Minutes of HERA Meeting      07.01.2003

HERA

• The superconducting cavities (west straight section) and the GO and GG magnets at H1 and ZEUS were warmed up Dec.22. In December the pressure in the cavity section was very poor with high positron current in the machine. The cavities and GO/GG magnets were cooled down again last week. The cavity vacuum is now about a factor of 10 lower than in December. The pressure at the north and south IRs is similar to before the warmup.
• The restart of the accelerators was delayed due to several problems (LINAC, RF amplifier tube, cooling system). The proton GR magnet tripped several times due to insufficient cooling. The main cooling system is not working properly at low ambient temperatures (frozen screens). The screens were removed today.
• There was one so called full house quench on Sunday, caused by a short in the electronics of the quench protection system.
• HERA delivered one luminosity fill: Ip = 30mA, Ie = 32mA
• The lumi procedure is unchanged: go to positron luminosity file, close ZEUS calorimeter, proton luminosity file.

ZEUS

• The detector was turned on again without problems. The CTD was not yet turned on, the gas is flushing.

HERMES

• Good data taking last night with good background conditions. A change of the positron timing signal was observed.

HERA B

• Calibration data were taken on Saturday.
• Good data taking last night.
• There was some discussion whether the ZEUS calorimeter movement caused damage of a HERA B wire on 20.12.2002. There was only proton beam in the machine. The calorimeter interlock was enabled by the HERA control room. It is not likely that the wire damage was caused by the calorimeter movement. In the future the calorimeter should however only be moved after the HERA B wires are retracted from the beam.

Note added after the meeting:
On December 20. the proton was lost at 10:43, see green line in archive plot . Opening of the ZEUS calorimeter started at 10:47, see blue line in archive plot. The damage of the HERA B wire was obviously not caused by the ZEUS calorimeter movement.

H1

• There were some initial problems with the luminosity measurement and radiation monitor. Otherwise the detector is in good state. The radiation monitor rate was low at high (38mA) positron current.

Schedule

• Continue luminosity operation: proton current 30mA, try to increase positron current to 40mA.

• HERMES is the coordinating experiments.

                Uwe Schneekloth