Crab cavity location for 2mrad xing

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Crab cavity location for 2-mrad x-ing

• December 7, 2004

A.S.
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Motivation

• In 2-mrad x-ing probably cannot install crab
  cavity in FD, because of its transverse size
• Try to place crab cavity in FF, far from FD
• For the moment, use NLC beamline and beam
  parameters, since it was easier to make a quick
  look

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Place crab cavity near QF5
This may be not the best location , since there
is dispersion higher order terms here, but
this is just a test
NLC optics and nominal beam parameters were used
in this test 250 GeV/beam, sx0243nm, sy03nm,
bx8mm, by0.11mm, sz0.11mm. Energy spread
Batman distribution with 0.8 full width.
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For crab-cavity near QF5 and half_cross_angle
10.0e-3 need kick with dangle/dz -
5.7912e-4 1/m
For comparison, for crab cavity 12m from the IP
need dangle/dz 6.0635e-4 1/m
Crab-cavity modeled as a thin element which
produce z-x kick, including the energy
dependence of the kick
half_cross_angle 10.0e-3 crab cavity effect
not removed sx/sx0 4.5873 sy/sy0 1.0101
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half_cross_angle 10.0e-3 sx/sx0 0.99698
sy/sy0 1.0101 Do no see any degradation of the
beam size
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Start to see effect on the beam size when the
crossing angle 50 mrad Half_cross_angle
0.1 sx/sx0 1.2541 sy/sy0 1.8084
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NLC optics and nominal beam parameters were used
in this test 250 GeV/beam, sx0243nm, sy03nm,
bx8mm, by0.11mm, sz0.11mm. Energy spread
Batman distribution with 0.8 full width.

• With 2mrad considered, this simple study show
  that it should be feasible to place crab-cavity
  in FF, far from FD.
• For sz0.3mm ILC beam the effect may be larger,
  but even if so, the margin seems to be sufficient
• Still, location of crab cavity in FF need to be
  optimized (near QF9?).
• Also need to consider ILC optics and parameters
  (may be even easier, smaller energy spread), and
  any other implications.