HEP Physicist – Data Preservation

What you'll do

Are you excited about giving a second life to a vintage but invaluable set of data, which has the potential to significantly enhance the quality of the preparation studies for the next flagship collider at CERN, the Future Circular Collider?

The LEP data@EDM4HEP project aims at migrating the data collected and LEP in the 1990s, and the corresponding Monte Carlo simulated events, to a new common format developed for the next generation of HEP experiments. This would enable the use of the tools under development for the electron-positron collision phase of FCC, to be tested on real data.

At the same time, the FAIRness of the data sample would be enhanced by improving on Accessibility and Interoperability, mitigating the risk of losing access to the data.

We are looking for a motivated particle physicist with software skills to continue the feasibility work prototyped so far using the ALEPH data. You will work as a member of the CERN EP-FCC group, in close contact with the Key4HEP team of the CERN EP-SFT group, the members of the DPHEP collaboration, and international teams at Brown University and MIT.

Your responsibilities

Consolidate the extraction chain of the ALEPH data into EDM4hep. This includes ensuring the right data structures are used, possibly proposing/implementing modifications, and optimising the involved applications for performance and easy-of-use.
Validate the above with a significant set of benchmark analysis, and apply the validated chain to the whole ALEPH data sample, including Monte Carlo simulated data, complemented with adequate documentation and help tools.
Consolidate wokflows to produce new Monte Carlo events with the legacy ALEPH software, still available through containers and/or VMS, in particular in what concernes the use of recent event generators.
Investigate ways to apply the same to DELPHI - and possibly OPAL - data. This will require contacts with the relevant DELPHI and OPAL people.
Support users of the migrated data in their attempts using their feedback to improve the provided data set and tools.
Present the result to relevant events.
If needed, supervise students on specific tasks relevant for the project.

Still here? Let's make a quick check about

Your profile

Familiarity with HEP data sets and HEP event data models and their use in analysis.
Familiarity in building data analysis libraries with C++, FORTRAN and Python.
Familiarity working on large codebase open source projects.
Familiarity with tools used in HEP analysis or data storage, such ROOT, and the Key4hep ecosystem.
Your studies focused on Computer Science, Physics, or similar.

Your skills

Proficient in Python, C++, Git, CMake.
Familiar with FORTRAN 77.
Flexible to learn new tools and techniques to a level adequate to the project needs.
Familiarity with Key4hep.
Spoken and written English, with a commitment to learn French.

Ideal start date: 04/01/2026

Contract duration (in months): 24

Job flexibility: Fully Onsite

Team supervision

Employment conditions

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

Global Benefits at CERN

A monthly stipend between 6372-7004 Swiss Francs per month (tax free) 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.

Let's get you ready

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.
By the application deadline, you have a master’s degree with 2 to 6 years of professional experience since graduation or a PhD with a maximum of 3 years of professional experience since graduation. You are not eligible with only a bachelor’s degree.
You have never had a CERN fellow or graduate contract before.
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)
A copy of your most relevant diploma or a certificate of achievement from your school (if you don't yet have your paper diploma)
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.