Search for cluster structure of excited states in C-14

摘要

We have studied three different 2n-transfer reactions on a C-12 target, the 2p pick-up reaction on O-16 and the He-5 transfer in the reaction Be-9(Li-7,d)C-14. Combined with a systematic search through experimental results for transfer reactions, inelastic excitations and other data, we have established an almost complete spectroscopy for C-14 up to 18 MeV excitation. We identify states with single-particle structure that have oblate shapes and states corresponding to proton excitations that are connected to oblate (triangular) cluster states. Further we list states of prolate shape which have no simple structure related to the low-lying oblate states of C-12. These are proposed to have strong alpha-clustering and to form rotational bands as a parity inversion doublet, with high moment of inertia. With these results it is possible for the first time to identify chain states expected in the isotope C-14.