Software Engineer - High-Performance Computing (EP-SFT-2026-137-LD)

Company Description

At CERN, the European Organization for Nuclear Research, scientists and engineers explore the fundamental structure of the universe using the world's most complex scientific instruments. Our collaborative environment fosters innovation and pushes the boundaries of knowledge.

Job Description: Software Engineer (EP-SFT Group)

This role focuses on improving and evolving software developed in the EP-SFT group, such as Geant4 and ROOT, which are essential frameworks for particle physics simulation and data analysis globally. The position involves optimizing and redesigning key components to run efficiently on modern high-performance computing (HPC) systems, with a strong emphasis on GPU acceleration and large-scale parallel processing. Responsibilities include contributing to next-generation technologies like AdePT for GPU-based particle transport, enhancing performance for exabyte-scale data processing, and developing tools for profiling, testing, and validation. You will work at the intersection of HPC, C++ software engineering, and experimental physics, directly supporting future research initiatives including the High-Luminosity LHC and the Future Circular Collider.

Functions

• Devise Performance Strategy: Define and execute the performance roadmap for Geant4 and ROOT, focusing on GPU architectures (CUDA, SYCL) and leveraging advanced C++ features.
• Hands-on Development: Implement and refactor critical code sections, optimize memory layouts, and manage kernel launches. Utilize state-of-the-art tools to identify and eliminate performance bottlenecks.
• Project Organization: Participate in the overall organization of data simulation, processing, and analysis activities within the EP-SFT group's projects, including work planning, workshop organization, and representing project visions.
• Community Engagement: Engage with user communities, foster collaboration within the SFT group, the EP department, and CERN, and encourage external contributions from laboratories and universities.
• Supervision and Coordination: Supervise team members and coordinate activities related to the EP-SFT data simulation, processing, and analysis projects.

Qualifications

• Master’s degree or PhD or equivalent relevant experience in Computer Science, Physics, or a related field.
• Experience:
• Demonstrated experience in high-performance computing, including GPU programming and C++ (template metaprogramming, SIMD, cache-aware design).
• Proven track record of optimizing large (100k+ lines) scientific or data-intensive software projects.
• Solid experience with performance profiling tools (e.g., Nsight, VTune, perf, Valgrind), debugging tools (GDB, LLDB), and continuous integration performance regression testing.
• Familiarity with Geant4, ROOT, or other high-energy physics simulation and analysis frameworks is advantageous.
• Experience contributing to LLVM/Clang or compiler-level optimization work is an asset.
• Knowledge of Monte Carlo particle transport algorithms or statistical data analysis is advantageous.
• A publication record or invited talks at major conferences is a plus.
• Experience in supervising and coordinating external contributors is desirable.
• Technical Competencies:
• Development of application software, advanced C++ and Python.
• Testing, diagnosing, and optimizing software, including GPU profiling, memory optimization, and parallel debugging.
• Knowledge of programming techniques and languages, including parallel programming techniques such as CUDA, std::thread, TBB, or MPI. Experience with Clang and LLVM is an advantage.
• Knowledge and application of software life-cycle tools and procedures (GitLab CI, JIRA, CMake, Spack) is an advantage.
• Behavioural Competencies:
• Achieving Results: Structured and organized approach, ability to set priorities and plan tasks with results in mind.
• Solving Problems: Ability to find necessary information and make objective judgments based on facts.
• Communicating Effectively: Expressing opinions, ideas, and suggestions logically and concisely.
• Learning and Sharing Knowledge: Willingness to share expertise and coach others.
• Demonstrating Flexibility: Adapting quickly and resourcefully to shifting priorities.
• Language Skills: Spoken and written English, with a commitment to learn French.

Additional Information

• Eligibility and Closing Date: Applications should normally reach us no later than 20.07.2026 at 23:59 CEST.
• Employment Conditions: Limited duration contract (5 years). Subject to certain conditions, holders of limited-duration contracts may apply for an indefinite position.
• Working Hours: 40 hours per week.
• Job Flexibility: Hybrid.
• Additional Requirements: Work during nights, Sundays, and official holidays, when required.
• Job Grade: 6-7.
• Job Reference: EP-SFT-2026-137-LD.
• Field of Work: Software Engineering and IT.
• Benchmark Job Title: Computing Engineer.

Global Benefits

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

Overview of CERN

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