Lead Simulation Physicist – High-Performance Detector Simulation

What you'll do

In this role you will be responsible for developing, maintaining, and validating physics simulation software used to model particle interactions in high-energy physics (HEP) detectors. Working within the Geant4 Simulation team, you will contribute to ongoing efforts to extend physics coverage, improve modelling capabilities, and enhance computing performance.

A major focus of the role is the development of detector and physics simulations for GPU and other parallel computing architectures, supporting the growing computational demands of the High-Luminosity LHC and future experiments. You will play an important role in advancing both physics models and the efficiency of their implementation in high-performance computing environments.

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Your responsibilities

Further develop the Geant4-based GPU-enabled component, AdePT, ensuring its smooth integration into the LHC experiments' software frameworks, and lead the consolidation and implementation of key components, possibly including relevant physics processes.
Design and run regression tests comparing GPU results against CPU reference physics, ensuring no degradation in physics fidelity.
Coordinate with LHC experiments (ATLAS, CMS, LHCb, ALICE) and FCC studies to prioritise related developments.
Contribute to the overall project organisation, including work planning, organising workshops and training activities, and representing the project and its vision.
Engage with Geant4’s worldwide user community, foster collaboration within the SFT group, the EP department, CERN, and external partners, and encourage contributions from laboratories and universities.
Supervise team members and coordinate tasks relevant to the Geant4 project.

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Your profile

Demonstrated experience with Monte Carlo techniques applied to particle transport simulation, particularly their implementation using modern software technologies and hardware architectures such as GPUs.
Proficiency in scientific computing and deep knowledge of advanced programming.
Knowledge in large collaborative software projects, particularly Monte Carlo simulation toolkits, relying on continuous integration, code reviews, as well as issue-based workflows.
Experience with tools and methods that support all phases of the life cycle of large scientific code bases particularly software design, development, testing, and performance optimisation.
A strong track record of scientific publications and high-level communication (for example, through invited conference presentations).
Experience in supervising and managing external contributors would be considered an advantage.
PhD or equivalent relevant experience in the field of Physics or a related field.

Your skills

Simulation, design and development of (parts of) detectors: Geant4.
Knowledge of programming techniques and languages: C++, CUDA, Python.
Development of application software.
Testing, diagnosing and optimisation of software: Unit tests, physics regression tests, GPU profiling.
Knowledge and application of software life-cycle tools and procedures: would be considered an advantage (e.g. GitLab CI, JIRA, Spack or Conda).
Has a structured and organised approach towards work; is able to set priorities and plan tasks with results in mind.
Shares knowledge and expertise freely and willingly with others; coaches others to ensure knowledge transfer.
Adapts quickly and resourcefully to shifting priorities and requirements.
Expresses opinions, ideas and suggestions with conviction and in a logical/structured manner; keeps to the point.
Finds the information needed to solve problems; makes objective judgments based on all the facts available.
Spoken and written English, with a commitment to learn French.

Ideal start date: 01/12/2026

Contract duration (in months): 60

Grade range: 6

Benchmark job: 200140 - Applied Physicist

Job flexibility: Hybrid

Team supervision

Employment conditions

Work during nights, Sundays and official holidays, when required by the needs of the Organization.

Global Benefits at CERN

A minimum net entry-salary of 9236 Swiss Francs per month, increasing in line with your years of relevant experience.
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, removal, travel expenses) depending on your individual circumstances.
Possibility to extend your contract up to 8 years + eligibility for indefinite contract tenure.

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Be sure to meet the eligibility criteria

You are a national of a CERN Member State or Associate Member State. Currently, we cannot consider applications from Pakistani and Lithuanian nationals for positions with a 2026 start date, as the ceiling defined under Article II.5 of the Associate Membership Agreement has been reached.
You have relevant qualifications and professional experience.
If you have previously held a Staff contract at CERN, you will not be eligible for these positions.
Please pay attention to the additional criteria and requirements for this specific position and mentioned above.

You will need these documents to complete your application

Your CV (English or French)
Any document you consider relevant to your application

Your CERNDepartment

The EP department conducts research in experimental particle physics in close collaboration with and supporting the wider scientific community working at CERN. This includes designing and operating experiments, developing and constructing detectors, acquiring and analysing physics data.

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!

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Still have a doubt ? Here are the most frequently asked questions

What should I expect during my first week at CERN?

Your onboarding at CERN includes a comprehensive induction programme, which starts with an official welcome session at the beginning of each month. In addition, you will receive important information both before and after your arrival to ensure a smooth transition into your new role. This process is designed to help you get acquainted with CERN’s environment, your team, and the tools and systems you’ll be using.
How big would the team be?

The size of the team you'll be working with at CERN depends on the specific role and department. Some teams are small and highly specialized, while others are larger and more interdisciplinary. During the interview process, you'll have the opportunity to learn more about the team structure for the position you are applying for.
What is the working language at CERN?

The working languages at CERN are English and French. However, it is not always mandatory to speak both languages to work at CERN. We offer language training to help you acquiring the other language.
What support does CERN provide for relocation?

CERN does not offer direct assistance with relocation. However, depending on your role and specific criteria, you may be eligible for certain benefits such as an installation allowance and coverage of travel expenses to join CERN. These benefits are designed to help ease the transition when relocating to the Geneva area. For more information, please consult the “Salary, Benefits and Support“ page.
Do I need a visa to work at CERN?

Whether you need a visa to work at CERN depends on your nationality and the duration of your stay. CERN assists with the necessary visa and work permit processes for its employees and visitors. The specific requirements will be communicated to you during the recruitment process.
What would my salary be?

Salaries at CERN are determined by a structured scale. Salaries are based on your role, qualifications, and experience, and are not subject to negotiation. Specific details will be provided as your application progresses. For more information, please refer to the dedicated page.