Cross sections for 3α-particle breakup of 12C deduced from α-multiplicity measurements

The study of incomplete fusion reactions in collisions of 12C with 160Gd revealed that only a part of the 'fast' α-particles produced in these collisions results from a capture of 8Be on 4He, i.e. from (12C, αxn) and (12C, 2αxn) reactions respectively. Particularly it has been found that at a bombarding energy of 120 MeV the α-production cross section measured inclusively, sigmasub(α) (incl.), is 850mb, whereas the cross sections integrated over all channels for the (12C, α) and (12C, 2α) reactions are: sigma(1α) = 177 +- 18 mb and sigma(2α) = 75 +- 8 mb. This paper describes a possible explanation for the 'missing' cross section as originating from 3α-particle breakup of 12C. (C.F.)