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.

Your responsibilities

• 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.

Your profile

• 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.

Skills

• 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.