129Xe-Rb Spin-Exchange Optical Pumping with High Photon Efficiency

Here we present a Rb-Xe-129 spin-exchange optical pumping polarizer capable of rapid generation of large volumes of highly polarized Xe-129 gas. Through modeling and measurements we maximize the Xe-129 nuclear spin polarization output to enable the generation of polarized Xe-129 gas imaging volumes (300 cm(3)) every 5 min within a clinical setting. Our model is verified by experiment to correctly predict the optimum Rb vapor density for maximum Xe-129 nuclear polarization for a flux 3.4 W/cm(2) of circularly polarized Rb D-1 photons incident on an 80 cm long cylindrical optical cell. We measure a Xe-129 magnetization production efficiency of eta(pr) = 1.8%, which approaches the photon efficiency limit eta(gamma) = 3.3% of this system and enables the polarization of 2.72 x 10(22) Xe-129 spins per hour, corresponding to 1013 cm(3) of 100% polarized Xe-129 at STP. This magnetization production rate is threefold higher than the highest previously published Xe-129 magnetization production rate and has enabled routine clinical lung magnetic resonance imaging (MRI) with hyperpolarized( 129)Xe doses available on demand at run time, as well as high-SNR Xe-129 MRI of the human brain and kidneys.