Extraction of $R=\frac{{\sigma }_L}{{\sigma }_T}$ from Deep Inelastic $e-p$ and $e-d$ Cross Sections

The quantity $R=\frac{{\sigma }_L}{{\sigma }_T}$ is extracted for the proton, deuteron, and neutron from deep inelastic $e-p$ and $e-d$ scattering cross sections measured in recent experiments at Stanford Linear Accelerator Center. For $\omega <~5$ the kinematic behavior of $\nu R_p$ is consistent with scaling, indicative of spin-½ constituents in a parton model of the proton. We also find that within large statistical errors, $R_d$ and $R_n$ are consistent with being equal to $R_p$.