Search for cluster structure of excited states in 14 C

Abstract

We have studied three different 2n-transfer reactions on a 12C target, the 2p pick-up reaction on 16O and the 5He transfer in the reaction 9Be(7Li,d)14C. Combined with a systematic search through experimental results for transfer reactions, inelastic excitations and other data, we have established an almost complete spectroscopy for 14C 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 12C. 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 14C.