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

The Detector Simulation Physicist will join CERN's Geant4 team to create and enhance GPU‑accelerated Monte Carlo detector simulation software, with a special emphasis on optical photon transport. Day‑to‑day work involves designing and implementing GPU algorithms for optical photon simulation, integrating them into the Monte Carlo particle‑transport framework, and validating the results against existing CPU‑based implementations. You will also build unit, regression and physics‑validation tests, profile the applications to locate performance bottlenecks, and apply optimisation techniques. Close collaboration with software groups from Large Hadron Collider experiments and active participation in the international Geant4 community are essential parts of the role. The position requires you to be a national of a CERN Member or Associate Member State and to hold a Master's degree in Physics, Computer Science or a closely related discipline. You must have a solid track record of developing scientific or physics‑simulation software using modern C++, as well as proven experience with GPU programming or other heterogeneous computing architectures. Experience in software testing, numerical validation, performance profiling or optimisation is also mandatory, together with fluent spoken and written English. Additional assets include familiarity with Monte Carlo optical photon transport and prior work with Geant4 or related profiling tools such as gdb, Compute Sanitiser, perf, Nsight Systems or Nsight Compute. A willingness to learn French and experience in collaborative, international scientific projects are also valued. What the role asks for: - CERN Member or Associate Member State nationality - Master's degree in Physics, Computer Science or related field - Proven modern C++ scientific software development experience - Demonstrated GPU programming experience - Fluent spoken and written English - Knowledge of Monte Carlo optical photon transport (nice‑to‑have) - Experience with Geant4 and related profiling tools (nice‑to‑have)