A preliminary assessment of the electron cloud effect for the FNAL main injector upgrade

We present results from a preliminary assessment, via computer simulations, of the electron cloud density for the FNAL main injector upgrade at injection energy. Assuming a peak value for secondary emission yield (delta)max = 1.3, we find a threshold value of the bunch population, Nb,th ∼ 1.25 x 1011, beyond which the electron-cloud 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, both of which yield similar results for both Nb,th and the steady-state value of ρe. Possible dynamical effects from the electron cloud on the beam, such as emittance growth and instabilities, remain to be investigated separately