Software Engineer Computing; EP-SFT--LD

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

At CERN, the European Organization for Nuclear Research, physicists and engineers are probing the fundamental structure of the universe. Using the world's largest and most complex scientific instruments, they study the basic constituents of matter - fundamental particles that are made to collide together at close to the speed of light. The process gives physicists clues about how particles interact, and provides insights into the fundamental laws of nature.

Introduction

This role focuses on improving and evolving software developed in the EP‑SFT group such as Geant4 and ROOT, two core software frameworks used for particle physics simulation and data analysis at CERN and laboratories worldwide. The position involves optimising and redesigning key components to run efficiently on modern high-performance computing systems, with a strong emphasis on GPU acceleration and large-scale parallel processing.

Responsibilities include contributing to next‑generation technologies such as AdePT for GPU‑based particle transport, enhancing performance for exabyte‑scale data processing, and developing tools for profiling, testing, and validation. Working at the intersection of HPC, C++ software engineering, and experimental physics, the role directly supports 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, also focusing on GPU architectures (CUDA, SYCL) and the exploitation of advanced features of programming languages, such as C++.
• Hands‑on Development:
  Implement and refactor critical hot loops, memory layouts, and kernel launches. Use state‑of‑the‑art tools to identify and eliminate bottlenecks.
• Take part in the overall organisation of data simulation, processing, and analysis activities within the EP‑SFT group’s
• Projects, including work planning, the organisation of workshops and trainings, and representing the projects and their vision.
• Engage with the projects’ user communities, foster collaboration within the SFT group, the EP department, and CERN, and encourage external contributions from laboratories, universities, and other partners.
• Supervise team members and coordinate activities related to the EP‑SFT data simulation, processing, and analysis projects.

Master's degree or PhD or equivalent relevant experience in the field of 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).
• A proven track record of optimising large (100k+ line) 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 would be an advantage.
• Experience contributing to LLVM/Clang or compiler‑level optimisation work is considered an asset.
• Knowledge of Monte Carlo particle transport algorithms or statistical data analysis is advantageous.
• A publication record or invited talks at major conferences (e.g., Supercomputing, CHEP, IEEE/ACM performance workshops) is considered a plus.
• Experience in supervising and coordinating external contributors would be desirable.
• Development of application software, advanced C++ and Python.
• Testing, diagnosing and optimisation of software, GPU profiling, memory optimisation, parallel debugging.
• Knowledge of programming techniques and languages, parallel programming techniques such as CUDA, std::thread, TBB, or MPI. Experience with the usage of Clang and LLVM would be considered an advantage.
• Knowledge and application of software life‑cycle tools and procedures (Git Lab CI, JIRA, CMake, Spack) would be considered an advantage.
• Achieving Results: having a structured and organised approach towards work; being able to set priorities and plan tasks with results in mind.
• Solving Problems: finding the information…