Research Physicist

Job Posting Organization:
CERN, the European Organization for Nuclear Research, was established in 1954 and is one of the world's largest and most respected centers for scientific research. With a mission to probe the fundamental structure of the universe, CERN employs thousands of scientists, engineers, and support staff from over 100 countries. The organization operates in multiple countries, primarily in Europe, and is known for its groundbreaking work in particle physics, utilizing the world's largest and most complex scientific instruments to study fundamental particles and their interactions.

Job Overview:
The position of Research Physicist is part of the Next-Generation Trigger (NGT) initiative, specifically focusing on the Real-time Reconstruction Revolution (R³). This role is crucial in transforming the High-Level Trigger (HLT) farm into a full reconstruction farm capable of processing vast amounts of data with offline-like quality. The successful candidate will be responsible for defining next-generation data formats that maximize data reduction while ensuring high physics performance. This includes developing workflows to quantify the impact of lossy compression on physics performance, benchmarking compression methods, and improving lossless compression techniques. The role requires a deep understanding of high-energy physics (HEP) experiments and the ability to work collaboratively in large international teams, contributing to the advancement of scientific software and data processing methodologies.

Duties and Responsibilities:
The duties and responsibilities of the Research Physicist include:

• Defining and optimizing next-generation data formats that enhance data reduction while maintaining physics performance.
• Developing workflows to assess the impact of lossy compression on physics performance, including establishing clear metrics and conducting automated regression tests.
• Benchmarking various compression and decompression methods by evaluating CPU/GPU costs, I/O throughput, memory usage, and latency under realistic workloads.
• Enhancing lossless compression of raw data by refining existing methods and innovating new techniques that utilize R³-reconstructed objects and AI methodologies.
• Collaborating with international teams to ensure effective code review, continuous integration/continuous deployment (CI/CD), and comprehensive documentation of processes and methodologies.

Required Qualifications:
Candidates must demonstrate significant contributions to large-scale scientific software or trigger/reconstruction in high-energy physics (HEP) or related fields. A practical understanding of the operational aspects of large HEP experiments is essential, particularly the entire process from detector measurements to analysis-level objects and final physics results. Experience in large international collaborations, including code review and CI/CD practices, is highly desirable. Strong technical skills in programming languages such as C++, Python, and ROOT are required, along with a solid understanding of event reconstruction and calibrations in HEP. Familiarity with LHC experiments, data compression techniques, AI/ML methods for data reduction, and GPU programming will be considered advantageous.

Educational Background:
The ideal candidate should possess a professional background in Physics, Applied Physics, Data Science, or a related field. Candidates must 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. It is also required that candidates have never held a CERN fellow or graduate contract before.

Experience:
The position requires candidates to have a demonstrated level of experience in large-scale scientific software development or in the trigger/reconstruction domain within high-energy physics or similar fields. The experience should ideally include practical involvement in the full chain of data processing from detector measurements to final analysis, as well as familiarity with collaborative work in international settings.

Languages:
Fluency in spoken and written English is mandatory, and candidates should be committed to learning French as part of their professional development.

Additional Notes:
The contract duration for this position is 24 months, with the possibility of extension up to a maximum of 36 months. The working hours are set at 40 hours per week, and the job offers a hybrid working model. The target start date for the position is January 1, 202

• The job reference is EP-CMG-2025-179-GRAP, and the field of work is Applied Physics. The compensation includes a monthly stipend ranging from 6287 to 6911 Swiss Francs (net of tax), comprehensive health coverage for the employee and their family, and various allowances depending on individual circumstances. Additionally, employees are entitled to 30 days of paid leave per year and access to on-the-job training and formal training opportunities at CERN.