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.