Lead Simulation Physicist - High-Performance Detector Simulation (EP-SFT-2026-136-LD)

Introduction

In this role, you will be responsible for developing, maintaining, and validating physics simulation software used to model particle interactions in high-energy physics (HEP) detectors. Working within the Geant4 Simulation team, you will contribute to ongoing efforts to extend physics coverage, improve modeling capabilities, and enhance computing performance. A major focus of the role is the development of detector and physics simulations for GPU and other parallel computing architectures, supporting the growing computational demands of the High-Luminosity LHC and future experiments. You will play an important role in advancing both physics models and the efficiency of their implementation in high-performance computing environments.

Functions

• Further develop the Geant4-based GPU-enabled component, AdePT, ensuring its smooth integration into the LHC experiments’ software frameworks, and lead the consolidation and implementation of key components, possibly including relevant physics processes.
• Design and run regression tests comparing GPU results against CPU reference physics, ensuring no degradation in physics fidelity.
• Coordinate with LHC experiments (ATLAS, CMS, LHCb, ALICE) and FCC studies to prioritize related developments.
• Contribute to the overall project organization, including work planning, organizing workshops and training activities, and representing the project and its vision.
• Engage with Geant4’s worldwide user community, foster collaboration within the SFT group, the EP department, CERN, and external partners, and encourage contributions from laboratories and universities.
• Supervise team members and coordinate tasks relevant to the Geant4 project.

Qualifications

• PhD or equivalent relevant experience in the field of Physics or a related field.

Experience

• Demonstrated experience with Monte Carlo techniques applied to particle transport simulation, particularly their implementation using modern software technologies and hardware architectures such as GPUs.
• Proficiency in scientific computing and deep knowledge of advanced programming.
• Knowledge in large collaborative software projects, particularly Monte Carlo simulation toolkits, relying on continuous integration, code reviews, and issue-based workflows.
• Experience with tools and methods that support all phases of the life cycle of large scientific code bases, particularly software design, development, testing, and performance optimization.
• A strong track record of scientific publications and high-level communication (e.g., through invited conference presentations).
• Experience in supervising and managing external contributors would be considered an advantage.

Technical Competencies

• Simulation, design, and development of (parts of) detectors: Geant4.
• Knowledge of programming techniques and languages: C++, CUDA, Python.
• Development of application software.
• Testing, diagnosing, and optimization of software: unit tests, physics regression tests, GPU profiling.
• Knowledge and application of software life-cycle tools and procedures: would be considered an advantage (e.g., GitLab CI, JIRA, Spack, or Conda).

Behavioral Competencies

• Achieving Results: Structured and organized approach to work; ability to set priorities and plan tasks with results in mind.
• Learning and Sharing Knowledge: Freely and willingly sharing knowledge and expertise; coaching others to ensure knowledge transfer.
• Demonstrating Flexibility: Adapting quickly and resourcefully to shifting priorities and requirements.
• Communicating Effectively: Expressing opinions, ideas, and suggestions with conviction and in a logical/structured manner; staying concise.
• Solving Problems: Finding necessary information to solve problems; making objective judgments based on all available facts.

Language Skills

• Spoken and written English, with a commitment to learn French.

Additional Information

Eligibility and Closing Date:
Diversity is an integral part of CERN’s mission and values. We welcome applications from all Member States and Associate Member States. This vacancy will be filled as soon as possible. Applications should normally reach us no later than 2026-07-17.

Employment Conditions:

• Contract type: Limited duration contract (5 years). Holders of limited-duration contracts may apply for an indefinite position under certain conditions.
• Working Hours: 40 hours per week.
• Job Flexibility: Hybrid.
• This position involves work during nights, Sundays, and official holidays when required by the Organization's needs.
• Job grade: 6-7.
• Job reference: EP-SFT-2026-136-LD.
• Field of work: Experimental Physics.
• Benchmark Job Title: Applied Physicist.

Global Benefits

• A competitive salary (tax-free), increasing with relevant years of experience.
• 30 days of paid leave per year plus 2 weeks annual closure.
• Coverage by CERN’s comprehensive health insurance scheme (for yourself, your spouse, and children) and membership in the CERN Pension Fund.
• Family, child, and infant monthly allowances depending on individual circumstances.
• A relocation package (installation grant, removal, travel expenses) depending on individual circumstances.
• Possibility to extend your contract up to 8 years, with eligibility for indefinite contract tenure.

Overview of CERN
At CERN, the European Organization for Nuclear Research, physicists and engineers probe the fundamental structure of the universe using the world's largest and most complex scientific instruments. We study the basic constituents of matter, colliding particles at near light speed to gain insights into fundamental laws of nature. CERN fosters an environment where innovation and collaboration thrive, bringing together diverse professionals from various fields. We face exciting challenges daily, contributing to cutting-edge research that shapes our understanding of the universe. Diversity is a core value, central to our mission and success. Join a dynamic, inclusive community pushing the boundaries of knowledge. Be part of our mission to uncover what lies at the heart of the universe! TAKE PART!

More information about us: careers.cern