Central region design studies for a proposed 250 MeV proton cyclotron

The results of design studies of the central region for a proposed superconducting cyclotron for advanced cancer therapy are presented here. The studies considered a four sector cyclotron operating in the second harmonic (h = 2) acceleration mode capable of producing 250 MeV protons. The studies were based on detailed beam orbit calculations and the results presented here cover design considerations on the basis of beam centering, vertical focusing, and with an emphasis on phase selection.