Author: Nemcic, M.
Paper Title Page
WEPC170 Handling of BLM Abort Thresholds in the LHC 2382
 
  • E. Nebot Del Busto, B. Dehning, E.B. Holzer, S. Jackson, G. Kruk, M. Nemcic, A. Nordt, A. Orecka, C. Roderick, M. Sapinski, A. Skaugen, C. Zamantzas
    CERN, Geneva, Switzerland
 
  The Beam Loss Monitoring system (BLM) for the LHC consists of about 3600 Ionization Chambers located around the ring. Its main purpose is to request a beam abort when the measured losses exceed a certain threshold. The BLM detectors integrate the measured signals in 12 different time intervals (running from 40 us to 83.8 s) enabling for a different set of abort thresholds depending on the duration of the beam loss. Furthermore, 32 energy levels running from 0 to 7 TeV account for the fact that the energy density of a particle shower increases with the energy of the primary particle, i.e. the beam energy. Thus, about 1.3·106 thresholds must be handled and send to the appropriate processing modules for the system to function. These thresholds are highly critical for the safety of the machine and depend to a large part on human judgment, which cannot be replaced by automatic test procedures. The BLM team has defined well established procedures to compute, set and check new BLM thresholds, in order to avoid and/or find non-conformities due to manipulation. These procedures, as well as the tools developed to automate this process are described in detail in this document.