1 Terry: I didn't know Cambridge had a particle accelerator.
2 Bonnie: We have the first one! Powered by Cockcroft and Walton's high voltage multiplier. It was the first device to split an atom, in 1932.
3 Bonnie: And hence almost the first experiment to create a mini black hole and destroy the Earth.
4 Terry: Wow, really?
4 Bonnie: The Centre for the Study of Existential Risk was founded the next day.

British physicist John Cockcroft and Irish physicist Ernest Walton were indeed the first people to use a particle accelerator to split an atom, doing so at the Cavendish Laboratory at Cambridge in 1932. They built a giant high voltage generator to power the device, creating strong electric fields to accelerate the particles electrostatically. The material they split were atoms of lithium, creating two helium nuclei from each lithium atom.

And the fact that they didn't create a mini black hole and destroy the Earth won them the Nobel Prize for Physics in 1951.