It took some time to recover from the maintenance days. There were several
problems with the proton RF system. The main tube of system B was
exchanged during the access, but not tested with high current.
Both systems are working again.
HERA delivered 4 - 5 luminosity fills, only one long fill. The positron
current was increased to 35 to 40mA without problems. A new
luminosity record was obtained at ZEUS (2.5 10**31 cm-2 s-1).
Last night there were frequent background spikes. The source of the
spikes is not known. Some electron magnet power supplies are being
checked.
One PETRA electron klystron failed due to vacuum problems. Only one
transmitter is presently in operation.
Empirical polarization tuning is still very slow. A more systematic
approach is being studied.
The positron ramp procedure was modified. The luminosity optics file
is now used at the end of the ramp.
ZEUS
Background conditions were very spiky last night. HV could only be
turned on for part of the fill. Otherwise there were no problems.
The electronics board for the calorimeter interlock, which will allow
beam dumps and positron injection with the calorimeter closed, should be
ready next week.
H1
Background conditions were good when HERA started delivering luminosity
last Thursday. H1 suffered from background spikes last night.
The radiation monitor issued a fake alarm. The system is being checked
by experts.
HERMES
Some quadrupole magnets were moved by about 1mm during the access. The
beam position and slope at the IP was retuned.
Previously background conditions were very good. During the last few fills
the background was much worse. Conditions were stable once the background
was re-optimized.
A turbo-pump failed this morning. An access of a few hours may be required
for repair.
Polarimeter
The LPOL cavity is still swamped by large synchrotron radiation
background. A beam scraper scan should be performed at low positron
current. Water cooling was connected to the scrapers during the access.
A special meeting will be held on Friday to discuss the re-activation
of the depolarization kicker.
Schedule
Luminosity operation with increasing positron currents.
HERMES high density runs will start at Ie=15mA.
A beam scraper scan will be performed at low positron current (4mA)
at the end of a fill to
study the LPOL cavity synchrotron radiation background.