Beam Physics Seminar
Polarized beam scattering experiments require frequent reversals of the polarization direction (spin flips) to reduce the systematic errors in the measured asymmetry. An rf-induced spin resonance can be used to flip the particle spins. A spin flipper rf dipole magnet has been developed at the University of Michigan. The achieved spin flip efficiency were 99.9% for protons and 94.5% for electrons. We recently stored a polarized deuteron beam in the COSY Ring to study the spin dynamics of spin-1 particles in the rf field. The spin flipping efficiency in first run was only 50% since a deuteron has small Gγ compared with a proton. We improved the field strength and realized higher spin flip efficiency more than 90%. The experimental results for the deuteron beam will be presented in this talk.
The other tool is an ultra-cold polarized Hydrogen gas jet target. The jet uses a very high magnetic field and an ultra-cold separation cell coated with a superfluid 4He film to produce a slow monochromatic electron-spin-polarized atomic hydrogen beam. This beam is focused by a parabolic mirror coated with superfluid 4He and a superconducting sextupole magnet. An rf transition unit will then convert this beam into a fully proton-spin-polarized beam. The superfluid 4He film strongly suppresses recombination of hydrogen atoms on the mirror surface. By building a thick 4He superfluid film, we were able to produce a high intensity spin-polarized hydrogen beam, which operated with good stability during an 18-hours long run.