The Nikhef organization 

Nikhef is the national institute for subatomic physics in The Netherlands. At Nikhef, approximately 190 physicists and 80 technical staff members work together in an open and international scientific environment. Together, they perform theoretical and experimental research in the fields of particle and astroparticle physics. The Nikhef institute is a collaboration between six major Dutch universities and the Dutch Foundation for Scientific Research (NWO).

Nikhef participates in large research collaborations, including the ATLAS, LHCb and ALICE experiments at CERN, the KM3NeT neutrino telescope in the Mediterranean, the VIRGO interferometer in Pisa, the XENONnT dark matter experiment in Gran Sasso, the Pierre Auger cosmic ray observatory in Argentina and the eEDM research programme in Groningen. Nikhef also hosts a group in theoretical physics, and groups for Physics Data Processing and detector R&D, excellent electronic- and mechanical engineering groups, all with good connections to the experimental programs. 

The Nikhef ATLAS group consists of groups in Amsterdam and Nijmegen, for a total of 15 staff, and typically 5 postdocs and 20 PhD students. As a founding member of the ATLAS collaboration, the group has a long-term involvement in both detector construction as well as operations. For the phase-2 upgrade (2025-2027), we will assemble and commission one of the end-caps of a new all-silicon inner tracking system (ITk) in Amsterdam and develop a new universal readout system (FELIX) for all ATLAS detector systems.

The group also has a strong record in physics data analysis, with strong focus on Higgs boson physics, top quark physics and searches for new physics signatures. Nikhef also hosts an ATLAS Tier-1 data processing centre, and offers substantial additional computing resources for end-user data analysis and simulation.

You will investigate the breaking of electroweak symmetry and the origin of particle masses through precision studies of properties of the Higgs boson particle.

Since its discovery in 2012, the ever-increasing samples of Higgs bosons produced at the LHC provide an opportunity to precisely study these key roles of the Higgs boson. With data taking starting again in 2022, the LHC is expected to more than double its data set by the end of 2025. Recent advances in theory allow to perform highly sensitive consistency tests of all Higgs measurements to date to look for any physically meaningful patterns of deviations that could arise from new fundamental physics at high energy.

We are looking for two PhD candidates to focus on the following topics:

- Development of new machine-learning assisted data analysis strategies. 

At present, the hunt for deviations in the SM Higgs-boson properties are mostly based on measurements of their inclusive production and decay rates. This approach is highly sub-optimal as theory predicts that most interesting deviations of these properties emerge as subtle changes in kinematic distributions rather than inclusive rate changes. By redesigning the entire analysis chain from event selection through statistical analysis order-of-magnitude improvements are possible in some of the most poorly measured properties. In particular the use of novel machine-learning based techniques will play a large role in these new designs.

- Combined measurement of Higgs in the search for CP-violation. The absence of anti-matter in the universe is the consequence of particles and anti-particles behaving in subtly different ways (‘CP-violation’). The mechanism behind this is not fully understood and the Higgs boson gives a unique opportunity to explore CP-violation in this sector in detail for the first time. With the ongoing run of the LHC there will be enough data to study differences in Higgs couplings to particle and anti-particles, when combining all different decay channels of the Higgs boson.

You will join a strong team of fellow PhD candidates, postdocs and staff at Nikhef with expertise in many aspects of LHC data analysis and Higgs boson physics. We offer excellent supervision, networking opportunities and a specialized training program in data analysis techniques, as well as state-of-the art computing facilities. For those interested, there are also opportunities to be involved in our detector construction activities as part of the PhD program. 

We are looking for a candidate with a (almost) completed master degree in high-energy physics, or a closely related field.

The ideal candidate has a strong interest in data analysis, has good software skills (C++, python, ROOT) and has (some) research experience in experimental particle physics.

The candidate will be employed by the NWO-I-foundation and will obtain the status of junior scientist and will receive a 4-year contract with a competitive salary. The conditions of employment are excellent, and can be found on the website of the employer NWO-I. Apart from this, non-Dutch applicants may be eligible for the so called ’30% tax ruling’, which results in a net income advantage.

The educational program of the Dutch research school for subatomic physics offers annual graduate schools for PhD candidates, as well as frequent series of lectures on advanced topics in (astro)particle physics.

Qualified applicants are encouraged to visit https://www.nikhef.nl/en/vacancies/ , select the vacancy entitled 'Two PhD positions in the Nikhef ATLAS group' apply by clicking the 'apply' button at the bottom of that page. Please be prepared to upload a curriculum vitae and a motivation letter, and provide the email address of two referees who are willing to send a letter of recommendation on your behalf. In your motivation letter please indicate in which positions you are interested.

The deadline for applications is April 15th, 2024. Interviews with selected candidates are foreseen to take place in the second half of May. The tentative starting date is summer or fall 2024, decided in mutual agreement with the candidate.

For further information, feel free to contact prof. dr. Vreeswijk (h73@nikhef.nl) or dr. Lydia Brenner (lbrenner@nikhef.nl) for the respective positions, or prof. dr. Verkerke (verkerke@nikhef.nl) for general information about the Nikhef ATLAS group.  

 Nikhef is committed to diversity, equity and inclusion in the workplace, and strongly encourages candidates from under-represented minorities to apply.