Post doctoral position : Beam Dynamics

SOLEIL is the French national synchrotron facility, located on the Saclay Plateau near Paris. It is a multi-disciplinary instrument and research laboratory whose mission is to conduct research using synchrotron radiation, to develop cutting edge instrumentation on the beamlines, and to make these developments available to the scientific community. SOLEIL synchrotron, a unique tool for both academic research and industrial applications across a wide range of disciplines including physics, biology, chemistry etc., opened in 2008. It is used annually by thousands researchers from France and abroad. SOLEIL is based on a synchrotron source that is state-of-the-art both in terms of brilliance and stability. This large scale facility, a partner of the Université Paris Saclay, is a “publically owned” private company, founded by the CNRS and the CEA.

The 354 m circumference storage ring that generates synchrotron radiation stores a 2.75 GeV electron beam and runs continuously 24 hours a day, 7 days a week, with uninterrupted periods of up to 13 weeks. It consists of an extended DB (Double Bend) lattice, which is fully optimized in terms of straight section lengths for insertion devices, beam sizes and divergences at the source points, and of beam lifetime. It provides a low beam emittance of 4 nm·rad horizontally and 40 pm·rad vertically with excellent stability at the nominal beam current of 500 mA. Top-up injection as well as several feedback systems are running at all times. Besides, it can run in 4 modes of operation, differing in filling and intensity of the stored bunches, to fulfill the demands of a wide range of experiments, carried out in the beamlines.

Studies are currently underway for a major upgrade of the SOLEIL ring, in phase with an explosive wave of constructing of a new generation of LS rings, called Diffraction Limited Storage Rings (DLSR), thanks to a marked progress of the technology over the last decade in the international light source (LS) community. To be able to continue serving as a top-class light source in the future, SOLEIL has officially launched R&D studies for its upgrade since the beginning of 2019, and a CDR (Conceptual Design Report) was compiled at the end of 2020. The project is presently in the TDR (Technical Design Report) phase with the goal of delivering a TDR by the end of the year 2024.

Background situation linked to this postdoctoral position:

Building a DLSR imposes a series of major challenges in terms of accelerator physics and technology. A lattice achieving ultra-low horizontal emittance typically suffers from strong nonlinear effects that reduce the transverse and longitudinal dynamic acceptances and increase their sensitivity to imperfections. Moreover, in the case of an upgrade of an already existing machine such as SOLEIL, another fundamental difficulty faced is the adjustment of the source points of the synchrotron radiation of the existing beamlines. Considering all this into account, the SOLEIL Upgrade Project team came up with a lattice giving a natural horizontal emittance of 80 pm.rad and satisfying, to a large extent, the geometric constraints imposed by the existing beamlines. The team is continuing its effort with the objective of completing the evaluation of the technical feasibility of the TDR lattice from all possible points of view, both in terms of the accelerator physics and engineering-wise. In view of the importance of upgrading the performance of the booster, a new ambitious design of the booster lattice has been accomplished in 2021, capable of producing a natural horizontal emittance of as low as 5 nm.rad at the extraction energy of 2.75 GeV.

I.Missions

The successful candidate shall be engaged in:

-Continuation of the ongoing robustness studies of the SOLEIL II TDR lattice by considering all relevant imperfections and by integrating the updates in progress of the TDR lattice, where in particular, refinement of the modeling of the magnets is made using 3D numerical data provided by the Magnetism and Insertions Group.

-Collaboration with the colleagues from the Accelerator Physics (AP) group for other ongoing studies (injection, collimation of scattered particles, etc.).

-Maintenance and improvement of the numerical tools used by the group such as AT, SC, ELEGANT, TRACY on the internal and external numerical servers used by the group.

-Collaboration with the colleagues from the AP group and other concerned groups (diagnostics, power supplies, etc.) to develop measurement and rapid correction techniques vital for the future machine. These new beam-based techniques, such as AC-LOCO, LOCOM and AC-BBA, shall take advantage of the all-new fast orbit feedback architecture (fast data streams and synchronization) and multi-purpose and versatile power supplies which are being selected. Compatible tests are possible with both SOLEIL and SOLEIL II. The goal is to develop test benches on the current storage ring to validate these techniques before its shutdown.

-Provide support for the current accelerators’ tuning in the control room during restarts, service tasks and participate in accelerator physics-oriented machine sessions.

The successful candidate will join the accelerator physics group of SOLEIL in the Accelerator and Engineering Division. The group currently consists of 6 physicists, 3 postdoctoral fellows, and 1 doctoral student. He (or she) may also participate in the beam-based experimental studies which could be organized either at SOLEIL or at other machines. In addition, he (or she) shall likely interact with colleagues in his (or her) group and from various engineering groups to study the interdisciplinary aspects of his (or her) studies.

He (or she) shall be regularly given opportunities to participate in conferences and workshops and to present his (or her) works, as well as making publications of the outcomes in appropriate journals.

II. Experience required

The candidate is expected to possess a PhD degree in physics or equivalent competence. We are looking for a motivated candidate with a very strong university background in physics (classical physics and electrodynamics), mathematics (linear algebra, numeric methods, statistics), as well as in computer science (programming in MATLAB, Python, C, C++, etc., as well as knowledge of numerical codes for accelerators). Experience with synchrotron radiation, accelerator physics, high energy physics or relevant engineering fields would be a particularly important asset. The working language is English. Ability to speak French shall be an added value.

III. General condition

The offer concerns a postdoctoral contract whose duration can be up to 4 years for candidates who have obtained their PhD degree in less than three years at the date of signing the contract with SOLEIL. For those who do not fulfill this condition, the contract shall be for a 12-month period with the possibility of renewal for one year.