Professor Brebis Bleaney

Oxford physicist whose research developed out of his wartime work on microwaves in radar technology

Brebis Bleaney, physicist: born London 6 June 1915; Lecturer in Physics, Balliol College, Oxford 1947-50; Fellow and Lecturer in Physics, St John's College, Oxford 1947-57, Tutor 1950-57, Honorary Fellow 1968; Research Fellow, Harvard University and MIT 1949; University Demonstrator and Lecturer in Physics, Oxford University 1945-57, Dr Lee's Professor of Experimental Phiosophy 1957-77 (Emeritus); FRS 1950; CBE 1965; Warren Research Fellow, Royal Society 1977-80, Leverhulme Emeritus Fellow 1980-82; Fellow, Wadham College, Oxford 1957-77, Senior Research Fellow 1977-82, Emeritus Fellow 1982-2006; married 1949 Betty Plumpton (one son, one daughter); died Oxford 4 November 2006.

Brebis Bleaney was an outstanding figure in Oxford physics from the post-war period until his retirement in 1977. He was a member of a group working in the Clarendon Laboratory during the Second World War years on the development of microwave techniques for radar and towards the end of the war he realised that these techniques could be applied to fundamental problems in condensed matter physics.

With these microwave techniques he dominated the development of an important new field of research, electron paramagnetic resonance (EPR) of solids, for a decade. He was the clear choice to succeed Sir Francis Simon in 1957 to the Dr Lee's Chair of Experimental Philosophy at Oxford University and the Headship of the Clarendon Laboratory. During his tenure of the chair there was a major expansion of Physics in Oxford, making the Department of Physics one of the largest in Europe.

Brebis Bleaney was born in 1915, in London, into a modest household. He won a scholarship to Westminster City School and the grounding in science he received there enabled him to secure entrance to St John's College, Oxford, in 1934 as an Open Scholar in Physics. He took Physics Finals in 1937 and completed his research for the DPhil degree in 1939.

Between 1939 and 1945 he was employed with others by Oxford University, on behalf of the Admiralty, to develop radar technology. This work resulted in the production of tunable reflex klystrons giving up to 100 milliwatts of microwave power at wavelengths of 3cm and 1.25cm, waveguides to channel the radiation and silicon-tungsten point contact diodes for detection. A newly developed centimetre wave klystron that Bleaney took over to MIT (the Massachusetts Institute of Technology) has been described as the most important single package to cross the Atlantic during the war.

Bleaney became a University Lecturer in Physics at Oxford in 1945 and Fellow of St John's College in 1947. He was already looking into the possibilities of using the new microwave technology for fundamental research, in the first half of 1945, and his first experiments were made in the Clarendon Laboratory on the inversion spectrum of ammonia. At about the same time the observation of nuclear magnetic resonance in solids in the United States suggested that the analogous EPR technique could be observed in solids using microwaves and a major effort in this direction started in the Clarendon Laboratory. Unknown to Bleaney and colleagues in Oxford a successful EPR experiment was carried out by E.K. Zavoisky at Kazan in the Soviet Union in 1944.

The first EPR experiments carried out in Oxford, in 1946, showed that resonance could not be detected at room temperature in many paramagnetic substances. In such substances, interactions of magnetic ions with thermal lattice vibrations can be so strong that resonance lines are broadened beyond detection. Bleaney and his research group then began measurements at low temperatures to freeze out lattice vibrations. Resonances in a wide range of paramagnetic substances now became observable and Oxford quickly became the major world centre for research in EPR.

This dominance was enhanced by dilution of concentrated paramagnetic materials by a diamagnetic isomorphous salt, enormously reducing resonance line widths and making nuclear hyperfine structure observable. Bleaney's first paper on EPR was published in 1948 ("Paramagnetic Resonance at Low Temperatures in Chrome Alum" in Proceedings of the Physical Society) with his colleague Roger Penrose and his second paper in 1949 ("Paramagnetic Resonance in the Copper Tutton Salts" in Proceedings of the Royal Society) with Penrose and his student Betty Plumpton, who became Bleaney's wife.

The dominance of Bleaney and his research group in the field of EPR continued until 1954 and Bleaney's abilities on both the experimental and theoretical side were a major factor. Progress was greatly stimulated by collaboration with distinguished theoretical physicists at Oxford and, in particular, Maurice Pryce's spin-Hamiltonian ideas of 1950 provided an ideal meeting place for theory and EPR experiment. Progress was also underpinned by the Clarendon's expertise at very low temperatures and this expertise was largely responsible for the success of a proposal by Bleaney in 1951 to produce nuclear alignment at extremely low temperatures. After 1954, the field of EPR spread rapidly worldwide and became an important technique not only in physics but also in chemistry and biology.

Bleaney's contribution to the dominance of Oxford in EPR in the post-war years was recognised by his election to Fellowship of the Royal Society in 1950, at the early age of 35, and he was awarded the society's Hughes Medal in 1962. He transferred from St John's College to Wadham College in 1957 when he became Dr Lee's Professor.

Despite the heavy administrative load that the chair involved he continued to lead the activities of a research group engaged in EPR and to stimulate the activities of others. He retired from the chair in 1977 to concentrate on his research and was Warren Fellow of the Royal Society from 1977 to 1980. He continued to publish until 2003, writing many single-author papers on innovative subjects, and was a daily visitor to the Clarendon Laboratory until recently.

Bleaney's achievements were recognised worldwide and the overseas honours bestowed on him were many. His impact in the US was particularly pronounced: he held visiting professorships at Columbia in 1956 and Berkeley in 1961; he gave the Harkins Lecture at the University of Chicago in1956 and the Morris Moeb Lecture at Harvard in 1981; and he was appointed a Foreign Honorary Member of the American Academy of Arts and Sciences in 1977.

Brebis Bleaney was a physically active person and he and his wife were a formidable tennis doubles pair. He enjoyed music, playing the violin in quartets and trios, with Betty at the piano, and he regularly attended concerts in the Holywell Music Room at Oxford. He was held in great affection by all who knew him and a meeting held at Oxford to celebrate his 80th birthday attracted a large gathering from around the world.

W. Hayes