On the breakup of excited ¹⁶O projectiles into four alphas at intermediate energies

Mechanisms of the breakup into four alpha particles of ¹⁶O projectiles excited from peripheral collisions with ¹⁹⁷Au target nuclei have been investigated at 50 and 70 MeV/N. The experimental distributions of relative angles between alpha particles in the rest frame of the primary oxygen nucleus are compared to theoretical predictions based on prompt fragmentation and binary sequential decay. The results are compared to similar studies for that channel at loweer energy, 32.5 MeV/N, where the breakup of ¹⁶O was shown to be consistent with sequential emission of alpha particles.