Our dear colleague and friend Karel Cornelis passed away unexpectedly on 20 December 2022.
After finishing his studies in physics at the University of Leuven (Belgium), Karel joined CERN in 1983 as engineer-in-charge of the Super Proton Synchrotron (SPS) at the time when the machine was operated as a proton–antiproton collider. During his career Karel greatly contributed to the commissioning and performance development and follow-up of the SPS during its various phases as proton–antiproton collider, LEP injector, high-intensity fixed-target machine and as the LHC injector of proton and ion beams. He had a profound and extensive knowledge of the machine, from complex beam dynamics aspects to the engineering details of its various systems, and was the reference whenever new beam requirements or modes of operation were discussed.
Karel was an extremely competent and rigorous physicist, but also a generous and dedicated mentor who trained generations of control-room technicians, shift leaders and machine physicists and engineers, helping them to grow and take on responsibilities while remaining available to lend a hand when needed. His positive attitude and humour have left a lasting imprint, so much so that “Think like a proton: always positive!” has become the motto of the SPS operation team, and is now visible in the SPS island in the CERN Control Centre.
Karel had the rare gift of explaining complex phenomena with simple but accurate models and clear examples, whether it was accelerator physics and technology, or physics and engineering more generally. He gave a fascinating series of machine shut-down lectures covering the history of the SPS, synchrotron radiation and one of his passions, aviation, with a talk on “Air and the airplanes that fly in it”.
Karel was a larger-than-life tutor, friend, reference point, expert and father figure to generations of us. He was much missed in the SPS island and beyond following his retirement in September 2019, and will be even more so now.
