Search for the 6 condensed state in 24Mg using the 12C+12C scattering

We searched for the 6a-condensed state in 24Mg by measuring the 12C+12C scattering with the SAKRA Si detector array at Ecm = 17.5-25.0 MeV. By using the invariant-mass method for the detected 3a particles, the inclusive cross sections for the 12C +12C -* 12C(0+2) + ?????? and 12C(3-1) + ?????? reactions were determined. In addition, the missing-mass spectroscopy was successfully utilized to determine the excitation energy of the residual 12C nucleus and the exclusive cross sections for the 12C + 12C-* 12C(0+2 ) + 12C(0+1 ), 12C(0+2 ) + 12C(2+1 ), and 12C(0+2 ) + 12C(0+2 ) reactions. In both the inclusive 12C(0+2) + ?????? channel and the exclusive 12C(0+2) +12C(0+1) channel, the cross section peaked at Ecm = 19.4 MeV, which correspond to the excitation energy of E ?????? = 33.3 MeV in 24Mg. This 19.4-MeV state is a candidate for the 6a-condensed state because of the agreement of the excitation energy with the theoretical value and its decay property. In the exclusive 12C(0+2 ) + 12C(0+2 ) channel, a broad state was observed at Ecm = 22.5 MeV, which correspond to the excitation energy of E ?????? = 36.4 MeV in 24Mg. From the angular distribution of the differential cross section, the spin and parity of this 22.5-MeV state was assigned to be 4+. In addition, a 2+ state was suggested at the low-energy side of the 22.5-MeV state. Because their excitation energies are higher than the theoretical value of the 6a-condensed state, these states might be excited states of the 6a-condensed state such as the 2+2 and 4+1 states in 12C.