Induced radioactivity Uses Everybody’s doing it Commentary

Irène Joliot-Curie, Frédéric Joliot-Curie physics

Induced radioactivity

• After bombarding atoms with protons
• to measure the recoil of nuclei,
• Irène and Frédéric Joliot-Curie
• discovered that they had made
• non-radioactive elements radioactive.
• They transmuted stable elements
• into heavier radioactive elements,
• creating radioactive nitrogen from boron,
• unstable isotopes of phosphorus from aluminum,
• and radioactive silicon from magnesium.

Uses

• Their work led to the production
• of radioactive isotopes for medicine,
• the discovery of the positron and the neutron.
• and the discovery of nuclear fission.
• In 1939, the Joliot-Curies
• locked up their documents on nuclear fission
• to prevent it being used to make bombs.

Everybody’s doing it

• Ernest Rutherford bombarded nitrogen
• with protons to make oxygen.
• Irène and Frédéric Joliot-Curie bombarded boron
• to make nitrogen;
• they bombarded aluminum, bombarded magnesium.
• They made heavier elements out of lighter ones.
• Enrico Fermi bombarded uranium with neutrons,
• trying to make heavier elements.
• Otto Hahn and Fritz Strassmann bombarded uranium
• but they found they had made boron, a lighter element.
• Lise Meitner said they split the nucleus;
• Otto Frisch called it fission.
• Frédéric Joliot-Curie said
• it was a chain reaction.
• Once the Germans did it
• then the Americans had to do it.