Commissioning and optimization of the LHC BLM System

Due to rapid progress with the LHC commissioning in 2010, set-up beam intensities were soon surpassed and damage potential was reached. One of the key systems for machine protection is the beam loss monitoring (BLM) system. Around 4000 monitors are installed at likely or critical loss locations. Each monitor has 384 associated beam abort thresholds (12 integrated loss durations from 40 μs to 84 s for 32 energy intervals). A single integrated loss over threshold on a single monitor aborts the beam. Simulations of deposited energy, critical energy deposition for damage or quench and BLM signal response backedup by control measurements determined the initial threshold settings. The commissioning and optimization of the BLM system is presented. Test procedures were used to verify the machine protection functionalities. Accidental magnet quenches were used to fine-tune threshold settings. The most significant changes to the BLM system during the 2010 run concern the injection, the collimation and the beam dump region, where hardware changes and threshold increases became necessary to accommodate for increasing beam intensity.