Optically pumped polarized [formula omitted]He[formula omitted] ion source development for RHIC/EIC

Abstract

The proposed polarized 3He++ acceleration in RHIC and the future Electron-Ion Collider will require about 2×1011 ions in the source pulse. A new technique had been proposed for production of high intensity polarized 3He++ ion beams. It is based on ionization and accumulation of the 3He gas (polarized by metastability-exchange optical pumping and in the 5T high magnetic field) in the existing Electron Beam Ion Source (EBIS). A novel 3He cryogenic purification and storage technique was developed to provide the required gas purity. An original gas refill and polarized 3He gas injection to the EBIS long drift tubes, (which serves as the storage cell) were developed to ensure polarization preservation. An infrared laser system for optical pumping and polarization measurements in the high 3–5T field has been developed. The 3He polarization 80–85% (and sufficiently long ∼30min relaxation time) was obtained in the “open” cell configuration with refilling valve tube inlet and isolation valve closed. The development of the spin-rotator and 3He4He absolute nuclear polarimeter at 6MeV 3He++ beam energy is also presented.