Cobalt-60

The cobalt-60 isotope undergoes beta decay with a half-life of 5.24 years.

This particular radioisotope is historically important for several reasons. It is involved in the radioactive fallout from nuclear weapons. For many years, the gamma radiation from this decay was the main source for radiation therapy for cancer. This decay was used in the famous experiment by C. S. Wu in which she demonstrated the nonconservation of parity .