Author: Bai, M.
Paper Title Page
TUP006 Simulation and Shot-by-Shot Monitoring of Linac Beam Halo 191
 
  • A.S. Fisher, M. Bai, T. Frosio, A. Ratti, J. Smedley, J. Wu
    SLAC, Menlo Park, California, USA
  • I.S. Mostafanezhad, B. Rotter
    Nalu Scientific, LLC, Honolulu, USA
 
  FELs re­quire a re­pro­ducible dis­tri­b­u­tion of the bunch core at the un­du­la­tor en­trance for ro­bust and re­li­able las­ing. How­ever, var­i­ous mech­a­nisms drive par­ti­cles from the core to form a beam halo, which can scrape the beampipe of the un­du­la­tor and dam­age its mag­nets. Col­li­ma­tors can trim the halo, but at the 1-MHz rep­e­ti­tion rate of SLAC’s LCLS-II su­per­con­duct­ing linac, the col­li­ma­tor jaws can be ac­ti­vated and dam­aged. The Ma­chine Pro­tec­tion Sys­tem (MPS) can de­tect ex­ces­sive ra­di­a­tion and halt the beam, but re­peated MPS trips lead to sig­nif­i­cant down­time. Halo con­trol be­gins by study­ing its struc­ture, for­ma­tion, and evo­lu­tion, using a sen­si­tive halo mon­i­tor. To that end, we are de­vel­op­ing a pixel­lated di­a­mond sen­sor. Di­a­mond of­fers a dy­namic range of up to 7 or­ders of mag­ni­tude, ex­tend­ing from the edge of the core to the faint halo ex­pected at greater dis­tances. Nalu Sci­en­tific has de­vel­oped fast elec­tron­ics for high-rate shot-by-shot read­out. Ini­tial tests are start­ing with a pro­to­type 16-pixel sen­sor at the beam dump of SLAC’s FACET-II test fa­cil­ity. The tests and sim­u­la­tions will guide more elab­o­rate sen­sor de­signs.  
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DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP006  
About • Received ※ 07 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 12 September 2023 — Issue date ※ 19 September 2023
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