Dynamically Polarized Target for the g_2~p and G_E~P Experiments at Jefferson Lab

摘要

Recently, two experiments were concluded in Hall A at Jefferson Lab which utilized a newly assembled, solid, polarized hydrogen target. The primary components of the target are a new, high cooling power ~4He evaporation refrigerator, and a re-purposed, superconducting split-coil magnet. It has been used to polarize protons in irradiated NH_3 at a temperature of 1 K and at fields of 2.5 and 5.0 tesla. Maximum polarizations of 55% and 95% were obtained at those fields, respectively. To satisfy the requirements of both experiments, the magnet had to be routinely rotated between angles of 0°, 6°, and 90° with respect to the incident electron beam.