As part of an experiment with x-rays in 1909, Rutherford was shooting a beam of alpha particles (or alpha rays, emitted by the radioactive element radium) at a sheet of gold foil only 1/3000 of an ...

Rutherford's most groundbreaking work came when he conducted the famous gold-foil experiment in 1909. In collaboration with ...

1909-1911 Rutherford (and Geiger and Marsden) Some positively charged particles fired at gold foil bounced back when they were expected to pass straight through. Atoms have a central positive nucleus.

The vacuum is important because any deflection of the alpha particles would only be because of collisions with the gold foil and ... came straight back off the foil Rutherford had discovered ...