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 ³He utilizing circularly polarized photons from High-Intensity Gamma Source (HIg gamma S) at Duke Free Electron Laser Laboratory (DFELL), a new high-pressure polarized ³He 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 ∼ 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 ∼ 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 ³He target cell used previously at HIg gamma S. This is the first time that the sol-gel coating technique has been used in a polarized ³He target for nuclear-physics experiments.