Walton, Ernest Thomas Sinton (1903–1995)

Irish physicist who collaborated with John Cockcroft on investigating the structure of the atom. They shared the Nobel Prize for Physics in 1951 for their success in 1932 in splitting the nucleus of an atom for the first time.

Walton and Cockcroft built the first successful particle accelerator. This used an arrangement of condensers to produce a beam of protons and was completed in 1932.

Walton was born in County Waterford and studied at Trinity College, Dublin, and 1927–34 at the Cavendish Laboratory in Cambridge, England. He returned to Trinity and was professor there 1947–74.

Using the proton beam to bombard lithium, Walton and Cockcroft observed the production of large quantities of alpha particles, showing that the lithium nuclei had captured the protons and formed unstable beryllium nuclei which instantaneously decayed into two alpha particles travelling in opposite directions. They detected these alpha particles with a fluorescent screen. Later they investigated the transmutation of other light elements using proton beams, and also deuterons (nuclei of deuterium) derived from heavy water.