| Although the 5% partial Siberian snake has been demonstrated to be able to overcome the imperfection spin resonances in the AGS, it is still too weak to correct the intrinsic spin resonances in the AGS as well. To accelerate polarized protons to 25 GeV/c, the injection energy of the Relativistic Heavy Ion Collider, seven intrinsic spin resonances are encountered, i.e. 0 + nu z, 12 + nuz, 24 +/- nu z, 36 +/- nuz and 48 - nu z. Four of them are strong ones: 0 + nuz, 12 + nuz and 36 +/- nuz , and every one of them can partially or even fully destroy the beam polarization.; To overcome these strong intrinsic spin resonances, an RF dipole was employed in the AGS polarized proton acceleration. A strong coherent oscillation was excited by the RF dipole at each of the spin resonances. Particles in the beam core then experienced stronger focusing fields and the average effective spin resonance strength of the beam was greatly enhanced. If the driven coherent oscillation is strong enough, a full spin flip can be induced under the normal AGS acceleration rate. This has been proven in the recent AGS polarized proton acceleration experiments. Unlike other non-adiabatic beam manipulations, the coherent oscillation can be excited in an adiabatic manner by slowly turning on and off the RF dipole and beam emittance can be preserved.; The principle of the adiabatic excitation of a coherent oscillation by an RF dipole is discussed in this thesis. The experimental data of using an RF dipole to overcome intrinsic spin resonances are presented. The results of a new type of second order spin resonance observed in the AGS polarized proton acceleration experiment are also included. |
