CERN honours Carlo Rubbia as he turns 75
On 7 April CERN hosted a celebration to mark Carlo Rubbia's 75th birthday and the 25th anniversary of the award to him of the Nobel Prize in Physics. "Today we will celebrate 100 years of Carlo Rubbia," quipped CERN's director-general Rolf Heuer in opening the symposium held in Rubbia's honour.
Rubbia received the 1984 Nobel Prize in Physics together with Simon van der Meer for their contributions to the discovery of the W and Z bosons, the carriers of the weak interaction. During the symposium colleagues recalled the accelerator and detector developments that made possible this discovery – and with it the first Nobel prize for research at CERN. Speakers also looked at other areas of science to which Rubbia has made decisive contributions and in which he retains a passionate interest.
Michel Spiro, director of the French National Institute of Nuclear and Particle Physics of the CNRS, began with an overview of neutrinos in particle physics and astrophysics. He reminded the audience of Rubbia's experiments from the 1960s and 1970s that had involved neutrinos, as well as his important contributions to innovative technologies in use now, and in the future, for neutrino physics and neutrino astronomy. These include the large-scale water Cherenkov detectors and the liquid-argon time-projection chamber.
CERN's Lyn Evans was closely involved with the accelerator work that made possible the conversion of the SPS into the world's first proton–antiproton collider, the machine that enabled the discovery of the W and Z particles. As early as 1968, van der Meer had the idea of "stochastic cooling", in which beam fluctuations are damped down by feedback from the fluctuations themselves. He initially thought his idea "too far-fetched", but the technique was demonstrated at the Intersecting Storage Rings in 1974. It formed a key part of Rubbia's proposal to convert the SPS into a proton–antiproton collider to reach a higher energy regime. Authorization for the modifications to the SPS came in 1978 and their implementation began in 1980, followed by the first proton–antiproton collisions on 10 July 1981. The experience gained by the accelerator teams was later to bear fruit with the successful start up of the LHC in September 2008.
Rubbia's experiment to search for the W and Z, named UA1 after its location on the ring, was put together by a collaboration of some 130 physicists and engineers (CERN Courier May 2003 p26). Alan Astbury, now with the University of Victoria and one-time co-spokesperson of UA1, looked at the task the experiment and its sibling, UA2, had to fulfil to find the predicted W and Z particles. UA1 was very much a general-purpose detector, the first ancestor of detectors such as ATLAS and CMS at the LHC, while UA2 was more specialized. The path to the W and Z was not without obstacles, as Astbury recalled, but by 1983 both experiments had clear evidence for the W and Z events.
The results from UA1 and UA2 emerged just as collaborations were putting together technical proposals for the experiments at LEP, the 27 km electron–positron collider that was to be built at CERN in the 1980s. Former CERN director-general Herwig Schopper talked about the background to the LEP proposal and its subsequent success. It later gave way to the LHC, the existence of which owes a great deal to Rubbia, who pushed for it strongly, in particular during his own mandate as director-general.
Moving beyond CERN and terrestrial particle physics, Giovanni Bignami, former president of the Italian Space Agency and professor at the IUSS School for Advanced Studies in Pavia, took a delightful journey into space. He described the current frontiers of astronomy, 400 years after Galileo Galilei began to use a telescope to study the heavens, showing how important "particle astronomy" is now becoming.
Hans Joachim Schellnhuber of the Potsdam Institute for Climate Research and Sven Kullander of the Royal Swedish Academy of Science both spoke about an issue to which Rubbia has dedicated himself in recent years – renewable energy. While president of the Italian alternative-energy agency ENEA (between 1999 and 2005) Rubbia developed a novel method for concentrating solar power at high temperatures for energy production, known as the Archimedes Project, which is currently being developed by industry for commercial use.
• The presentations and a recording of the symposium are available at http://indico.cern.ch/conferenceDisplay.py?confId=54479.