SEARCH FOR HIGH-SPIN COLLECTIVE STATES IN C-12(STAR)-]3-ALPHA

Sequential decay modes for the four-body final-state reaction, C-12 + C-12 --> 3-alpha + C-12, are reported at a bombarding energy of 7.5 MeV/u. Position and energy measurement of all three alpha particles allows the kinematic reconstruction of the relative energies of all decay particle combinations. Several known natural parity states are observed from the alpha-particle decay of O-16* and C-12*, and in addition unnatural parity states of C-12 never before observed in in-elastic heavy-ion scattering are seen. The branching fraction for the alpha-particle decay of the 14.08 MeV 4+ state of C-12 to the Be-8, 2+ state is measured to be 0.83 +/- 0.04. Monte Carlo calculations for the effective solid angle for detection of each process are presented. No evidence is found for any spontaneous three alpha-particle decay of C-12 excited states and no previously unknown states are reported.