PhD contract (M/F) : Search for exotic currents in the beta decay of 6He : analysis of the systematic effects and prospects for the phase II of the bSTILED project.

Job Description

Thesis Subject

Context
The search for exotic currents in the weak interaction is a major challenge in fundamental interaction physics, aiming to explore physics beyond the Standard Model. The Fierz interference parameter in beta decay is a privileged probe for this purpose. The ANR bSTILED project, a collaboration between several French laboratories and the IRL NPA (CNRS-Michigan State University), aims for the measurement of this parameter with a precision that rivals the constraints obtained from high-energy experiments at the LHC. Two experimental campaigns have been conducted at GANIL using YAP:Ce scintillators, enabling the extraction of the beta particle energy spectrum with sufficient statistics. The ongoing analysis has identified two critical systematic effects:
• Bremsstrahlung radiation from electrons, which distorts energy measurements.
• Uncertainty in the linearity of the YAP:Ce detector response, requiring highly precise calibration or alternative analytical approaches.

PhD Objectives
1. Finalize Data Analysis (Phase I)
The core of the thesis will involve characterizing and correcting the identified systematic effects by combining experimental approaches and simulations.

• Bremsstrahlung radiation: One or two measurement campaigns will be conducted at the Facility for Rare Ion Beams (FRIB), located on the campus of Michigan State University (MSU), starting in 2027. These will use the MTAS detector (from Oak Ridge National Laboratory), which is particularly well-suited for quantifying this effect with high precision.
• Linearity of YAP:Ce detectors: The PhD student will perform calibration measurements at the Laboratoire National Henri Becquerel (CEA) using specially designed radioactive sources and will develop simulations to model detector response.
This work will culminate in the publication of new limits on the Fierz parameter in a Gamow-Teller-type decay, marking the conclusion of Phase I of the bSTILED project.

2. Prospects for Phase II
Phase II aims to improve precision by a factor of 4. To achieve this, the PhD student will explore the feasibility of either semiconductor-based detection, or large-volume inorganic scintillators.
This phase will include:
• A design study of the detectors and their integration into an experimental setup.
• An evaluation of expected sensitivity gains through simulations and preliminary tests.

The PhD student will be required to make regular visits to the IRL NPA to conduct measurements with the MTAS detector at FRIB, and fully benefit from the supervision of Professor O. Naviliat-Cuncic, the initiator of the bSTILED project and a member of the IRL NPA.

Required Profile
Master's Degree (year 2) of Nuclear Physics and, if possible, Particle Physics.
Proficiency in data analysis and simulation tools (ROOT, GEANT4, or equivalents).
Experience in nuclear instrumentation, particularly in calorimetry (scintillators, semiconductors, etc.).- Proficiency in English at level B2 or better (according to the Common European Framework of Reference for Languages)

Funding for this thesis was provided by the CNRS through the MITI's interdisciplinary programmes.

Your Work Environment

The successful candidate will be posted to the “Laboratoire de Physique Corpusculaire” de Caen (LPCC - UMR6534), team “Mesures de Précision à Basse Énergie”, which has of 18 staff members: 6 permanent staff, 2 tenure-tracks junior professors positions, 4 research fellows, and 6 PhD students.
The LPC CAEN, with about 120 staff, is a joint research unit (UMR6534) depending on three supervisory bodies: the CNRS, the University of Caen Normandy (UNICAEN) and the École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN). It is located on Campus 2 of the University of Caen Normandy (Campus Côte de Nacre) and is part of the research park of ENSICAEN (www.lpc-caen.in2p3.fr/).

Constraints and risks

Ionizing radiation / Travel within France and in the USA : FRIB, Michigan State University.

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

The research professions