Breakup channels for C12 triple-α continuum states

September 2009 • 2009PhRvC..80c4316D

Authors • Diget, C. Aa. • Barker, F. C. • Borge, M. J. G. • Boutami, R. • Dendooven, P. • Eronen, T. • Fox, S. P. • Fulton, B. R. • Fynbo, H. O. U. • Huikari, J. • Hyldegaard, S. • Jeppesen, H. B. • Jokinen, A. • Jonson, B. • Kankainen, A. • Moore, I. • Nieminen, A. • Nyman, G. • Penttilä, H. • Pucknell, V. F. E. • Riisager, K. • Rinta-Antila, S. • Tengblad, O. • Wang, Y. • Wilhelmsen, K. • Äystö, J.

Abstract • The triple-α-particle breakup of states in the triple-α continuum of C12 has been investigated by way of coincident detection of all three α particles of the breakup. The states have been fed in the β decay of N12 and B12, and the α particles measured using a setup that covers all of the triple-α phase space. Contributions from the breakup through the Be8(0⁺) ground state as well as other channels—interpreted as breakup through excited energies in Be8—have been identified. Spins and parities of C12 triple-α continuum states are deduced from the measured phase-space distributions for breakup through Be8 above the ground state by comparison to a fully symmetrized sequential R-matrix description of the breakup. At around 10 MeV in C12, the breakup is found to be dominated by 0⁺ strength breaking up through the ghost of the Be8(0⁺) ground state with L=0 angular momentum between the first emitted α particle and the intermediate Be8 nucleus. For C12 energies above the 12.7 MeV 1⁺ state, however, L=2 breakup of a C12 2⁺ state through the Be8(2⁺) excited state dominates. Furthermore, the possibility of a 2⁺ excited state in the 9-12 MeV region of C12 is investigated.

Links

• ELECTR http://link.aps.org/doi/10.1103/PhysRevC.80.034316