Artificial radioactivity produced from an isotope that has been previously obtained in the laboratory by a nuclear reaction. This isotope is radioactive with all laws governing the natural radioactivity.
In 1919, Rutherford, by bombarding nitrogen with particles from a radioactive substance, caused the first nuclear reaction leading to the "artificial" production of an isotope of oxygen. The N is transformed into O and emitting a proton.

In 1934, the spouses Irene and Frederic Joliot Curie, studying the production of neutrons by bombarding an aluminum foil with alpha particles, they discovered that it was a radioactive isotope of phosphorus. They found that in addition to neutrons, positrons appear not expect, nor expected, and that did not stop to stop bombing occur, as happened with neutrons.

The projectiles used for the production of neutrons are isotopes as having no electrical charge to not experience electrostatic repulsion forces by proton nuclei in penetrating to destabilize.
Positron production is more abundant in artificial radioactivity in the natural and occur spontaneously alpha and beta particles and gamma radiation.

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