Simulation Developer

Geneva, Switzerland
10 Sep 2018
End of advertisement period
09 Oct 2018
Contract Type
Fixed Term
Full Time

Company Description

At CERN, the European Organization for Nuclear Research, physicists and engineers are probing 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 made to collide together at close to the speed of light. The process gives physicists clues about how particles interact, and provides insights into the fundamental laws of nature. Find out more on

Job Description


You will join the software development for experiments (SFT) Group ( that develops and provides support of scientific software for the experimental collaborations at CERN and worldwide. The Group is currently involved in an innovative programme of work to improve the performance of the simulation (Geant4) and analysis toolkits (ROOT) by exploiting the parallelism offered by modern CPU architectures and other techniques. This consists of work on a number of R&D activities that will form part of a major reengineering of existing software to be ready for the HL-LHC.

Your job will be to investigate fast simulation techniques that could be integrated into the Geant4 simulation toolkit (, which is used by nearly all High Energy Particle Physics experiments world-wide as well as in many medical and space applications. It is a versatile software toolkit written in C++ that can be adapted to simulate the transport of particles through matter for a very large variety of detector geometries, materials, particles types and energy ranges. Detector simulation is an essential activity in modern High Energy Particle Physics and its importance will grow for future experiments. Simulation accounts for more than half of the CPU consumption of the LCG Worldwide Computing Grid and its performance and accuracy are crucial to the achievement of CERN’s scientific goals. The importance of this job is to incorporate fast simulation techniques within the Geant4 toolkit to improve its CPU performance. In most cases, Fast Simulation implies a trade-off between simulation precision and computational speed.


As a Simulation Developer in EP-SFT, you will:

  • Collect and analyse the fast simulation state-of-the-art and requirements for the present and future CERN experimental activities.
  • Investigate and develop fast simulation techniques, using for example parameterizations, machine-learning techniques, biasing techniques, etc.
  • Work on the modularization of Geant4 in order to incorporate new fast simulation components.
  • Implement generic fast simulation libraries or modules to further extend the Geant4 toolkit/framework in order to seamlessly mix detailed and approximated simulations.
  • Contribute to the maintenance and development of the Geant4 detector simulation code with specific responsibility for the code that interfaces with fast simulation.
  • Collaborate with the LHC experiments on their fast simulation developments and support them in adopting the new fast simulation functionality.


Master's degree or PhD or equivalent relevant experience in the field of physics or computing engineering or a related field.


  • Demonstrated experience in collaborative development of C++ code for High Energy Physics.
  • Experience in analysis of user requirements and collaboration with the users of the simulation code.
  • Experience in comparing simulation and real data using advanced statistical methods.
  • Experience in programming high performance CPU architectures would be an advantage.
  • Experience as a developer or as a user of the Geant4 toolkit would be an advantage.

Technical competencies:

  • Knowledge of programming techniques and languages: proficiency in the C++; experience in high performance CPU architectures would be an advantage.
  • Development of application software: development of MonteCarlo codes for HEP experiments for fast or detailed simulation.
  • Knowledge and application of statistical and numerical mathematical methods: advanced statistical analysis algorithms required by the MonteCarlo simulations.

Behavioural competencies:

  • Achieving results: delivering high quality work on time and fulfilling expectations.
  • Learning and sharing knowledge: thinking "out of the box" and proposing fresh ideas, insights and methodologies.
  • Demonstrating flexibility: adapting quickly and resourcefully to shifting priorities and requirements.
  • Communicating effectively: expressing opinions, ideas and suggestions with conviction and in a logical/structured manner; keeping to the point.

Language skills:

  • Spoken and written English with the ability to draw-up technical specifications and scientific reports and to make oral presentations. 
  • Knowledge of the French language or the willingness to acquire this rapidly would be an advantage.

Additional Information

Eligibility and closing date:

Diversity has been an integral part of CERN's mission since its foundation and is an established value of the Organization. Employing a diverse workforce is central to our success. 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 09.10.2018.

Employment Conditions

Contract type: Limited duration contract (5 years). Subject to certain conditions, holders of limited-duration contracts may apply for an indefinite position.

These functions require:

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

Job grade: 6-7

Job reference: EP-SFT-2018-94-LD

Benchmark Job Title: Applied Physicist

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