Spin Manipulating 2 GeV/c Polarized Protons and Deuterons Stored in Cosy

We recently studied the spin manipulation of a vector and tensor polarized deuteron beam stored at 1.85 GeV/c in COSY. We manipulated the deuteron's polarization by sweeping the frequency of a ferrite RF dipole through an RF-induced spin resonance. We first experimentally determined the resonance's frequency and then varied the RF dipole's Δf and Δt to maximize the spin-flip efficiency. We obtained a measured vector spin-flip efficiency of about 97 ± 1%. We also studied the detailed behavior of the tensor polarization during spin manipulation.

We later studied higher-order spin resonances using 2.1 GeV/c stored vertically polarized protons. By changing the vertical betatron tune within the range 3.51 to 3.71, with the horizontal tune fixed at 3.575, we found full spin flip when the 1^st-order spin resonance was crossed; we also found partial depolarization near several 3^rd-order resonances and possibly near one 2^nd-order resonance.

We also spin-flipped 2.1 GeV/c vertically polarized protons stored in COSY, by sweeping the frequency of a strong ferrite RF dipole through an RF-induced spin resonance. After finding the resonance's frequency, we varied the RF dipole's strength, frequency ramp time Δt and frequency range Δf to maximize the spin-flip efficiency. We then used the multiple spin flip technique to measure a spin-flip efficiency of 99.92 ± 0.04%.