Minutes of HERA Meeting
14.12.2004
HERA
F.Willeke summarized HERA operation of last week.
- The vacuum leak NR was found during the maintenance day last Wednesday.
It turned out to be a broken feed-through of the NEG pump. The repair
was rather complicated (required to open and close the vacuum system
several times).
Another leak in the north (NL11) was found and repaired by rewelding
the vacuum chamber. The vacuum is improving slowly.
A leak test will be performed NL tomorrow to check whether the leak
was fixed.
- Machine operation resumed on Friday and Saturday. The plan was beam
bake-out and polarization studies. There was not much progress on the
weekend due to several problems.
The beam was lost several times due to problems with the orbit
stabilizer. The available beam aperture SL200 is limited to 30mm
instead of 60mm. Pressures of up to 10**-5 mbar were observed when the
aperture limit was reached. This morning valves in the east closed,
caused by a electrical short due to water.
A new set of machine files was prepare with different electron
energies. Polarization increased to 20%.
The maximum electron current was 15mA.
ZEUS
- Background conditions were high yesterday around noon. The beam abort
signal was sent late.
H1
- The beam was dumped yesterday due to a fake temperature alarm. The
temperature sensor was disconnected.
- H1 will extend the Christmas break. Shifts will resume 3.01.2005.
The luminosity monitor should be available before.
HERMES
- The detector was switched on during the fill before the maintenance day.
Data was successfully taken.
- The target dissociator glass tube was not broken.
- The LPOL calorimeter has not yet been installed.
- Beam tuning is needed to reduce the background in the TRD.
Schedule
Schedule until 5.01.2005
- NEG pumps will be activated (regenerated) tomorrow in the north (south).
- Luminosity operation will resume in the night shift 15.-16.12.
(setup with 10 bunches, continue with 60 bunches).
- The machine shifts are reduced to one day before the break.
- NEG pumps will be regenerated 23.12. if necessary, to be decided in the
next HERA meeting.
- The present plan is to have only a short break (probably until noon)
during the Jan.5 maintenance day.
ZEUS is the coordinating experiment.
Uwe Schneekloth