Can cluster physics shed some light on the puzzles of our experimental findings with energetic particles? At first a short review will be given about the size and charge distribution of clusters produced by different energetic particles in Si-crystals. From a model based on this, it will be suggested that the behavior of interstitial atoms together with clusters can explain positive and negative annealing. It will be shown that the enhanced charge carrier recombination and the beneficial role of oxygen as a getter for vacancies and interstitial atoms are a straightforward consequence of the model.