Optically polarized ³He

Area of Science:

• Atomic physics
• Quantum optics
• Nuclear physics

Background:

• Highly spin-polarized helium-3 (³He) nuclei are crucial for applications like polarized targets and neutron spin filters.
• Producing large quantities of polarized ³He efficiently has been a long-standing challenge.

Purpose of the Study:

• To review the physics and technological advancements in producing highly spin-polarized ³He nuclei.
• To highlight improvements in spin-exchange optical pumping (SEOP) and metastability-exchange optical pumping (MEOP).

Main Methods:

• Review of spin-exchange optical pumping (SEOP) using spectrally narrowed lasers and K-Rb mixtures.
• Review of metastability-exchange optical pumping (MEOP) with nearly lossless compression and high magnetic field operation.
• Discussion of advancements in storage methods for long spin-relaxation times and precision polarimetry.

Main Results:

• SEOP now achieves higher polarization and polarizing rates.
• MEOP enables rapid production of polarized ³He and operation at higher pressures, revealing new phenomena.
• Storage methods have extended spin-relaxation times to hundreds of hours.

Conclusions:

• Both SEOP and MEOP have seen substantial improvements in capabilities.
• These advanced techniques are now widely applicable in fields such as polarized targets, neutron spin filters, MRI, and precision measurements.