BETA DECAY OF 10C

The decay of 10C is studied using a Ge(Li) detector with a view to determining the branching ratio to the if Jπ = 1+ 2.15 MeV state of 10B. This branch isfound to be of (6.4 ± 2.0) × 10-3% corresponding to logft = 4.8 ± 0.15. Comparison with the speed of the analogue M1 transition between the 2.15 and 1.74 MeV states of 10B shows that the contributions to the Ml matrix element from the spin and orbital operators are approximately equal and are of the same sign. This disagrees strongly with the predictions of the Cohen-Kurath wave functions; the possibility is explored, following Warburton et al. that better wave functions for the first two Jπ = 1+ states of 10B (the one studied here and that at 0.72 MeV) may be given by appropriate linear combinations of the Cohen-Kurath wave functions. Good agreement with the beta decay and its M1 analogue is indeed found for a mixture close to that found by Warburton et al. to satisfy certain other transitions involving the Jπ = 1+ states. © 1969.