A high-pressure polarized 3He gas target for nuclear-physics experiments using a polarized photon beam

Following the first experiment on three-body photodisintegration of polarized 3 He utilizing circularly polarized photons from High-Intensity Gamma Source (HI gamma S) at Duke Free Electron Laser Laboratory (DFELL), a new high-pressure polarized He-3 target cell made of pyrex glass coated with a thin layer of sol-gel doped with aluminum nitrate nonahydrate has been built in order to reduce the photon beam-induced background. The target is based on the technique of spin exchange optical pumping of hybrid rubidium and potassium and the highest polarization achieved is similar to 62% determined from both NMR-AFP and EPR polarimetries. The phenomenological parameter that reflects the additional unknown spin relaxation processes, X, is estimated to be similar to 0.10 and the performance of the target is in good agreement with theoretical predictions. We also present beam test results from this new target cell and the comparison with the GE180 He-3 target cell used previously at HI gamma S. This is the first time that the sol-gel coating technique has been used in a polarized He-3 target for nuclear-physics experiments.