Hello all.     Plotting (time1-time2) for all the randoms coincidences, I notice that the lower value is a sharp cutoff (just as I expect) but the higher value is over and beyond the coincidence window. With my coincidence window set to 6 ns, I see (time1-time2) values as high as 89 ns. I have plotted (time1-time2) and uploaded the plot here: <a href="http://img337.imageshack.us/img337/4598/gatetalkhm9.gif">http://img337.imageshack.us/img337/4598/gatetalkhm9.gif</a> The relevant lines from my digitiser are: /gate/digitizer/Coincidences/setWindow 6.0 ns /gate/digitizer/Coincidences/minSectorDifference 7 /gate/digitizer/Coincidences/MultiplesPolicy takeAllGoods /gate/digitizer/name delay /gate/digitizer/insert coincidenceSorter /gate/digitizer/delay/setWindow 6.0 ns /gate/digitizer/delay/setOffset 500.0 ns /gate/digitizer/delay/MultiplesPolicy  takeAllGoods I am interested in knowing why I get randoms coincidences beyond the coincidence window. Thanks for any help. Karthik.