How can knowledge about building ESO’s world-class telescopes help accelerate tiny particles at CERN? Surprisingly, it can be vital! Organisations that are part of the EIROforum often share resources and knowledge, and two ESO engineers were recently involved in designing CERN’s newest particle acceleration experiment, contributing expertise that was essential in the successful start of the experiment earlier this year. In this week’s blog post those two scientists, Marco Quattri and Paolo La Penna, describe their role in the project.