Researcher in Physics
University of Helsinki
Finland
Background
The positions are opened in the HIP CMS experiment group, which contributes to the analysis of data from the CERN CMS experiment, calibration, and the development of analysis tools and software. Our key focus areas are the physics of jets, top quarks, and EWSB, including the development of novel machine-learning methods for high-energy physics. Our experimental responsibilities include trigger algorithms and performance, detector calibration, and jet energy corrections.
The two appointed candidates will work within the research project “JEC4Prompt”, funded by the Research Council of Finland. The goal of the project is to implement special calibration streams and calibration workflows providing jet energy corrections (JEC) with dijet and photon+jet events for Prompt data (reconstructed 48h from recording), aiming to maintain a 0.1% time stability with online data, maximizing CMS physics impact for the HL-LHC era. JEC are needed by 90% of physics analyses, and they are the final missing pieces required by many precision physics analyses. The implemented streams provide a factor 10—100 increase in the amount of calibration data, enabling a fully automated Prompt calibration which can save tens of person years, millions of CPU hours and speed up the typical CMS analysis cycle times by several years. In addition, it allows better optimization of the trigger for physics and better monitoring. Usage of special parking (delayed-reconstruction stream) and scouting (trigger-level analysis) datasets will also be studied. There is a unique convergence of trigger, calibration and jet physics expertise in Finland, providing a solid base and collaborators for this project. In addition, the selected candidates have the opportunity to contribute to other research areas within the HIP CMS experiment group.
The positions are opened in the HIP CMS experiment group, which contributes to the analysis of data from the CERN CMS experiment, calibration, and the development of analysis tools and software. Our key focus areas are the physics of jets, top quarks, and EWSB, including the development of novel machine-learning methods for high-energy physics. Our experimental responsibilities include trigger algorithms and performance, detector calibration, and jet energy corrections.
The two appointed candidates will work within the research project “JEC4Prompt”, funded by the Research Council of Finland. The goal of the project is to implement special calibration streams and calibration workflows providing jet energy corrections (JEC) with dijet and photon+jet events for Prompt data (reconstructed 48h from recording), aiming to maintain a 0.1% time stability with online data, maximizing CMS physics impact for the HL-LHC era. JEC are needed by 90% of physics analyses, and they are the final missing pieces required by many precision physics analyses. The implemented streams provide a factor 10—100 increase in the amount of calibration data, enabling a fully automated Prompt calibration which can save tens of person years, millions of CPU hours and speed up the typical CMS analysis cycle times by several years. In addition, it allows better optimization of the trigger for physics and better monitoring. Usage of special parking (delayed-reconstruction stream) and scouting (trigger-level analysis) datasets will also be studied. There is a unique convergence of trigger, calibration and jet physics expertise in Finland, providing a solid base and collaborators for this project. In addition, the selected candidates have the opportunity to contribute to other research areas within the HIP CMS experiment group.
Doctoral researcher position
The doctoral researcher will work on the implementation of a general JEC online calibration framework with DQM-type monitoring, and on a related physics analysis, for instance HLT scouting jet analysis of boosted Z->bb or H->bb, or a Higgs boson measurement or search for new physics in hadronic final states where jet performance is critical for sensitivity. A 6-12 -month presence at CERN is foreseen in 2026 to familiarize oneself with the software environment and to start implementation already during the last data-taking months of LHC Run-3. Length of the contract is until 31.8.2029.
We are seeking a talented and motivated doctoral researcher (PhD student) who recently completed their MSc degree in the field of experimental particle physics, applied physics, computer science or in a closely related field. MSc students near the completion of their degree are also encouraged to apply.
The candidate should have:
Willingness to pursue a PhD degree in experimental particle physicsGood skills in written and spoken EnglishInterest in performing research on topics close to the project scopeResearcher's mindset and ability for independent creative thinkingSkills in computer programming and experience with Linux and possibly machine learning
The appointee should either already have the right to pursue a doctoral degree at the University of Helsinki by the start of the appointment or apply for the right and obtain it within the probationary period of six months of their appointment. If the candidate does not already have the right to pursue a doctoral degree at the University of Helsinki, it must be applied for separately. Please find more information how to apply to doctoral programmes and the requirements for pursuing a doctoral degree at the University of Helsinki.
