Minutes of HERA Meeting
23.09.2003
HERA
M.Bieler summarized HERA operation of last week.
- Most of the time was spent on polarization tuning. 35% has been achieved
so far. It is not yet very reproducible.
Two energy scans were made. The highest polarization was obtained at
27.62GeV.
The positron current was about 20mA in order to have stable operation.
- There were no major technical problems.
- Yesterday a fiber optics cable of the HERA e HIT system was damaged in the
west hall. It was temporarily replaced by a cable used for the p HIT system, which caused some timing shift. The fiber optics cable will be repaired
today or tomorrow.
- It would be desirable to inject and ramp proton beam in order to make
sure that there are no problems with the proton machine.
Polarimeters
- Both polarimeters are working properly. There is presently a 7 to 10%
difference between the transverse and longitudinal polarimeters. The
performance is better a higher currents. LPOL is gets less reliable below
10mA.
- 1 to 2 stable fills at high polarization are needed for tuning (beam
position and tilt steering). It is planned to depolarize the beam and
to look at the rise time curve.
H1
- Yesterday and today the background conditions (radmon and SPACAL) were
bad. The rear beam pipe cooling is now turned on.
- The chamber HV will be turned on today for the first time. The isolated
bunch should be moved from 213 to 200.
- The detector will remain closed during the maintenance day next week.
There will be some activities on the VFPS.
ZEUS
- Friday around midnight there was a severe beam loss. The dark current
in the radiation monitor increased by 0.5nA. The beam was dumped by
the GO quench protection system.
- The HV of the tracking detectors has been turned on several times.
- The detector will be opened during the access. Some shielding SR will
be opened.
HERMES
- Background conditions were poor at high currents and very good at low
currents.
- A quadrupole magnet in the east straight section is not at the correct
position. This will be checked and realigned if necessary.
Schedule
- Continue with polarization studies. H1 and ZEUS will be turned on for
background studies. Isolated bunch at 200.
- 1 - 2 stable fills for polarimeter tuning starting tomorrow afternoon.
- HERA needs a short access before the weekend.
- Friday: Low current proton beam during polarization studies.
- Schedule for open day: dump positron beam 28.09. 06:00hrs, no beam operation Saturday to Monday night, tunnel will be closed 29.09. 15:00hrs, interlocks
set 22:00hrs.
- Machine studies Monday to Tuesday night.
- Tuesday start preparing for luminosity operation.
H1 is the coordinating experiment.
Uwe Schneekloth