The GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt operates one of the leading particle accelerators for science. Currently, the new FAIR ( F acility for A ntiproton and I on R esearch) one of the world's largest research projects, is under construction through international cooperation. GSI and FAIR offer the opportunity to work in this international environment with a team of employees committed to world-class science.

In cooperation with the Johannes Gutenberg-Universität Mainz the LINAC department offers a

PhD student position (all genders)
in Accelerator Physics

Reference number: 25.141-6680

for a contract starting at the earliest possible date.

Our project / Your tasks:

The position is embedded in the development program for the superconducting linear accelerator HELIAC (HElmholtz LInear ACcelerator).

HELIAC consists of a normal-conducting injector LINAC and a superconducting section comprising up to four cryogenic modules.

The candidate will be responsible for the development of the superconducting re-buncher for the third cryogenic module of HELIAC. Another important task will be the design and implementation of an automated test stand for superconducting cavities of HELIAC, which are currently under fabrication. The work will include aspects of RF design, cryogenic integration, and test automation, in close collaboration with experts from the RF, cryogenics, and control systems groups.

The successful candidate will be responsible for:

• The RF design and simulation of superconducting re-buncher cavity using CST Studio
• The thermal and mechanical design of superconducting the re-buncher cavity
• The development of a dedicated test stand for high-power RF testing of the superconducting accelerator cavities.

Other tasks include:

• Participation in operation of first cryogenic module of HELIAC
• Participation in beam times
• Operation of cryogenic infrastructure.

Your qualifications and skills:

• University Master Degree in physics
• Ability and interest to work with RF-systems and accelerator installations
• Knowledge in one or more of these fields: rf-technics, accelerator physics, computational physics
• Team-oriented, a structured approach to work and safe working methods
• Good language skills in English and German.

The following qualifications and skills are desirable:

• Experience in Python programming
• Experience with analog and digital electronics

You may expect a multifaceted and interesting position within an internationally leading research institution. Teamwork and the willingness to undergo further training are essential for us. GSI also offers various options for balancing family and career, mobile working, company health management services, company social counselling services, personal training and qualification opportunities, a job ticket, supplementary pension benefits, additional company leisure time and a company sports club ‘Schnelle Ionen’.

The position (65% part-time) is limited until 31.08.2028. Salary is as specified in the collective agreement for public employees (TVöD Bund), effective at GSI.

GSI promotes the professional development of women and expressly welcomes applications from women. Handicapped persons will be preferentially considered when equally qualified.

Further information about FAIR and GSI is available at www.gsi.de and www.fair-center.eu.

If you find this position interesting and challenging and would like to work in an exceptional, international, strongly technical environment, please send your full application documents with information of your earliest possible starting date and the reference number 25.141-6680 above by 09.12.2025 at the latest via the online portal on our job site:

Online-Bewerbungsportal

GSI Helmholtzzentrum für Schwerionenforschung GmbH

Human Resources Department

GERMANY

This research center is part of the Helmholtz Association of German Research Centers. With more than 42,000 employees and an annual budget of over € 5 billion, the Helmholtz Association is Germany's largest scientific organisation.