Rutherford scattering experiments
Series of experiments by Hans Geiger and Ernest Marsden, directed by Ernest Rutherfofrd, at the University of Manchester, proving the existence of the atomic nucleus through alpha particle scattering on gold foil
The Rutherford scattering experiments were a landmark series of experiments by which scientists learned that every atom has a nucleus where all of its positive charge and most of its mass is concentrated. They deduced this after measuring how an alpha particle beam is scattered when it strikes a thin metal foil. The experiments were performed between 1906 and 1913 by Hans Geiger and Ernest Marsden... Wikipedia