Evidence for "Massive Transfer" in Heavy-Ion Reactions on Rare-Earth Targets

Particle-$\gamma$ coincidence experiments have been performed to study heavy-ion-induced reactions at 6-9 MeV/nucleon which lead to fast $\alpha$ particles. Experimental evidence is presented that the $\alpha$ particles are emitted in a new class of reaction called "massive transfer" which involves fusion of the remaining projectile mass. Such reactions are shown to occur with large cross section. High-spin states in the residual nuclei are populated, but side-feeding $\gamma$-ray intensities are distinctly different from those observed in (HI, $\mathrm{xn}\gamma$) reactions [HI is heavy ion].