Ernest Thomas Sinton Walton was born on October 6, 1903, in Dungarvan, County Waterford, on the south coast of Ireland. He was the son of a Methodist minister from County Tipperary. In 1922, Walton entered Trinity College in Dublin to study mathematics and physics. An excellent student, he graduated in 1926 with first-class honors in both subjects and then received his M.S. degree in 1927. That same year, he received a research scholarship and traveled to Cambridge University in England to work under Ernest Rutherford (1871–1937) at the Cavendish Laboratory. Walton received his Ph.D. in physics from Cambridge University in 1931 and remained at Cambridge as a postgraduate scholar until 1934.
Walton’s most significant contribution to nuclear technology occurred at the Cavendish Laboratory. Starting in 1928, he began investigating various methods for producing high-energy particles by means of acceleration. Limited by available power supplies, his first two attempts were unsuccessful, although his techniques were used later in the betatron and the linear accelerator. The following year, he began to collaborate with Sir John Cockcroft (1897–1967). They devised an accelerator that was capable of producing a sufficient number of energetic particles at lower energies. The researchers used this machine to bombard lithium nuclei with protons of energy sufficient to shatter the target nuclei into alpha particles. They achieved the first artificial transmutation of an atomic nucleus, and the energy balance of the nuclear reaction provided the first experimental evidence of the equivalence of mass and energy, as postulated in Albert Einstein’s special relativity theory (E = mc2).
The two physicists had achieved an important milestone in nuclear technology on a very limited budget. Walton’s ability to scavenge odd pieces of equipment, like gasoline pumps and automobile batteries, and then combine these bits and pieces into serviceable equipment greatly contributed to the overall success of their effort. In particular, the two scientists constructed a device, later called the Cockcroft-Walton accelerator, which by the multiplication and rectification of the voltage from a transformer was able to produce a nearly constant voltage of about 600,000 volts. They also fabricated a discharge tube in which energetic hydrogen nuclei (protons) could be accelerated into a layer of lithium target nuclei. Walton and Cockcroft shared the 1951 Nobel Prize in physics for this “pioneering work on the transmutation of atomic nuclei by artificially accelerated atomic particles.”
Walton returned to Trinity College in Dublin in 1934 as a fellow. He became Erasmus Smith Professor of Natural and Experimental Philosophy (i.e., a professor of physics) there in 1946. Starting in 1952, Walton also served as chairman of the School of Cosmic Physics at the Dublin Institute for Advanced Studies. After four decades of dedicated instruction to generations of Trinity College physicists, he retired in 1974. Walton died on June 25, 1995, in Belfast, Northern Ireland. His great contribution to nuclear technology was the collaborative development of the first particle accelerator—a powerful new tool that allowed nuclear physicists to probe into the atomic nucleus and unlock the mysteries within it.
Ernest Orlando Lawrance (1901 – 1958)
