PERFORMANCE OF HIMAC

The NIRS heavy-ion two-synchrotron medical facility, HIMAC, was approv ed in the 1987 fiscal year and clinical trials were started in late Ju ne 1994 as previously arranged. The operation experiences show that th e entire HIMAC facility can work well with high stability and excellen t reproducibility. For example, the intensity of beam extracted slowly from the rings can be reduced as low as 500 particles per pulse becau se stable and reproducible acceleration can be achieved in the rings i n spite of no beam feedback. This performance enables direct counting of the beam and its fragments in the preparatory experiments toward cl inical treatments and provides a promising basis for acceleration and storage of radioactive beams toward simultaneous treatment and diagnos is in future.