Accelerator physicist Vittorio Giorgio Vaccaro passed away on 11 February 2023 in his hometown of Naples, Italy, after a short illness.
Vittorio graduated in 1965 from the University of Naples Federico II. He soon moved to CERN as a fellow, where he remained from 1966 to 1969, contributing to the design and commissioning of the first high-intensity hadron collider, the Intersecting Storage Rings. At CERN, Vittorio introduced the concept of beam-coupling impedance to model the instabilities that were experienced above transition energy, writing a seminal report (entitled “Longitudinal instability of a coasting beam above transition, due to the action of lumped discontinuities”), in which he described for the first time the action of discontinuities in the transverse section of a beam pipe as an impedance. His theory, which after his initial intuition he developed together with Andy Sessler, Alessandro G. Ruggiero and many other colleagues, has become a fundamental tool in the design of particle accelerators.
In 1969 he returned to his alma mater in Naples as professor of electromagnetic fields at the faculty of engineering, and continued teaching until he retired. He created an accelerator-physics team in association with INFN within the faculty of physics, and throughout his career remained closely linked to CERN, where he visited regularly and sent many of his students.
Vittorio collaborated with practically all the studies and accelerator projects in Europe, from the CERN machines to DAFNE, the European Spallation Source and HERA-B at DESY. The group in Naples became, thanks to him, a reference in the world of accelerators for the development of the theory of beam-coupling impedance of accelerator components and the associated bench measurements. From the mid-1990s, he became increasingly interested in the development of linear accelerators for proton therapy, participating in a large collaboration with the TERA Foundation, CERN and INFN. In 2003 he led a new collaboration between the University of Naples and several sections of INFN, which produced the first linac module at 3 GHz capable of accelerating protons from a 30 MeV cyclotron.
In 2019 Vittorio was awarded the IPAC Xie Jialin Award for outstanding work in the accelerator field “for his pioneering studies on instabilities in particle-beam physics, the introduction of the impedance concept in storage rings and, in the course of his academic career, for disseminating knowledge in accelerator physics throughout many generations of young scientists”.
It is difficult to find the words to recall Vittorio’s immense human qualities, his deep culture and his profound humanity. Several of his students are now scattered around the world, continuing his efforts to propose technical solutions to accelerator-physics problems based on a deep understanding of the phenomena of beam instability. Vittorio was moved by a sincere passion for science and an irresistible curiosity for everything and everyone around him, which always brought him to approach anyone with an open and friendly spirit.
We will deeply miss a passionate mentor and colleague, his wide knowledge, energy, friendship and humanity.
His friends and colleagues