Mario Weiss (1927 – 2008)

It was with great sadness that we learned that our colleague and friend Mario Weiss passed away on February 11th. A feeling of emptiness overtook us all. Mario was a reassuring reference in the small community of linear accelerator experts, as he continued to come to CERN regularly and discuss accelerator problems with passion for many years after his official retirement.

Mario came to CERN in 1960 and in the PS Division worked on beam dynamics of low-energy high-intensity proton beams, soon becoming a world-level expert in the field. He took an active part in the construction of Linac2, where he was responsible for the low-energy beam transport system.

In the early 80’s he turned his interest to the Radio Frequency Quadrupole (RFQ), a novel concept for acceleration which allows the problems related with bunching and injecting low-energy beams to be overcomed. After starting a fruitful collaboration with the Los Alamos scientists, at the time world leaders in the field of RFQs, he was among the first to introduce the RFQ concept and technology into Europe. His colleagues at Los Alamos became lifetime friends, as did most of the people who had the privilege of working with him.

Mario designed and directed the construction of CERN RFQ1 (1983) and was then project leader for RFQ2, which eventually replaced the old Cockroft-Walton as injector to Linac2, becoming the operational RFQ with the highest beam current in the world. RFQ2 has been reliably serving as the first stage of acceleration for all the protons at CERN since 1993.

After his retirement in 1992, Mario continued consulting work for CERN and for other laboratories, and his knowledge and advice have been fundamental to the success of the heavy-ion RFQ at Linac3. It was at this time that he started to be involved with medical linear accelerators, an activity that eventually occupied his last 10 years. As leader of the LIBO (Linac Booster) project within the TERA collaboration, he realized a prototype of a high-frequency medical accelerator that is still a masterpiece of linac technology and is now on display at the MICROCOSM.

Mario had many facets to his personality: the world-renowned scientist and the humble researcher, the rigorous mentor and the sympathetic friend, the humanist and the man of science. Anyone who met Mario will always remember his cultured manners, his sharp intelligence and his acute sense of humour.

Mario always liked to be surrounded by young collaborators, creating through his work and through his teaching a community of young scientists that he trained and supported in the critical starting phase of their careers. They all have learned invaluable lessons from him, and now that many of them occupy positions of responsibility in laboratories throughout the world they are perpetuating his teachings and will keep his memory alive.

His colleagues and friends