The candidate will be able to attend international conferences and present their scientific work in local and international meetings. As an employee of the University of Helsinki, the researcher will receive occupational health care, and will be entitled to sports facilities, and opportunities for professional development such as CERN Data-analysis School (CMSDAS) and CERN School of Computing (CSC). The employment contract will include a probationary period of six months.
Postdoctoral researcher position
The postdoctoral researcher will work on the general JEC online calibration framework, focusing on JEC global fit, exploiting the various channels and JEC validation. A 6-12 -month presence at CERN is foreseen in 2026 to familiarize with the software environment and to start implementation already during the last data-taking months of LHC Run-3. Length of the contract is until 31.8.2029.
We are seeking a talented postdoctoral researcher, who has completed their doctoral degree in the field of experimental particle physics or a closely related field, and is looking forward to challenging projects, which they can lead and develop. Work duties include performing research, writing articles, supervising M.Sc and possibly PhD students as well as contributing to teaching in the Master's Programme in Particle Physics and Astrophysical Sciences.
The candidate should have:
A good knowledge of experimental particle physics, previous expertise in jet energy corrections, trigger systems and calibration is considered an assetStrong programming skillsInterest in performing research on topics close to the project scopeExcellent skills in written and spoken EnglishResearcher’s mindset and ability for independent creative thinking
The candidate will be able to attend international conferences and present their scientific work in local and international meetings. As an employee of the University of Helsinki, the researcher will receive occupational health care, and will be entitled to sports facilities, and opportunities for professional development. The degree requirement must be met by the beginning of the employment. The employment contract will include a probationary period of six months.
Why work for us
Finland is a member of EU, has high quality free schooling, generous family benefits and healthcare, and was recently ranked as the best country in the world for expat families and in the world’s top ten most livable cities. Finland and the Helsinki region possess top expertise in sciences in terms of a vibrant talent pool, leading research, strong support services and functioning collaboration networks. Please find more information about working at the University of Helsinki and living in Finland.
The starting salary of the doctoral researcher will be ca. 2700-2900 euros/month and the starting salary of the postdoctoral researcher ca. 3800-4000 euros/month, depending on the appointees’ qualifications and experience.
The Helsinki Institute of Physics (HIP) is a joint research institute between five member universities – University of Helsinki, Aalto University, University of Jyväskylä, Lappeenranta-Lahti University of Technology LUT, and the University of Tampere. In addition, STUK, the National Authority for Nuclear Safety is an affiliated interim member. HIP has the national mandate to coordinate Finnish research at international accelerator facilities. The institute is responsible for the Finnish research collaboration with CERN and FAIR GmbH.
How to apply
Please apply with
a motivation letter describing your background, research interests, and your ideas for reaching the goals of the JEC4Prompt projectCVpostdoctoral researcher applicants: a publications list (with the five most important publications highlighted, specifying the applicant's contributions)postdoctoral researcher applicants: the doctoral degree diplomadoctoral student applicants: the Bachelors/Masters degree certificate and transcript including Bachelors/Masters thesis topic and its grade2-3 reference letters
Please submit the documents using the University of Helsinki Recruitment System by clicking the button “Apply now”. We will start processing the applications on 15 August 2025. Full consideration will be given to applications submitted by 15 August 2025. The positions will be filled when suitable candidates are found. Final deadline for applications is 31 August 2025. The reference letters can be sent separately to recruitment-cms@hip.fi within a week from the submission of the application.
For more information about the position, please contact
recruitment-cms(at)hip.fi, mentioning “JEC4Prompt” in the subject. This address reaches Prof. Mikko Voutilainen and Senior Researcher Tapio Lampén. Please note that answering to email is sporadic on 7-31 July due to summer holidays.
For information about the recruitment process or the recruitment system please contact hr-kumpula@helsinki.fi.
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Open position
Due Date: 31.8.2025Unit: Faculty of Science
Sub-unit: Helsinki Institute of Physics (HIP)
ID: 4186
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