Prof. Dr. Karl Slifer (UNH): Using Polarized Targets to Understand the Hyperfine Splitting in Hydrogen

The hyperfine interaction has played a major role in radio astronomy, big bang cosmology and even searches for extraterrestrial intelligent life. The hydrogen line has been measured with stunning experimental precision in spectroscopy, but theoretical predictions of this fundamental quantity lag far behind. The main uncertainty arises from the proton's spin dependent substructure which can not at present be calculated from first principles, but is instead determined via high energy scattering from polarized protons. We discuss how polarized target technology has been used to investigate this process, and to reduce the overall error of this quantity by a factor of two.