Professor T. E. Allibone

Leader in British fusion research who worked with Rutherford

Thomas Edward Allibone, physicist and engineer: born Sheffield 11 November 1903; head, High-Voltage Laboratory, Metropolitan-Vickers Electrical Co 1930-46; Director, Research Laboratory, AEI, Aldermaston 1946-63; FRS 1948; CBE 1960; Chief Scientist, Central Electricity Generating Board 1963-70; External Professor of Electrical Engineering, Leeds University 1967-78 (Emeritus); Visiting Professor, City University, 1971-2003, Robert Kitchin (Saddlers) Research Professor 1983-2003, Frank Poynton Professor 1984-2003; married 1931 Dorothy Boulden (died 2001; two daughters); died Holyport, Berkshire 9 September 2003.

Fifty-five years have passed since he was elected as a Fellow of the Royal Society; 77 years since he first made significant contributions as a Wollaston Scholar at Gonville and Caius College, Cambridge, to the work of the Cavendish Laboratory. T. E. Allibone can claim to have been the last remaining scientific colleague to have worked with Sir Ernest Rutherford.

Allibone was already in his mature heyday when I saw a lot of him in his capacity as Chief Scientific Officer of the Central Electricity Generating Board, sweeping into hearings of the Public Accounts Committee with Sir Christopher Hinton, later Lord Hinton of Bankside OM, the CEGB Chairman. A biographer of Sir John Cockroft, he was said to be the bridge between these two giants, who heartily disliked one another.

Thomas Edward Allibone was born in Sheffield in 1903 of a steel-making family. After attending the Central School in Sheffield, he went to Sheffield University, becoming a Linley Scholar. And thence to Caius College, Cambridge, where he attained first class Honours in Physics and came to the notice of the great men of Cambridge physics.

Awarded a Metropolitan-Vickers scholarship to work on the preparation of metallic zirconium and its alloys in Sheffield University, in November 1925 Allibone went to a lecture by C.D. Ellis from the Cavendish on the transmutation experiments of Rutherford and James Chadwick: these involved the alpha-particle that was the nucleus of a helium atom travelling with an extremely high velocity - one which when it left a radium atom could only be equalled if it were to be accelerated through an electric potential of about eight million volts.

Rutherford and Chadwick had succeeded in disintegrating several other elements and the idea became well established that nuclei of the heavier elements were probably composed of those of hydrogen and helium particles, together with particles having no electric charge, neutrons.

After the lecture Allibone went up to Ellis and asked about the possibility of getting a postgraduate scholarship to Cambridge. Allibone had already learnt about W.D. Coolidge, of the General Electric Company of America, generating a voltage of 300,000 volts and applying these to an X-ray tube; and, as he had some experience of high-voltage work in the Metro-Vick Company, he suggested to the Director, A.P.M. Fleming, that he might go to Cambridge and try to produce disintegrations with particles accelerated to 300kV or more in a vacuum-discharge tube.

He made his application to Sir Ernest Rutherford and to his surprise was invited to meet the great man on 29 March 1926 at the Cavendish. After listening to Allibone's proposals for building a very high-voltage generator and discharge tube, Rutherford took him down to the "biggest room we have" - big in linear dimensions and higher than any other room in the laboratory. There Allibone was introduced to John Cockcroft working in one corner and to the Australian Leslie Martin in another. "Is this room high enough for you?" barked Rutherford.

Allibone could only reply that he would try to generate the highest voltage possible in that height, about 500,000 volts, and that he would need half the room to accommodate the apparatus with sufficient clearance for safety. Years later, in 1958, I first met Allibone when he was President of Section A of the British Association; he reflected on his sheer brass neck in taking on and making demands of Rutherford.

Rutherford accepted the headstrong Allibone and he entered the Cavendish in October 1926 on the strength of a Wollaston Research Scholarship at Caius augmented like Cockcroft by financial support from Sir Alexander Fleming, who also offered to help in the supply of some of the apparatus. Allibone consulted his colleague in the Metro-Vick works Brian Goodlet, head of the high-voltage laboratory, who recommended the construction of a Tesla transformer for 500-600kV, as being far smaller and lighter than a power-frequency transformer of the same voltage.

Rutherford had suggested that electrons should be accelerated in the discharge tube as, at that time, he considered that it was not possible for positive ions of modest energy to get near to a nucleus, whereas electrons might enter a nucleus. By the autumn of 1927, Allibone had built the Tesla transformer and was experimenting with a discharge tube able to withstand several hundred kilovolts.

This led Rutherford in his Royal Society anniversary address of 30 November 1927 to indicate a new line of research. A supply of electrons and atoms capable of being artificially accelerated to very great speeds, Rutherford concluded,

could not fail to give us information of great value, not only on the constitution and stability of atomic nuclei but in many other directions; it has long been my ambition to have available for study a copious supply of atoms and electrons which have an individual energy far transcending that of the alpha- and beta-particles from radioactive bodies. I am hopeful that I may yet have my wish fulfilled, but it is obvious that many experimental difficulties will have to be surmounted before this can be realised, even on a laboratory scale.

