Depolarization calculations for the J-PARC

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Depolarization calculations for the J-PARC Rapid
Cycling Synchrotron and possible remedies for the
spin resonances in RCS
M. Bai, H. Huang, T. Roser
July 11, 2005, Spin_at_J-PARC Teleconference
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• Qx6.735, Qy6.356

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(No Transcript)
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• emittance 10? mm-mrad
• repetition rate 25Hz
• sinusoidal ramping
• kinetic energy 400MeV 3GeV

• intrinsic resonance strength for a particle
• at an emittance of 10? mm-mrad

?6.18x10-5
Full spin flip by an ac dipole
?7.63x10-5
?6.60x10-5
?2.33x10-5
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• required amplitude of the coherent oscillation
  by an ac dipole to
• achieve gt 99 spin flip

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Harmonic correction
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• Summary
• Intrinsic resonance
• Only three non-negligible resonances
• With the RCS ramp rate, there are three strong
  resonances
• cause a polarization loss of more than 10 for
  a 10?
• beam. The strongest one causes a polarization
  loss of
• 50. All should be able to be overcome by an ac
  dipole
• within the aperture of the RCS beam pipe
• imperfection resonance
• limited resonances
• harmonic corrections should be able to avoid
  polarization
• loss at the imperfection resonances