James Chadwick

Chadwick started with an experiment that was similar to the experiments of Frédéric and Irène Joliot-Curie, German physicist Walter Bothe, and his student Herbert Becker. They had been studying the radiation that came from beryllium after it had been hit with alpha particles.

Frederic and Irene came to the conclusion from their own similar experiment that the radiation coming from the beryllium had "knocked loose" the protons away from the hydrogen atoms in the paraffin wax target they had used. Instead of saying that the unidentified radiation was actually neutrons, they said that it was high energy gamma photons.

Chadwick disagreed. He thought that photons weren't heavy enough to knock the heavy protons away from the target. In his own experiment, he found that the radiation was actually a neutral particle, similar in mass to a proton.

With Chadwick's discovery, scientists were able to figure out that if they were to hit uranium with neutrons, a large amount of energy would be released. This introduced the beginning of the creation of atomic bombs. The energy released from the uranium and neutrons is what was able to aid the development of these nuclear weapons.

• In 1935, Chadwick received the Nobel Prize for Physics.

• In 1923, he became the Assistant Director of Research at the Cavendish Laboratory where he eventually discovered the neutron.

• Chadwick worked on the Manhattan Project during World War II, which essentially helped to produce the first nucleur weapons.