Rutherford Gold Foil Experiment - Backstage Science -

While most did pass through, Rutherford was shocked to find that:

A detector that would flash when hit by an alpha particle. The Unexpected Result Rutherford Gold Foil Experiment - Backstage Science

Videos about some of Britain's most amazing science facilities While most did pass through, Rutherford was shocked

Chosen because gold is incredibly malleable and can be beaten into a sheet only about 1,000 atoms thick. While most did pass through

Positively charged particles emitted from a radioactive source (radium).