Consistent analysis of the 2+ excitation of the 12C Hoyle state populated in proton and α-particle inelastic scattering.

The 12C excitation energy spectra populated in both proton and α-particle inelastic scattering measurements are examined. The data indicate the existence of a 2+ state at Ex = 9.75(0.15) MeV with a width of 750(150) keV. It is believed that this state corresponds to the 2+ excitation of the 7.65 MeV, 0+, Hoyle state, which acts as the main path by which carbon is synthesized in stars. A simultaneous Ä-matrix analysis of the two sets of data indicates that the 2+ state possesses a very large α-reduced width, approaching the Wigner limit. This would indicate that the state is associated with a highly clustered structure. The potential geometric arrangements of the clusters is discussed. [ABSTRACT FROM AUTHOR]