elerator construction, there was pioneering work on what was then a new and exciting device, the synchro-tron. Several small 30 MeV rings were built and larger ones designed for universities at Oxford, Glasgow and Birmingham. Then when planning started for CERN – which was not greeted with much enthusiasm by some in the UK who already had their own machines – it was Cockcroft who appointed Frank Goward from Harwell to assist Odd Dahl and Kjell Johnsen in the design of the PS. Soon afterwards he also encouraged two other important figures from Harwell to join in, with lasting impact on CERN: Donald Fry and John Adams.
In 1951, Cockcroft and Walton shared the Nobel Prize in Physics for the "transmutation of atomic nuclei by artificially accelerated particles". Why had it taken so long to recognize the achievement, when Lawrence was instantly rewarded in 1932 for the invention of the cyclotron? The reason seems to be that there was a long list of giants still waiting to be recognized – Heisenberg among them – before Cockcroft and Walton could take their proper place. The awarding of the Nobel prize to Lawrence for the cyclotron helped to establish the pattern of rewarding instrument building for its own sake, introducing "innovation" into the criteria of the Nobel committee, in addition to "discovery".
Cockcroft later held many important and influential scientific and administrative positions. He was president of the UK Institute of Physics and the British Association for the Advancement of Science, and was chancellor of the Australian National Academy, Canberra. His work was also acknowledged in many ways, including honorary doctorates and membership of many scientific academies. In 1959 he was appointed master of Churchill College, Cambridge. He died, aged 70, on 18 September 1967 – a year after the celebration of Chadwick's 75th birthday at the newly created Daresbury Laboratory. It is at Daresbury that another important step forward for accelerator physics has begun, with the Cockcroft Institute named in honour of the accelerator "giant" who, along with Walton, first split the atom 75 years ago.
About the author
Mike Poole, John Dainton and Swapan Chattopadhyay, Cockcroft Institute.