Partial helical snake for AGS

M. Okamura, T. Tominaka, T. Katayama, RIKEN
N. Tsoupas, BNL

In order to achieve high polarization of proton beams at RHIC, a helical partial snake magnet will be useful device. This new snake will be installed at AGS instead of existing solenoid partial snake magnet. With an RF dipole, the existing solenoid partial snake magnet could increase polarization up to 50 % at 21 GeV in AGS, however this result still does not fulfill the requirement of the project. It has been observed that much of the remaining depolarization occurring in the AGS is associated with transverse coupling resonance, which is due to the strong longitudinal field of the existing snake magnet itself. By replacing with the helical partial snake, the coupling will be reduced dramatically. The new partial snake system will be composed single normal conducting helical dipole and with steering magnet on both sides. Planned field strength, bore radius and length are 1.5 T, 75 mm and 1.5 m respectively. Detailed design of this magnet will be presented.