Minutes of HERA Meeting
11.06.2002
HERA
- Maintenance of several machine components was done during the access
Tuesday and Wednesday. The NEG pumps were activated in the south IR and
regenerated in the north. There was no ground fault anymore.
- Beam operation started again Wednesday at 22:00hrs. The vacuum system
was baked-out with beam until Friday morning.
- Three shifts were spent on background optimization for ZEUS.
- The proton machine was restarted on Sunday, took about one shifts.
- Sunday to Monday night collisions were set up with 10 bunches.
- During the machine studies yesterday the aperture of the proton beam at
injection energy was improved, scraper studies (positron beam) were done
at injection energy.
- The new calibration of the electron machine beam position monitors is
now available.
- Stable proton beam was delivered to the experiments last night. Collimator
positions were not optimized.
- The vacuum pressure has improved considerably (mainly in the south IR).
At currents above 20mA there is an increase of the pressure. This
threshold like behavior is not understood.
- It is still not possible to drive in the polarization tunes.
ZEUS
- Background studies were performed with three positron fills starting at
2, 8 and 12mA. Although the background conditions were considerably
better than end of May, due to the improvement of the vacuum pressure
in the south IR, they are similar to the conditions before the venting
of the IR. The slope chamber current as a function of positron beam
current is still more of a factor of 5 too high. Beam orbit movements
and optimization of collimators did not results in any significant
improvement. Distinguishing between beam gas and synchrotron radiation
background is somewhat difficult. The data are still be analyzed.
- Requests: one long positron fill at full energy and a short fill at
injection energy in order to distinguish between beam gas and synchrotron
radiation background.
H1
- The detector was not turned on during the ZEUS background studies.
On Sunday the luminosity monitor didn't see any collisions. The timing
was off. Proton data were taken last night.
- Would like to go to collisions next.
HERMES
- The detector was not turned on during the ZEUS background studies.
The beam abort alarm is disabled during injection. Background spikes
were observed when the positron beam was dumped.
- Would like to have 4 to 5 shifts of data taking starting next week.
HERA B
- The stable proton beam last night was used to get the DAQ system running,
to check the synchronization, for global alignment, studies of the
pre-trigger efficiency and SLT behavior.
Schedule
- This week set up collisions with small currents (20 colliding bunches).
Repeat this about 20 times in order to establish the procedures.
- Friday 12GeV positron fill with luminosity optics and orbit.
- Monday machine studies.
- Next week collide beams with increasing intensities.
- ZEUS is the coordinating experiments.
Uwe Schneekloth