Minutes of HERA Meeting 31.05.2005
HERA
F.Willeke summarized HERA operation of last week
- HERA restarted after recovering from the vacuum repair NR.
Luminosity operation started again on Thursday. It took some
time to re-establish routine operation.
- The specific luminosity is indeed lower with the present mirror
tunes. The maximum was 1.73 10^30 cm-2 s-1 mA-2. The average was
20-25% than before. Luminosity optimization is not yet completely
done.
- The vacuum NR is improving.
- The current was limited to about 30mA. High temperatures are observed
NR14/SR14. Additional cooling is being prepared.
- The emphasis was (and still is) to get back to efficient luminosity
operation. Trying to improve the specific luminosity. It is
not yet clear what will be maximum. It does not make sense to start
polarization tuning before the luminosity is understood and
optimized. Another week of studies is needed.
The proposal was to do 3 days of machine studies: decouple machine
(requires H1 and ZEUS magnets to be off), optics checks and
optimization.
H1
N.Gogitidze summarized the H1 status (transparencies 1,
2)
- The normalized fast track trigger rate is 2.5 - 3 higher than before
the leak. It is now similar to the situation in February. The
average HV efficiency is less than 40%. Chamber trips occurred due to
background spikes.
- The specific luminosity is significantly lower than before.
ZEUS
- Background conditions are usually good in the beginning, below the
parameterization. They deteriorate towards the end of a fill.
F.Willeke remarked that the proton emittance growth is quit
large, a factor of 2 higher than before.
HERMES
- On the weekend HERMES suffered from the high temperature of the
cooling water due to the ambient conditions. It should be checked whether
the cooling can be improved.
- The cooling of the lambda wheels cannot be repaired next week.
Schedule
- Start 3 days machine studies today.
First results will be discussed Friday at 15:00hrs.
In the HERA meeting 14.06. the situation (in particular specific luminosity)
will be discussed
and decided whether HERA will continue operation with mirror tunes
or go back to the old tunes
- The next maintenance day will be Wednesday 8.06.2005. The GO/GG
magnets north and south will be warmed up, NEG pumps regenerated.
- Depending of the vacuum conditions, HERA will go to 150 bunches
after the maintenance day.
HERMES is the coordinating experiment.
Uwe Schneekloth