Log entry time 11:50:41 on April 14, 2004

Entry number 82175

Run Coordinator's Report for 12 April Swing to 13 April Swing

Summary

Significant News

• Jacques Arvieux and Paul King installed a "newer" DMCH Interface box. Paul checked and made sure it is working in 120Hz mode. The box has still to be tested with beam.
• Jianglai fixed LUMI7 (Log-entry: 82127 ).
• Shifts were cancelled due to unavailability of useful beam in the hall. MCC will perform INJ studies and compatibility studies between the halls over night. Shifts will be resumed as soon as we get beam back. This is likely to be Thursday evening (according to schedule the Physics program resumes Friday OWL shift). If the accelerator needs feedback on beam quality Kaz and the RC will man the shifts and provide MCC with the necessary information.
• If you are on shift the next few days check your email on a regular basis for updates or call the RC cell-phone at 876-1791

Short term Plans

• Restore parity quality beam to the hall (IA/PZT scans, beam position, Halo, ....).
• Moller/IHWP insertion/Moller as soon as we get good beam back, then every three days.
• Test the "newer" DMCH interface box
• Continue with LH2 production running.

Longer term Plans

• Deadtime study at 20, 30, 40 uA (three 1hr runs at Angela's request)
• PMT gain calibration at 1uA (6hrs at Julie's request)
• Deadtime study is planned, but depends on collaboration approval and the smoothness of the recovery from the downtime:
  Another suggestion that was made was to demonstrate that the background asymmetry underneath the elastic peak in the TOF specta is not an artifact of some systematic dead time effect that is not being taken into account through the Wells plot determination of the helicity correlated dead time, which does a good job of correcting for the data inside the elastic TOF cut, but not as well for the inelastic proton TOF cut or the pion TOF cut. The asymmetry of the inelastic protons at larger Q^2 are large and of opposite sign than the elastic asymmetries, and could result in a sizeable correction in extracting the elastic asymmetry. To demonstrate that this is a real physics background and not a consequence of uncorrected dead time, we could take data at 10 uA rather than 40 uA, in which case the dead time would be reduced by a factor of four. To acquire the necessary statistics for a 4 sigma measurement would require 24 beam hours (or two calander days, given a 45% efficiency). Due to the large amount of time required to make such a measurement, I wanted to get feedback from the collaboration, and would still recommend postponing this measurement, should we deem it useful, until after we have surpassed 90% of the statistics we expect to achieve for the entire forward angle mode of the experiment.
• Continue with LH2 production running until Monday when the accelerator shuts down again for the CD-0/DOE tour.
•  We are now on our official 3 day cycle for Moller measurements/IHWP state changes.

Concerns

• Spikes in French electronics
• Non-statistical widths in detectors 13 and 14 of octants 4 and 8.
• NA LTD errors still occurring at a small rate. Brian has generated a "HowTo" document (located on the G0 web page under http://g0web.jlab.org/manual/Electronics_manuals.html) for trouble shooting.