Minutes of HERA Meeting
07.10.2003
HERA
M.Bieler summarized HERA operation of last week.
- The vacuum in the south IP is improving after the beam bake-out over
the weekend. GO and GG were warmed up yesterday. The released gas load
was relatively small. NEG pumps were regenerated.
- A lot of time was spent on the BU magnet ground fault NL. A water leak
inside the coil was found. The magnet was operated at 4000A over the
weekend in order to heat and dry the coil. The short was still present
this morning. It is unlikely that the water leak is causing the ground
fault.
The machine group wants to continue operation with the defective magnet.
The magnet grounding was already changed on Thursday. First tests show
that it is working. There is however some risk in case of another short.
The plan is to exchange the defective coil sometime next year when spares
are available.
- A leak in the cavity section OR occurred on the weekend. The mass spectrum
showed a clear water peak (at 10**-5 mbar). Yesterday morning the vacuum
group tried to find the leak. Since this turned out to be too time
consuming (heating the water pipe to remove the water), it was decided to
exchange 4 plungers. The pressure is now better than before the exchange.
A final leak test is in progress. The cavities will be conditioned for
24 hours.
- A hot spot (10 microSv/h) was found in the electron machine at OR33. One
of the correction coils had to be powered at the maximum current.
The position of two quads which were moved during the access 29.09. was
changed again. There was a sign error.
- Last night proton beam was accelerated to 300 GeV without problems.
- Positron orbit studies, which should lead to an understanding of what
caused the leak at absorber 4 SR11, were not yet done.
ZEUS
- The ZEUS solenoid is still off. Sensors cannot be read out properly.
A spare piece arrived today. Unfortunately, it was a wrong delivery.
Ansaldo, who built the magnet and control system, is involved. It
will take at least a few days until the magnet is up again.
H1
- The solenoid should not be ramped down. At present there is no spare motor
for the He pump. A defective motor is being repaired and should be back
next week.
- The beam loss monitors of the VFPS cannot be read out. They will be
checked today. A 4 hour access is needed for the FPS. This
should be possible tonight or during the next maintenance day in November.
Polarimeters
- The laser of the longitudinal polarimeter is defective. It was removed
and is being repaired. It should be back in 2 weeks.
Schedule
- Condition cavities OR until tomorrow morning.
- Test of BU grounding scheme.
- Inject positron beam. Prepare new orbit files after magnet adjustment OR.
- Setup luminosity with small beam currents.
HERMES is the coordinating experiment.
Uwe Schneekloth