Generalization of the Poisson distribution for the case of changing   probabilities of consecutive events
  In this paper the generalization of the Poisson distribution is derived for the case when each consecutive event changes event rate. A simple formula for the probability of observing of a given number of events for the selected period of time is derived for a given set of rates. Application of this distribution in high-energy physics calculations is discussed. 
E.A.Kushnirenko
physics.data-an hep-ex