Minutes of HERA Meeting 27.09.2005

HERA

• HERA operation was quite efficient. There were no serious problems. About 1 pb-1/fill was achieved in 2 fills. The proton current, 80 - 100mA in 150 bunches, was increased by improving the performance of the pre-accelerator chain. The electron current was increased in small steps from 28 to 38mA. The injection efficiency is quite high for both beams. New injection files were made.
• Technical problems: High temperatures at a cavity window SR caused several beam dumps. The power of the transmitter was reduced. The cavity window will be replaced in the winter shut-down. This morning there was a break due to defective temperature sensors SR and SEDAC alarms of beam position monitors.
  The power glitch on Sunday morning was observed on all 3 power stations.

• The beam energy and first order harmonic bump scans were done. The 2nd order scan are almost done. 50% polarization was achieved with pilot bunches. This indicates that there is no large polarization asymmetry for different rotator settings. The proton bunch intensities, 600 - 700 muA, are quite high. Polarization of the colliding bunches is reduced by beam beam effects. The electron tunes were reduced until the H1 electron background started to increase.
• An energy fine scan will be done in the next days.

ZEUS

• In general, running conditions were quite good. Proton spikes appeared in recent fills. The last fill was excellent.
• The data taking efficiency was good for the first half of the week. It was rather poor over the weekend due to problems with the CTD readout and calorimeter power supplies. The CTD HV has been stable.
• The calorimeter is presently closed all the time because of problems with the calorimeter breaks. The ZEUS shift crew should be called in case of problems during injection or proton ramping or when the injection procedure is changed.
• The access next week is needed for work on the calorimeter.

H1

• The background conditions are fine. The normalized fast track trigger rate is below the goal. Last week the HV efficiency was 83%, the best value of this running period.
• An delivered integrated luminosity of 200pb-1 is still reachable if the present rate of luminosity production continues.

HERMES

• The running conditions were good. The electron background was very low. The proton background was relatively high, some triggers had to be pre-scaled.
• The lumi studies (beam scans) have not been done. The scans are still pending.
• The maintenance day next week is not needed, although it was planned to exchange the dissociator tube.

Schedule

• Continue luminosity operation. Increase electron current.
• The maintenance day next Wednesday will be as usual, i.e. stop beam operation at 06:00hrs. Access to the tunnel will be possible until 14:00hrs. All interlocks should be set by 22:00hrs.
  The NEG pumps in the north and souths IRs will not be regenerated.

                Uwe Schneekloth