12C and the β-decays of 12B and 12N

The beta-decays of the mirror nuclei B-12 and N-12 both populate states in C-12 and they are therefore a precious source of information about this nucleus. Figure I shows the two decays and the relevant states in C-12. There is a substantial literature on experimental studies of the B-12 and N-12 decays, however, somewhat surprisingly the attention has in the past almost 40 years mainly focused on decays populating the ground state and the first exited 4.44 MeV state; prior to 2001 the latest published measurement of alpha-particles from the unbound states was completed in 1966 [1]. In 2001 we started a series of new measurements of the decays of B-12 and N-12 with special focus on the unbound states. I will first give an overview of our motivation for new measurements and give references to what has been published already, then outline our experimental approach, and present preliminary results from analysis of new data from 2004-2005. I will end the paper with an outlook on future plans.