Demonstrated that the beam Irene Joliot Curie discovered wasn’t gamma rays but was a particle with the same mass as a proton (neutrons).

Robert Millikan was the American physicist who discovered the charge of an electron in his “Oil Drop Experiment”.

Joseph John Thomson was an English physicist who invented the CRT (Cathode Ray Tube) and identified electrons and the subatomic particle.

Studied at McGill University in Montreal
Discovered radioactivity involved emission of 2 kinds of particles, alpha and beta.
Discovered that an atom contained a small highly dense positively charged center, known as the nucleus.

The oil drop experiment was performed by Robert A. Millikan and Harvey Fletcher in 1909 to measure the elementary electric charge (the charge of the electron). The experiment entailed observing tiny charged droplets of oil between two horizontal metal electrodes.

The Rutherford-Geiger Experiment is also known as the Gold Foil Experiment. They were a landmark series of experiments by which scientists discovered that every atom contains a nucleus where its positive charge and most of its mass are concentrated.