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 δ_max = 1.3, we find a threshold value of the bunch population, N_b,th 1.25 ×10¹¹, beyond which the EC density ρ_e reaches a steady-state level that is ~10⁴ times larger than for N_b<N_b,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 N_b,th and the steady-state value of ρ_e. Possible dynamical effects from the EC on the beam, such as emittance growth and instabilities, remain to be investigated separately.

Received 27 March 2006
Published 28 November 2006