Abstract
We present results from a preliminary assessment, via computer simulations, of the electron-cloud (EC) density for the FNAL Main Injector upgrade at injection energy. Assuming a peak value for secondary emission yield δmax = 1.3, we find a threshold value of the bunch population, Nb,th≃ 1.25 ×1011, beyond which the EC density ρe reaches a steady-state level that is ∼104 times larger than for Nb<Nb,th, essentially neutralizing the beam, and leading to a tune shift ∼0.05. Our investigation is limited to a field-free region and to a dipole magnet region, both of which yield similar results for both Nb,th and the steady-state value of ρe. Possible dynamical effects from the EC on the beam, such as emittance growth and instabilities, remain to be investigated separately.