The requirements on the trigger/DAQ system of the KLOE experiment are a challenge in this field: this system has to deal with data rates of the order of 1011 events/year while rejecting background rates at least 103 times larger. Moreover, since the major aim of KLOE is to perform CP violation studies at sensitivities of O(10-4), very stringent conditions are imposed on it, to insure that no biases are introduced at such level.
Bossi F. (Tue,) studied this question.