Detector Simulation Physicist (EP-SFT-2026-152-GRAP)

In this role, you will develop and improve GPU-accelerated Monte Carlo detector simulation software within the Geant4 team, with a particular focus on optical photon transport. You will contribute to software design and implementation, physics validation against established CPU simulations, performance optimisation, and integration into experimental software frameworks.

- Design, develop, and integrate GPU algorithms for optical photon simulation within a Monte Carlo particle-transport framework. - Compare and validate GPU simulation results against established CPU implementations. - Develop unit, regression, and physics-validation tests. - Profile applications, identify performance bottlenecks, and optimise computational performance. - Collaborate with software teams from the Large Hadron Collider experiments to integrate GPU-enabled particle transport into their simulation frameworks. - Engage with the international Geant4 collaboration and its user community, particularly in the area of optical photon simulation. - Contribute to the documentation, maintenance, and long-term quality of the developed software.

- Experience in developing scientific or physics-simulation software, preferably using modern C++. - Experience with GPU programming or software development for heterogeneous computing architectures. - Experience with software testing, numerical validation, performance profiling, or optimisation. - Knowledge of Monte Carlo methods or experience with particle-transport simulation would be an advantage, particularly in the area of optical photon transport. - Experience contributing to collaborative software projects or working within an international scientific environment would be an advantage.

- Programming languages and technologies: modern C++, CUDA, Python. - GPU programming, heterogeneous computing, and performance optimisation. - Git and collaborative software development. - Unit testing, regression testing, and numerical validation. - Experience with Monte Carlo particle-transport codes such as Geant4 would be considered an advantage. - Debugging and profiling tools such as gdb, Compute Sanitiser, perf, Nsight Systems, or Nsight Compute would be considered an advantage. - Spoken and written English, with a commitment to learn French. Eligibility criteria: - You are a national of a CERN Member or Associate Member State . - You have a professional background in Physics, Computer Science, or a related (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.