The SpinQuest polarized target

The polarized target system to be used in SpinQuest is a high-cooling-power evaporation refrigerator connected to a large pump stack (14,000 m3/hour) and a microwave generator used to dynamically polarize the nucleons in the target. The magnet has a 5-T field with a homogeneous region of 8 cm and will be used to polarize protons and neutrons in the sample.

Here the target system is shown the polarized target lab at the University of Virginia where the system was setup for testing and optimization. This system has the longest (along the beam-line) target cell to date for an evaporation refrigerator; this requires a unique microwave distributing horn and three NMR coils per target-cell to further reduce systematics in the polarization measurement.  This system was configured with the intention of having the greatest instantaneous luminosity of any previous evaporation refrigerator system by having a beam intensity of 3×1012 protons/sec for 5 seconds while using a large pump system (14,000 m3/hour).  We are also running an experiment with both polarized protons and neutrons which share different sensitivities to the overall figure of merit of the Drell-Yan asymmetry.