Production of fast alpha particles in 20Ne+ 197Au collisions studied by counting the simultaneously emitted neutrons.

The number of neutrons emitted in heavy-ion reactions is counted eventwise with high efficiency in a 4\ensuremath{\pi} neutron counting device. This number is taken as a measure of the energy converted into internal excitation of the heavy reaction residues produced in $^{20}\mathrm{Au}$ collisions at 220, 290, and 400 MeV. Forward emitted \ensuremath{\alpha} particles are found preferentially with either a low number of coincident neutrons or a high neutron number. The former component is identified with \ensuremath{\alpha} particles produced by projectile breakup, the latter with nonequilibrium emission of \ensuremath{\alpha} particles. The inclusive cross section can be decomposed into the contributions of these two processes, and separate energy distributions and excitation functions are given. The nonequilibrium component is compatible with a massive-transfer picture of the responsible process.