Minutes of HERA Meeting      15.02.2005

HERA

• HERA operation was very efficient last week. The integrated luminosity was 6.4pb-1, peak luminosity 4.1 10**31 cm-2 s-1 measured by H1 (presently the online value is about 10% too high). The overall efficiency is improving. Last week the efficiency was 66% (42% since December).
• Yesterday morning the number of bunches was increased from 120 to 150 without any problems. The number of colliding bunches is 144.
• Background conditions are critical. Oscillations and occasional large spikes are still present. The source is still unknown.
• Polarization is still disappointing, around 30%. An energy scan and lowest order harmonic bump scans were performed last week.
  Further plans are another energy scan, optimizing higher order harmonics and scan of the vertical rotator magnets.
• Several electron lifetime brake-downs occurred last week, similar to the observations during HERA I operation. Last fill the lifetime was low (5-10h) for several hours. It improved just before the meeting.

ZEUS

• Good data taking. The proton background deteriorated since Thursday causing some CTD HV trips. Two minute frequency background oscillations are clearly visible. Conditions were excellent yesterday afternoon, the first fill with 150 bunches, but got worse after 1 1/2 hours. The background was lower during last nights fill, although the oscillations were still present.
• Congratulations to HERA for the successful switch to 150 bunches.
• The proposal to regenerate NEG pumps in the south IR was discussed. The machine group is somewhat reluctant since there is always a risk of damage (feed-throughs or short to ground of NEG strip).
  Note added after the meeting: NEG pumps will also be regenerated in the south IR.

H1

HERMES

• HERMES is happy with the background conditions. Still waiting for higher electron current and polarization.
• It will be checked whether the glass tube can be exchanged Wednesday or Thursday this week. If the March maintenance day is skipped, HERMES may need a 6 hour access to replace the glass tube.

Schedule

• Consolidate operation with 150 bunches. Increase beam currents. Ie=43mA should be possible. Try to improve background conditions.
• Note added after the meeting: The NEG pumps will be regenerated on Thursday this week. Beam operation will stop, warmup of GO/GG will start between midnight and 03:00hrs depending on the start of the fill. Beam operation will resume after about 24 hours.
• The present plan is to skip the maintenance day scheduled for March 2.

                Uwe Schneekloth