Applied Physicist

Job Posting Organization:
CERN, the European Organization for Nuclear Research, is a leading scientific research organization established in 195

• It is headquartered in Geneva, Switzerland, and is known for its groundbreaking work in particle physics. CERN employs thousands of scientists, engineers, and support staff from over 100 countries, making it a hub for international collaboration in scientific research. The organization operates the world's largest particle physics laboratory and is home to the Large Hadron Collider (LHC), which is instrumental in advancing our understanding of the fundamental structure of matter and the universe. CERN's mission is to uncover the fundamental laws of nature through the study of particle interactions and to foster a diverse and inclusive workforce that drives innovation and scientific discovery.

Job Overview:
In this role as an Applied Physicist at CERN, you will be tasked with the development, maintenance, and validation of physics simulation software that models particle interactions in high-energy physics (HEP) detectors. You will work within the Geant4 Simulation team, contributing to the enhancement of physics coverage, modeling capabilities, and computing performance. A significant aspect of your work will involve developing detector and physics simulations for GPU and other parallel computing architectures, which are essential for meeting the computational demands of the High-Luminosity LHC and future experiments. Your contributions will be vital in advancing both the physics models and the efficiency of their implementation in high-performance computing environments, ensuring that CERN remains at the forefront of particle physics research.

Duties and Responsibilities:
Your responsibilities will include further developing the Geant4-based GPU-enabled component, AdePT, ensuring its seamless integration into the LHC experiments' software frameworks. You will lead the consolidation and implementation of key components, which may involve relevant physics processes. Additionally, you will design and execute regression tests to compare GPU results against CPU reference physics, ensuring that there is no degradation in physics fidelity. Coordination with LHC experiments such as ATLAS, CMS, LHCb, and ALICE, as well as FCC studies, will be essential to prioritize related developments. You will also contribute to the overall project organization, including work planning, organizing workshops and training activities, and representing the project and its vision. Engaging with Geant4’s worldwide user community, fostering collaboration within the SFT group, the EP department, CERN, and external partners, and encouraging contributions from laboratories and universities will be part of your role. Furthermore, you will supervise team members and coordinate tasks relevant to the Geant4 project.

Required Qualifications:
To qualify for this position, you must hold a PhD or possess equivalent relevant experience in the field of Physics or a related discipline. You 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 a deep understanding of advanced programming are essential. Familiarity with large collaborative software projects, particularly Monte Carlo simulation toolkits that rely on continuous integration, code reviews, and issue-based workflows, is also required. Experience 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 necessary. A strong track record of scientific publications and high-level communication skills, such as through invited conference presentations, is expected. Experience in supervising and managing external contributors would be considered an advantage.

Educational Background:
Candidates must possess a PhD or equivalent relevant experience in Physics or a closely related field. This educational background is crucial as it provides the foundational knowledge necessary for understanding complex physical principles and the technical skills required for simulation and modeling in high-energy physics.

Experience:
The position requires demonstrated experience with Monte Carlo techniques applied to particle transport simulation, particularly their implementation using modern software technologies and hardware architectures such as GPUs. Candidates should have a strong background in scientific computing and advanced programming, as well as experience with large collaborative software projects, particularly those involving Monte Carlo simulation toolkits. Familiarity with software life-cycle tools and procedures is also beneficial.

Languages:
Fluency in spoken and written English is mandatory, as it is the primary language of communication at CERN. Additionally, candidates should have a commitment to learning French, which is considered a valuable asset in the workplace.

Additional Notes:
This position is offered as a limited duration contract for 5 years, with the possibility of extension up to 8 years and eligibility for an indefinite contract tenure. The working hours are set at 40 hours per week, and the job flexibility is hybrid, allowing for a mix of remote and on-site work. The role may require work during nights, Sundays, and official holidays, depending on the needs of the organization. The job grade is classified as 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 coverage, family allowances, and a relocation package depending on individual circumstances.