Günther Plass, a former Director of Accelerators, passed away on 11 December 2020, aged 90. Günther made decisive contributions to the development and successful operation of many of CERN’s large facilities. After graduating from the Technical University Berlin-Charlottenburg, and a short detour via an industrial magnet laboratory in Germany, he joined CERN in 1956, participating in the construction of the Proton Synchrotron (PS) as member of the magnet group. Over the years, he made major contributions to the continuous upgrade of the PS complex, the heart of CERN’s accelerator chain to this day. With Berend Kuiper, he led the development of the machine’s novel fast-ejection system, which revolutionised PS operations in 1963 and enabled the first satisfactory neutrino beam benefitting from the magnetic horns invented by Simon van der Meer. Günther was then responsible for the infrastructure for Gargamelle, the bubble chamber where neutral currents were later discovered. As leader of the Synchrotron Ring group, he shaped the massive PS improvement programme launched in 1965.
Later, in 1978, he oversaw the construction of the new Linac2, which faithfully delivered protons to all CERN’s facilities for 40 years until it gave way to Linac4 in 2018. Günther Plass also left his mark as a member of the SPS Design Committee, as the author, together with Colin Ramm as early as 1961, of a suggestion to construct the SPS near the Meyrin site, well before the final decision for the SPS site was taken in 1970.
Once the antiproton–proton programme was successfully under way, a strong interest in the use of low-energy antiprotons developed. In 1980, he was among those proposing the Low-Energy Antiproton Ring (LEAR), which, after modifications, is now a key component of the LHC ion programme as the Low-Energy Ion Ring (LEIR). Günther displayed the full measure of his talent as leader and conductor of a large orchestra as deputy to Emilio Picasso, the LEP Project Leader, from 1981 onwards and from 1983 as LEP Division Leader. His contributions range from optimising the siting of the 27-km-long tunnel within the geological and environmental constraints of the region, planning during construction and integrating frequently last-minute demands by the experimenters, to handling arbitrations with difficult contractors. As Director of Accelerators from 1990, he lent full support to the upgrade of LEP by means of superconducting cavities and turned it into an official project, extending its energy reach from the Z° to an energy far beyond the W-pair mass, and he strongly encouraged the studies that would ensure the future of CERN, such as those for the LHC and CLIC.
Günther’s success was due to his unassuming character, his patience and ability to listen, his open and calm mind in the face of adversity, and his ability to identify the essential points and the right people for a task or project. We address our sincere condolences to his family.
His colleagues and friends