1. Luminosity Monitor MWPCs, test beam 22 results. A.Kiselev OLYMPUS Collaboration Meeting DESY, Hamburg, 27.06.2011

2. Original motivation Test new MWPC modules Check PCOS4 readout integration in Bonn DAQ Check mechanical co-existence with the GEM modules Try out combined GEM-MWPC tracking?

3. DORIS test run -> test beam 22 Lead Glass Calorimeter MWPC#1,2 with the onboard electronics 2x prop.chambers (1mm spacing, XUV) 864 channels total modern CROS3 electronics (Gatchina)  ~1/3 of the final setup!

4. DORIS test run (April’2011 slide) almost no noise clear timing correlation with the trigger very low leakage currents (few  A at most) rather low hit multiplicities no sensitivity to synchrotron background on-board electronics works fine in “partly off-board” configuration useful acceptance ~105x105mm 2 confirmed relatively low efficiency (~95%)  last Feb’2011 run #285: ~60mA after injection, Bhabha electrons flux ~700kHz:

5. MWPC efficiency: HV scan  all 6 planes U1..V2 at CROS3 threshold 40  efficiency plateau starts at ~3500V

6. MWPC efficiency: threshold scan  all 6 planes U1..V2 at 3500V  will determine the actual threshold based on the noise conditions in the experiment

7. Summary Two new MWPC modules tested Electronics checked under routine operation MWPC efficiency confirmed to be well above 99%