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Name of creator

Kjell Johnsen

Biographical history

Kjell Johnsen studied electrical engineering at the Technical University of Norway, in Trondheim where he obtained his degree in 1948.

Then after one year as a scientific assistant, he joined in 1948 Chr. Michelsens Intitute at Bergen.

For rather more than a year, in 1950-1951 he visited Imperial College in London to work on accelerator theory but also on plasma physics. These studies led to his Doctorate from the Technical University of Norway in 1954.

In July 1952, still at the Chr. Michelsens Institute, but 'on loan' to CERN, he joined the CERN Proton Synchrotron (PS) study group. Parallel projects for alternating-gradient proton synchrotrons (AGS) (CERN Courier) were launched at Brookhaven National laboratory (BNL) and at CERN in 1952. The two projects cooperated closely in the ensuing years, and Kjell Johnsen was a frequent visitor at Brookhaven, exchanging ideas with the BNL group.

In 1954 he came to Geneva work on linear accelerator problems, joining the LINAC group of the PS.

In 1957 he returned to Norway as professor of Theoretical Electrical Engineering at the University of Trondheim.

In 1959 after the completion of the PS, he returned to Geneva, joining the Accelerator Research Group. He was engaged mainly on problems arising from the running-in of the completed PS.

In 1961 AR Group became a division directed by A. Schoch. Some specific studies were started by the AR division on possible future CERN projects.

In 1962 Kjell Johnsen was appointed for one year as leader of Accelerators Research (AR) Division. In December he participated in the founding fathers accelerator meeting to prepare first ECFA meeting (FA-EC-1).

In 1963 He was appointed as member of an ECFA Working Party set up under the chairmanship of Eduardo Amaldi to prepare a report on the recommended programme of large accelerator construction for Europe. In this report (FA/WP/23/Rev.3) called the 'Amaldi report' the group recommended the construction of both the Intersecting Storage Rings (ISR) and the 300 GeV Proton Synchrotron.

In December 1965 the CERN Council approved the ISR project and continued to study the 300 GeV project (which was finally approved, as the SPS (Super Proton Synchrotron) in 1971).

From 1966 to 1973 appointed as leader of the ISR Construction Department, Kjell Johnsen directed the construction and commissioning of this project.

In March 1975 as high enery physics required more powerful instruments that could not be provided by individual countries, an International topical seminar on perpesctives in high energy physics held in New Orleans (USA). The seminar strongly recommended that a study group was formed by the USSR, USA and CERN delegations to examine the scientific and technological needs of a Very Big Accelerator (VBA).

In 1976 Kjell Johnsen, selected as CERN member of VBA Study group, participated at the first meeting of this study group held at the High Energy Physics laboratory of Serpukov, 17th to 25th May 1976.

He conducted several studies of new Large Storage Rings (LSR) at CERN (CERN-SD-Note-5, CERN-ISR-LTD-75-39) including a study on feasibility and design of a Large Electron Positron Storage Ring (called LEP) of about 200 GeV.

From 1980 to 1982 he went to BNL as the technical director of the ISABELLE project, a proposed 400 GeV proton-proton collider (cancelled in 1983). He was nominated Professor at the Technical University of Trondheim and for several years dedicated an important part of this time to the teaching at doctoral level and the training of young people.

In 1983 he was also the creator and inaugural Director of the CERN Accelerator School (CAS) with the main purpose of preserving and transmitting knowledge accumulated, at CERN and elsewhere, on particle accelerators and colliders of all kinds. He remained Director unitl 1985.

In June 1985, in order to plan the future of European High Energy Physics, the CERN Council set up an ad hoc committee called the Long Range Planning Committee (LRPC) on the technological and scientific future of CERN. The LRPC appointed three advisory subpanels to seek further expertise on some critical issues, including one on large linear colliders (CLIC Adivisory panel), under the chairmanship of Kjell Johnsen. (ECFA-85-094).

He retired from CERN in 1986.

* Source:

• CERN Courier: April 1963, September 1986, October 2007, October 2007
• CERN Council documents: CERN/0650, CERN/0670
• ECFA documents: ECFA-85-094, Amaldi report FA/WP/23/Rev.3,
   Founding fathers accelerator meeting, FA-EC-1
• ISR Documents: CERN-ISR-LTD-75-39

Immediate source of acquisition or transfer

Mrs Johnsen in May 2011