Studies of the 2α and 3α channels of the 12C+12C reaction in the range of E c.m.=8.9 MeV to 21 MeV using the active target Time Projection Chamber* *Supported in part by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB34020200), the National Key Research and Development program (MOST 2016YFA0400501) from the Ministry of Science and Technology of

Abstract

The 12C+12C fusion reaction was studied in the range of E c.m.=8.9 to 21 MeV using the active-target Time Projection Chamber. With full information on all tracks of the reaction products, cross sections of the 12C(12C,8Be)16Og.s. channel and the 12C(12C,3α)12C channel could be measured down to the level of a few milibarns. The 12C(12C,8Be)16Og.s. reaction channel was determined to be 10 mb at E c.m.=11.1 MeV, supporting the direct α transfer reaction mechanism. The 12C(12C,3α)12C reaction channel was studied for the first time using an exclusive measurement. Our result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al. [Phys. Rev. C 21, 579 (1980)]. Our comparisons with statistical model calculations suggest that the 3α channel is dominated by the fusion evaporation process at E c.m. > 19 MeV. The additional contribution of the 3α channel increases the fusion reaction cross section by 10% at energies above 20 MeV. We also find that an additional reaction mechanism is needed to explain the measured cross section at E c.m. < 15 MeV at which point the statistical model prediction vanishes.