Minutes of HERA Meeting      29.10.2002

HERA

• Last week HERA was still struggling to get the correct files. The optics is correct now.
• Sunday, a plunger of an electron RF WL got very hot and developed a vacuum leak. Some water got into the vacuum system. The overheating happened due to a lack of cooling. It is not yet clear why. The plunger was exchanged. The transmitter has not yet been turned on. The RF system is presently operating with 7 out of 8 transmitters.
• The correlation of luminosity at H1 and ZEUS was studied. No correlation was observed. The specific luminosity was only 1.15 10*30 cm-2 s-1 mA-2, consistent with the beam parameter. The proton emittance was relatively large.
• Operating at polarization tunes was not successful. At H1 the beam orbit had to be moved horizontally in order to get good beam lifetime.
• There were two stable proton fills for HERA B.

HERA B

• The stable proton fills were used for data taking.

H1

• The background conditions during the stable proton beam (Ip=60mA) Sunday night were very good. (At similar currents in September the background condition had been very poor.) During luminosity operation on Saturday, the background was high. Complete tuning of the synchrotron radiation background was not done.
• The calibration of the luminosity monitor was redone. The values of the specific luminosity since September were scaled up by 15%, which is now close to the expected specific luminosity.

ZEUS

• Background conditions similar to H1.

HERMES

• There are still problems with the HERA timing system. The e pick- up signal shows occasional jump, the proton timing is drifting with respect to the clock system.

Schedule

• Starting tomorrow, HERA will go into luminosity operation, conditions as defined below. Initially, positron currents will be lower.
• There will be no machine studies on Monday.
• There will be a 3 hour access on Monday to prepare for the access on Tuesday (bake-out of pump).
• The access will probably take until Wednesday noon. Interlocks of the experiments should be set Tuesday evening.

• HERMES is the coordinating experiments.

HERA Operation

• Proton current 20mA, positron current 30mA (at injection)
• 180 bunches (equally contributing to HERA-B target rate)
  Positron beam with isolated bunch (213)
• Positron beam dumped between 8 and 10mA
• Stable and reliable machine conditions to allow for maximum efficiency
• HERA-B target operation starts right after closing collimators
• HERMES turns on after luminosity is declared (before tuning of synchrotron radiation backgrounds for H1 and ZEUS drift-chambers)
• HERA coordination is done by all 4 experiments (not simultaneously!)

                Uwe Schneekloth