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User name dmckee
Log entry time 09:53:32 on March 03, 2004
Entry number 78530
keyword=RC's summary for Tuesday, 2 Mar. 2004 day -- Wednesday, 2 Mar. 2004 owl
RC Summary
Tuesday, 2 Mar. 2004 day
through
Wednesday, 2 Mar. 2004 owl
- Data taking on LH2 target with 40 ľA and with 6 mm
hole target.
- IHWP was OUT, has been switched to
IN Next change on Saturday 6 March.
- LH2 target parity quality
- 16.0 hours for this 24 hr period (runs 20401-20437) (But
we did take some DNL as well...)
- Overall efficiency: 44.2 (10.6/24) (poor)
- Beam (no trip) efficiency: 78.4% (10.9/13.9)
- Parity efficiency: 97.2% (10.6/10.9)
- Total parity hours: 194.4 (runs 19815-20437)
- Overall IN/OUT charge ratio: 0.974
Achievements and events
- Production running at 40 ľA and running with 6 mm halo
target.
- We took a energy modulation run (#20413),
and tested the GMS during parity data taking (run
#20241). Analysis is forthcoming.
- 120 Hz runs taken during
- Coil modulation runs taken during
- G0Integrity results recorded during the
- Convergence of beam parameter asymmetries checked
Plans
- The bulk of the week should be devoted to LH2 production
running.
- We will stop at roughly 9:00 AM every day for 1/2 hour to
perform Chow's
fOps test plan until further notice.
- The next polarization sequence (Moller measurement, followed by
IHWP reversal (to OUT), followed by another Moller measurement,
and then a RIP scan) will take place, on Saturday March 6th.
- We would like to do one energy modulation (in addition to
coil modulation) run per day. Permission has been
obtained from the Hall B Run Coordinator, but the shift
leader should inform the Hall B shift crew before begining the
modulation. (We don't think that they will be able to see
anything.)
- We may do some test to characterize the BPM misbehaviors
we're been chasing. A tentative
plan for a study is available, but nothing is scheduled
pending more input from experts and other interested parties.
Concerns and Their Resolution
- Three tests of coil modulation with the halo target in have
been carried out in preparation for "auto-coil-modulation" at
the beginning of each run. The earlier ones showed large
increases of halo rate during the scan which indicates that the
beam is either not centered or has a large halo, but on the most
recent one, the increase was limited to a factor of ~2. For now we will
continue doing coil modulation with the halo target out. Given
the large difference in halo rates between when the 6 mm hole
target is IN and when it is OUT, we can conclude that there is
a beam halo. Further more, it is larger than it was in early
February by a factor of 2 or 3 (see Log
Book Link and Log
Book Link). We noticed a marked improvement in the halo
rates when the beam focus was changed during the quad scan
carried out today. All of this suggests that we are actually
seeing halo and that it should be possible to improve it,
though by the rough calibration, we are well below our spec. We
need to be absolutely sure that 1) the halo is not affecting
our data and 2) the halo target is not affecting our data.
- We seem to be seeing more DAQ failures of late (see Log
Book Link, Log
Book Link, and Log
Book Link for example): something like once per shift. The
procedure for getting things going again usually involves
reloading all of the various ROCs and processes, a procedure
that can require 15-20 min (perhaps longer for inexperienced
shift leaders). Is this still a rate related issue (though our
rates are not so high now)? Is there any way to diagnose these
crashes and work toward eliminating them?
- Spikes in the French timing spectra appear from time to
time. Louis is here and will be investigating (Log
Book Link). The spikes seem to have grown scarcer of late,
but no explanation yet.
- More North American electronics errors have occurred (Log
Book Link). One of the offending LTDs was replaced. It had
a lose connector, possibly due to the currently practiced
method of eliminating errors (cable wiggling). The error rate
seems to be somewhat improved now.
- The issue of variation of BPM response with current has
been investigated by looking at the replay and the EPICS
archive (Log
Book Link). Indeed, for the Y coordinate of the girder BPMs
there appears to be a problem when using the 20 uA pulsed
beam. We need to find a way to run the harps at higher current
to find the proper BPM readings when we are doing real data
collection. It is also possible that the BPMs behave
differently with and without the raster. A test of this idea
will await a convenient point in the schedule. Steve WIllimason
has been contacted by Richard Dixon, who had some useful
information. Testes may be forthcoming.
- A couple of runs (20246
and 20291)
showed a large reduction in rates on both French and North
American detectors. Paul traced this problem to a brief shift
in the Musson box timing shift by about 0.5 ns. It is not clear
what caused the change in timing. There has been a slow trend
toward lower elastic proton rates also seen on both detector
packages, perhaps this can be explained by Musson box shifs at
a low level. The data that we have acquired so far should be
checked to determine how often Musson box shifts happen. We
also need a way to determine in real time that there has been a
shift (Realtime monitor plot? EPICS alarm on the control
voltage? StripTool plot of the control voltage?)
- A study of the effects of the 70-sec trip delay on
asymmetries (Log
Book Link) indicates that we should be able to shorten this
delay to something like 20 sec (500 mps). More checking needs
to be done. This would be good for us (more data) and good for
our relations with MCC.
- We should spend some time during the 4-day maintenance
period to try to find a way to turn the magnet power supply off
at full power without causing a fast dump and without
compromising our quench protection.
- IOCSE20 seems to be needing more trips. A older, slower
(but hopefully more robust) replacement is available. Time to
install ~2 hours. No guarantee of that it will help. We
probably want to have it put in during the maintenance period,
but don;t want to use beam time unless the problem becomes
worse.
Accumulated Data for the RC's Weekly report
Reportable week Owl shift of Tuesday, March 2nd through Swing shift
of Monday, March 8th.
ABU:
|
Owl |
Day |
Swing |
Daily Total |
| Tuesday |
5.15 |
3.47 |
6.13 |
14.75 |
| Wednesday |
5.99 |
|
|
|
| Thursday |
|
|
|
|
| Friday |
|
|
|
|
| Saturday |
|
|
|
|
| Sunday |
|
|
|
|
| Monday |
|
|
|
|
Total: 20.74
Non-trivial BANUs: (with causes)
|
Owl |
Day |
Swing |
Daily Total |
| Tuesday |
|
|
|
|
| Wednesday |
|
|
|
|
| Thursday |
|
|
|
|
| Friday |
|
|
|
|
| Saturday |
|
|
|
|
| Sunday |
|
|
|
|
| Monday |
|
|
|
|
Total: 0.0
Raw data: List of shift summaries