Beam Physics Seminar

Monday, March 29, 2004,10:30 AM
ARC Bldg. Room 231/233

Developing tools for high energy spin physics experiments
(Spin flipper rf dipole magnet and ultra-cold polarized Hydrogen gas jet target)

Katsuya Yonehara
Illinois Institute of Technology

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.

Talk Slides: (PDF)