Commissioning and first operation of the pCVD diamond ATLAS beam conditions monitor

The Beam Conditions Monitor (BCM) [1,5] of the ATLAS experiment protects the Inner Detector silicon trackers from high radiation doses caused by LHC beam incidents. It uses 16 1 × 1 cm 2 500 μ m thick polycrystalline chemical vapor deposition (pCVD) diamond sensors arranged in 8 positions around the interaction point. Time difference measurements with 2.56 GHz sampling are performed to distinguish between collision and background. In case of excessive beam background due to beam incidents, the BCM can trigger a beam abort. A FPGA based readout system performs the online data analysis and interfaces the results to ATLAS and the beam abort system. The diamond sensors, the detector modules and their readout system are described. Results of the operation with the first LHC beams are reported. Results of commissioning and timing measurements with cosmic muons in preparation for first LHC collisions are summarized.