One Million-Volt Particle Accelerator, 1938.
© Science Museum / Science & Society Picture Library
Model (scale 1:12), of particle accelerator made by N V Philips Gloeilampenfabrieken, and supplied by Philips Electrical Ltd to the Cavendish Laboratory, Cambridge in 1938. This is a cascade generator designed to produce the high voltage (up to 1.25 million volts) required to accelerate the particles. Physicists John Cockroft (1897-1967) and Ernest Walton (1903-1995) devised a technique for bombarding atomic nuclei with protons (hydrogen nuclei) that had been accelerated in a powerful electric field. The aim of these attempts to 'split the atom' was to explore the basic composition of matter. These experiments showed that the atomic nucleus was not an indivisible and basic unit, but had its own internal structure.