Ernest T.S. Walton, an Irish physicist who performed an atom-smashing experiment in 1932 that ushered in a new era of nuclear research, has died. He was 91.
Mr. Walton and a colleague, John Douglas Cockcroft, shared the 1951 Nobel Prize in physics for creating the first man-made machine for smashing atoms and using it in experiments from 1927 to 1932 at Cambridge University in England.
In their most famous experiment, they accelerated protons and bombarded lithium, showing that its nucleus split into two helium particles. The experiment was the first to transmute an atom with artificially accelerated particles. It also demonstrated that mass had been converted to energy, verifying Albert Einstein’s equation E equals mc squared.
Over the decades, particle accelerators have grown vastly in size and cost and have led to many useful applications, including the treatment of cancer with beams of protons or neutrons.
The method developed by the two physicists still is in use. For example, the protons in the huge Tevatron accelerator at the Fermi National Accelerator Laboratory in Batavia, Ill., west of Chicago, begin in a Cockcroft-Walton device.
Mr. Walton died Sunday in Belfast, Northern Ireland.
He is survived by two sons, Alan and Philip, and two daughters, Marian Woods and Jean Clarke.
