John Strong 1941-2006

John started his career and obtained his PhD in a group from Westfield College, initially working on experiments at Rutherford Appleton Laboratory (RAL). From the early 1970s onwards, however, his research was focused on experiments in CERN, with several particularly notable contributions. The Omega spectrometer adopted a system John had originally developed for experiments at RAL using vidicon Cameras (a type of television camera) to record the sparks in the spark chambers. This highly automated system allowed Omega to be used in a similar way to bubble chambers. He contributed to the success of NA1 and NA7, where he became heavily involved in the electronic trigger systems. In these experiments the Westfield group joined forces with Italian colleagues to measure the form factors of the pion and the kaon, and the lifetime of some of the newly discovered charm particles. Such has been the lasting impact of these measurements that the paper on the pion form-factor had been cited 323 times up to the time of John's death. This experiment also allowed the first measurement of pi0 production in pion-electron scattering and provided one of the few model independent tests of the existence of three colours at a time when this postulate still required experimental confirmation. After moving to Royal Holloway, University of London, he was responsible for the second level trigger system for the ALEPH detector and spent five years leading a team that designed and built the system, which following installation in 1989 ran for twelve years with only minor interventions. In 1990 he presented a paper on first ideas for second level triggering at LHC and he continued to take a leading role in developing these ideas. The data handling requirements for this trigger system were formidable, far beyond anything previously built. John was an early champion of the idea that large farms of PC's interconnected by commodity networks could meet the very demanding ATLAS requirements, and he made a number of key contributions to turn this idea into reality. He led development of the ATLAS second level trigger for a number of years and for a period was UK spokesman for the ATLAS collaboration. When he took early retirement in December 2002, design of the final system was almost complete but John continued to be involved with the Read Out Buffer (ROBin) cards as they moved from design to production. Even when his illness precluded further active contributions he retained a lively interest in the work and he was delighted to know that these cards, one of only two components in the final ATLAS Data acquisition / High Level Trigger system using custom electronics, were completed before he died. However, John did not only work on the experiments. He was a Lecturer, first at Westfield College and then at Royal Holloway. He was promoted to Reader in 1986 and appointed Professor of Experimental Physics in 1995. He served as Head of the Department of Physics at Royal Holloway from 2000 until his retirement. He was a dedicated teacher and supervisor who brought out the best in his students and inspired them by his positive approach. He was active on many committees, where his clarity of thought and diplomacy were invaluable assets. Most of all he was a man of the highest integrity and a friend to so many.