J. Friedman, H. Kendall, R. Taylor and coworkers did a scattering experiment. They used electron beams with energies ranging from 7 to 17 GeV. With that energy of the probe, they studied distances down to 10-17m. The proton and the neutron scattered electrons in a way that could only be explained by assigning an inner structure to the proton and neutron. Only electrons going very close to the particle and its quarks are scattered a large angle.
[home] [quarks] [leptons] [forces] [inside matter]