Beam mixing changes sample membership between turns through revolution-time differences. Repeatedly correlated samples and thermal noise limit stochastic cooling.[ref]
Stochastic Cooling and the Accumulation of Antiprotons by Simon van der Meer. Section 5, p.295, Mixing and thermal noise, Eqs.(3)–(4)
Fresh samples help across turns; losing pick-up–kicker correlation hurts. Useful feedback gain therefore depends on bandwidth, delay, beam dynamics and signal-to-noise ratio.
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