Minutes of HERA Meeting      02.09.2003

HERA

• Positron beam bake-out at 12 GeV continued last week with currents of 30 to 40mA.
• There were no major technical problems. Transmitter trips occurred at Ie > 40mA. The transmitter vacuum NR is relatively poor. Cavity windows WR are too hot, will be repaired during the access on Thursday.
• Proton beam was not stored during the bake-out. The quench protection system was not working on the weekend (was repaired yesterday). The ramp files from 820 to 920 GeV had to remade.
• The plan is to inject small proton current (few mA) this afternoon to made sure that the proton machine is operational and to re-optimize the ramp file. Parasitic proton machine studies will be performed during the positron beam bake-out.
• One of the broken RF transmitters in the south hall will be reinstalled soon.

H1

• During the bake-out the beam pipe maximum temperature has been around 75deg C at some sensors. This should be the maximum temperature. The beam was dumped twice yesterday due to temperature alarms. A faulty sensor was disconnected from the beam abort system.
• The detector will be opened during the access. It will be closed around 18:00hrs.

HERMES

• The background conditions are reasonable, much better than about 10 days ago. There were only a few triggers of the beam loss monitors. High temperature observed last week improved after orbit corrections.
• Some maintenance work will be performed during the access.

ZEUS

• A significant increase of the radiation monitor rate SR 60cm was observed recently. The beam orbit was optimized.
• Friday afternoon positron injection from PETRA into HERA was not working for about 2 hours due to wrong magnet settings. Many injection attempts were made, producing large background spikes at ZEUS. The dark current of one of the radiation monitors increased. Although there was no serious radiation damage, this is clearly not acceptable. The beam intensity should be reduced to the absolute minimum if injection is not working properly.
• The maintenance work, which can be done during the access Monday 29.09., will be somewhat limited because of the open day. It was there requested to extend this weeks access to Friday morning, set interlock by Friday 10:00hrs.
• The beam tilt was adjusted yesterday for the luminosity spectrometer. One hour of stable positron beam at 12 GeV was requested for checking the lumi photon detector.

Schedule

• This afternoon: ramp small proton current. Continue with bake-out. The proton beam will be kept for machine studies.
• Tomorrow morning: stable positron beam at 12 GeV for one hour.
• Access Thursday 06:00 to Friday 10:00hrs
  GO/GG magnets will be warmed up again, NEG and TSP pumps will be regenerated and activated, same time schedule as last week.
• Continue with bake-out after access.

                Uwe Schneekloth