The SIN Accelerators, Operational Experience and Improvement Programs

The SIN meson facility, in operation since 1974, consists of a 590 MeV ring cyclotron for protons and a 72 MeV injector cyclotron. The average beam current on target is presently about 50 ??A, the peak being 112 ??A. Extraction efficiency, once considered a severe handicap for cyclotrons, is now 99.6 to 99.9 % for the ring cyclotron and about 90 % for the injector. Many improvements in both accelerators allow single turn extraction in the ring cyclotron. The present current limit is given by the injector, while the ring itself could accept now a 600 ??A beam, with 2-4 mA as an ultimate limit. Some muon experiments require a pulsed beam with on-off times in the order of the lifetime of the muon. First trials with beampulse frequencies of 200 and 400 KHz and a 50 % duty cycle have been successful.