This is an experiment which studies scattering alpha particles on atomic nuclei. Nearly monoenergetic alpha particles (He nuclei) in a collimated beam from an source are scattered from thin foils of gold or titanium, and the intensities of the scattered alpha particles are measured with a silicon barrier detector at various scattering angles.
The energies of the incident alpha particles can be reduced by placing a gold foil in the beam. The differential scattering cross section of the target atoms is measured as a function of the angle of scattering, the energy of the particles, and the nuclear charge of the target atoms. The results are compared with the Rutherford theory of scattering by atomic nuclei.
Rutherford, Ernest. "The Scattering of Alpha and Beta Particles by Matter and the Structure of the Atom." Philosophical Magazine 21 (1911): 669-688. Sixth Series.
Geiger, H. "The Scattering of the Alpha-Particles by Matter." Proceedings of the Royal Society of London 83, no. 565 (1910): 492-504.