Obituary of Neil Anthony Porter

Neil Porter, an outstanding astrophysicist, died peacefully in Dublin on March 15h 2006. He made a number of original and fundamental contributions to his field, during a long career dedicated to research, teaching and scholarship. Neil’s interests were catholic in scope, ranging from peace studies (in which he got M.Phil), astro-archeology, and cosmic ray physics to the history of physicists who suffered persecution, a topic on which he published the book ‘Physicists in Conflict’ and also obtained an M.A. He was truly a renaissance man with wide interests and talents: a brilliant raconteur, an actor, a singer, in his youth a long distance runner, and a gentle man of deep faith.

Born in Urmston, Manchester, on September 4th 1930, Neil was educated at St. Bedes College, and the University of Manchester. In September of that year he was appointed a Research Scholar in the School of Cosmic Physics of the Dublin Institute of Advanced Studies. Between 1954 and 1958, Neil was a research Fellow at the Atomic Energy Research Establishment at Harwell, UK, working with the Cosmic Radiation research group. He returned to Dublin in 1958 as a lecturer at University College Dublin where he was appointed Professor of Electron Physics in 1963.

It is as a scientist of outstanding curiosity, inventiveness and flair that Neil will be most widely remembered. During the early years at Harwell he collaborated with J.V.Jelley on the development of new types of Cerenkov radiation detectors for measuring cosmic ray showers. During this time he published a very original paper proposing that the magnetic monopole might be an important constituent of cosmic radiation. In 1961 he visited MIT for two months, working with Bruno Rossi’s group and, together with Dave Hill, accomplished the remarkable technical achievement of using image intensifiers to photograph the feeble and transient Cerenkov light given off by energetic charged particles from cosmic ray showers in the atmosphere. A collaboration with Frank D’Arcy resulted in the successful detection of the passage of cosmic mu-mesons in the human eye by virtue of emitted Cerenkov radiation.Neil was a key figure in the application of radio technology to detecting cosmic ray showers. A paper by G.A.Askaryan in 1962 stimulated interest in the detection of the feeble coherent radio emission from extensive air showers, through the deployment of cheap radio receivers. Pulses were first detected from showers in 1964 through the collaborative efforts of scientists from Harwell, Dublin and Jodrell Bank.

However, perhaps Neil’s most important contribution to science has been his role in the development of the imaging atmospheric Cerenkov technique. A seminal paper written with J.V Jelley in 1964 described the future course that technique would take. In particular the paper outlined the concept of recording the images of the Cherenkov light from the gamma-ray initiated electromagnetic cascades and using the information contained therein to discriminate them from the much more numerous background hadron showers. The paper also advocated the use of stereoscopic imaging systems to further reduce background. It was twenty years before the concept saw practical realization. Neil was to be a co-author of the Whipple paper announcing the first credible detection of a TeV gamma-ray source (the Crab Nebula).

Neil was always mindful of alternative approaches to the detection of new and exciting phenomena. When Stephen Hawking suggested that Primordial Black Holes might evaporate with the emission of a burst of gamma rays, Neil immediately saw that a simple ground-based atmospheric Cherenkov experiment using separated detectors would be a sensitive way to detect such bursts. Although no bursts were detected in a series of elegant experiments, the limits were more sensitive than those obtained using other techniques (including those from the EGRET telescope on the Compton Observatory a decade later). It was one of Neil’s most satisfying achievements in his research career that these results were referenced in Hawking’s famous, much translated, “A Brief History of Time”. In the French edition Neil is referred to as the “savant irlandais”, a fitting epitaph.

Neil was an inspirational teacher who influenced generations of students in Physics with his engaging style of lecturing. Generations of Irish undergraduates and postgraduates in Experimental Physics owe an important component of their education to him. With his passing we have lost our mentor, colleague and good friend. We learned a lot from Neil, the least of which was physics.