Minutes of HERA Meeting
04.02.2003
HERA
B.Holzer summarized HERA operation of last week, see transparency.
- HERA delivered luminosity fills for most of last week with currents
of 13-19mA (proton beam) and 18-33mA (positron beam) as decided in the
last meeting. Increasing the positron current to 35mA was not successful.
The beam was aborted because of high background rates.
Yesterday the positron orbit had to be improved. There was a 5 to 6mm
orbit offset in the north IP. The hope is to go to higher current with
the improved orbit.
- There were a few technical problem: phasing of electron RF stations and
feedback, klystron WR and a polarity switch. A ground fault occurred on
Saturday. It could not be located. Will be checked during the access
this week.
H1
- The background conditions improved significantly after the back-out,
see chamber currents. The is not clear whether the
improvement was due to the beam bake-out. Background conditions should
be acceptable at a proton current of 30mA.
ZEUS
- The background conditions (C5 proton gated rate) and vacuum in
particular SR3, 6 and 8m improved last week. There is no indication
for a significant improvement of the vacuum at the IP. The lower
current proton fills were used to do HV studies of the CTD.
- The luminosity measured by the spectrometer is similar to the luminosity
measured by H1. The photon calorimeter measures a lower values. The
discrepancy is still being studied.
- One of the FCAL modules is defective. It will be repaired during the
access on Thursday.
HERMES
- HERMES took a lot of data last week, mostly with unpolarized
target. The polarized target had problems since Wednesday. The
atomic beam source was repaired yesterday during the access.
At the beginning of some fills the background was relatively high.
It was improved on Sunday and Monday. Background conditions should
be better after improving the positron orbit.
- The total data sample is 700k polarized DIS events, 500k
unpolarized DIS.
HERA B
- Good data taking last week. Large background spike were observed
a few times per shift with interaction rates of up 1 GHz. The HERA
crew is trying to find the source of the background spikes.
Schedule
- Continue luminosity operation: Ip=30mA, Ie=30mA try to increase Ie.
The positron beam should be dumped at 10mA.
- Thursday access: warmup GO/GG magnets, regenerate NEG pumps, increase
water flow of GI magnets (S/NR), replace HERA B target wire.
- Thursday night: positron machine studies. Check new optics.
- Friday morning: access, final leak check HERA B.
- Friday afternoon: stable high current (30mA) positron beam, heat TSPs
S/NL.
- Friday evening: continue luminosity operation.
- Polarization studies are scheduled for the last week of operation
before the shutdown.
- HERMES is the coordinating experiments.
Uwe Schneekloth