Decay rates and average luminosity in a B-factory

The different effects contributing to the decay of the electron and positron beam are discussed, and the coupled differential equations describing this decay in an asymmetric B-factory are given. The effect of the vacuum pressure rise by gas desorption owing to synchrotron radiation is taken into account. These equations can be solved numerically and the average luminosity can be calculated as function of the running time T for data taking the filling time F as a parameter. The proper choice of T for a given F can optimize the average luminosity. Examples relevant for a B-factory in the ISR tunnel at CERN (BFI) are given. >