From: Frank Geurts (geurts_at_rice.edu)
Date: Wed Feb 19 2003 - 21:26:43 EST
Xu, Zhangbu wrote:
[ ...]
>
> Frank and I will check two things:
> 1) measure the timing delay between first discriminator and
> the output from West and East coincidence.
During today's access, Zhangbu measured the timing between the input to
the 3rd discrimination of pVPD W3 (PS708, 1-11-6) and the output of the
WEST coincidence (LC365, 2-12-2) to be 27ns. For more details see
http://mac8.rice.edu/~TOF/TOFp/operations/manuals/local_trg.html and the
reference to the Run-III diagram.
> 2) Measure the effect of the second output from Model 706
> discriminator.
The second test we did was measuring the contribution to the time
resolution from loading one or two channels of a PS706 discriminator.
The setup (see diagrams in above link) involved temporarily replacing
the quad input, which is used as a fan-out unit (LC622, 2-9-1) with a
spare ps706 channel. In this test we either one or two of the PS706
outputs and ran the local DAQ in a pulsing stand-alone mode.
A quick analysis shows that on the average the time-resolution of all 72
TOFr channels, as expected, detoriates but only with some 0.02 to 0.03
TDC bins which translates into roughly 1 to 1.5ps.
3) Zhangbu removed the 4ns cable and the fan-out unit which sends the
EAST and WEST coicidences to his trigger rack. This should safe at least
some 12ns in the "STAR pVPD-trigger" timing. With the additional removal
of a discriminator on his side the STAR-pVPD trigger ought to be timed
in properly now.
-frank
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