hera_minutes_020827.html

B.Holzer summarized the HERA operation of last week, see transparency

The proton optics and BPMs were studied during the machine shifts on Monday. Two wrongly connected proton quadrupole magnets were found, which were causing a 50% beta beat.
During the proton beam energy scan a sudden increase of the vacuum pressure was observed when the beam was accelerated from 677 to 920GeV. A similar pressure occurred on Sunday, see transparency,transparency. Both times the proton current was above 60mA.
HERA tried to inject high positron currents on Wednesday. The longitudinal feedback was optimized. The maximum current was 38mA at 12GeV. During injection 10% of the beam was usually lost (first 100 turns). The main losses occurred near ZEUS.
There were several attempts to deliver luminosity. The positron beam was usually lost or dumped because of high background in the experiments. Saturday afternoon the schedule was changed to 2 shifts of stable proton running, followed by improving of positron injection and 2 shifts of stable positron running. Sunday evening HERA continued with the stable proton beam, since the positron injection problem could not be solved.
Yesterday, positron injection was studied instead of the scheduled machine development.

The positron beam background was very high during the weekend. A dose of 10krad was accumulated (60krad is the maximum yearly dose). The positron beam was dumped 4 times by the radiation alarm.

Last weekend the background was very high. The radiation monitor started to oscillate, which was probably due to radiation damage of the driver chip.

Had one data taking fill last week.
The electronics and part of the detector had to be turned off a few times. The temperature of HERA cooling water input was above 35deg C due to the high ambient temperature and humidity.

Stable proton beam was only available since Saturday afternoon. HERA B took lots of data during the weekend for commissioning of the detector and trigger.

Uwe Schneekloth