Author: Kwon, S.
Paper Title Page
TUP005 Commissioning the Beam-Loss Monitoring System of the LCLS Superconducting Linac 187
 
  • A.S. Fisher, N. Balakrishnan, G.W. Brown, E.P. Chin, W.G. Cobau, J.E. Dusatko, B.T. Jacobson, S. Kwon, J.A. Mock, J. Park, J. Pigula, E. Rodriguez, J.I.D. Rudolph, D. Sanchez, L. Sapozhnikov, J.J. Welch
    SLAC, Menlo Park, California, USA
 
  A 4-GeV su­per­con­duct­ing linac has been added to the LCLS x-ray FEL fa­cil­ity at SLAC. Its 120-kW, 1-MHz beam re­quires new beam-loss mon­i­tors (BLMs) for ra­di­a­tion pro­tec­tion, ma­chine pro­tec­tion, and di­ag­nos­tics. Long ra­di­a­tion-hard op­ti­cal fi­bres span the full 4 km from the elec­tron gun of the SC linac to the final beam dump. Di­a­mond de­tec­tors at an­tic­i­pated loss points pro­vide local pro­tec­tion. De­tec­tor sig­nals are con­tin­u­ously in­te­grated with a 500-ms time con­stant and com­pared to a loss thresh­old. If crossed, the beam is halted within 0.1 ms. Com­mis­sion­ing began in March 2022 with the 100-MeV in­jec­tor and with RF pro­cess­ing of the cry­omod­ules. At IBIC 2022 last Sep­tem­ber, we pre­sented com­mis­sion­ing re­sults from the in­jec­tor BLMs. In Oc­to­ber, the beam passed through the full linac and the by­pass trans­port line above the LCLS cop­per linac, stop­ping at an in­ter­me­di­ate dump. In Au­gust it con­tin­ued through the soft x-ray un­du­la­tor and achieved first las­ing. Here we pre­sent BLM com­mis­sion­ing at en­er­gies up to 4 GeV and rates up to 100 kHz. We dis­cuss mea­sure­ments and soft­ware using the fast di­ag­nos­tic-wave­form out­put to lo­cal­ize beam losses and to de­tect wire-scan­ner sig­nals.  
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DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP005  
About • Received ※ 06 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 27 September 2023
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