Fusion reactions and highly excited nuclear states

Heavy ion fusion reactions produce compound nuclei in highly excited states with large angular momentum. Such states can decay by emitting neutrons, protons, alpha-particles, other light fragments, gamma rays, and by fission. This paper reviews some of the basic results of compound nucleus theory and discusses their validity at high excitation energy. When the compound nucleus life time is very short, internal degrees of freedom may not reach equilibrium and the decay of the compound system may depend on the way in which it was formed. Relaxation times for various internal degrees of freedom are discussed and examples of transient effects are given