Obituaries
Rolf Hagedorn 1919-2003
Rolf Hagedorn, the theorist who introduced the concept that hadronic matter has a melting point, died on 9 March in Geneva.
As a young man Hagedorn was deeply marked by the upheavals of the war years in Europe. He studied physics and mathematics at Göttingen and graduated with a diploma in 1950 and a doctorate in 1952 on thermal solid-state theory, under Richard Becker. He also worked at the Max Planck Institute for Physics.
In 1954 Hagedorn had the opportunity to go to Geneva, where he initially helped with accelerator design for the new CERN organization. He joined the CERN Theory Group after its transfer from Copenhagen to Geneva in 1957, and he was a senior physicist in the division when he retired in 1984. After his retirement Hagedorn remained an active emeritus researcher.
As an accelerator physicist, Hagedorn developed theoretical predictions for the particle spectra observed when CERN's proton synchrotron first began operation. This was important for the planning and implementation of the first neutrino beams. He then developed the statistical theory of meson production in considerable detail up to very high energies. It was as a consequence of these studies that he found that one should expect a limiting temperature in hadronic collisions, the "Hagedorn temperature". This picture has had a major impact on theoretical thinking and on our understanding of the properties of hot hadronic matter, which is now important in the heavy-ion programme (see "The tale of the Hagedorn temperature"). Since the picture is applicable to any exponentially rising particle mass spectrum, it is also influencing the development of string theories.
Hagedorn developed some novel statistical physics methods, leading to the technical expertise we wield today in this field. He was also instrumental in the development of one of the earliest user-friendly interactive computing programs for algebraic manipulations, the SIGMA.
Rolf Hagedorn was a person of the highest scientific integrity and standards of reasoning. He was always willing to help colleagues and his comments were usually penetrating and deep. He will be much missed by friends and colleagues alike.
Torleif Ericson, CERN, and Johann Rafelski, University of Arizona.
•The CERN Theory Division is planning to hold a Hagedorn Memorium Symposium at CERN on 28 November 2003. For full details see http://wwwth.cern.ch.
Dubravko Tadiç 1934-2003
Dubravko Tadiç, a leading figure in Croatian particle physics, passed away on 6 February. Born in Zagreb in 1934, Tadiç graduated from the University of Zagreb in 1958, during the time of Vladimir Glaser, Borivoj Jaksic and Gaja Alaga. He studied for his PhD under Alaga on problems in nuclear beta decay and the structure of weak interactions, and then developed his research in parity violation, and in particular in parity-violating nuclear interactions. Subsequently, his main field of research became elementary particle physics, specifically electroweak interactions and quark models.
Tadiç began his international career in Birmingham at the time of Rudolf Peierls, and later worked at Brookhaven. He continued his connection with international science throughout his life, but unfortunately did not live to see his dream of Croatia becoming a full CERN member state.
Tadiç had a leading role in academic life in Zagreb and Croatia, and became the leader of a research group at the Rudjer Boskovic Institute early on in his career. He then became head of the theory division at the Faculty of Sciences (PMF-Zagreb) and a member of the Croatian Academy. Tadiç introduced particle physics to many physicists who are now leaders in Croatian science, and he always shared his joy of research with collaborators and in particular with younger colleagues. The style and standard by which he influenced the young researchers was often recognized as "the Zagreb school".
Tadiç accepted the challenge that questioned whether high-quality scientific work could still be done in a small country that suffers from a huge brain drain. He instigated numerous conferences in nuclear and particle physics in Croatia including, among others, the well established series of "Adriatic meetings". He was also extremely supportive of the development of particle physics in Split and of participation in the CMS experiment. Dubravko Tadiç will be deeply missed by the physics community and by his collaborators and friends.
S Pallua and I Picek, PMF-Zagreb, D Denegri, CERN/Saclay.
Frans Verbeure 1942-2003
Frans Verbeure, head of the Particle Physics Group at the University of Antwerp, passed away on 8 June after a long illness.
Born on 6 February 1942, Verbeure began his research career in the early 1960s, under the leadership of Fernand Grard, at the Laboratoire des Hautes Energies in Brussels. His research initially centered around the vigorous bubble-chamber physics programme, which had started in Saclay and continued at CERN. When the Universitaire Instelling Antwerpen (UIA) was created in 1972, he became the youngest professor in the Physics Department, and remained there until his untimely death.
