Challenges and Plans for the Ion Injectors

Abstract

We review the performance of the ion injector chain in the light of the improvements which will take place in the near future, and we derive the expected luminosity gain for Pb-Pb collisions in the collider during the HL-LHC era.

Heavy-Ion Operation of HL-LHC

“…With bunch spacings, S b /c = 100 ns, as foreseen in the original LHC design [1], this provides adequate separation at the parasitic beam-beam encounters around the IP. Some developments in the injectors [15] are aimed at increasing the number of bunches by achieving S b /c = 50 ns -half of the original design -for at least some of the spacings between bunches in the LHC. Figure 1 shows that, for this value, it is no longer possible to satisfy the usual separation requirements in AL-ICE together with Eq.…”

“…It then predicts the optimum number of PS injections per SPS cycle and can be used to compare different schemes for preparing batches in the PS. A further important ingredient is the minimum spacing of PS batches in the SPS which depends on the proposed upgrade of the injection kicker for ion beams in the SPS [15]. Here we shall assume a modest upgrade of the kicker which would allow a 100 ns spacing between the PS batches.…”

“…For present purposes, this model can be applied to one of the filling schemes [15] in which the PS delivers batches of four bunches, spaced at 50 ns to the SPS. a In more recent developments, a scheme providing two bunches spaced at 100 ns has been deemed the "Nominal" one for post LS2 operation.…”