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Collimator Damage PowerPoint Presentation
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Collimator Damage

Collimator Damage

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Collimator Damage

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  1. Collimator Damage Adriana Bungau The University of Manchester Cockcroft Institute “All Hands Meeting” , January 2006

  2. What we do: • Collaboration between RAL, Manchester University and Daresbury Laboratory • Goal: • determine optimal material and geometry for ILC collimators in order to • maximize the collimation efficiency and minimize the wakefield effects • Investigate the heating effects caused by various patterns of energy deposit using ANSYS (G. Ellwood -RAL, G.Kourevlev –Manchester Univ.) • Simulate the energy deposition in a spoiler of specified geometry due to a beam being mis-steered using FLUKA ( L. Fernandez – Daresbury) and Geant4 (A.Bungau – Manchester Univ. ) • Cross-check these studies with Lewis Keller’s results on spoiler survival (SLAC) • Study a range of geometry/material combinations that allows low wakefields and verify these experimentally

  3. Update report on material damage Geant4/Fluka results: Model of an isometric view of the collimator (geometry, material) Simulations of the energy deposition along z at several depths; distributions in various 2D projections of the energy density Calculations of the corresponding increase in temperature Kinetic energy of the outgoing particles Results passed on for ANSYS studies ANSYS results: Studies of steady state heating effects (3d isothermal contours-consistent) Comparation between ANSYS simulations and analytic calculations (good agreement) ANSYS used to predict stress induced in a 3d solid (apply to the collimator geometry)

  4. y x z Collimator geometry (modelled with Geant4) Dimensions: x = 38 mm y = 17 mm z = 21.4 mm Z = 122.64 mm θ = 324 mrad Material: Ti alloy (Ti-6Al-4V)  = 4.42 g/cm3 melting temperature 1649 C° c = 560 J/kg C°

  5. Beam profile • Ellipsoid with x =111 m y = 9 m • Simulated particles: 104 electrons/bunch • E = 250 GeV • Energy cutoff: e- kinetic energy cutoff = 2.0 MeV ->2.9 mm range in Ti alloy e+ kinetic energy cutoff = 2.0 MeV ->3.1 mm range in Ti alloy  energy cutoff =100.4 KeV ->6.18 cm attenuation length in Ti alloy

  6. Energy deposition in Ti alloy at 2 mm depth • the beam is sent through the collimator along z at 2 mm depth • Edep max in the second wedge at ≈14 mm • the mesh size should be smaller than the beam size for realistic results • at z≈14 mm: max energy deposition is 3 GeV/2e-3 mm3 -> ∆T = 215 K

  7. Energy deposition at 10 mm depth in Ti alloy • the beam goes through the collimator at 10 mm depth • max Edep at 10 mm depth is at ≈35 mm along z (second wedge) • at z≈35 mm, the max Edep is 6.66 GeV/2e-3 mm3 -> ∆T = 430 K

  8. e.m. shower for one 250 GeV e- at 2 mm depth e.m. shower for one 250 GeV e- at 10 mm depth

  9. Energy deposition at 16 mm depth in Ti alloy spoiler • the beam is sent through the collimator at 16 mm depth • max Edep is at ≈55 mm • max Edep = 8 GeV/2e-3 mm3 -> ∆T = 517 K

  10. e.m. shower for one 250 GeV e- at 16 mm depth

  11. Summary e- : multiplicity ≈ 4 e+: multiplicity ≈ 3 L.Keller: e+ : multiplicity ≈ 4 e- : multiplicity ≈ 4

  12. Direct Hits on Spoilers Maximum ∆T/2x1010 bunch at Hit Location, °C/bunch Geant 4 simulation L. Keller *with a spread in energy ∆E/E = 0.06 %

  13. Conclusion The instantaneous temperature rise at various depths were below the melting temperature of the Ti alloy ->collimators are not in danger in case of a direct hit from one bunch Little energy deposition in the material – a large fraction of the energy appears as photons emerging from the collimators Future plans Compare the Geant4 results with Fluka predictions Carry out a survey of materials (so far only Ti and Ti-6Al-4V were used) Pass on the energy deposits files for ANSYS studies ( RAL)