Evidence of intermediate structure in 12C plus 24Mg system

Studies of backward resonance structures have been performed for the 12C, 24Mg system at 1800 c.m. Excitation functions were measured using the 24Mg beam of the Saclay F.N. Van de Graaff and by detecting at 00 the 12C recoil nuclei with a QDDD magnetic spectrometer. Havar and/or gold foils were placed in front of the focal plane gas counter in order to stop the 24Mg beam. The target was made of a 50 μg/cm2 carbon layer plus a 10 μg/cm2 gold deposit for beam intensity monitoring. The results are presented between 11- and 27 MeV c.m. for the g.s. 0+, first 2+ state of 24Mg and first 2+ state of 12C. The step in energy is 133 keV c.m. The coulomb barrier is about 12 MeV. A certain correlation can be observed between the elastic and inelastic excitation functions. The coherence width calculated is about 600 keV for a average interval of 4.1 MeV c.m. The normalized cross-correlation coefficients are respectively -0.33 and -0.37 for correlation between g.s. and first 2+ of 24Mg and first 2+ of 12C. The cross-correlation cofficient between the two 2+ states is 0.01