A high-pressure polarized 3He gas target for the High Intensity Gamma Source (HIγγS) facility at Duke Free Electron Laser Laboratory

A new polarized 3He target has been developed for nuclear physics experiments utilizing the High Intensity Gamma Source (HIγγS) at the Duke Free Electron Laser Laboratory (DFELL). This target is designed for a broad program of physics employing high intensity polarized photons and a polarized 3He target as an effective polarized neutron target. We report the performance of this target based on the technique of spin-exchange optical pumping (SEOP). Due to the significantly larger photon beam size at the HIγγS facility than that of a typical electron beam at electron accelerator laboratories, the HIγγS 3He target contains a larger number of 3He nuclei than any polarized 3He targets reported previously. A target polarization on the order of 33–46% has been achieved from both a regular 3He–Rubidium (Rb) target and a hybrid target which contains a mixture of Rb and potassium. The target polarization has been determined within 3%3% using both the Electron Paramagnetic Resonance (EPR) technique and the NMR–AFP (Adiabatic Fast Passage) technique.