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User name V. Sulkosky
Log entry time 19:52:55 on October 28, 2008
Entry number 245196
keyword=Re: L1A Signal Added to TDC Part 3I have added a copy of the L1A (main trigger) to the left HRS TDC (1875)
in ROC 4, slot 18 channel 51. Frist I was using a copy that Kalyan sent
up to the HRS from BigBite before the retiming module. But I saw the
L1A for a normal trigger such as T1 or T3 compared to T5 (edtm
generated) that there was a 224 ns difference in the leading edges in
L1A for the different triggers relative to the TDC gate.
On the BigBite side, Kalyan didn't see a difference. It was decided that
I probably needed to use a copy of L1A after the retiming module. So I
added a copy of this signal instead. On a scope, the timing looked
great, but when I looked at run 2376, I found that the number of events
from the HRS copy that had an L1A signal in the TDC was half of that of
the BigBite copy. Hence something still isn't quite right. I will have
to revisit this when I have more time later.
This is important for the time-of-flight measurement using the RF time
from the beam.
Figure 1 and 2 show the L1A signal from BigBite and the left HRS for
run 2370. The copy is before the retiming module. The number of events
match, but all the T5 events are in the overflow channel since these
are coming after the gate.
A copy of this log entry has been emailed to: kalyan
Figure 1
Figure 2
