Particle tracks and the mechanism of decoherence in a model bubble chamber

We put forward a toy model for a "bubble chamber" and study its interaction with an incoming object particle. We discuss the notion of particle "track s" inside the bubble chamber and analyze the mechanisms that provoke a loss of quantum mechanical coherence (decoherence). The model is solvable and p rovides interesting insights into some of the most salient features of the interaction between a microscopic particle and a macroscopic device. (C) 19 98 Published by Elsevier Science B.V.