier, which is strongly influenced by shell correction energy. The knowledge of the fission barrier Bf(Z,N,I) not only offers insights into SHN existence but also serves as a critical benchmark for theoretical models. Moreover, performing this measurement in an odd-A nucleus is particularly significant: it sheds light on the influence of the unpaired nucleon, the role of the K quantum number, and the impact of reduced pairing correlations. It also enables a meaningful comparison with the uniquely measured fission barrier 254No, offering broader insight into nuclear structure in this mass region.
The experiment has been approved by the Program Advisory Committee (PAC) of the ATLAS facility (Argonne Tandem Linear Accelerator System) and will be conducted on-site in the USA. The experimental setup involves coupling GRETINA (Gamma-Ray Energy Tracking In-beam Nuclear Array) for the (H, K) distribution measurements with the FMA (Fragment Mass Analyzer) to separate 253No nuclei from the beam. Data analysis will be carried out using the GEBSort package, the ROOT framework, and the AI/ML-based GRETO tracking code. As part of this project, enhancements to the performance of GRETO—particularly in the low-energy regime—will be pursued to meet the specific challenges of this study.
The successful candidate is expected to:
1. Actively contribute to the preparation and execution of the experiment at the world-leading ATLAS facility at Argonne National Laboratort
2. Perform data analysis using both conventional and AI/ML-based gamma-ray tracking algorithms.
3. Demonstrate solid programming skills in C and Python, along with a strong background in nuclear structure physics.
4. Perform simulation work using the GEANT4 package, if needed.
Bibliographical references
[1] G. Henning et al, Phy. Rev. Lett 113 (2014) 262505
[2] T. Lauritsen et al, Phys. Rev. Lett 69 (1992)2479
[3] T. Lauritsen et al, Phys. Rev. C 62 (2000)044316
[4] T. Lauritsen, A. Korichi et al, Phys. Scr. 92 (2017) 074002
[5]T. Lynn, S. Leyffer, A. Korichi, T. Lauritsen et al, in preparation

Contexte de travail

This PhD project will be carried out within the Nuclear Physics Division of Irène Joliot-Curie Laboratory (IJCLab), a joint research unit (UMR) under the supervision of CNRS/IN2P3 and Université Paris-Saclay. IJCLab is located on the Paris-Saclay campus in Orsay, a major scientific and academic hub just south of Paris. The project involves close international collaboration, notably with Argonne National Laboratory (USA), where a key part of the experimental campaign will be conducted using the ATLAS facility and state-of-the-art instrumentation such as GRETINA and the FMA.
IJCLab is committed to promoting equality, diversity, and inclusion—core values that support both individual development and collective excellence. The candidate will benefit from the laboratory's extensive technical infrastructure, high-performance computing resources, and in-house expertise in detector development, data analysis (including AI/ML methods), and advanced simulations, making it an ideal environment to carry out high-level doctoral research.

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 selected candidate will be enrolled in the PhD program of the PHENIICS Doctoral School. The project involves regular collaboration with international partners, and frequent travel to the United States should be anticipated for experimental activities. Progress meetings will be held on a monthly basis, during which the candidate will be expected to present the progress.

Informations complémentaires

Candidate Profile and Application Requirements
The candidate must hold a Master's degree in nuclear physics. A solid background in nuclear physics, gamma-ray spectroscopy, data analysis as well as knowledge of common programming languages such as C and python are mandatory.
Communication skills—both written and oral—in French and English. These are necessary for presenting at international conferences and publishing in peer-reviewed scientific journals.
The ability to work collaboratively and independently within teams is essential.
Application Documents
Applicants must submit the following materials:
• A detailed curriculum vitae
• Contact details for at least two referees
• A one-page cover letter
• A one-page summary of the Master's thesis
• Academic transcripts for Master 1 and 2