Minutes of HERA Meeting      19.03.2002

HERA

• HERA is still working on setting up the electron machine. The goal is luminosity optics with polarization tunes.
• Files (magnet and collimator positions) have been established for acceleration. A new collimator file still has to be made for 27.5 GeV.
• The synchrotron radiation background from BI at 90m is much smaller than before due to the collimators at 66 and 15m.
• Background rates are low at 27.5 GeV (injection optics).
• High backgrounds and a reduction of the beam lifetime from a few hours to minutes is observed when the luminosity optics file is loaded at 27.5GeV. Although the beam orbit is quite good, typical rms values of 1.2mm horizontally and 0.9mm vertically, a 0.4mm beam movement can lead to breakdown of the lifetime. This is probably caused by an aperture limitation.
• Yesterday afternoon the positron beam was lost when the ZEUS solenoid tripped. In the future, the beam dump should be activated in case the H1 or ZEUS solenoid trips.
• The Ti sublimation pumps will be activate during the access today.

ZEUS

• The electron beam abort signal was connected and tested on Thursday.
• The solenoid tripped twice (yesterday and last night) and caused a beam loss. The power supply is being checked by MKK.
• The CTD HV will be turned on during the access today.

H1

• The pump for the insulation vacuum of the solenoid will be repaired during the access today. Cooling of the FPS station at 90m will be checked.
• Background conditions are quite good at 27.5 GeV (flat top). The background gets worse when the luminosity optics file is loaded. Dedicated background studies haven't been done.
• The limit of the radiation monitor is 10kHz.
• One shift of stable positron beam (beam synchronized to proton clock) was requested for commissioning and calibration of the lumi monitor.

HERMES

• Background conditions were quite bad last week. About 600 beam dump triggers of the beam loss monitor were recorded. Backgrounds improved since Friday.
• The positron beam is probably not centered properly.

HERA B

• No shifts. Waiting for proton beam.

Schedule

• Study and localize aperture limitation. Will be done at 27.5GeV (flat top).
• Optimize background conditions at H1.
• Close ZEUS calorimeter and optimize background conditions.
• Stable positron beam for luminosity monitors.
• Turn on proton machine.
• Continue according to schedule presented last week.
• The schedule will be re-discussed on Friday 15:00hrs HERA control room.

                Uwe Schneekloth