Minutes of HERA Meeting
09.11.2004
HERA
M.Bieler and B.Holzer summarized the HERA status:
- Electron beam was successfully stored in HERA Tuesday last week. The
transfer beam line was optimized. The transfer efficiency (only
transfer line) was 80%.
Tuesday to Friday there was an access for survey and moving of the
normal conducting
IR magnets to the electron position. Beam was immediately stored
with the new magnet positions. The injection efficiency was 72%
(somewhat higher
than for positron operation). Orbit response measurements were
performed to check the optics at 12GeV. All transmitters were
phased in. Acceleration was not yet possible during the weekend.
The survey of the IR magnets showed that the magnet bridge north
right was misplaced by about 1mm towards ring inside. This
will be corrected today.
In general, switching to electron operation was very successful and
quite fast.
- Sunday evening a ground fault warning appeared in the proton ring. Two
hours later there was a fire alarm in the north left straight
section. No damage was found.
Yesterday morning a serious damage of the proton quadrupole GN NL20
was found. The lower inner coil was burnt. The magnet has to be
replaced. The replacement requires: removing of shielding in the
west area, installation of the HERA tram, opening 4 magnets and
removal of the proton and electron vacuum chambers. The time estimate
is 4 to 5 days. The plan is to restart on Friday or Saturday.
It is not yet understood why the coil was damaged. There was no
temperature alarm. The cooling will be checked.
Schedule
- Preparations for the exchange of the GN magnet NL are in progress.
The hope is to close the vacuum system again tomorrow afternoon.
Leak test on Thursday. Start beam operation again on Saturday.
- The shielding in the north and south halls will be completed this week.
The date depends on the availability of the hall crews.
- During beam operation the solenoids of H1 and ZEUS should be
off until next week.
Uwe Schneekloth