Collimator design and short range wakefields

1
Collimator design and short range wakefields

• Adriana Bungau

Christmas meeting - 2006 Manchester
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Collimator Design and Material Damage

• Aim design the optimal spoilers for the ILC (
  geometry and material specification)
• Project collaboration between Birmingham Univ,
  Manchester Univ, Daresbury Laboratory,
• SLAC and RAL
• Geant4 simulations in Manchester
• Collimator design - two types of spoilers a full
  metal spoiler and a combinations of metal and
  graphite
• Three materials used Ti4Al6V, Copper, Aluminium
• Beam was sent through the collimator at 2 depths
  2mm and 10 mm from the top
• Decision of the best spoiler candidate was based
  on
• - instantaneous temperature rise
• - outgoing particle multiplicities
• - energy spectra of outgoing particles
• The best spoiler candidate was Ti alloy with
  graphite
• Results were cross-checked with Fluka and EGS4 -
  passed on at RAL for ANSYS studies

EUROTeV reports and EPAC papers

• Geant4 Simulations of Energy Deposition in ILC
  spoilers - A.Bungau, R.Barlow, N.Watson, EUROTeV
  Report-2006-021
• Shower simulations, comparison of FLUKA,
  GEANT4 and EGS4 - L.Fernandez, A.Bungau,
  L.Keller, R.Barlow, N.Watson, EUROTeV-Report-2006-
  034

3
Wakefield simulations with Merlin

• Current situation
• mathematical formalism for incorporating higher
  order mode wakefields (R.Barlow)
• formalism implemented in the Merlin code
• SLAC beam tests simulated (good agreement
  between analytical calculations and
• experiment
• so far, only simple beamlines were studied (ie.
  Drift, Collimator, Drift)

EPAC paper
Simulation of High Order Short Range Wakefields
- R.Barlow, A. Bungau, EUROTeV-Report-2006-051
Studies are now extended to the ILC-BDS beamline
- emittance growth due to wakefields and
luminosity loss
4
Wakefield Measurements at SLAC-ESA
Motivation to optimize the collimator design by
studying various ways of minimising wakefield
effects while achieving the required performance
for halo removal

• Collaboration between SLAC, Birmingham,
  Lancaster, Manchester, Daresbury
• Commissioning Jan 2006 (4 old collimators) -
  Successful
• Physics first run Apr/May second run July
  (8 new collimators CCLRC)

Experimental tests
- tested 8 collimators fabricated at RAL -
inserted collimators in beam path (x mover),
moved collimator vertically (y mover),measured
centroid kick to beam via BPMs - analysed
kick angle vs collimator position (good runs as
also bad runs)
EUROTeV reports and EPAC papers

• "Test Beam Studies at SLAC End Station A for the
  International Linear Collider" -M.Woods et all,
  EUROTeV-Report-2006-060, SLAC-PUB-11988
• "Direct Measurement of Geometric and Resistive
  Wakefields in Tapered Collimators for the
  International Linear Collider" - N.Watson et all,
  EUROTeV-Report-2006-059, SLAC-PUB-12029

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Plans for 2007

• Colimator damage
• beam tests for material damage (SLAC, CERN ?)
• Wakefield simulations
• studies for the ILC_BDS collimators with higher
  order modes
• implement Gdfidl predictions in Merlin
• Experimental tests at ESA
• next run March 2007 with 8 new collimators
• BPM reprocessing on the Manchester cluster
• data analysis finished for 2006 and also for
  2007
• data comparison with the first 8 collimators
  used in 2006
• Particle Accelerator Conference, June 2007-New
  Mexico - 5 abstracts