The Scattering of α and β Particles by Matter and the Structure of the Atom
1911
Rutherford's 1911 paper on why a few alpha particles bounce back from thin gold foil. Using counts of flashes on a screen recorded by Geiger and Marsden, he argues that one hard encounter with a tiny, concentrated charge at the center of the atom fits the counts at every angle, where many small deflections could not.