J Thomson, was engaged in experiments on
a-particles emitted by some radioactive elements In 1906,
he proposed a classic experiment of scattering of these
a-particles by atoms to investigate the atomic structure This experiment was later performed around 1911 by Hans
Geiger (1882–1945) and Ernst Marsden (1889–1970, who
was 20 year-old student and had not yet earned his
bachelor’s degree)