The JLab Frozen Spin Target

A polarized, frozen spin target has been designed and constructed at Jefferson Lab for use inside the CEBAF Large Acceptance Spectrometer. Protons in TEMPO‐doped butanol are polarized via dynamic nuclear polarization (DNP) to approximately 90% using microwaves and an external, 5 T solenoid magnet. The target sample is then cooled to approximately 30 mK while an internal 0.56 T superconducting magnet is used to maintain the polarization. Relaxation times in excess of 3500 hours have been observed.