Spin-Flipping Polarized Deuterons At COSY

We recently stored a 1.85 GeV/c vertically polarized deuteron beam in the COSY Ring in Jtilich; we then spin-flipped it by ramping a new air-core rf dipole's frequency through an rfinduced spin resonance to manipulate the polarization direction of the deuteron beam. We first experimentally determined the resonance's frequency and set the dipole's rf voltage to its maximum; then we varied its frequency ramp time and freqiiency range. We used the EDDA detector to measure the vector and tensor polarization asymmetries. We have not yet extracted the deuteron's tensor polarization spin-flip parameters from the measured data, since our short run did not provide adequate tensor analyzing-power data at 1.85 GeV/c. However, with a 100 Hz frequency ramp and our longest ramp time of 400 s, the deuterons' vector polarization spin-flip efficiency was 48±1%. Recently polarized deuteron experiments have become an accessible and interesting area of subatomic physics. Studying the spin-flipping and polarization dynamics of polarized deuteron beams is an important step towards polarized deuteron, and thus polarized neutron, scattering experiments. Many polarized scattering experiments require frequent spin-direction reversals (spin-flips), while the polarized beam is stored, to reduce their systematic errors. Earlier we used an rf solenoid to study, for first time, spin flipping and spin manipulation of a simultaneously vector and tensor polarized 270 MeV deuteron beam stored in the IUCF Cooler Ring and obtained rather interesting results [ 1 ]. We recently studied spin flipping with an rf dipole of a simultaneously vector and tensor polarized 1.85 GeV/c deuteron beam at COSY's higher energy. In any flat circular accelerator or storage ring, each deuteron's spin precesses around the Stable Spin Direction (SSD), which is defined by the ring's magnetic structure. With no horizontal magnetic fields in the ring, the SSD points along the vertical fields of the ring's bending magnets. The spin tune vs, which is the number of spin precessions during one turn around the ring, is proportional to the deuteron's energy