3Ra(T721602)2CO(72=263) 30.306leV a4, 589MeV a4.777Mev y1.17 Mev 94.3%0 y133 Mev 1×MeV 60 222 86Rn 28 图81220Ra和6Co的核衰变图8.1 226Ra和60Co的核衰变