Reference number ESD-80679

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The European Spallation Source (ESS) is building the world’s most powerful neutron source, enabling research in materials science, energy, health, and the environment. ESS is expanding the Data Reduction Team at the Data Management and Scientific Computing Centre (DMSC), located just north of Copenhagen in Denmark. We are seeking outstanding candidates for one scientific software developer position.

About the team
We are six developers responsible for the software that turns raw detector data into scientifically usable datasets. This process, known as data reduction, produces structured datasets for downstream analysis software. We develop Scipp (scipp.github.io) and related libraries, working primarily in Python. With ten new ESS instruments coming online next year, our software will play an important role in supporting their scientific commissioning and operations. As a small team, we work on problems that are both technically challenging and central to the success of the facility.

About the role
The work spans library development, scientific workflow design, performance engineering, and user interfaces. You will work closely with neutron scientists, distil requirements from them, determine what belongs in the core library versus a downstream package, and frequently decide what not to build. There is room to specialize over time, but in your first year you should expect to touch various parts of the codebase.

Our team uses AI coding tools heavily but tries to be smart about it. To us, using AI is about amplifying human thought, not outsourcing it. We see these tools as aids for exploration, iteration, and productivity — not replacements for engineering judgement.
About you
We care more about how you think than which tools you have used. We do not have a fixed technology checklist. What matters:

• You have shipped software that real users depend on.
• You think critically about code quality and welcome constructive discussion and alternative ideas
• You can engage with scientific problems on their own terms — a physics background is welcome but not required.
• You can take ownership of an area, work with scientists to gather requirements, and make decisions with incomplete information.
• You are comfortable working in English in an international team.

Experience with the scientific Python ecosystem, performance engineering, or work at neutron/photon sources is beneficial but not required. Familiarity with technologies and practices such as Jupyter, C++, CI/CD, integration testing, or systems architecture would also be valuable.

What we offer
DMSC is located on the DTU campus in Kongens Lyngby, north of Copenhagen, while the ESS neutron facility is based in Lund, Sweden. Together, they form a unique cross-border scientific environment in the Øresund region.

You will join a dynamic and highly collaborative international workplace with colleagues representing nearly 60 nationalities across ESS and DMSC. We offer opportunities for professional development, and close interaction between computational science, instrumentation, and large-scale experiments.

Benefits include 25 + 5 annual leave days in addition to public and company holidays, an attractive pension scheme, preventative healthcare benefits, and relocation support for international hires where applicable.

This is a full-time, permanent position based in Kongens Lyngby, Denmark, and we need someone who can start as soon as practically possible.

Learn more about living and working in Scandinavia: https://ess.eu/living-working-scandinavia.

For further information
For information about the position, contact the Group Leader for Research Software Engineering (RSE), Fredrik Bolmsten, at [email protected]

For recruitment-related questions, contact Recruitment Officer Janne Erwolter at [email protected].

How to apply
Please submit your application, with cover letter and CV, no later than 26 August 2026.

As part of your cover letter, please pick one of these two questions and answer it in your application:

• Tell us about a technical decision you made that you would make differently today, and what changed your mind.
• Tell us about a piece of software you admire, not because of what it does, but because of how it is built, and what you learned from looking at it closely.

We look forward to receiving your application.

For more information regarding the ESS recruitment process in general, please follow this link: Careers | ESS

URL to this pagehttps://europeanspallationsource.se/careers/vacancies?rmpage=job&rmjob=2030&rmlang=UK

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