Dipolar and scalar ${}^3$He-${}^{129}$Xe frequency shifts in stemless cells

We study nuclear spin frequency shifts in a ${}^3$He-${}^{129}$Xe comagnetometer caused by spin polarization of ${}^3$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 ${}^3$He magnetization in the regime of fast spin diffusion. Using this control we observe a scalar ${}^3$He-${}^{129}$Xe collisional frequency shift characterized by an enhancement factor $\kappa_{$\text{HeXe}$} = -0.011\pm0.001$ in excellent agreement with theoretical calculation.