Dipolar and scalar He 3 − Xe 129 frequency shifts in stemless cells

We study nuclear spin frequency shifts in a $^{3}\mathrm{He}\text{\ensuremath{-}}^{129}\mathrm{Xe}$ comagnetometer caused by spin polarization of $^{3}\mathrm{He}$. We use stemless cylindrical cells to systematically vary the cell geometry and separately measure the cell shape-dependent and shape-independent frequency shifts. We find that a certain aspect ratio for a cylindrical cell cancels the dipolar effects of $^{3}\mathrm{He}$ magnetization in the regime of fast spin diffusion. Using this control, we observe a scalar $^{3}\mathrm{He}\text{\ensuremath{-}}^{129}\mathrm{Xe}$ collisional frequency shift characterized by an enhancement factor ${\ensuremath{\kappa}}_{\text{HeXe}}=\ensuremath{-}0.011\ifmmode\pm\else\textpm\fi{}0.001$, which is in excellent agreement with theoretical calculations.