Log entry time 22:47:17 on February 23, 2004

Entry number 77574

• Data taking on LH2 target with 40 uA with 6 mm hole target
  
• IHWP is now Out (since this Saturday morning)
• LH2 target parity quality
• 14.4 hours for this period (runs 20115-20142)
• Overall efficiency: 60% (14.4/24)
  
• Beam (no trip) efficiency: 87% (14.8/16.9)
  
• Parity efficiency: 97% (14.4/14.8)
• Total parity hours: 108.2 (runs 19815-20142)
• Overall IN/OUT charge ratio: 0.950
  

• More good data (at high efficiency) with beam at 40 uA and running with 6 mm halo target
• Moller measurement of beam polarization (-73.16% ± 0.42%) (see also a nice review of the February measurements).
  
• 120 Hz data taken during Swing Shift and Owl Shift.
• Coil modulation data taken during the Swing Shift and Owl Shift.
  
• G0Integrity results recorded by the workers during the Owl Shift and  Day Shift.
  
• Integrated helicity correlated differences were checked during the Owl Shift and Day Shift.
  

• The Swing (Monday) and Owl (Tuesday) shifts will be dedicated to the usual production data taking cycle (coil pulsing twice per 8 hr, 120 Hz once per 8 hr, 1-hour production runs).
• Following the meeting with Arne Freyberger and Matt Brikley (Log Book Link) and some elucidation about the precision of our harp positioning as well as confirmation that bad BPM survey offsets are at the root of our alignment problem, I would like to spend time on Tuesday during the day shift to perform the following steps to define the beam position.
  
• Remove the Halo target.
  
• Position the beam at the 4 harp positions (two at the pivot, two on the girder) as it was positioned just prior to the target centering that took place back in December (Log Book Entry).  This may be an iterative procedure using the BPMs to provide a measure of beam position between harp scans.
• Record the BPM positions when the beam is properly positioned on those old harp positions.  That becomes our new official nominal BPM positions.
• Perform a "clean" halo target scan to determine the halo target centers with this properly centered beam.
Note that we can not assume that the survey offsets (the BPM positions) of the original centering were correctly set.  We also assume in this procedure that the harps have not moved since December.  This should get us back on the line that we were on in December.  We must carefully check the survey offsets (Log Book Link) in the IOCs when ever there is a crash (or any unusual steering problems).  My hope is that this procedure will not take more than about 4 hours.  It should be performed immediately after the 9:00 AM fOps test (see below)

• The next BCM calibration will take place next Wednesday.  At the same time, a BCM calibration will be done with the "frame target" (requested by Silviu and Jianglai).
  
• Need target expert around
  
• Need to change administrative limit on beam current
• Al frame target at 20 uA
• We will stop at roughly 9:00 AM  every day for 1/2 hour to perform Chow's fOps test plan until further notice.

• Nothing has been done about the slowly diverging PITA voltages as yet.  Kaz has e-mailed Matt Poelker to find out what can be done to reduce the voltage difference.  At the same time we have noticed that the IA control voltage is slowly decreasing.  Could these trends be correlated?

• Laser phase noise (Log Book Link) continues to come and go.  The result of this is a wide charge asymmetry which is, for the moment narrower than our spec.

• We have seen increased non-statistical widths of the elastic proton asymmetries lately.  The cause of this is not clear but the effect is seen in both French and North American detectors as well as in the Lumi asymmetries.  Mysteriously the problem seemed to disappear (except in detector 14 where it got larger) at the end of the weekend. No correlation with bad beam or other beam parameters has been discovered.  The analyis team is on the case and very recently, Jianglai may have found a correlation with variation in the V/F clock (Log Book Link).
  

• There has been a slow trend toward lower elastic proton rates also seen on both detector packages.  No good explanation yet.
  

• Spikes in the French timing spectra (Log Entry Link and followup) still appear from time to time.  Jacques has suggested raising the threshold to 75 or 100 mV as a test.  The intermitency of the effect and time required to verify that the problem is present will make this tricky.  We will try to do this test following clarification  of a few points.  In the mean time a list of effected runs has been compiled (by Damon) and forwarded to the French experts to help with the investigation of this problem. Louis Bimbot has noticed some interesting correlations between the spikes and alerts.
  

• The rate of alerts associated has remained at a tolerable level following our realization that the problem can happen when a CAEN channel 16 gets in an overvoltage state.  We are planning to stop using channel 16 on all CAEN boards.  This will require re-cabling to spare channels with new patch cables.  Bill Vulcan has been informed.  Paul King will provide the needed length as well as a map (to Steve Wood) of how the channels will be re-connected so that the High Voltage GUI can be reconfigured.

• The North American electronics has been generating numerous errors (Log Book Link).  The usual fix for this is to "wiggle cables" (Log Book Link) but that seemed not to do much.  Paul attempeted to replace one of the splitter boards in an effort to remove the problem. While that didn't work, when he put the old board back, the problem had disappeared! (Log Book Link)
  

• Beam position continues to be a big concern.  I believe we have a strategy (see above) to re-align the beam and to check for offset changes. It remains to be seen whether our deductions about the causes of our problems are correct.  Your RC's dilema is that just about any plan that would really fix this problem would consume huge amounts of time, but at the same time, we don't want to take bad data because we didn't stop to fix the problem.

• We have been so efficient in collecting data during the last two days that the original plan to catch up on OUT data by skipping an IHWP change now seems like it wasn't such a good idea since we now overbalanced in favor of OUT.  Never-the-less, we will stick with the plan, continuing to take OUT data, to avoid the overhead of two Moller measurements and a RIP scan.

Sunday Swing and ABUs
Monday Owl and  ABUs
Monday Day and ABUs