Large aperture magnets for a future high power proton synchrotron

A high intensity, high power proton synchrotron is currently under consideration at Fermilab. The machine known as the Proton Driver - would accelerate 3/spl times/10/sup 13/ protons from 400 MeV to 12 GeV (stage I) or 16 GeV (stage II) and ultimately deliver in excess of 1 MW of beam power. To minimize losses and insure beam stability, the space charge-induced tune shift must be kept well below 0.5. This is accomplished by spreading out bunches both longitudinally and transversely. While the former strategy favors high voltage low frequency RF, the latter leads to magnets with unconventionally large apertures. This requirement, combined with a 1.5 T bending field and rapid cycling operation results in a number of serious but not insurmountable challenges. In this paper, we discuss the design of the Proton Driver magnets and the rationale behind it.