Optimum beam duty cycle for coincidence experiments

It is argued that continuous beam is commonly thought to be ideal for a coincidence experiment because it minimizes the false coincidence rate. A false coincidence rate up to a factor of two lower can be obtained (for fixed average current) by a pulsed beam with relatively short pulses separated by the resolution time of the detector. The micropulse structure of the beam is discussed. Most RF accelerators produce a train of micropulses within a macropulse during which the RF is on. Macropulse timing is generally very long compared to resolution times, hence a macropulse structure that is continuous is desirable. An analysis is given of the errors associated with different duty cycle lengths