The LHC beam loss monitoring system’s data contribution to other systems

The strategy for machine protection and quench prevention of the Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is presently based on the Beam Loss Monitoring (BLM) system. At each turn the BLM system is able to acquire and process in real-time data from approximately 4000 detectors in order to decide if the beams should be permitted to continue circulating or their safe extraction is necessary. At the same time in the system, by making full use of its VME based processing cards, data is continuously recorded from both the acquisition, the processing results as well as the status of the electronics which later will be provided to various systems in the LHC. Part of the recorded data will be used to drive an on-line event display and write an extensive logging database at a refresh rate of 1 Hz. Other parts of the same processing units, initiated by external triggers, will provide fast updates of the loss pattern seen in the last 84 ms by 2.54 ms integrals, necessary for the automated collimator adjustments, 100 ms worth of data for every beam injection and scheduled dump to verify the correctness of those procedures, and the last 1.7 s by 40 us integrals to be used for post-mortem analysis in the event of an unforeseen dump as well as FFT analysis studies. The paper discusses the realization of each of those recording functions and their verification with beam measurements.