A C-12+C-12 CLUSTER MODEL OF MG-24

A recently proposed cluster model of 24Mg based on two 12C component nuclei is re-examined with a view to justifying some of its assumptions and parameter values. The 12C clusters are allowed to occupy their 01+ (0.00 MeV), 21+ (4.44 MeV), O2+ (7.65 MeV), 31- (9.64 MeV) or 11- (10.84 MeV) states, and hence give rise to a variety of bands of states of both positive and negative parity in 24Mg. Coupled-channels calculations, invoking the bound-state diagonalisation approximation, are performed to evaluate the energies and wave functions of these states up to excitation energies of about 16 MeV and are found to describe almost the entire experimentally known T = 0 spectrum in this region. Reduced E2 electromagnetic strengths for transitions between the low-lying positiveparity states are also calculated in good agreement with measured values, without the need to introduce effective charges. Finally, form factors for elastic and inelastic electron scattering (the latter via the 21+ and unresolved 41+ + 22+ states) from 24Mg are examined, and found to imply a charge radius somewhat larger than that deduced from other analyses, and a breakdown of the applicability of the plane-wave Born approximation at the higher values of the momentum transfer. © 1990.