Recognizing the importance of national, as well as international, collaboration, Verbeure associated his research group closely with the other experimental particle-physics groups at the Université Libre de Bruxelles and the Vrije Universiteit Brussel. In the early 1980s, under his leadership, the UIA group expanded its activity from bubble-chamber experiments to "hybrid" experiments. When the time of the bubble chambers was over, the group took part in the Belgian effort in DELPHI at LEP, and over the past eight years Verbeure's efforts were directed towards the active participation of his group in the CMS experiment at the LHC.
Verbeure's talents as an efficient administrator were recognized early in his career, and he took on several important duties as head of the Physics Department, dean of the Science Faculty, president of the University Research Council and vice-rector of the UIA. He was also an active member of the Belgian Federal Council for Research Policy and the Flemish Interuniversity Council. For two years he became dean of the European Academy of Sciences and Arts, and last but not least was a member of the Belgian delegation in the CERN Council and Committee of Council. In all these activities, his actions were inspired by a great sense of duty and service to the community.
Despite all these roles, Verbeure never lost his excitement for particle physics. As permanent secretary of the International Symposia on Multiparticle Dynamics (ISMD) he ensured the continuing success of this series of conferences in a field to which he devoted a major part of his research. As a scientist he always had a clear grasp of the problems at hand and of the most efficient way to solve them. Frans Verbeure was admired and respected by his collaborators and students and will be remembered as an extremely kind and helpful colleague and friend, full of joy, optimism and activity.
From his colleagues and friends.
Ian Kogan 1958-2003
Ian Kogan, an outstanding theoretical physicist and professor at Oxford University, died of heart failure on 4 June.
Ian was born into a Jewish family on 14 September 1958 in Glazov, a small town in the northern Urals, far from the cultural centres of what was then the Soviet Union. Life in the town revolved around a uranium plant, where Ian's parents worked for more than 40 years. Ian graduated from the Moscow Institute of Physics and Technology in 1981, completing his education in parallel at the Institute of Theoretical and Experimental Physics (ITEP). That he came to the ITEP was fortunate both for Ian and the institute. The ITEP Theory Department, with its creative atmosphere and respect for deep thought, was just the right place for him.
Ian began his professional career in hadron physics, a topic he repeatedly returned to. His scientific horizons rapidly expanded though, and within three years he was an early explorer of Chern-Simons electrodynamics. His interests were remarkably broad - from quantum chromodynamics to solid-state physics, from financial market fluctuations and risk assessment to string theory, from quantum gravity to conformal field theory. This was a unique quality in the age of narrow specialization, and in every field he left a profound imprint.
Ian was one of the co-discoverers of phase transitions in strings and more recently of the logarithmic conformal field theory and theory of multi-gravity. He championed the application of logarithmic conformal field theory and string theory in solid-state physics, and it would be fair to say that he circumnavigated theoretical physics. He had the spirit of a pioneer, at the front line of research and quite often beyond, and he had the stamina to go in directions others did not have the courage to pursue.
Ian's attitude to physics was romantic. His admiration of the beauty of the laws of nature never faded and was as strong in 2003 as it was in 1980 at the beginning of his physics journey. He was always simmering with ideas and often had more than he could possibly sort through. He shared his ideas generously with his students at Oxford University and Balliol College, of which he became a permanent member in 1994.
During the two decades of his professional career, Ian published almost 200 scientific papers involving 60 collaborators. Indeed, his soul and mind were open to all and he had many friends, not only in Russia, England and the US, but throughout the world. Ian was truly cosmopolitan, in the best sense of the word.
Ian was a daydreamer, both in physics and in life. He combined a childish joyful attitude with the wisdom and seriousness of a great man. He was a very kind person and helping those in need was natural to him. He drove through life in the fast lane, always wanting to understand more and to do more, and was at the peak of his creative powers, full of plans for the future, but his heart could not cope. It suddenly stopped, after he had given a long afternoon seminar on multi-gravity the day before at ICTP in Trieste. When such people leave us, the world becomes emptier and colder. His death is a tragedy for the entire physics community.
Mikhail Shifman, University of Minnesota.