Alpha particles following the β-decay of 12B and 12N

Abstract

The 10.3±0.3 MeV state in 12C, populated by the β-decay of 12B and 12N, decays by α-particle emission to the ground state of 8Be; its width is 3.0±0.7 MeV. The population and decay of the 10.3 MeV state limit the spin to J π = 0 + or 2 +. The 12.7 MeV state in 12C, populated by the β-decay of 12N, decays by α-particle emission to the J π = 2 + first excited state of 8Be. The formation and decay of the 12.7 MeV state uniquely determine the spin as J π = 1 +. The estimated value of log ft = 3.7 +0.3 −0.5 for the β-decay of 12N to the 12.7 MeV state suggests that this state is closely related to the 12N ground state.