Lead Simulation Physicist Detector Simulation; EP-SFT--LD

Company Description

At CERN, the European Organization for Nuclear Research, physicists and engineers probe 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 collided together at close to the speed of light, providing clues about how particles interact and insights into the fundamental laws of nature.

Position:
Applied Physicist
Job reference: EP-SFT--LD
Job grade: 6‑7
Contract type:
Limited‑duration contract (5 years)

Working hours:

40 hours per week
Job flexibility:
Hybrid

In this role you will develop, maintain, and validate physics simulation software used to model particle interactions in high‑energy physics (HEP) detectors. Working within the Geant4 Simulation team, you will contribute to extending physics coverage, improving modelling capabilities, and enhancing computing performance, with a major focus on GPU and parallel computing architectures for the High‑Luminosity LHC and future experiments.

• Further develop the Geant4‑based GPU‑enabled component AdePT, ensuring integration into LHC experiment software frameworks and implementing key physics components.
• Design and run regression tests comparing GPU results against CPU reference physics to ensure no degradation in physics fidelity.
• Coordinate with LHC experiments (ATLAS, CMS, LHCb, ALICE) and FCC studies to prioritize related developments.
• Contribute to overall project organization, including work planning, workshop and training organization, and representation of the project vision.
• Engage with the Geant4 worldwide user community, fostering collaboration within the EP department, CERN, and external partners.
• Supervise team members and coordinate tasks relevant to the Geant4 project.

• PhD or equivalent relevant experience in Physics or a related field.

• Demonstrated experience with Monte Carlo techniques applied to particle transport simulation, especially using GPUs.
• Proficiency in scientific computing and advanced programming.
• Knowledge of large collaborative software projects, including continuous integration, code review, and issue‑based workflows.
• Experience with tools and methods supporting all phases of large scientific code bases, particularly design, development, testing, and performance optimisation.
• Strong track record of scientific publications and high‑level communication, e.g., conference presentations.
• Experience supervising and managing external contributors is an advantage.

• Simulation, design and development of detector components using Geant
  4.
• Programming languages: C++, CUDA, Python.
• Application software development.
• Testing, diagnosing and optimisation: unit tests, physics regression tests, GPU profiling.
• Knowledge of software lifecycle tools (Git Lab CI, JIRA, Spack, Conda) is an advantage.

• Achieving results: structured, organized approach, prioritizing tasks for outcomes.
• Learning and sharing knowledge: freely share expertise, coach others for knowledge transfer.
• Demonstrating flexibility: adapt quickly and resourcefully to changing priorities.
• Communicating effectively: clear, logical, structured expression of ideas.
• Problem solving: objective judgment based on available facts.

• Spoken and written English; commitment to learn French.

Diversity has been an integral part of CERN’s mission. We welcome applications from all Member States and Associate Member States. This vacancy will be filled as soon as possible, and applications should normally reach us no later than 19.07.2026 at 23:59 CEST.

• Contract type:
  Limited duration contract (5 years).
• Work during nights, Sundays and official holidays if required.
• Job grade: 6‑7.
• Field of work:
  Experimental Physics.

• Competitive (tax‑free) salary, increasing with experience.
• 30 days paid leave per year plus 2 weeks annual closure.
• Coverage by CERN’s comprehensive health insurance scheme; CERN Pension Fund membership.
• Family, child and infant monthly allowances.
• Relocation package (installation grant, removal, travel expenses).
• Possibility to extend contract up to 8 years and eligibility for indefinite tenure.

19.07.2026 at 23:59 CEST