John Douglas Cockcroft and Kempton, c 1940s.

Cockcroft (1897-1967) (right), was responsible, in 1932, for a brilliant experiment with E Walton which turned on its head G Gamow's (1904-1968) theory of particles tunnelling out of nuclei, to produce transmutation, an artificial nuclear reaction caused by particles tunnelling into nuclei and disintegrating them. Kempton was a physicist who worked at the Cavendish Laboratory, Cambridge.