Breakup of the projectile at 35 MeV/nucleon

Projectile breakup processes are probed by studying the emission of α particles in coincidence with projectile-like fragments as a function of the dissipated energy in the collisions of 35 MeV/nucleon ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ with ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$. Energy correlations between α particles and projectile-like fragments at small-angle geometries allow the separation of the sources of α emission from projectile-like and target-like fragments. We find that the slope parameters of the decay energy distributions, the average excitation energies, and the α particle multiplicities of the projectile-like fragments increase with increasing dissipation of energy. If the linear dependence, exhibited by the data, of the slope parameter with the dissipated energy is included in model calculations, the majority of the coincidence yield in the forward hemisphere can be explained. However, an excess yield of the data on the opposite side of the beam from the observed projectile-like fragment still remains. Such analysis of the data suggests that the breakup of the projectile is the dominant source of light particles at forward angles. Processes resulting in the breakup of the projectile must be better understood in order to study other processes leading to similar phenomena.