Alignment issues for MICE coils

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Alignment issues for MICE coils

• U. Bravar Univ. of Oxford 3 March 2004
• Figures of merit
• One coil misalignment
• Multiple coil misalignment
• P method
• error field grid method
  
• 100 m channel
  conclusions

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Figures of merit

• Mice proposal all systematic effects within 10-3
  absolute.
• i) 15 cooling, fluctuations within 1 relative.
  
• ii) Design for 100 m long channel, not only for
  MICE.
• Figures of merit
• i) Transmission
• ii) Reduction in normalised transverse emittance
  
• De /e (ein eout) / ein

3
Misalignment of one magnet

• Used ICOOL Monte Carlo code
• Misaligned (tilted or displaced) ONE focus coil
• Studied deterioration of transmission and DeT/eT
• For 1 effects on MICE
  dq_at_8 mrad, dd_at_4 mm
• For 5 effects on MICE
  dq_at_20 mrad, dd_at_10 mm
• Very loose criteria, but we need to study random
  misalignment of ALL coils design for LONG
  cooling channel

4
Misalignment of multiple magnets

• Simple theory for random misalignments
  dq
  ALL COILS _at_ dqONE COIL /SQRT()
  with
  number of coils in the channel.
• For MICE 8, therefore dq 3 mrad, dd 1.5
  mm.
• For a LONG channel _at_ 100, i.e. dq 1 mrad, dd
  0.5 mm.
• Draft specifications for MICE
  dq
  2 mrad, dd 1 mm
• Further simulations
• Misalignment coefficient 1 CM (dq 2 mrad
  dd 1 mm). Gaussian misalignments, s CM,
  tolerances as a function of CM.

5
Error field grid method

• ICOOL OPERA error field
• Correlation DeT/eT vs. number of particles lost
  in the channel for different values of CM.
• Initial emittances eT,in 3000
  to 12000 mm mrad.
• Gaussian coil misalignments, cutoff 2 s.
• Figure eT,in 6000 mm mrad, initial number of
  m 10,000
• CM 0, CM 1, CM 2, CM 5, CM 10, CM 15,
  CM 20

6
Current conclusions

• e,in 6000 mm mrad
• De/e 0.130.34.10-4 (CM)3
• 1 effect on MICE CM 3.4
  dq 6 mrad, dd 3 mm
• 5 effect on MICE CM 5.75
  dq 12 mrad, dd 6 mm

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