Design and Experiences with the Beam Condition Monitor as protection system in the CMS Experiment of the LHC.

The Beam Condition Monitor (BCM) is used as a protection system at the Compact Muon Solenoid (CMS) experiment at the LHC. In order to prevent damage to the pixel and tracker detectors it can trigger a beam dump when high beam losses occur. The system consists of two sub systems, BCM1L and BCM2, at different locations. Poly-crystalline Chemical Vapor Deposition (pCVD) diamonds are used as detector material. The readout electronics is identical to the Beam Loss Monitor (BLM) system of the LHC. From cross calibration measurements a direct comparison between BLM and BCM system is possible. The BCM system is therefore a transparent extension of the BLM system into the CMS cavern. The BCM2 system has been active in the LHC beam abort system since first beam in the LHC. This paper shows the experience with the BCM system and measurements of selected events showing the abilities of the system for monitoring purposes.