Minutes of the weekly HERA Meeting   14.10.2003

1. HERA last week (M. Bieler):
   • 4 plungers were exchanged in 2 cavities East Right, curing the vacuum leak. Lab inspections found a defect on one of them. The cause is not undrstood yet.
   • The cavity vacuum was conditioned with a new procedure: controlled RF heating with water cooling turned off for 2 days.
   • The cavities are already back to 50% power.
   • The proton dipole is now operated with the ground fault in one of the NL BU magnets.
   • Magnet cycle procedures and ground fault detection system were adjusted.
   • Collisions were established on Sun 10.10.
   • After magnet file adjustements, specific lumi reached 1.5 10³⁰/cm²/s/mA² in ZEUS and H1 at I_e*I_p = 8*40 mA². The proton emittance is enlarged due to an instability during p ramp at 70 GeV.
   • 24% polarization was reached without dedicated tuning.
   • Need tunnel access to install air flow cooling around the 11m flanges.

2. ZEUS (W. Zeuner):
   • Solenoid kryo control repaired last week. Spare components are being obtained from TU Hannover.
   • On Tue 7.10. a power supply burnt in the electronics trailer. Extinguished by Inergen release. The drift chamber readout is affected and expected operational again early next week.
   • CTD HV was operated successfully with beams. Background spikes cause several trips.
   • Repair of a calorimeter power supply requires 4h access.

3. H1 (N. Gogitidze):
   • Drift chambers were ramped to full HV on Mon and Tue with 4*40 and 7.5*48 mA². CJC2 currents were 70 and 110 $gmu.A, which don't extrapolate well to higher beam currents (absolute limit 200$gmu.A). Spikes in the proton background caused several trips.
   • On Fri 10.10. a faulty He pump motor for the solenoid was exchanged, and a spare motor arrived from repair.
   • A faulty beam pipe temperature sensor caused an e beam dump on Sun. This sensor is disabled now, 17 remain along the central H1 beam pipe.
   • The lumi system needs to do a timing scan with stable lumi conditions.
   • To reduce systematic errors from acceptance corrections, the photon beam position should be at 0, 0 with +-1 cm on the lumi calorimeter. In the first 3 fills it was at y = +1.3cm.
   • The Forward Proton spectrometer needs 2h access to the tunnel NL to replace a multi-channel PM.

4. Hermes (J. Stewart):
   • First turn on on Sunday without problems.
   • On Mon the TRD proved sensitive to beam condtions, but could be operated after steering.
   • A problem the atomic beam source mass spectrometer prevents the measurement of target polarization. Requires 2h access.

5. Plans (B. Holzer):
   • Steady lumi running with I_p = 40-50 mA in 120 bunches.
   • Gradually increase I_e as backgrounds an RF allow.
   • Give time for lumi, polarization and background studies, and data taking by experiments.
   • Wed 15.10. few hours access for ZEUS, H1 FPS, Hermes, HERA.