Log entry time 00:51:12 on February 25, 2004

Entry number 77723

• Data taking on LH2 target with 40 uA with 6 mm hole target and beam positioning study.
  
• IHWP is now Out (since this Saturday morning)
• LH2 target parity quality
• 12.2 hours for this period (runs 20143-20165)
• Overall efficiency: 50.8% (12.2/24)
  
• Beam (no trip) efficiency: 87% (12.2/14.3)
  
• Parity efficiency: 100% (12.2/12.2)
• Total parity hours: 120.4 (runs 19815-20165)
• Overall IN/OUT charge ratio: 0.777
  

• Production running during the swing and owl shifts at 40 uA and running with 6 mm halo target
• At the expense of nearly 12 hr of data collection, some progress was made in the understanding how our beam is positioned (Log Book Link).
• New nominal beam positions established (Log Book Link).
• New halo positions were determined (Log Book Link).
• 120 Hz data taken during Swing Shift and Owl Shift.
• Coil modulation data taken during the Swing Shift and Owl Shift.
  
• G0Integrity results recorded during the Owl Shift (see Log Book Link and  Log Book Link).
  
• Integrated helicity correlated differences were checked during the Owl Shift.
  

• The beam positioning study, begun after the 9:00 AM beam studies, will continue until "closure is reached".  This involves the completion of the halo target centering study and reestablishment of production running conditions.  The remainder of the Swing (Tuesday) and Owl (Wednesday) 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).
• 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 Moller run, followed by IHWP reversal (to IN), followed by another Moller measurement, and then a RIP scan will take up about 1/2 of the day shift on Wednesday.
  
• The remainder of the Wednesday day shift will be devoted to completion of a BCM calibration. Following that, a BCM calibration will be performed with the "frame target" (requested by Silviu and Jianglai). For that:
  
• Need target expert around
  
• Need to change administrative limit on beam current
• Al frame target at 20 uA
• If there's any time left, in the day shift, we will return to production LH2 running -- which will continue for the remainder of this run coordinators stint without further interruption (Lord willing).
  

• Kaz has e-mailed Matt Poelker to find out what can be done to reduce the voltage difference.  Matt does not seem to worried at the moment, but the trend of the voltage difference should be watched.
  

• Laser phase noise problem has also been noticed by MCC (see accelerator log book entry).  Joe mentioned that there might be a way to improve this.  We need to follow up on this offer of help by sending a plot of what we have been seeing.

• The increased non-statistical widths of the elastic proton asymmetries that we have seen lately are apparently caused by a bad V/F clock (Log Book Link).  Alteration of the analysis code to use a different one seems to fix the problem (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 still appear from time to time.  We now have a new option in g0realtime that allows the shift crew to watch selected time spectra (Log Book Link).  If spikes appear, they can be cleared by stopping the run and restarting a new one.  This is not a permanent fix, just a diagnostic.  There also seems to be a correlation between the appearance of alerts and spikes (at least sometimes).

•  The North American electronics has been errors again.  More plugging and wiggling fixed the problem for now (Log Book Link).  It would be nice to find a more permanent fix for this anoying problem.

• As documented in Greg's log entry and associated followup's a large block of time was devoted to re-centering the beam, under the assumption that we now understand why the beam was moving around (so we won't have to recenter again).  The job which should have taken about four hours expanded to more like 12 hours due to a serious mistake in the reporting of harp positions (X sign was opposite to the lab convention for BPMs).  But we now have a new (and final) set of nominal BPM positions and a new halo target position.  Note that we did NOT re-center the LH2 target.  We assumed that the original centering and beam positioning at the start of the run was correct.  We merely tried to reproduce that original beam position.  There remain a few problems associated with beam positioning:
  • Our 4 harps certainly do not report positions that lie on a line, though if you look at the survey numbers they should.
  • I suspect that the last harp, G0A, may have moved in X since the beginning of the run by ~.2mm.  This conclusion comes from its consistently different behavior relative to the other harps and compared to its behaviour at the beginning of the run.
  • It seems more difficult for the operators to position our beam on the new BPM positions with 40 uA CW beam compared to the 20 uA pulsed beam that was used during the beam studies today.  I wonder if this might be due to a current dependent response of one or more of the BPMs.

• We have spent (wasted) quite a bit of time on the beam position problem.  I'm not exactly sure how this time should be reported to the lab.  My first instinct is to call it "Beam Not Available". Tomorrow, we will spend almost a shift doing a combination of Moller running, RIP scans, and BCM calibrations.  That of course is "Beam In Use", but not "Parity Quality Data Taking"  I am concerned about mainting our efficiency.
  

Monday Swing and ABUs
Tuesday Owl and  ABUs
Tuesday Day and ABUs