Applied Physicist

Job Posting Organization:
CERN, the European Organization for Nuclear Research, is a leading scientific research institution established to probe the fundamental structure of the universe. It employs physicists and engineers who utilize the world's largest and most complex scientific instruments to study the basic constituents of matter. CERN's mission is to advance knowledge and understanding of the universe through groundbreaking research and innovation. The organization operates in multiple countries and employs a diverse workforce, fostering an environment of collaboration and inclusion. CERN has a strong commitment to diversity, which has been integral to its mission since its foundation.

Job Overview:
The Applied Physicist role at CERN involves developing, maintaining, and validating physics simulation software that models particle interactions in high-energy physics (HEP) detectors. The position is situated within the Geant4 Simulation team, focusing on enhancing physics coverage, improving modeling capabilities, and optimizing computing performance. A significant aspect of this role includes developing detector and physics simulations for GPU and other parallel computing architectures, addressing the increasing computational demands of the High-Luminosity LHC and future experiments. The successful candidate will contribute to advancing physics models and the efficiency of their implementation in high-performance computing environments, ensuring that CERN remains at the forefront of scientific research.

Duties and Responsibilities:
The duties and responsibilities of the Applied Physicist include: further developing the Geant4-based GPU-enabled component, AdePT, and ensuring its integration into the LHC experiments' software frameworks; leading the consolidation and implementation of key components, including relevant physics processes; designing and executing regression tests to compare GPU results against CPU reference physics to maintain physics fidelity; coordinating with LHC experiments (ATLAS, CMS, LHCb, ALICE) and FCC studies to prioritize developments; contributing to project organization, including work planning, workshops, training activities, and representing the project vision; engaging with the Geant4 user community and fostering collaboration within CERN and with external partners; supervising team members and coordinating tasks relevant to the Geant4 project.

Required Qualifications:
Candidates must possess a PhD or equivalent relevant experience in Physics or a related field. They should have 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 advanced programming is essential, along with knowledge of large collaborative software projects, particularly Monte Carlo simulation toolkits. Familiarity with tools and methods that support all phases of the life cycle of large scientific code bases, including software design, development, testing, and performance optimization, is required. A strong track record of scientific publications and high-level communication skills, such as through invited conference presentations, is also necessary. Experience in supervising and managing external contributors is considered an advantage.

Educational Background:
The educational background required for this position includes a PhD in Physics or a related field, or equivalent relevant experience. This advanced education is crucial for understanding the complex principles of high-energy physics and the technical skills needed for simulation software development.

Experience:
Candidates should have substantial experience in Monte Carlo techniques and particle transport simulation, particularly in the context of high-energy physics. Experience with modern software technologies and hardware architectures, especially GPUs, is critical. Additionally, familiarity with large collaborative software projects and the software life cycle is essential. The ideal candidate will have a proven track record of scientific publications and experience in managing collaborative projects.

Languages:
Fluency in spoken and written English is mandatory, with a commitment to learning French considered beneficial. Proficiency in these languages is essential for effective communication within the diverse international environment at CERN.

Additional Notes:
The position is a limited duration contract for 5 years, with the possibility of extension up to 8 years and eligibility for an indefinite contract tenure. The job requires a commitment of 40 hours per week, with hybrid work flexibility. The role may involve working during nights, Sundays, and official holidays as required by organizational needs. The job grade is 6-7, and the reference for this position is EP-SFT-2026-136-LD. CERN offers a competitive salary that is tax-free and increases with relevant experience, along with 30 days of paid leave per year, comprehensive health insurance, family allowances, and a relocation package depending on individual circumstances.