Log entry time 22:44:34 on February 21, 2004

Entry number 77348

• Data taking on LH2 target with 40 uA with 6 mm hole target
  
• IHWP is now Out (since this morning)
• LH2 target parity quality
• 8.7 hours for this period (runs 20056-20081)
• Overall efficiency: 36.3% (8.7/24)
  
• Beam (no trip) efficiency: 85% (9.5/11.2)
  
• Parity efficiency: 86% (8.7/9.5)
• Total parity hours: 79.4 (runs 19815-20081)

• Moller polarization measurements (Log Book Link)
  
• Beam at 40 uA and running with 6 mm halo target
• RIP scan completed (Log Book Link).
  
• 120 Hz data taken during Swing Shift and Owl Shift.
• G0Integrity results recorded by the workers during Swing Shift, Owl Shift, and  Day Shift.
  

• We expect to perform essentially 100% production LH2 running Saturday and Sunday.
• Because we have taken about two times as much IHWP IN data as OUT data, we will not change the IHWP state for four days (next change on Wednesday).
  
• The next BCM calibration will also 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.
• A meeting is planned for Monday afternoon to discuss the current state of the beam positioning and steering and strategies for ensuring that the beam is correctly positioned and oriented at the target.
  

• The PITA voltages for positive and negative helicity have been gradually diverging (see for example this Log Book Link).  The effect of this will be, eventually, to introduce some linear polarization into the laser light, which will generate helicity correlated position differences due to the analyzing power of the crystal.  Beam position asymmetries seem OK for the moment so this is not a terribly pressing problem.  We (Kaz) need to check with Matt Poelker to find out what can be done to reduce the PITA voltage difference.

• We have seen rather large charge asymmetry widths from time to time.  These seem to correlate with laser phase noise (Log Book Link).  This has caused some warnings in the G0Integrety checks.  Our spec is that the width be <2000 ppm so for the moment we have to live with the 1000 to 1500 ppm widths that we are seeing.

• We have also been seeing increased non-statistical widths of the elastic proton asymmetries lately.  The cause of this is not clear.  Presumably this could come from some noise in our electronics (for example oscillations in the gain).  The analyis team is also investigating the possibility that the problem is software related.

• There has been a slow trend toward lower elastic proton rates.  The adjustment of the high voltage may have improved the situation, but some analysis detective work needs to be done to be sure it is gone or to verify that the trend is continuing.
  

• Spikes in the French timing spectra (Log Entry Link and followup) continue to be detected by the G0Integrety checks.  Probably the French data is unusable once a spike appears.  This problem is insideous because we can not detect it while running (only after analysis).  When a run is re-started, the problem is cleared.  The source of the problem is not known but has the markings of an electronics failure.  The "remote" French electronics experts are being consulted via e-mail.
  

• Alerts also appear from time to time -- sometimes rather spectacularly in the real-time analysis.  Is this going to be a problem or can it be ignored? The "remote" French electronics experts are being consulted via e-mail.

• A review of past harp scans and a comparison to near-by BPMs seems to indicate that we do NOT have a problem with harp alignment changes because the difference between harp and BPM has remained consistent over the run.  Furthermore, the four harps which are before our target, while not lying on a line, still seem to systematically deviate from linearity in the same direction and by the same amount.  The harps were surveyed (externally) to < 0.1 mm, but the deviations from linearity are typically 0.25 to .5 mm.  This suggests either faulty internal alignment, or some kind of read-out offset problem.  Hopefully consultation with experts will clear this up.  Looking at the harp scans, it is hard to imagine that one could accurately define the orientation and location of the beam at the target with only the G0 girder harps -- their deviation from linearity is just too big.

• There was a concern that, even with the halo target out, the halo detectors were seeing an increase in rate during coil modulation (which would indicate really bad beam) (Log Book Link).  This was not reproduced when the next coil modulation run was done (Log Book Link).  Possibly MCC had not removed the halo target when the original problem was seen.  We need to check the GUI to be sure the halo target is out before doing a coil modulation run.

• We have now accumulated 7.592 Coul of IHWP IN data and 3.818 Coul of OUT data, almost 2 times as much IN data as OUT data.  We will therefore stay at the current (OUT) position for the next 4 days to attempt to balance this ratio.
  

Friday Swing and ABUs
Saturday Owl and  ABUs
Saturday Day and ABUs