Cobalt-60 (60Co) is a raioactive isotope of cobalt, with a half life of 5.27 years. 60Co decays by negative beta decay to the stable isotope nickel-60 (60Ni). In the process of decay, 60Co emits one electron with an energy of up to 315 keV and then two gamma rays with energies of 1.17 and 1.33 MeV, respectively.