hera_minutes_021112.html

The main activities during the access last Tuesday and Wednesday were related to the vacuum system. The GO/GG magnets were warmed up. NEG and TSP pumps were regenerated again. Operating the beam pipes at room temperature did not work.
In total, there were 5 luminosity fills lasting 30 hours.
On Saturday a damaged current lead of a GB magnet was replaced.
The timing system was unstable and had to be adjusted.
The cooling of the electron cavities is not yet sufficient. Improvements are being prepared.

Background conditions were reasonable last week, somewhat worse on Monday, better again today.
Saturday the photon spot were not centered in the luminosity detector. The C5 background rate was low. The CTD background was not optimized properly.

The CJC chamber current improved slightly yesterday after re-optimizing the upstream collimator positions.
Last night the background was low. There were however spikes in the proton background causing HV trips. The background spikes are being studied by HERA. They are not related to HERA B.

In general good running conditions. The background was high on Sunday. It improved after adjusting the positron orbit.
Only 20000 DIS events were taken last week. At the beginning of a fill the positron current is usually 20mA, which is too low for efficient data taking. The current should be increases to 30mA.

Sunday and Monday data was taken 30% of the time (24 hrs). The were HV trips due to background spikes. The carbon wire is now being used with an interaction rate of 1 MHz. The coasting beam contribution is small, a few %.
The collimator WR33u position should be readjusted. Usually it is closed too tightly.

Luminosity operation as before with increasing positron currents. Before a new luminosity run, the proton beam will be dumped and re-injected if the beam was stored for >5h with collisions or >10h without collisions.
There will be an access today for HERMES and to increase the temperature of the GO/GG beam pipes at H1 to 170K.
TSPs will be heated in the north IR during ep operation.
Some machine studies will be performed today (in parasitic mode), Thursday (evening and night shifts) and on Tuesday
ZEUS is the coordinating experiments.

Uwe Schneekloth