Sep 27, 2013 - He was a person of the highest scientific integrity and standards of reasoning. Johann Rafelski, Department of Physics, University of Arizona, ...
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Rolf Hagedorn (1919--2003)
This content has been downloaded from IOPscience. Please scroll down to see the full text. 2004 J. Phys. G: Nucl. Part. Phys. 30 (http://iopscience.iop.org/0954-3899/30/1/E02) View the table of contents for this issue, or go to the journal homepage for more
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INSTITUTE OF PHYSICS PUBLISHING
JOURNAL OF PHYSICS G: NUCLEAR AND PARTICLE PHYSICS
OBITUARY
Rolf Hagedorn (1919–2003) Rolf Hagedorn studied particle spectra and developed the statistical theory of meson production. He found that hot hadronic matter has a maximum temperature which later he understood to be the melting point of hadrons. After his retirement in 1984 he remained an active emeritus researcher, and followed the developments in the field of relativistic heavy ion collisions.
Figure. Rolf Hagedorn (1919–2003). Scientific rise Rolf Hagedorn received his PhD at G¨ottingen as a student of R Becker, of thermal physics fame. This was followed by a two-year postdoctoral training post in Theoretical Subatomic Physics and Cosmic Ray Interactions at the G¨ottingen Max Planck Institute. From there with W Heisenberg’s recommendation he arrived on 1 April 1954 at the CERN Geneva site. In his 6 March (1954) acceptance letter Hagedorn writes to John Adams: I am very pleased to work with CERN proton synchrotron group. . . . Hagedorn brought to CERN the rare mix of experience in both statistical and subatomic physics. However, for his first 5 years at CERN he was working as an accelerator physicist helping in the development and design of the proton synchrotron (PS). Hagedorn published, as of 1960, on statistical models of particle production. He made the theoretical predictions for comparison with the particle spectra observed when the CERN–PS first entered in operation, an important contribution in the planning of further operations. He developed the statistical theory of meson production. Elaboration of these studies led to his prediction of a limiting temperature.
Obituary
Among the most cited physics papers of the period is 1965 paper entitled Statistical Thermodynamics of Strong Interactions at High Energies (Nuovo Cim. Suppl. 3 147–86), which proposes the statistical bootstrap model of particle production, and introduces the maximum hadron temperature into the particle physics vocabulary. Meeting Hagedorn the teacher I first met Hagedorn (as he wanted to be called) in the winter of 1975–76. After his Physics Colloquium on the Statistical Bootstrap Model, I had the opportunity to discuss his work. He took every issue very seriously, and followed through with clear answers and explanations. This lead on to my fellowship application at CERN. Rolf was an extraordinary teacher in the two years (1977–79) of our very close collaboration and subsequent cooperation that lasted until the summer of 2002. Hagedorn taught several disciples how to use statistical methods in the study of strong interaction physics, literally providing the world with the technical expertise we wield today. He patiently worked out many details for his ‘students’. Hagedorn enjoyed doing ‘theory’, and ‘computing’, demonstrating how simple it was to carry through computations with the user-oriented computer language Sigma he had developed. Influence Before the period 1964–84, the Fermi hadronization model had been falling into oblivion, and statistical methods were not accepted by particle physicists. Hagedorn single-handedly and against significant and important opposition opened up the study of thermal properties of strongly interacting matter. The Hagedorn temperature TH = 160 MeV is today a brand name. Thermal equilibration of strongly interacting hadronic matter is an accepted phenomenon. Hagedorn discovered singular behaviour of equations of state of finite systems. These originate in the exponentially rising particle mass spectrum and have great significance in connection with the heavy ion experimental programme and the development of string theories. He was a person of the highest scientific integrity and standards of reasoning. Johann Rafelski, Department of Physics, University of Arizona, Tucson, USA
