We provide a brief status report on measurements and simulations of the electron cloud in the Fermilab Main Injector. Areas of agreement and disagreement are spelled out, along with their possible significance.

We present simulation results of the build-up of the electron-cloud density ne for the two proposed ILC damping ring lattices, DC04 and DSB3, with particular attention to the potential benefit of an antechamber. We examine a field-free region and a dipole bending magnet, with or without an antechamber. We assume a secondary electron emission model for the chamber surface based on approximate fits to measured data for TiN, except that we let the peak value of the secondary emission yield (SEY), delta max, be a variable. We conclude that there is a critical value of delta max below which the antechamber provides a substantial benefit, roughly a factor ~;;40 reduction in ne relative to the case in which max exceeds the critical value. We estimate the steady-state value of ne as a function of delta max, and thereby obtain the critical value of delta max for all cases considered. Thus, from the perspective of the electron-cloud effect, the inclusion of an antechamber in the design is justified only if delta max is below the critical value. The results presented here constitute a slight extension of those previously presented in March and September, 2010 [1, 2].

A replacement for the PS storage ring is being considered, in the context of the future LHC accelerator complex upgrade, that would likely place the new machine (the PS2) in a regime where the electron-cloud (EC) effect might be significant. We report here our current estimate of the EC density ne in the bending magnets and the field-free regions at injection and extraction beam energy, for both proposed bunch spacings, tb = 25 and 50 ns. The primary model parameters exercised are the peak secondary emission yield (SEY) delta max, the electron-wall impact energy at which the SEY peaks, Emax, and the chamber radius a in the fieldfree regions. We present many of our results as a function of the bunch intensity Nb, and we provide a tentative explanation for the non-monotonic behavior of ne as a function of Nb.