Faites connaître cette offre !
Reference : UMR8552-GENTAS-001
Workplace : PARIS 05
Date of publication : Thursday, September 16, 2021
Scientific Responsible name : Geneviève TASTEVIN
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 2 November 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Scientific context: the HELPING project
This selected candidate will actively contribute to a research project supported by the ANR, called HELPING (High field Enhancement of nucLear Polarisation In Noble Gases, 2021-2025), that is jointly carried out by the Kastler Brossel Laboratory, LKB (UMR 8552, Paris) and the LSDM laboratory at NIMBE (UMR 3685, CEA Saclay). 
The HELPING project aims at the development of innovative schemes for hyperpolarisation of noble gases at high magnetic field strength. It primarily targets the nuclear-spin-1/2 isotopes (3He and 129Xe), involved in a variety of basic or applied physics experiments, as well as in NMR-based studies in chemistry, material sciences, biology, or medicine. Operation inside or next to the high-field area, scarcely explored up to now, is of fundamental interest (investigations can shed light on the influence of the applied magnetic field on build-up and decay processes) and potentially advantageous in practice (it can help reduce, or even eliminate, dead times and polarisation losses due to gas handling and transfer into the measurement apparatus).
Physicists and NMR specialists undertake theoretical and experimental investigations that should lead to an improved understanding of the hyperpolarisation mechanisms and of their potential limits at high field strength processes MEOP. This will provide a solid ground development of new strategies and devices yielding a significant boost in nuclear polarisation and, hence, in detection sensitivity. A super-wide bore NMR spectrometer/imager, located at CEA Saclay, will host experimental devices for in-depth studies up to 7 T and proofs of concept NMR measurements.
PhD work will focus on hyperpolarisation processes in radiofrequency He gas discharges: laser optical pumping at 1083 nm (Metastability Exchange Optical Pumping, MEOP) and a laser-free hyperpolarisation scheme recently discovered for 3He (Polarisation of Atoms in a Magnetised Plasma, PAMP ). The objectives are in-depth theoretical, numerical, and experimental investigations of 3He hyperpolarisation dynamics at high field (0.1 T – 7 T).
Measurements will combine laser absorption spectroscopy with optical and NMR polarimetry. They will be performed in pure 3He gas samples, will be extended to isotopic 3He-4He gas mixtures, and will include additional tests at low temperature or with other odd nuclei. New features are expected, owing to field-dependent atomic level structures, collisional interactions, and nuclear relaxation processes . Suitable rate equations models will be developed to account for all findings and to make reliable predictions in a variety of operating conditions.
 Project homepage: http://www.lkb.upmc.fr/polarisedhelium/polarised-helium-and-quantum-fluids/helping-project/
 https://arxiv.org/abs/1806.07624, "Nuclear hyperpolarization of ³He by magnetized plasmas", Maul A. et al., Phys. Rev. A (2018) 98, 063405.
 https://arxiv.org/abs/1612.04178, "Optically polarized ³He", Gentile T.R. and al., Rev. Mod. Phys. 89, 045004 (2017).
The host laboratory (Laboratoire Kastler Brossel, LKB - http://www.lkb.science) ranks among worldwide leaders in the domain of quantum physics and excels in the use of light as a tool to probe and control atoms. It contributes to the advance of fundamental knowledge and applications through a variety of research activities dealing with ultra-cold gases, quantum optics and information, atoms and light in complex media, tests of fundamental interactions, and metrology.
The 'Polarised Helium' host team pursues research at LKB in the ENS Physics Department (24 rue Lhomond, Paris 05, France), dealing with the physics of noble gas hyperpolarisation, the use of hyperpolarised gases for a variety of applications, and unconventional tools or strategies for low-field NMR and MRI. Details on activities and collaborations can be found on the team's homepage:
Additional information on the work place: Part of the experimental work (measurements in a 7-T NMR instrument) will be completed at CEA Saclay, in the "Structure and Dynamics by Magnetic Resonance" Laboratory ( LSDRM) of the NIMBE research unit ("Nanosciences and Innovation for Materials, Biomedicine, and Energy").
Additional information on the start date: PhD work should start as soon as possible, in fall 2021. The exact start date is somehow flexible. However, a strict deadline for PhD start date set by total duration of ANR funding for the project that must include the entire (36-m long) doctoral contact.
Requested training and skills: Master degree in physics or equivalent. A strong background in basic physics is needed. Candidates with advanced training in atomic physics, light-matter interactions, and laser spectroscopy will be preferred. Good communication and writing skills (in English, optionally in French), and relational comfort, are expected. Appetite for autonomy, experimental and computer work, and data interpretation will be appreciated.
We talk about it on Twitter!