Nicolaas “Nico” Kos began his career at CERN in 1994 with technical responsibilities for vacuum-component contracts for LEP2, liaising with European industry to ensure the highest standards. A year later, he joined the LHC project, quickly becoming a key member in the development of beam screens, overseeing prototypes, contract negotiations and large-scale production.

Nico’s role during installation was equally crucial. He led leak testing on cryogenic lines and cryomagnets in the LHC’s Long Straight Sections. In recent years, he made innovative contributions to the design and development of the new beam screens for the High-Luminosity LHC upgrade that are a testament to his technical expertise and forward‑looking vision.

Beyond his project-specific work, Nico served as chairman of the Vacuum Equipment Standardisation Committee, in which he guided CERN-wide standards in vacuum technology; then, he took the role of contract manager for new technical services; finally, he was a member of the Peer Review Committee, ensuring excellence across CERN.

Among colleagues, Nico was admired not only for his deep technical expertise, but also for his warmth and professionalism. He was known for his cheerful manner, combining intelligence with an approachability that gave confidence to those around him.

Though deeply respected for his technical leadership, Nico is perhaps best remembered as the person behind the engineer: a committed collaborator, a positive spirit in the workplace and a devoted friend to many of us.

His friends and colleagues

We deeply regret to announce the death of Nicolaas Kos on 6 July 2025.

Mr Nicolaas Kos, born on 26 June 1965, worked in the TE department and had been at CERN since 1 February 1994.

The Director-General has sent a message of condolence to his family on behalf of the CERN community.

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