Ph.D. candidate in Nuclear Physics for applications in nuclear energy (M/F)

Job Description

Thesis Subject

Measurement and modeling of 239Pu(n, xn) cross sections relevant to the nuclear energy application

This thesis aims to improve our understanding of the (n, xn) on 239Pu through the analysis of data from a new measurement conducted at the JRC-Geel GELINA facility and to explore the theoretical description of the process through the development of an integrated numerical tool enabling the precise evaluation of the impact of uncertainties on the total inelastic cross section, reconstructed from partial measurements.

Context
The CNRS (DNR team—Nuclear Data for Reactors at the Institut Pluridisciplinaire Hubert Curien), the CEA-DAM (Nuclear Physics Division, DAM/DIF/SPN), and the CEA-DES (Laboratory of Physics Studies, CEA/DEN/LEPh) have been collaborating for 10 years (within the framework of the interdisciplinary NEEDS program until 2024, followed by APED-2026/2030) to improve nuclear data relevant to nuclear power. The three teams thus coordinate their efforts in experimental development (CNRS/IPHC), theoretical advances (CEA/DAM), and nuclear data evaluations (CEA/DES).
In this context, it is observed that our understanding of the cross-section data for total inelastic scattering (n,n'), partial inelastic scattering (n,n'γ), and reaction (n,2n), (n, 2n γ), which we will hereafter collectively refer to as (n,xn) reactions, is still notoriously insufficient today, despite recent efforts. This results in significant uncertainties regarding certain reactor parameters. Analysis of the evaluation chain for these reactions has shown that improving our understanding of them necessarily requires an experimental effort to produce more accurate and comprehensive data, as well as the development of more predictive theoretical models.

Work Description
The experimental method used to study (n, xn) processes is prompt γ spectroscopy coupled with time-of-flight measurements, which enables measurements using “white” neutron beams (with a continuous energy distribution, as opposed to monoenergetic neutrons). The IPHC has developed the GRAPhEME (GeRmanium array for Actinides PrEcise MEasurements) to measure the (n, xnγ) cross sections. Measurement campaigns are currently being conducted using the GELINA white neutron beam (JRC-EC-Geel, Euratom) and at the NFS-SPIRAL2 facility (GANIL, Caen). The next experiment will focus on plutonium-239, for which the analytical challenges are important: numerous detection channels, significant background noise (target radioactivity and fission product decay), and long acquisition times. Measurements of plutonium 239 began in 2025 and will continue through the end of 2026. Special attention should be paid to quality control of uncertainties and estimating correlations In addition, a theoretical study will complement the experimental analysis, drawing on modeling tools for (n, xnγ) reactions. The goal is to develop a numerical tool integrated into the existing workflow, capable of assessing the impact of uncertainties on the total inelastic cross section reconstructed from partial measurements. The tool will aim to propagate the uncertainties associated with these data—including missing data—in order to quantify their effect on the total cross section obtained and to better determine the precision that can actually be achieved
The thesis will be conducted at IPHC-Strasbourg. As part of the joint supervision of the dissertation, the experimental component will be supervised by Maëlle Kerveno, with co-supervision by Greg Henning, and the theoretical component will be supervised by Marc Dupuis.
References (a selection)
Neutron inelastic scattering
M. Kerveno, EPJ Web of Conferences 322, 08001 (2025)
GRAPhEME: performances, achievements (@EC-JRC/GELINA) and future (@GANIL/SPIRAL2/NFS)
M. Kerveno, et al., EPJ Web of Conferences 284, 01005 (2023)
Measurement of partial (n, n') reaction cross-sections on highly radioactive nuclei of interest for energy
production application.
F. Claeys, et al., EPJ Web of Conferences 284, 01014 (2023)
Measurement of 238U(n, n') cross section data and their impact on reaction models
M. Kerveno, M. Dupuis, et al., Physical Review C 104, 044605 (2021)
How to produce accurate inelastic cross sections from an indirect measurement method?
M. Kerveno, G.Henning, et al., European Physical Journal N 4, 23 (2018)
From  emissions to (n, xn) cross sections of interest: The role of GAINS and GRAPhEME in nuclear reaction
modeling
M.Kerveno, et al., Eur. Phys. J. A (2015) 51: 167
Measurement of 235U(n,n' ) and 235U(n,2n ) reaction cross sections
M.Kerveno, J.C.Thiry, et al., Physical Review C 87, 24609 (2013)

Your Work Environment

This Ph.D. program will be affiliated with the “Physics and Physical Chemistry Doctoral School” at the University of Strasbourg (ED182). The candidate (M/F) will be based at the Institut Pluridisciplinaire Hubert Curien (IPHC) in Strasbourg (DRS Department).
The IPHC, a joint research unit jointly supervised by the CNRS and the University of Strasbourg (UMR7178), is a multidisciplinary laboratory where research teams from different scientific backgrounds (ecology, physiology and ethology, chemistry, and subatomic physics) develop high-level research programs based on scientific instrumentation. The IPHC is organized into three departments and has a total staff of 393 employees (M/F), including 257 permanent staff (119 researchers and faculty members and 138 engineers and technicians, M/F), 46 employees on fixed-term contracts, and 102 doctoral students (M/F).
The candidate (M/F) will join the IPHC's Nuclear Data for Reactors team, which consists of three researchers and one emeritus researcher. The team works in close collaboration with the JRC-Geel (Belgium) and IFIN-HH (Bucharest, Romania) institutes, as well as with two teams from CEA DES/Cadarache and CEA/DAM/DIF. The collaboration contributes to the JEFF project (OECD/NEA), and its work is internationally recognized. The thesis work is part of Project 1, “Nuclear Data for the Fuel Cycle and Reactors,” of the PEPR “Upstream Nuclear Fission Science” (SCIAM) program, funded by the APED (Program Agency for Research on Decarbonized Energies), France 2030.
He or she will have access to a staff cafeteria, partial reimbursement of transportation costs, a works council, the option to work remotely for some tasks, and training to help them adapt to the job.
Strasbourg is one of the most attractive cities in Europe. It boasts a rich historical and architectural heritage, with Strasbourg's historic center listed as a UNESCO World Heritage Site. Its human scale, pedestrian-friendly downtown, and 500 km of bike paths make it a very pleasant city to explore. Vibrant and affordable, Strasbourg is a true student city offering an excellent environment for learning and living (watch the New York Times video: 36 Hours in Strasbourg).
Requirements:
• Master's degree in nuclear physics
• Skills in gamma spectroscopy, nuclear physics instrumentation, data analysis, and programming in C/C++ and Python
• Strong knowledge of nuclear physics (nuclear reactions, nuclear structure), instrumentation, and data analysis
• Ability to work independently, tenacity, flexibility, creativity, and high motivation
• Good level of English, both spoken and written, at the B2 level according to the Common European Framework of Reference for Languages, to interact with all project partners and communicate results in scientific publications and conference presentations.
Applicants must submit a resume and cover letter, their master's thesis and associated grades, as well as contact information for references and, if applicable, one or two independent letters of recommendation.

Constraints and risks

· Travel to participate in experimental campaigns, collaborative meetings (primarily in France and Europe), and workshops/conferences in the field.
· Stays at the CEA/DAM will be organized to facilitate the student's supervision during the theoretical part of the thesis.
· Part of the work will involve access to controlled areas (ionizing radiation) and will require radiological monitoring.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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