Kjell Johnsen

Kjell Johnsen (born June 11, 1921 in Meland , Norway ; † July 18, 2007 in La Rippe , Switzerland ) was a Norwegian physicist who studied the physics of particle accelerators.

Johnsen graduated from the Technical University of Trondheim with a degree in electrical engineering in 1948 . 15 months he was at Dennis Gabor at Imperial College in London . While working on his dissertation (Trondheim 1954), he joined Odd Dahl's group in Bergen , who led the development of a proton synchrotron for CERN , which had just been founded in 1952 . In 1953 Johnsen went to Geneva, where he became assistant to Hugh Hereward , who headed the linear accelerator group for the synchrotron. He was significantly involved in the proton synchrotron (PS) at CERN, which was created parallel to the proton synchrotron AGS at Brookhaven National Laboratory , which Johnsen often visited during this time. During this time, Johnsen became one of the leading accelerator experts. After the proton synchrotron was completed, he led an accelerator research group with Arnold Schoch and Kees Zilverschoon that built the first experimental storage ring at CERN (CESAR). It was in the group that the plans for the Intersecting Storage Ring (ISR), the world's first proton-proton collider, were developed, and Johnsen was the project manager. The project was very controversial at the time, but had the support of CERN director Victor Weisskopf , whom Johnsen and his colleagues were able to convince. Construction began in 1966 and was completed in 1971. It paved the way for many later colliders up to the LHC .

Johnsen was also in the first study group for LEP (and gave the project its name), was involved in the Brookhaven National Laboratory's ISABELLE project from 1980 as technical director (where he was also visiting professor at the Massachusetts Institute of Technology ) and in studies for CLIC (Compact Linear Collider), a planned electron-positron collider in the multi-TeV range. After his time in Brookhaven, he returned to CERN in 1982.

From 1957 to 1959 he was a professor at the TU Trondheim and later a part-time professor in Bergen.

Johnsen was the founding director of CERN's Accelerator School. At DESY he was chairman of the HERA Machine Committee.

In 1990 he received the Robert R. Wilson Prize , mainly for the ISR. He was an honorary member of the Norwegian Academy of Sciences.

literature

• Andrew Sessler, Edmund Wilson Engines of discovery , World Scientific 2007
• Johnsen, P. Bryant Principles of Circular Accelerators and Storage Rings , Cambridge University Press 1993

Web links

• Obituary at Physics Today

Individual evidence

1. ↑ The 200 plus 200 GeV Proton-Proton Collider was under construction from 1978 and was abandoned in 1982/83. Parts flowed into the RHIC .