User name R. Michaels
Log entry time 11:13:10 on July17,2003
Entry number 104247
This entry is a followup to: 104243
keyword=Event type NOT a problem
It should be noted that because of the trigger supervisor (TS) programming, the
CODA event type is not necessarily the trigger type. We program the TS such that
if a trigger type N appears alone it will be event type N, but if two trigger types
appear and overlap within10 nsec we must define the CODA event type. Due to
long experience with people getting confused, we decided to program all overlaps as event type 5.
Note, there are no trigger 5 plugged in. The way to see what triggers
were involved is to look at the so-called trigger latch pattern, which is a TDC 1877
in ROC3, slot 5, channels 1-16 (see adaql1:~adaq/evchk/README and associated
code there). Below is a 2D plot showing correlation of CODA event type to trigger
latch pattern for run 21381. Although we tried before the experiment to make sure
trigger 3 arrives well before (30 nsec) all other triggers, evidently with beam T2 and
T3 overlap within 10 nsec, and the prescale factors were one. If you put ps2 high
(as I suggest you do) and keep mostly T3 you would see mostly CODA event type 3.
I suggest the experiment start looking at this trigger latch pattern.