Novel aspects of the carbon-decay mode of radium

The effects of residual coupling interactions on the newly discovered decay ${}_{}{}^{222}{}_{}{}^{}\mathrm{Pb}$ are investigated. The couplings to the low-lying collective excitations of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ produce an order of magnitude enhancement in the tunneling probability. A new possible mechanism for this decay is discussed whereby a ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ fragment is transformed into ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ by picking up two neutrons as it tunnels out.