CERN LHC Project Report 90 (1997)

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Emittance growth due to fluctuations and the head-on beam-beam interaction in the LHC

Tanaji Sen

January 1997

Abstract:

Fluctuations in the offset between the two beams at collision and tune fluctuations lead to emittance growth and possibly loss of luminosity. Using a recent analytical model we calculate the expected emittance growth at design parameters and reasonable fluctuation amplitudes. Tolerances are put on the allowable noise spectral densities at harmonics of the betatron frequency. We also suggest methods to reduce noise amplitudes and the emittance growth.

 
• 1 Introduction
• 2 Sources of fluctuations
• 3 Model for fluctuations
• 4 Diffusion Coefficients due to the beam-beam and fluctuations
  • 4.1 Offset fluctuations
  • 4.2 Tune fluctuations
• 5 Emittance growth due to fluctuations
  • 5.1 Offset Fluctuations
  • 5.2 Tune Fluctuations
• 6 Conclusions
• References
• About this document ...