Minutes of HERA Meeting 23.08.2005

HERA

• HERA provided several luminosity runs last week. Injection was quite fast. All procedures are working fine. The only serious problem was the reduced proton lifetime, sometimes as low as 20 hours.
• A machine setting was found yesterday with proton lifetimes of 200hrs. The dynamical and geometrical apertures were improved. Yesterday morning it was discovered that the electron tune was close to the 5th order resonance. Changing the electron tune and re-tuning the protons, the horizontal and vertical tunes were swapped, resulted in a large increase of the proton lifetime.
  There are no indications that the poor lifetime and high background conditions were due to technical problems or the beam beam limit.
  All quadrupole settings were checked.
  The present fill is the third run since yesterday morning with good proton lifetime and background conditions.
• The distance of the proton collimators to the beam is slightly larger than the file values. Fine-tuning of collimator positions will be done. This does not required switching off the HV.
• The beam currents were slightly reduced due to inefficient ejection in PETRA. HERA injection is working fine.
• Polarization tuning will be restarted again.
• The proton beam position monitors were improved. In the past the timing of the external trigger could not be changed due to software problems. This was fixed.
  The situation of the BPMs in the straight sections is still critical. Electronics underneath the shielding in the tunnel is failing. New electronics is being prepared for the shutdown. In addition, the cooling will be improved.
• Conditioning of the superconducting cavities is difficult due to discharges at the input coupler.
• The cavity, which was removed a few weeks ago, is repaired. It is however not cold tested. The present plan is to install it in the shutdown.
• Yesterday 8 new BU coils arrived from St.Petersburg.

ZEUS

• Background conditions were fairly bad until Sunday. The conditions have been stable since Monday morning.
• The specific luminosity is typically 10% lower than at H1 and should be improved.
• Occasionally, the C5 timing histogram shows a 3rd peak, sometimes as large as the proton and electron peaks. This is usually due to out of time protons when the lifetime is poor.
  There are no indications for electrons which are not in the proper RF bucket.

H1

• Background conditions were varying: nice fills on Wednesday and Thursday, acceptable background over the weekend (with reduced beam currents) and good conditions for the last few fills. The HV efficiency was only 80%.

HERMES

• Pretty routine data taking. Spikes in the proton background caused HV trips.
• The TPOL/LPOL measurements are again in agreement. It is not clear why.

Schedule

• Continue luminosity operation.
• The electron helicity will be changed during the next maintenance day.

                Uwe Schneekloth