Author/Authors :
Pierce، نويسنده , , J. and Maxwell، نويسنده , , J. and Badman، نويسنده , , T. and Brock، نويسنده , , J. and Carlin، نويسنده , , C. and Crabb، نويسنده , , D.G. and Day، نويسنده , , D. and Keith، نويسنده , , C.D. and Kvaltine، نويسنده , , Candice N. and Meekins، نويسنده , , D.G. and Mulholland، نويسنده , , J. and Shields، نويسنده , , J. and Slifer، نويسنده , , K.، نويسنده ,
Abstract :
We describe a dynamically polarized target that has been utilized for two electron scattering experiments in Hall A at Jefferson Lab. 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 NH3 at a temperature of 1 K and at fields of 2.5 and 5.0 T. The performance of the target material in the electron beam under these conditions will be discussed. Maximum polarizations of 28% 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. This was accomplished using a new rotating vacuum seal which permits rotations to be performed in only a few minutes.
