High Quality Content by WIKIPEDIA articles! Cobalt-60, 60 27Co, is a synthetic radioactive isotope of cobalt. Due to its half-life of 5.27 years, 60 27Co is not found in nature. It is produced artificially by neutron activation of 59 27Co. 60 27Co decays by beta decay to the stable isotope nickel-60 (60 28Ni). The activated nickel nucleus emits two gamma rays with energies of 1.17 and 1.33 MeV, hence the overall nuclear equation of the reaction is