Hiromi Hirabayashi 1934–2008

Hiromi Hirabayashi, a leading figure and professor emeritus of KEK, passed away on 11 April 2008. He was an internationally renowned pioneer in the field of applied superconductivity and cryogenics for high-energy physics.

Hirabayashi was born in Gifu Prefecture, renowned for the Shirakawa-go world heritage site. He was educated in nuclear engineering at the graduate school of Tokyo Institute of Technology, where he gained his PhD in 1966, before becoming a research associate at the Institute of Nuclear Study at the University of Tokyo. He worked on preparations for the National Laboratory for High Energy Physics, or KEK, now the High Energy Accelerator Research Organization, in particular in developing a hydrogen bubble chamber, essential for high-energy physics experiments in Japan. At the same time he established cryogenics – the necessary basic engineering – as a new academic discipline in Japan, and contributed to the development of applied superconductivity and cryogenics in collaboration with Japanese industry.

Moving as an associate professor to KEK when it was set up in 1971, Hirabayashi became a key person in the development of the KEK 1 m bubble chamber. From 1979, as professor, he led the construction of the primary proton and secondary (kaon and pion) beam lines at the KEK 12 GeV proton synchrotron. With excellent foresight, he advocated the importance of applied superconductivity and cryogenic engineering for accelerator science at the energy frontier of particle physics and was able to develop these areas through his strong leadership. His activities in these fields extended internationally through the developments of a superconducting secondary beam line at KEK, superconducting magnets for the TRISTAN project, a challenging 10 T dipole magnet for future accelerators, and collaborations on superconducting magnet development for the Superconducting Super Collider project, the g-2 experiment at Brookhaven, the WASA experiment at Uppsala University and the LHC project at CERN. He made Japanese superconducting magnet technologies for accelerator and particle physics highly appreciated throughout the world.

Hirabayashi went on to become head of the Experiment Management Division, head of the Cryogenics Center, and director of the Applied Research Laboratory at KEK. In 1995 he was invited to head the Safety and Environment Research Center at the National Institute for Fusion Science, where he used his extensive experience and knowledge to advise on the construction of the Large Helical Device.

He contributed to several boards and committees, as a member of the international cryogenic engineering committee in 1990–1999, chairman of the cryogenic society of Japan in 1992–1994, and a member and chairperson of the superconductivity and cryogenics panel of the international committee for future accelerators in 1987–1995. He was also the Asian editor of Cryogenics from 1987–1996. His exceptional work in the field was recognized with the IEEE Award for Continuing and Significant Contributions in the Field of Applied Superconductivity and the special award for superconducting technology from the Society of Non-Traditional Technology.

After retirement in 1998, with a view to the environment and energy saving, Hirabayashi highlighted the need for the "convergence of liquid hydrogen and superconducting technology". His ideas for future society and technology leave an important legacy.

Hirabayashi’s most important contribution was to devote energy to train the next generation to work in the fields of superconductivity and cryogenics and the development of these technologies. He trained many young scientists who now work actively in accelerator science and particle physics.

Hirabayashi’s sudden death has been received with deep sadness not only by people in Japan but worldwide.

Takakazu Shintomi and Akira Yamamoto, KEK.

Uwe Timm 1924–2008

Uwe Timm, a senior physicist at the DESY Laboratory, died aged 84 on 1 May 2008.

Coming from the University of Hamburg, Timm joined DESY in 1958, before its official foundation in 1959. He was among a group of idealistic and enthusiastic young people whom Willibald Jentschke had attracted to build a 6 GeV electron synchrotron. The group succeeded in building a superb accelerator, even though they had all been amateurs in the field. Timm’s responsibility was the 40 MeV electron linac injector which performed well from the beginning when the first electron beam was accelerated on 25 February 1964.

Timm subsequently turned to experimental high-energy physics. His unique contribution to this field was building a beam of high-energy coherent bremsstrahlung: an electron beam hitting a diamond target under precise conditions produces coherent gamma radiation with high linear polarization. For this achievement Timm received the Röntgen award from the University of Giessen in 1966. The polarized photon beam offered new ways to study photoproduction and Timm’s group used it to measure r photoproduction and Compton scattering on the proton with polarized gamma rays, producing spectacular early results at DESY. The polarized gamma beam was also used by other DESY groups and helped the F35 group, for example, to study pion photoproduction and win the "Physikpreis" of the German Physical Society in 1970.

When DESY turned to storage-ring physics, Timm became spokesman of the PLUTO collaboration at the DORIS storage ring. PLUTO soon had good data on the total hadronic cross-section and on inclusive muons, which confirmed the existence of the τ lepton. The collaboration’s pioneering work on gamma–gamma physics is still quoted today. The investigation of the Υ resonance decaying into three gluons established early indirect evidence for the existence of the gluon and for its spin. The PLUTO detector moved to the PETRA storage ring where the collaboration saw the first clear two-jet events and took part in the first round of experiments connected with the discovery of the gluon.

Yet another challenge awaited Timm at the end of his career, with the approval in April 1984 of the electron–proton storage ring HERA. Its construction required an enormous coherent effort from the DESY staff. Many physicists and engineers from the experimental groups joined the teams building HERA. As one of them, Timm again did a great service to the laboratory by, perhaps not surprisingly, building a 50 MeV proton linac (Linac III) of the Alvarez-type. It was ready for duty in November 1988, well in time before Timm retired officially in April 1989.

Timm was one of those people who do not seek the limelight, but who are vital to keep a laboratory successful. In collaborations he provided the necessary leadership and saw to it that consensus and harmony prevailed, and that the collaboration remained on a successful course. He will be remembered by his colleagues and friends at DESY as a personality who was instrumental in shaping the physics and the spirit of the laboratory.

Erich Lohrmann, DESY.