High-Level Trigger Calibration Scientist (EP-CMS-TDQ-2026-150-GRAP)

The Compact Muon Solenoid (CMS) experiment's High-Level Trigger, as deployed during the LHC's 2009-2026 running period, reconstructs high-energy proton-proton collision events using detector conditions that often lag behind the best available calibrations. Closing that gap by delivering near-real-time, offline-quality calibrations to the online system, also known as "Optimal Calibrations," is one of the central challenges of High-Luminosity (HL)-LHC operations, and it is the challenge this role will face. This position is part of the Next-Generation Trigger programme .

- Work with the CMS Detector Performance Groups (DPGs) and Physics Object Groups (POGs) to develop new and improve calibration algorithms. - Maintain the successful NGT Demonstrator System, developed during LHC Run 3, ensuring it remains operational and capable of running in replay mode against archived data throughout Long Shutdown 3. - Building on the NGT Demonstrator System experience, contribute to the design of a realistic, production-grade NGT Data Acquisition and Calibration System implementing the Optimal Calibrations required for CMS's High-Level Trigger during the HL-LHC era. This includes exploring the design space across different compute and storage availability scenarios. - Integrate and test the production-grade system within the CMS online infrastructure, working closely with system administrators and software engineers to ensure seamless compatibility. - Conduct thorough testing of the NGT system in a realistic environment, simulating various LHC and CMS operational scenarios to assess performance and reliability. - Produce detailed reports evaluating the impact of improved online calibrations on the physics performance of the High-Level Trigger. - This role includes team supervision responsibilities.

- Experience in the design, development, and validation of calibration workflows for high-energy physics experiments. - Knowledge and application of Python and C++ programming, as well as database management systems. - Experience with Trigger and Data Acquisition (TDAQ) systems, including their hardware and associated tools. - Practical experience developing software algorithms within an integrated framework. - Proficient use of software development tools (e.g. GitHub, GitLab) and continuous integration practices.

- Knowledge of modern Git, Python, and C++. - Basic knowledge of DevOps and Continuous Integration (CI). - Familiarity with high-energy collider and detector operations. - Basic knowledge of high-energy physics. - Spoken and written English, with a commitment to learn French. Eligibility criteria: - You have a professional background in Applied Physics (or a related field) and have either: - a Master's degree with 2 to 6 years of post-graduation professional experience; - or a PhD with no more than 3 years of post-graduation professional experience. - You have never had a CERN fellow or graduate contract before.