Minutes of HERA Meeting      26.03.2002

HERA

• The aperture limitation of the positron beam observed last week, which led to break downs of the lifetime at full energy, was improved on Thursday by using a reference orbit of February. The available space in the machine is now about 4mm instead of 0.5mm. The new orbit resulted in a significant improvement of the background conditions. The H1 and ZEUS tracking detectors could be turned on to full HV for the first time.
• Collimator positions are not yet optimized. Some outgassing is still observed for some collimators when moved into the synchrotron radiation fan.
• Closing of the ZEUS calorimeters caused a few beam losses, when the polarity of the power supply was changed, and instable oscillations of the orbit feedback. This was improved by changing the gain of the feedback loop.
• Polarization tunes were achieved Sunday evening.
• The positron beam feedback transmitter tripped at high currents. It is now possible to store higher beam currents.
• The fast cycling procedure of the proton machine magnets is now implemented. Electron machine magnets are cycled at the same time.
• The proton machine was turned on Sunday night. The injection efficiency (70 - 80%) still has to be optimized. Proton beam was accelerated to full energy. Files (magnet settings and orbits) are now being optimized. (Last optimization was done in December.)
• The Ti sublimation pumps were activated several times.

ZEUS

• Thursday night the rear and forward detectors were at full HV with low chamber currents (I_e = 0.2mA).
• Friday all tracking detectors were at full HV
• Saturday night and Sunday morning background conditions were poor.
• Sunday afternoon all tracking detectors were at full HV (I_e=2.5mA). Although the background conditions have improved significantly, further improvements are necessary.

H1

• Thursday afternoon tracking detectors at full HV, low chamber currents
• Saturday evening all tracking detectors at full HV (I_e=3mA), RMUON detector had high background. First analysis of the data shows mainly beam gas interactions, much less off-momentum positrons than in December. Presently, could tolerate beam current of 15mA.

HERMES

• The beam loss monitor rates improved since last week.
• The detector hasn't been turned on.

HERA B

• Still waiting for proton beam.

Schedule

• Establish proton files.
• Start finding collisions on Thursday.
• Optimize background conditions.
• Increase beam currents.
  

• Next access will be Tuesday, 2.04.2002 as scheduled. Beam operation will stop at 6:00hrs.
• NEG pumps will be activated without warming up GO and GG magnets.
  

• H1 is the coordinating experiments.

                Uwe Schneekloth