It rankled deeply, Allibone was to tell me years later, that Rutherford never bothered to refer to him by name, though he had done most of the work. Rutherford, unlike Max Perutz years later, was a credit pincher for other people's works. Even though Leslie Martin was to leave the laboratory in 1927 and be replaced on 9 December 1927 by Ernest Walton, with whom Allibone got on with extremely well, later to share the Nobel Prize with John Cockcroft, Allibone decided that his own future lay in industry rather than in pure academia. Metro-Vick was delighted to make their young prodigy the leader of the high-voltage laboratory in Manchester.

Then came the Second World War. Allibone joined the Manhattan Project in 1944-46, working with the British Mission at Berkeley, California, and Oakridge, Tennessee. Alvin Weinberg, later to be Director of Oakridge, who formed a lifelong friendship and co-ordinated Allibone's American hosts for the next 30 years, told me at a conference in London in 1963 that Allibone, in his opinion, was one of the really useful British scientific contributors.

When the war ended, Allibone was an obvious choice to become the Director of the Research Laboratory of Associated Electrical Industries at Aldermaston, where he remained until 1963. He worked well with John Cockcroft, not least because as colleagues at the Cavendish Allibone stepped in when Cockcroft was distracted by his many visitors:

I saved his apparatus time and again when he switched on, then dashed out to do something and forgot to turn on the cooling water for the pumps.

The good relationship had also been cemented in that Dorothy in 1929 had stayed at 31 Sedley Taylor Road on the south-east of Cambridge in the Cockcrofts' house when she was newly engaged to Allibone, at the start of what was to be a supremely happy marriage lasting 70 years. She encouraged him in his work and was a marvellous hostess to his legion of friends; in turn he did everything to support her talented musical performances.

Allibone nurtured his relationship with the Russians and visited the famous Russian physicist A.F. Joffe at the Institute of Sciences in Leningrad in 1930. An even closer relationship was formed with the Kapitsa family. In 1963, when I visited the Russian Academy of Sciences, Pyotr Kapitsa enquired about Allibone from my colleague on the Science and Political Delegation David Shoenberg, then director of the Mond low-temperature laboratory in Cambridge. In 1971, Allibone himself had lunch with the Kapitsa and he said wryly that he was offered a fine sherry, claret and a cognac - but no Russian wines.

Kapitsa had obtained Leonid Brezhnev's permission to issue a postage stamp to commemorate the centenary of the birth of Rutherford that summer. Allibone was upset that he had failed to get the British Postmaster General to do the same for the New Zealander Lord (as he became in 1931) Rutherford. It hurt the more as Allibone, all his life, was a philatelic scholar and a phenomenally well-organised stamp collector.

Allibone was before his time in many developments. In the late 1940s, Sir George Thomson, then Professor of Physics at Imperial College, formed a small group to develop the torus concept using vessels made first of glass, then of quartz, and then of porcelain. At the same time, a young Australian physicist, Peter Thonemann, had with another small group begun to work quite independently at the Clarendon Laboratory in Oxford. Cockcroft took a great interest in the work of the two groups, giving some financial help to Imperial and in 1951 accepting Thonemann to continue this work in Harwell.

Neutrons are one of the products of the fusion reaction and it was realised that if fusion experiments were successful a source of neutrons would become available and might be used to produce plutonium for a weapon. So the Atomic Energy Authority decided that all the work had to remain secret.

Thomson disliked the idea of secret work being carried out in a university laboratory and he did not want it to go to Harwell, where it would have played second fiddle to Thonemann's work. He therefore asked Allibone to take charge of fusion research, which would be transferred from London to the Associated Electrical Industries Laboratory at Aldermaston. The AEI board accepted the responsibility and offered to pay for the whole of the work to be done but Cockcroft decided that the authority must accept financial responsibility, as the work had to remain under its absolute control. So the Imperial College team moved to Aldermaston and the Harwell and AEI teams worked closely together for the next 16 years.

Allibone's contribution was, first, as a superbly tactful team leader and, secondly, in making a crucially important contribution himself for the design for a steel torus built up in segments. Incidentally, Cockcroft had asked Allibone to discuss Sir George Thomson's top secret patent with a head of department by the name of Klaus Fuchs, which he did in 1949. Presumably the Russians were given a nice head start.

By 1955 Allibone's teams had discovered a good deal about the properties of the plasma state of matter and something about the mechanism of plasma instabilities. On the basis of this knowledge, Cockcroft approved the construction of a large metal toroidal apparatus having a mean diameter of one metre, later called Zeta (Zero Energy Thermonuclear Assembly). This was the first practical demonstration of thermonuclear fusion.

Starting with his Christmas lectures at the Royal Institution in 1959, Allibone began to devote himself to wider activities. His interest in archaeology led to his being a valued trustee of the British Museum. He was also for many years on the Advisory Council of the Science Museum.

Over 70, he wrote beautifully not only about Cockcroft (Cockcroft and the Atom, with Guy Hartcop, 1984) but about Rutherford (Rutherford: father of nuclear energy, 1972), about the Royal Society (The Royal Society and its Dining Clubs, 1976), about Metro-Vick and the Cavendish Laboratory (for John Hendry's collection Cambridge Physics in the Thirties, 1984) and, at the age of 84, made a supremely eloquent contribution to The Making of Physicists (edited by Rajkumari Williamson, 1987).

Tom Allibone was one of the great men of practical physics.

Tam Dalyell