Ernest Walton
1903–1995, Dungarvan, Ireland, Belfast, Northern Ireland
Irish physicist who, with John Cockcroft, carried out the first artificial 'splitting of the atom' in history.
Walton was born in Dungarvan, County Waterford, and studied at Trinity College Dublin before winning a research scholarship to Rutherford's Cavendish Laboratory in 1927. There he partnered with John Cockcroft to build their voltage-multiplier accelerator and used it to perform the celebrated lithium disintegration of 1932. In 1934 he returned to Trinity College Dublin, where he became Erasmus Smith's Professor of Natural and Experimental Philosophy in 1946 and remained for the rest of his career, shaping physics education in Ireland for decades.
Nobel-winning work
Walton arrived at the Cavendish Laboratory in 1927 and began collaborating with John Cockcroft on an electrostatic accelerator built around a voltage-multiplying rectifier circuit — the Cockcroft–Walton generator. The machine produced proton beams of several hundred keV, far beyond other sources then available. In April 1932 they directed the proton beam at a lithium target and observed, on a scintillation screen, the emission of two alpha particles — the first 'splitting of the atom' by artificially accelerated particles.
The experiment demonstrated that lithium-7 captures a proton and then decays into two helium nuclei, with an energy balance consistent with Einstein's E = mc². The work opened the accelerator era of nuclear physics and earned Cockcroft and Walton the 1951 Nobel Prize in Physics 'for their pioneer work on the transmutation of atomic nuclei by artificially accelerated atomic particles'.
Workplaces: Cavendish Laboratory, University of Cambridge, Trinity College Dublin
Ireland