Figure 2: a: Trigger time for a Multiplicity trigger when the triggerfraction is set at 33%. b: Due to the trigger fraction being low theCFD can fire early if a nose pulse precedes the shower pulse by more then 7.5ns (the CFD delay) and less then 10 ns (the PCFD pulse width). c: Samepulse as for b but with a trigger fraction of 66% for the CFD. Usingthis value for the trigger fraction eliminates most erroneous pre-triggers.
\begin{figure}\begin{center}\mbox{\epsfysize=0.75\textheight\epsfbox{trigger2.eps} }\end{center}\end{figure}