may 1, 1932 - James Chadwick - Discovering the Neutron

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Chadwick discovered the neutrons after an experimented he conducted, where he had some alpha particles from the natural radioactive decay of Polonium and had them placed with Beryllium. The particles reacted with the Beryllium in a way that couldn't be explained by the known particles at the time. From that he suggested the existence of another particle, now known as the neutron.

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