Post-doctoral position : Detector Group/SEXTANTS beamline

Located on the Paris-Saclay plateau, about 20 kilometers from the capital, the SOLEIL synchrotron is one of France's leading research facilities. Since it began operating in 2008, it has served the national and international scientific communities. Research conducted at SOLEIL covers a wide range of scientific and industrial fields — including physics, biology, chemistry, materials science, environmental science, Earth sciences, and cultural and natural heritage — all connected to current societal challenges. Experiments carried out on the beamlines rely on the use of synchrotron light emitted by electrons accelerated to nearly the speed of light within a storage ring. SOLEIL is jointly supervised by the CNRS and the CEA and offers its staff a dynamic, innovative, multidisciplinary, and international working environment.

At the forefront of technology, SOLEIL II is an ambitious project designed to provide new opportunities for scientific and industrial research. SOLEIL II consists of a major upgrade of the existing infrastructure and aims to significantly improve the performance of electron accelerators and beamlines. It is designed to address major current and future societal challenges, particularly in areas such as advanced materials research, energy and sustainable development, health and well-being, and the environment.

Construction work on the SOLEIL II project began in 2024, marking the start of a phase of development and technological innovation. In parallel, the existing facility will remain operational until the fall of 2028. SOLEIL II is scheduled to start operations in 2030, with a gradual ramp-up phase continuing until 2035.

As part of an instrumentation upgrade program, SOLEIL is developing a new time-resolved 2D detector system dedicated to pump–probe experiments in the soft X-ray range (300 eV – 1 keV). This project is part of the “SOLEIL” targeted project of the ANR PEPR DIADEM research program which is devoted to high throughput data acquisition, automation data analysis at Synchrotron SOLEIL. 

The detector will be installed on the SEXTANTS beamline and will enable diffraction and imaging experiments with sub-nanosecond time resolution. The system combines:

  • A microchannel plate (MCP) electron multiplier for X-ray photon-to-electron conversion and amplification.
  • A fast phosphor screen for electron-to-visible photon conversion
  • A dedicated optical coupling system
  • A Timepix3 Quad hybrid pixel detector (512 × 512 pixels, 55 µm pitch) with event-driven readout and pixel-level timestamping at the nanosecond scale.

This postdoctoral project focuses on the design, optimization, integration, and commissioning of the complete detection chain.

1.Scientific and Technical Objectives :

The main objective is to design and implement a high-performance, time-resolved detector optimized for soft X-ray pump–probe experiments.

Key challenges include :

  • Modelling and optimizing detection efficiency and signal-to-noise ratio ;
  • Designing and validating the optical coupling system ;
  • Ensuring nanosecond-scale gating capability ;
  • Maximizing spatial and temporal resolution ;
  • Integrating the detector into the SOLEIL control system (TANGO) ; 

Particular emphasis will be placed on timing performance at the nanosecond scale, high-rate event-driven acquisition, and detector operation under ultra-high vacuum conditions.

2.Responsibilities :

The postdoctoral researcher will contribute to the following tasks :

  • Modelization and characterization of the detector in laboratory and beamline environments ;
  • Optimization of detector performance (gain, timing, and gating configuration) ;
  • Participate in optical system design and alignment ;
  • Develop and validate calibration procedures ;
  • Development and optimization of data processing algorithms (clustering, timing corrections, centroiding) ;
  • Lead detector commissioning and performance evaluation at the beamline ;
  • Contribute to technical documentation and scientific publications.

The project is interdisciplinary and involves close collaboration with detectors, optics, vacuum, and beamline scientists, as well as with mechanical engineering, data acquisition, and motion control teams.

The position is hosted within the Detector Group at Synchrotron SOLEIL, under the supervision of a detector scientist, and in close collaboration with the SEXTANTS beamline team.

3.Expected Profile :

Required :

  • PhD in experimental physics, detector physics, instrumentation, or a related field
  • Strong background in radiation detectors or fast timing systems
  • Data acquisition and analysis skills (Python and/or C++)
  • Ability to work in a multidisciplinary technical environment

Desirable :

  • Experience with vacuum systems and/or photon/electron detection
  • Experience with MCP-based detectors
  • Knowledge of hybrid pixel detectors
  • Experience in synchrotron or X-FEL environments

4.General conditions :

This 24-month fixed-term postdoctoral position is based at Synchrotron SOLEIL.

The selected candidate will benefit from the following conditions and opportunities :

  • Participation in the development of a state-of-the-art time-resolved soft X-ray detector ;
  • Direct involvement in beamline commissioning and advanced synchrotron experiments ;
  • Opportunity to publish in instrumentation and applied physics journals.