Anisotropic Hyperfine Interactions Limit the Efficiency of Spin-Exchange Optical Pumping of 3He Nuclei

Abstract

We use accurate ab initio and quantum scattering calculations to demonstrate that the maximum He3 spin polarization that can be achieved in spin-exchange collisions with potassium (K39) and silver (Ag107) atoms is limited by the anisotropic hyperfine interaction. We find that spin exchange in Ag-He collisions occurs much faster than in K-He collisions over a wide range of temperatures (10–600 K). Our analysis indicates that measurements of trap loss rates of S2 atoms in the presence of cold He3 gas may be used to probe anisotropic spin-dependent interactions in atom-He collisions.