HIMAC SYNCHROTRON MAGNETS

HIMAC is a Heavy Ion Medical Accelerator in Chiba now under constructi on at NIRS (National Institute of Radiological Sciences). The first be am is expected at the end of 1993. The dipole and quadrupole magnets o f the synchrotron have demountable pole end pieces. The integrated fie ld of all the dipoles of the synchrotron ring were adjusted with a pre cision of +/-0.8x10(-4) at 1 T by field measurements. Deviations in th e integrated field of each dipole were also measured at different exci tation levels. By proper location of the dipoles to reduce 3rd and 4th harmonics of the error distribution in the ring, the closed orbit dis tortion (COD) due to the harmonic errors was estimated to be less than 2.7 mm over the entire excitation range. The shims at the ends of the quadrupole poles were adjusted to obtain a gradient length product th at was uniform to within 8x10(-3) at low field and 3x10(-3) at high fi eld over a width of 244 mm along the horizontal axis.