User name J. Volmer
Log entry time 13:05:19 on November 16,1999
Entry number 349
This entry is a followup to: 346
Followups:
keyword=electronic live timesFollowing Rick Mohrings thesis (Figs. 3.8 and 3.9), I did a new attempt at finding out the electronic live times for the HMS and SOS. Fig. 1 shows both plotted against the respective elreal rates. The method used here is to take two of the three scalers EL60, EL90 and EL120, make an assumption about their true gate widths, and extrapolate to elreal=0. This will yield the number of counts that should have been detected without dead times, normalized by the number of counts detected with the actual dead time. The inverse of this number is the electronic live time, and this is what is shown in Fig. 1. It is equivalent to what DaveM suggested and what I showed in fpilog #346.
The red dots correspond to using the el60 and el90 scalers, the blue dots are derived with the el60 and el120 scalers, and the green ones with the el90 and el120 scalers. The electronic live time scatters around 0.937 for the HMS and 0.948 for the SOS. It has been assumed that the HMS el60 and el90 gates are actually 60 and 90 ns long, but the el120 gates has only a width of 100.3 ns. In the SOS all nominal lengths are assumed, with the exception of el60=59 ns.
Generally, the values where el60 has been used are less sensitive to small errors in the gate widths and should therefore be trusted.
FIGURE 1
