collinear laser quantum control of nuclear spins

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TRIUMF's (Canada's particle accelerator centre) laser nuclear-polarization facility, consisting of a continuous-wave, narrow-bandwidth dye laser system and a polarizer beam line, utilizes "optical pumping" to deliver various nuclear-spin-polarized radioactive isotopes to a multitude of experiments. In the optical pumping process, circularly polarized laser light, as a carrier of angular momentum in a specific direction, can transfer the momentum to the atoms/ions of interest via absorption and emission of photons, and further to the nuclei of the atoms/ions via electron-nucleus interactions. This method can provide nuclear polarization of up to 80%, which is highly desired and referred to as "hyperpolarization" by the Nuclear Magnetic Resonance community. Situated in the isotope separator and accelerator facility at TRIUMF, the polarizer facility is one of a few in the world which can provide access to highly nuclear-spin-polarized beams of short-lived radioactive nuclei. This facility has opened unique avenues to investigate material properties, biochemical processes, nuclear structures and fundamental symmetries. With growing demands from user communities, a major expansion of user stations is under preparation as part of TRIUMF's 20 year plan. This application seeks funding support for HQP training in developing nuclear-spin-control schemes and techniques for a variety of isotopes for emerging research. The short term goal is to develop practical schemes to nuclear-spin polarize 230,232Ac and 58,74Cu, due to their promising applications to Alzheimer's disease and cancers. Due to unique atomic properties such as isotope shifts (IS) and hyperfine structures (HFS) for different isotopes, a thorough investigation must be made for each isotope to establish a proper optical pumping scheme. The long term goal is to develop a universal polarization technique. "Cavity-assisted" optical pumping using pulsed lasers will be investigated. The broad bandwidth inherent to pulsed lasers can enable simultaneous pumping of all HFS sublevels, thus achieving polarization without distinguishing IS and HFS of different isotopes. The current optical pumping method uses continuous-wave lasers, due to the long interaction time needed for enough pumping cycles until polarization is achieved. With the assistance of a pulse-stretching optical cavity, this limitation of pulsed lasers can be overcome. Another avenue is to utilize a spin-polarized alkali-vapor mixture as a spin-exchange medium to transfer polarization to atom/ion beams, thus simplifying the laser system to one setup for general use. The program will train the next generation of researchers in this expanding interdisciplinary application of laser spin-manipulation techniques, expose them to collaborations with users of polarized beams, as well as drive R&D towards efficient and simplified nuclear spin control system to supply a variety of nuclear species demanded from different scientific communities.