Ernest Thomas Sinton Walton, Irish physicist, is awarded the Nobel Prize in Physics on November 15, 1951, for his work with John Cockcroft with “atom-smashing” experiments done at Cambridge University in the early 1930s, and so becomes the first person in history to artificially split the atom.

Walton is born on October 6, 1903, in Abbeyside, Dungarvan, County Waterford to a Methodist minister father, Rev John Walton and Anna Sinton. In those days a general clergyman’s family moves once every three years, and this practice carries Ernest and his family to Rathkeale, County Limerick, and to County Monaghan. He attends day schools in counties Down and Tyrone, and at Wesley College Dublin before becoming a boarder at Methodist College Belfast in 1915, where he excels in science and mathematics.

In 1922, Walton wins scholarships to Trinity College, Dublin for the study of mathematics and science. He is awarded bachelor’s and master’s degrees from Trinity in 1926 and 1927, respectively. Walton receives seven prizes for excellence in physics and mathematics, including the Foundation Scholarship in 1924. Following graduation he is awarded an 1851 Research Fellowship from the Royal Commission for the Exhibition of 1851 and is accepted as a research student at Trinity College, Cambridge, under the supervision of Sir Ernest Rutherford, Director of Cambridge University’s Cavendish Laboratory. At the time there are four Nobel Prize laureates on the staff at the Cavendish lab and a further five are to emerge, including Walton and John Cockcroft. Walton is awarded his PhD in 1931 and remains at Cambridge as a researcher until 1934.

During the early 1930s, Walton and John Cockcroft collaborate to build an apparatus that splits the nuclei of lithium atoms by bombarding them with a stream of protons accelerated inside a high-voltage tube. The splitting of the lithium nuclei produces helium nuclei. This is experimental verification of theories about atomic structure that have been proposed earlier by Rutherford, George Gamow, and others. The successful apparatus, a type of particle accelerator now called the Cockcroft-Walton generator, helps to usher in an era of particle-accelerator-based experimental nuclear physics. It is this research at Cambridge in the early 1930s that wins Walton and Cockcroft the Nobel Prize in physics in 1951.

Walton is associated with the Dublin Institute for Advanced Studies for over 40 years, serving long periods on the board of the School of Cosmic Physics and on the Council of the Institute. Following the 1952 death of John J. Nolan, the inaugural chairman of the School of Cosmic Physics, Walton assumes the role, and serves in that position until 1960, when he is succeeded by John H. Poole.

Although he retires from Trinity College Dublin in 1974, he retains his association with the Physics Department at Trinity up to his final illness. His is a familiar face in the tea-room. Shortly before his death he marks his lifelong devotion to Trinity by presenting his Nobel medal and citation to the college. Ernest Walton dies in Belfast on June 25, 1995, aged 91. He is buried in Dean’s Grange Cemetery, Dún Laoghaire–Rathdown.