Introduction

Are you an experienced Applied Physicist who wants to take part in the most advanced scientific experiment in particle physics? Join our CERN CMS detector and software development group (EP-CMG-DS) and take a leading role in the development of general purpose, high-performance software to perform event reconstruction using our next-generation high-granularity calorimeters.

Proton-proton collisions at high luminosity (at the HL-LHC with a pile-up of 200 and more, and at the potential longer-term FCC-ee and FCC-hh colliders) will pose significant challenges for radiation tolerance and event pileup on detectors, especially for forward calorimetry. As part of its HL-LHC upgrade program, the CMS collaboration is designing a High Granularity Calorimeter (HGCal) to replace the existing endcap calorimeters. The HGCAL features unprecedented fine transverse and longitudinal segmentation for both the electromagnetic and the hadronic compartments. Moreover, the detector will operate in an unprecedentedly challenging experimental environment, and the real-time selection of the most interesting LHC collisions will pose even greater challenges.  Given the anticipated complexity of collisions at the HL-LHC, the previously used reconstruction algorithms are expected to fail. Therefore, new techniques and algorithms spanning several fields, from computation geometry to clustering, machine learning, graph theory, and modern computer architectures, taking into account also the information from the tracking and timing detectors of CMS, must be planned for, designed and implemented. Event Reconstruction in a typical HEP experiment includes both code that can benefit from hardware acceleration and code that is better suited for more conventional processing. As a result, there is no single type of processor that is best suited for all computations: the design should target heterogeneous architectures, possibly including versions of the contained algorithms for several accelerator platforms, eventually using code portability libraries that are already available. This makes the proper design of the underlying reconstruction framework and the overall software particularly crucial for the success of the CMS physics program.

Functions

You will play an important role in the development of the event reconstruction for the next generation high granularity calorimeters, with particular emphasis on the high pileup scenarios of HL-LHC and beyond. This effort has to be done in collaboration with other groups at CERN that are focusing on similar activities. Your functions will include:

• Coordinating the design and development of fast algorithms for data processing in calorimeters, such as clusterisation, shower reconstruction, particle flow event interpretation and calibration algorithms.
• Packaging the aforementioned algorithms in a plug-and-play, stand-alone library that could be used by different experiments.
• Providing high-level consultancy and expert help to the software developers working on the performance optimization of the algorithms.
• Developing test procedures and quality assurance of the algorithms developed and contained in the stand-alone library.

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

Experience:

• Demonstrated experience in High Energy Physics reconstruction frameworks, with a deep knowledge of the building and distribution tools used within these frameworks.
• Extensive experience in C++ programming, including the latest C++ standards (C++11,14,17).
• Familiarity with implementing and optimizing algorithms on GPUs.
• Initial experience with deep learning frameworks would be a plus.

Technical competencies:

• Knowledge and application of physics reconstruction techniques: clusterisation, cellular automata, particle shower reconstruction, particle tracking and particle flow techniques.
• Development of application software: object-oriented design and development, parallel programming, algorithm development and optimisation, building and software distribution packaging.
• Knowledge and application of software life-cycle tools and procedures: git/github/gitlab; JIRA.

Behavioural competencies:

• Solving problems: addressing complex problems by breaking them down into manageable components; finding the information needed to solve problems; making objective judgments based on all the facts available; being open to original ideas and creative options by which to address issues; continually driving change by seeking new ways to improve outcomes.
• Achieving results: delivering high quality work on time and fulfilling expectations; following through on new ideas and innovations; planning and implementing application; objectively assessing and monitoring own work; regularly reporting on progress and advising of any changes in schedule or priorities.
• Learning and sharing knowledge: keeping up-to-date with developments in own field of expertise and readily absorbing new information; taking steps to expand knowledge in other areas of expertise beyond own field; sharing knowledge and expertise freely and willingly with others; coaching others to ensure knowledge transfer.
• Working in teams: working well in groups and readily fitting into a team; participating fully and taking an active role in team activities; cooperating constructively with others in the pursuit of team goals; balancing personal goals with team goals; seeking to help other team members when own work is done; supporting others.
• Demonstrating flexibility: demonstrating openness to new ideas and situations; readily absorbing new techniques and working practices; proposing new or improved ways of working; actively participating in the implementation of new processes and technologies.

Language skills:

• English: very good command in spoken and written
• French: basic command or willingness to acquire the language

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 15.01.2021 until 12:00 pm CET time.

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-CMG-DS-2020-147-LD

Benchmark Job Title: Applied Physicist