hera_minutes_011016.html

There has been no proton beam because of technical problems with the alarm system. New computer code will be installed today. This requires ramping down of the main proton dipole magnets.
The DESY III septum had a water leak (leaking into the vacuum system). A spare part was installed. Pump down is in progress. Proton beam operation is expected to continue tomorrow evening.
Last week the positron current was increased to 5mA. Ramp and luminosity files were established without high rates in the background monitors. The photon beam was centered in the H1 and ZEUS luminosity monitors.
The readout of the beam position monitors at 2m was improved.
Yesterday, the effect of the ZEUS F/RCAL movement on the beam was studied again. The initial magnet settings were quite different than during the previous study. The correction procedure is not yet a routine operation.

The HV of the central tracking detector was turned on on Friday. The whole chamber tripped at about 70% of the nominal HV.
Part of the detector is presently being turned on: MVD bias voltages (high currents in the rear part), forward detector (STT) plane close to the IP not at full HV, read detector (RTD) tripped 150V below the nominal voltage.

Good progress was made on Thursday when the GO currents were changed. The SPACAL rate decreased from a few MHz to kHz. The outer jet chamber voltage was ramped to 200V below the nominal voltage without problems.
Background conditions were similar on the weekend.
After background optimization, the photon beam is now out of the horizontal acceptance of the luminosity monitor.
A short access is required to install Si diode background monitors.
Note added after the meeting. During the meeting the inner and outer jet chambers were successfully ramped to full HV. Background rates in the SPACAL are acceptable.

Good background conditions during the stable positron runs. Presently, no problems are expected scaling the rates to 30mA.

All target wires were moved in Tuesday to Wednesday night (15mA in 60 bunches). The interaction rate was 0.5MHz. All vertex detector pots except one were moved in. An access is required to repair the detective pot. The beam was lost before the detector was turned on.
Want to continue target and vertex detector operation and turn on the detector.

Uwe Schneekloth