Bunched beam stochastic cooling in a collider

Abstract

Bunched beam stochastic cooling in the Relativistic Heavy Ion Collider (RHIC) at 100 GeV has been achieved. The longitudinal cooling system is designed for heavy ion operation but was tested using protons. A very low intensity bunch with 10 9 protons was prepared so that cooling times and voltage requirements would be comparable to the heavy ion case. With this bunch a cooling time of the order of an hour was observed through shortening of the bunch length and narrowing of the Schottky lines.

Mitigation of the electron-cloud effect in the psr and sns proton storage rings by tailoring the bunch profile

“…The amplification factor per macroparticle may exceed 10 4 during a single bunch passage when δ max = 2. Simulation results for the SNS obtained with a different code [7] show a qualitative agreement with our results, although they yield a lower estimated electron density at this SEY value [5]. We assume in these simulations that pro- Figure 3: Simulated electron neutralization factor in a SNS field-free region.…”

“…The SNS beam pipe chamber will be coated with TiN. Recent measurements of an as-received sample of the TiN coated stainless steel SNS vacuum chamber, has shown a secondary electron yield δ max = 1.9 ± 0.2 [5,6].…”

“…Although the neutralization factor may exceed 10% near the tail of the beam, the resulting electron cloud tune shift is moderate. Linear stability studies and current threshold estimates are deferred to a separate publication [5]. Many generations of secondary electrons may occur during a long bunch passage leading to an high electron cloud density owing to trailingedge multipacting.…”

Beam Instabilities in Hadron Synchrotrons

“…[249] is narrower than that of Ref. [247,248], since in the former the strong space charge approximation was applied, i.e. the space charge tune shift was assumed to be large compared to the synchrotron tune and the wake-driven coherent tune shifts.…”

“…This relates to the influence of space charge on the coherent modes: their shapes, growth rates, and Landau damping. Two theoretical articles of M. Blaskiewicz [247,248] shed certain light on this issue. In particular, a compact analytical description of the coherent modes was found there for a square well model with a short-range wake function, without any assumption for the relative values of the space charge tune shift, the synchrotron tune, and the coherent tune shift.…”