Shift Summary, 10/10/99 Day Shift

Tony Barker (tonyb@cuhep.Colorado.EDU)
Sun, 10 Oct 1999 14:31:48 -0600 (MDT)

Shift Summary for Day Shift, 10/10/99

On Shift: Valeri Jejer, Tony Barker

Hours of beam available at all intensities: 0:00
Hours of beam available at nominal intensity: 0:00
Hours of E832 data (special runs not included): 0:00
Hours of special runs (laser scans, muon runs...): 0:00

Accounting of lost time: Stuck TeV vacuum valve requires
rewarming of C1 cryo string. This
will delay beam until Monday.

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Accesses during shift: none

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Overview of shift: Not much going on.

L3 Accept Fraction Problem studied in lieu of actual
datataking...

BobT, Elliott, and Tony looked at saved online
plots and plots from Pat T. for runs 14794/14795
to try to understand the L3 accept fraction
problem seen in Run 14794. We found, using
Trigger 1 data:

(1) Problem begins abruptly on 4 out of 6 CPU's
in Plane 4 (this was the plane that wrote the
tape that Pat looked at; other plans also showed
a mix of bad/good cpu's) at Spill 48: no problem
is seen before Spill 48.

(2) After Spill 48, there is a roughly 50% loss
of Trigger 1 3pi0D events in the bad CPU's.

(3) In the bad spills (after 48), there is a
large reduction in illumination of the
top left quadrant of the CsI: clear
quadrant boundaries can be seen. We don't
yet know whether the top left quadrant is
completely or only partially dead for the
bad cpu's.

(4) Comparing a bad cpu to a good cpu for
spills in which the bad cpu is bad, there
is an especially large deficit of events
with 4 and 5 clusters.

(5) The L3 log file for 14794 recorded over
200,000 CSICLUS errors in which no energy
was found to match HCC cluster seeds.

(6) Very few of these errors were seen in the
surviving Trigger 1 events saved by L3.

(7) Big distortions are seen in chamber illumination
for good events, but this is very likely just
a reflection of the CsI illumination problem,
since missing top-left clusters will cause
the remaining good events to have missing top
and left tracks.

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