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

Job description

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. Your responsibilities 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. Your profile 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. Skills 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. Job closing date: 11.10.2026 at 23:59 CEST. Contract duration: 24 months, with a possible extension up to 36 months maximum. Working hours: 40 hours per week Job flexibility: Hybrid Target start date: 01-January-2027 This position involves: Work during nights, Sundays and official holidays, when required by the needs of the Organization. Job reference: EP-SFT-2026-152-GRAP Field of work: Applied Physics Benchmark job: 200140 - Applied Physicist Global Benefits A monthly net stipend of either 6372 or 7004 Swiss Francs per month depending on your degree. 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 of the CERN Pension Fund. Family, child and infant monthly allowances depending on your individual circumstances. A relocation package (installation grant and travel expenses) depending on your individual circumstances. Possibility to extend your contract up to 36 months. On-the-job and formal training including language classes. Overview of CERN - Discover a world where the impossible is made possible! At CERN, the European Organization for Nuclear Research, we are pushing the frontiers of science and technology. Our groundbreaking work brings together not only physicists but also a diverse range of professionals from engineering, technical, scientific, and administrative fields. Together, we foster an environment where innovation and collaboration thrive. Every day, we face exciting new challenges and opportunities to contribute to cutting-edge research that shapes our understanding of the universe. We meet these challenges through the diverse perspectives within our teams, ensuring every contribution is valued and driving our shared sense of inclusion and purpose. Diversity is a core value of CERN since its foundation, and it remains central to our mission and continued success. If you are ready to be part of a dynamic, inclusive community pushing the boundaries of knowledge, CERN is the place where your curiosity and skills can thrive. Be part of our mission to uncover what lies at the heart of the universe! TAKE PART! More information about us, here: