Minutes of HERA/Experiment Coordination Meeting  05.10.2004

Agenda

• Brief summary of shutdown activities
• Schedule and operation
  • re-commissioning
  • start-up with electrons
  • machine studies
  • luminosity operation
  • operation over Christmas and new year holidays
  • date of maintenance days

• Date of next meeting
• AoB

Minutes:

F.Willeke: HERA Status

• Most of the shutdown activities, including the exchange of BU coils NL, is finished. There is a 3 day delay of the schedule. This will be recovered by an early recommissioning of the electron beam transfer line and startup of the proton machine on weekend.
• The modified GM vacuum chamber is not yet installed NL. The NEG pump had to be replaced. It will be activated this morning.
• The reason for the vacuum leaks in the rotator sections is understood. The corresponding flanges were stiffened by additional welding seams.
• A detailed schedule was presented (see transparencies). The main points are:
  • interlock tests until 14.10.2004
  • startup injection beam line: 14. - 18.10.2004
  • power supply tests: 14. - 22.10.2004
  • Startup with protons: 22.10.2004
  • Startup with positrons: 29.10.2004
  • Move and survey IR magnets: 3. - 5.11.2004
  • Start electron injection and studies: 5.11.2004
  • Start luminosity setup and tests: 20.11.2004
  • Luminosity operation: 27.11. - 20.12.2004
  • Maintenance day: 8.12.2004
  • Accelerator studies: 20.12. - 23.12.2004
  • Christmas break: 23.12. - 27.12.2004
  • Startup operation: 27.12.2004
  • Start lumi operation: 29.12.2004
• The electron orbit and magnet positions will be as in the original upgrade design. The alternative solution will not be used. Beam on-axis in the GI and GJ magnets on the right side of the IR would reduce the total synchrotron radiation power by about 10%. The disadvantage is an increase of the horizontal synchrotron radiation fan, which is more likely to hit the C5 collimators. Another option is to change the electron orbit, without changing the magnet positions with respect to the upgrade design.
• Different electron tunes will be studied. Using mirror tunes should increase the specific luminosity according to previous studies.
• There are a number of operational improvements:
  • The GI vacuum chambers NR/SR7 were equipped with temperature sensors to avoid any further damage. Tests will be performed with low positron currents.
  • New optical match from the electron beam line into HERA and new BPMs.
  • New tables for non-linear ramp of GI magnets
  • New BPM data acquisition system
  • Decoupling of optic transfer and saturation effects.
  • A 70Hz electron RF frequency shift for 10% emittance reduction.
  • Systematic horizontal IP bump.
• Presently, there are no plans for dedicated electron beam scrubbing. It will be scheduled after the machine studies end of November if necessary.
• For the time being all HERA halls will remain controlled areas.

D.Pitzl: H1 Status

• The total delivered luminosity in 2003/2004 was 99pb-1 (91pb-1 in 2004) including offline corrections. 58pb-1 were written to tape with full chamber HV. The HV efficiency was significantly lower than in 2000, 69% instead of 85%.
• The damage of the FST was due to a leak in the water cooling. A crimp connection of a plastic water tube failed after 3 years of operation. The leak caused serious corrosion of hybrids. The FST will be rebuilt using more radiation hards readout electronics.
• The BST has blocked cooling pipes. It will be repaired in Zeuthen. The plan is to reinstall the complete vertex detector next summer.
• A new background monitor, one scintillator plane with PMT readout, will be installed instead of the BST pad radiation monitor.
• The central Si tracker (short between receiver diode and PCB) and central inner tracker were repaired.
• New FPS Roman pot stations were installed at NL 61, 80/81 and 90m. Vacuum tests are finished. Lead shielding needs to be installed.
• The VFPS was successfully commissioned in the running period. A 5.8mm proton orbit displacement was tested to improve the acceptance. Optical readout cables were moved under the tunnel concrete floor for radiation protection.
• All shutdown activities are completed. The detector was closed 30.09.2004. Cosmics will be taken 4.-13.10.2004. Shifts for the test lumi runs will start 20.11.2004.
• The background conditions are expected to be difficult due to the long venting period and the new GI NR7 vacuum chamber. H1 will not be limiting the HERA currents provided there is no danger of radiation damage.
• Left-handed electron beam is preferred.
• H1 will be operated over New Year if some meaningful data taking can be expected.

W.Zeuner: ZEUS Status

• The main shutdown activities were: repair/maintenance of electronics (calorimeter, HES, muon chambers, Si-diodes of radiation monitor, Si-MVD and luminosity photon detector), improvements of calorimeter and BAC trigger, improved shielding of lumi spectrometer, new control system for the solenoid feedbox, exchange of 2 under-carriages of the iron yoke and hardware changes of the CDAQ system. All work was successfully completed.
• The detector was closed. The interlock is set. Chambers are being flushed with gas. The central DAQ system is being setup. Cool down of the solenoid will start tomorrow. Cosmics running will start next week.
• The remaining problems are breakdowns of the insulation vacuum of the solenoid when the straw tube tracker electronics is turned on and small water leaks of the HES. The breakdown of the insulation vacuum was the reason for the occasional ramp downs of the solenoid during the last running period. The STT cooling is not sufficient to remove the heat dissipated close to the cryostat. Thermal stress leads to a small leak of the cryostat flange when the STT electronics is switched on or off. For the time being, the STT will not be turned on. Other solutions are currently under investigation.

P.Di Nezza: HERMES Status

• The maintenance work has been completed: lumi detector crystals, cooling and electronics of Lambda-wheels changed, DVC support improved, work on LPOL, survey of FCs and BCs and work on the target. The target commissioning has started and will take 10 days. The shutdown activities are on schedule.
• The construction and testing of the recoil detector is in progress. Full assembling and cosmics data taking is planned for beginning of 2005.
• HERMES will run shifts after the short Christmas break if necessary.

S.Schmitt: Polarimeter Status

• The TPOL was operating stably in 2003/2004. The silicon detector and readout have been improved. New calibration was applied to the data presented at ICHEP 2004. The focus correction will be applied online after the shutdown. The TPOL should be well calibrated after the HERA startup.
• The LPOL crystal calorimeter was back in operation for the last weeks of the running period. Spare crystals were ordered. Some improvements were made during the shutdown. Expect reliable LPOL operation after the HERA startup.
• The electronics of the LPOL cavity was repaired and installed in a radiation-save location. The optics was realigned, the cavity locked successfully.

  D.Pitzl: The design of the new quartz fiber/tungsten calorimeter is well advanced. The calorimeter should also provide vertical information, in addition to horizontal position information. This will make the mechanical design more complicated. Construction of the calorimeter should be relatively fast. Installation is planned for early 2005.

HERA B

• The shutdown activities in the west hall, moving part of the HERA B detector out of the beam position, are almost finished. The shielding will be completed this week.

Schedule

• Schedule as presented by F.Willeke (schedule)
  Please note that the maintenance days were changed to Wednesdays after the meeting, i.e. the first maintenance day will be 8.12.2004.
• HERA will start luminosity operation with left handed electrons.
• The weekly HERA meetings will resume Tuesday 26.10.2004 10:00hrs.

Date of next meeting

Uwe Schneekloth