California, Therapy Center at Massachusetts General Hospital in Boston in U.S.A., Paul
Scherer Institute in Villigen – Switzerland, the Heavy-Ion Research at GSI in Germany, the
Shizouka , HYOGO Medical Center, Kashiwa Center, Wakaza Bay project, the KEK in
Tsukuba and other medical centers in Japan, the Faure hospital in South Africa, Uppsala in
Sweden and many other facilities are either being built or have very strong support and
proposals.
Advantages of the non-scaling FFAG with respect to the synchrotrons are the fixed
magnetic field and possibilities of higher repetition rates for spot scanning. The cyclotrons
are made of very large magnets (weight is more than a ton) and could not easily change the
final energy. The exact energy sweep is necessary due to the ion energy deposition inside of
the patient’s body precisely localized by the “Bragg peak” localized at the tumor location.
The non-scaling FFAG adjusts the final energy by adjusting the number of turns during
acceleration. The very strong focusing provides not only a smaller aperture but also a better
orbit control than in cyclotrons, thus leading to lower losses.
2. Basic Lattice Cell
The non-scaling FFAG basic cell, as presented in Figure 1, is composed of only two kinds of
combined focusing magnets: the main bend with the defocusing gradient located at the center