Using spin resonances to manipulate the polarization of spin-1/2 and spin-1 particle beams

Polarized beam experiments are now an important part of the programs in many accelerators and storage rings. Developing polarized beam capability in a circular ring is complicated due to the presence of many first- and higher-order spin resonances, which could cause a partial or complete polarization loss during the beam's acceleration and storage. We studied these spin resonances in several ways using vertically polarized protons stored in the COSY Cooler Synchrotron in Julich, Germany. For example, after acceleration, we ramped the stored beam's vertical betatron tune through different spin resonances and observed their effect on the polarization. We found a full spin flip when a first-order spin resonance was crossed; we also found partial depolarization near several third-order spin resonances and possibly near a second-order resonance.; An arrangement of magnets called a full (partial) Siberian snake, which rotates the spin by 180° (less than 180°), can be used to preserve the beam's polarization during its acceleration and storage. Full and partial Siberian snakes were shown to overcome many of the spin resonances. However, depolarization may occur even when a full Siberian snake is present in the ring; this is called a snake depolarizing resonance. We studied a snake resonance with a horizontally polarized proton beam stored in the Indiana University Cyclotron Facility Cooler Ring containing a full Siberian snake. After adjusting the spin and betatron tunes to satisfy the spin resonance condition, we observed several second- and third-order snake depolarizing resonances.; An rf-dipole induced spin resonance can be used for a highly efficient spin flipping of a polarized proton beam stored in an accelerator or storage ring in the presence of a nearly, but not exactly, full Siberian snake. However, it is usually preferable to adjust the snake to very near 100% where it is the most efficient. It has been suggested that adjusting the snake to exactly 100% may change the induced spin resonance's ability to spin-flip. We studied the spin flipping of a horizontally polarized proton beam stored in the IUCF Cooler Ring containing a Siberian snake, which could be adjusted to exactly 100%. When we attempted to spin-flip with the Siberian snake set at exactly 100%, we observed a complete depolarization of the beam. Our experimental data indicate that an efficient spin flipping is not possible in this case.; Recently, polarized deuteron experiments have become an accessible and interesting area of subatomic physics. Many polarized scattering experiments require frequent spin-direction reversals, while the polarized beam is stored, to reduce their systematic errors. Thus, we studied spin flipping and other spin manipulation of a simultaneously vector and tensor polarized stored deuteron beam, first at the IUCF Cooler Ring and then at a higher energy at COSY. We measured maximum spin-flip efficiencies of 94.2 +/- 0.3% at IUCF and 98.5 +/- 0.3% at COSY. We also found rather interesting behavior of the spin-1 tensor polarization and then studied it in considerable detail first at IUCF and later at COSY.