Obituary: Bjorn Wiik

BJORN WIIK was an outstanding scientist and leader in European and world particle physics, equally expert in performing experiments, in the design and construction of accelerators, and in interacting with governments.

He was born in Bruvik, Norway, in 1937. After evacuation to England with his family in a British submarine for a period during the Second World War - his father was a resistance leader - he attended high school in Bergen before moving to Darmstadt in Germany to study nuclear physics. Although never again resident in Norway, he visited frequently and later became a visiting professor in Bergen and a member of various Norwegian academies and government advisory committees.

His interests turned to particle physics during a seven-year period of post-doctoral research at Stanford University, California. Returning to Germany in 1972 to take up an appointment at the Deutsches Elektronen Synchrotron (Desy) in Hamburg, he became involved in the study of electron- positron collisions. He was a key participant in the so-called Tasso experiment at Desy's electron-positron collider (Petra), which was commissioned in the autumn of 1978.

Wiik and collaborators (Soding, Wolf, Wu and others) used the Tasso data to provide the first direct evidence for the existence of a particle known as the gluon and to establish its properties. The discovery of the gluon, which serves to bind quarks together to form neutrons and protons, was a fundamental contribution to our knowledge of the strong (nuclear) force. Furthermore, the success of Petra (which pre-empted a similar project at Stanford) was an important milestone in establishing the self-confidence of European particle physics.

From the early 1970s, Wiik had been interested in the possibility of colliding beams of electrons and protons in order to extend to higher energies the pioneering "fixed-target" electron-proton scattering experiments at Stanford, which had produced the most direct evidence for the "reality" of quarks. In 1981, he became responsible for designing the very ambitious superconducting proton storage ring of the proposed electron-proton collider (Hera) at Desy, and three years later was appointed co-project leader when construction was approved. Technically the unique Hera machine, which was commissioned in 1992, has been a great success, and experiments at Hera have produced excellent physics and deepened our knowledge of the structure of the proton.

As Director of Desy from 1993, Wiik oversaw the exploitation of Hera and led on-going research and development on very high performance superconducting radio frequency cavities. This development, which demonstrated Wiik's deep intuitive understanding of the technically possible, has already defied sceptics by producing accelerating gradients of 33 million volts per metre. It remains to be seen whether this technology will be adopted for the construction of a large linear electron-positron collider, as originally intended, but there is no doubt of its potential; the technology might be used for example in the construction of a free electron laser/light source for biological studies.

Wiik was a scientific statesman whose advice was sought world-wide. As a member of various national and international advisory bodies, including the International Committee for Future Accelerators (Icfa) of which he was chairman at the time of his death, Wiik played an important role in setting the agenda for European and world particle physics. He was a chairman of the Super Proton Synchrotron Committee and served on the Scientific Policy Committee at Cern in Geneva, where his name was considered on several occasions as a possible Director General - a post he would almost certainly have been offered had he wished.

Bjorn Harvard Wiik, physicist: born Bruvik, Norway 17 February 1937; Staff Physicist/Senior Scientist, Deutsches Elektronen Synchrotron (Desy), Hamburg 1972-81, Hera Project Leader 1981-92, Director 1993-99; Professor of Physics at II Institute for Experimental Physics, University of Hamburg 1981-99; Chairman, International Committee for Future Accelerators 1997- 99; married 1978 Margaret Becker (one son, two daughters); died Appel, Germany 26 February 1999.