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Dr Leslie Hodson

Dr Leslie Hodson, former Senior Lecturer in the Department of Physics, died on 1 March 2010.

Leslie Hodson was born in 1925 and attended Thorne Grammar School, near Doncaster. He took up a place to read Physics at the University of Manchester in 1943, and obtained a very good First; owing to the war, his course was compressed into two years and one term. He remained at Manchester to undertake research into cosmic rays (high-energy particles originating in outer space). Dr Hodson was an outstanding member of the very influential research group directed by the eminent physicist, Professor (later Lord) P M S Blackett, FRS, and his work, which led to several significant papers, won praise for its high degree of originality. He was awarded his MSc in 1947 and his PhD, for a thesis on cosmic ray showers, in 1951. Cosmic ray physics continued to be his area of research interest throughout Dr Hodsons long academic career.

Having been an Assistant Lecturer at Manchester from 1947 to 1951, Leslie Hodson moved to the USA to become a Research Associate at Princeton University where he worked with G T Reynolds. His research continued to garner many plaudits and he assumed the main responsibility for a major cloud chamber experiment in Colorado. (Originally developed at the turn of the century by the Scottish physicist, C T R Wilson, the cloud chamber is a device to detect and photograph elementary particles, the most basic physical constituents of the universe, and other ionizing radiation.) The experiment involved Dr Hodson spending much of his time eleven thousand feet up Mt Evans at Echo Lake in Colorado, since this location enabled cosmic ray research to be conducted with reduced effects from atmospheric interaction. He accepted with cheerful good grace his isolation from his fellow-physicists for long periods of time. His work produced a number of important breakthroughs relating to the new unstable particles that had recently been discovered in cosmic rays. While at Echo Lake he had the good fortune to take the cloud chamber photograph that proved the existence of an unstable particle, now called the K+ meson (or kaon), and he had the pleasure of announcing its existence to the world at the May 1954 meeting of the American Physical Society in Washington. The K+ was identified by its decay products, a positively and a negatively charged pion. By a remarkable chance the neutral pion decayed in the double Dalitz mode which has a chance of occurring only about once in ten thousand decays. This was the first time that this decay had been observed. Thus he made two brilliant discoveries with one photograph.

Leslie Hodson was appointed to a lectureship in the Department of Physics at Leeds in 1954 and was promoted to Senior Lecturer in 1964. One of his first tasks at Leeds was to design and construct what was then the largest cloud chamber ever made, weighing more than ten tons, with the aim of making measurements of interactions at energies well beyond the reach of man-made accelerators. This daunting and demanding enterprise, which stretched over several years, Leslie Hodson carried through with unquenchable enthusiasm, drive and persistence, and matchless skill. Consolidating his reputation as a superlative experimentalist, he made extensive use of the new cloud chamber and associated detector arrays to continue his studies of high energy cosmic rays. In particular, many years were spent on refining the search for cloud chamber tracks that would provide evidence of the existence of free quarks with his efforts being focused on the detection of the quark that was thought to have one-third of the charge of the electron. Towards the end of this enormous experimental effort theoreticians showed that there were strong reasons to believe that no such free quark could exist. Had they been free, and thus observable in a cloud chamber, there is little doubt that Dr Hodson would have seen them.

Hand-in-hand with his passion for research went Leslie Hodsons dedication as a teacher. He was unstinting in his commitment to the intellectual development of his students, both undergraduate and postgraduate, and willingly shouldered heavy teaching and supervision commitments. He was a legend in the Physics final-year laboratory, which he directed for many years. Dr Hodson also served his Department well in a variety of other ways, not least through the prominent part he took in designing and monitoring the construction of a new building for Physics during the 1960s, much to the benefit of the buildings inhabitants. (He was proud of his insistence that it must not contain asbestos, which was then fashionable, even though his stubbornness over this issue did not make him universally popular.) He used some of his experiences gleaned from this activity to design his own home.

Dr Hodson retired in 1990, after thirty-six years service to the University.

Leslie Hodson leaves a widow, Joyce, three sons, David, Brian and John, all of them science or engineering graduates, and a grand-daughter, Nicola.

Published: 24 March 2010