From: Frank Geurts (geurts_at_rice.edu)
Date: Thu Feb 20 2003 - 16:20:35 EST
John,
we need you :) ... could you take a look at page 20 of the tofp NIM
paper and tell me what you think about it.
Here's the deal ... we see in physics running mode occasional strobe
events which we always attributed to events in which we received a star
L0 but didn't get a pVPD coincidence. In the daq software this situation
is always covered by the 'ship fake data' mode in which we fill our
event w/ 0s and ship it to STAR. Remember, the 'fake data' mode is our
STAR-compliance mode: STAR asks => we deliver.
Now, one would expect that no-TRG means no local trigger => no data =>
the software has to come up w/ a fake data event (0s all over the
place). That is not true. Clearly, we see strobe events instead of 0s.
So, that means that we either strobed ourselves (through the Jorway) or
we *were* strobed through the TCD 'TRIG CMD 4' ... clearly, we don't
strobe ourselves, that is only used in the daq emulation mode. Which
leads to no other conclusion than CMD-4 pulses are send to us *every*
event. Only a timely busy from "Local BUSY" can prevent the cmd4 to
common-start and -stop the TDCs and ADCs. In case of a TRG, this will
set the local busy preventing the CMD4 (or test pulse) to fire PULSE.
So, am I right to conclude that TCD Out-4 a.k.a "TRIG CMD 4" is always
fired for every event and that the Local Busy prevents
Common-Start/Stops in case we have a real coincidence? My understanding
was that "TRIG CMD 4" was only fired in when STAR ran in pedestal mode!
cheers,
-frank
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