Saturation of shadowing at very low Bjorken x.

The ratio of cross sections for inelastic muon scattering on xenon and deuterium nuclei was measured at very low Bjorken {ital x} (0.000 02{lt}{ital x}{sub Bj}{lt}0.25). The data were taken at Fermilab experiment E-665 with a 490 GeV/{ital c} muon beam incident on liquid deuterium and gaseous xenon targets. Two largely independent analysis techniques gave statistically consistent results. The xenon-to-deterium per-nucleon cross-section ratio is constant at approximately 0.7 for {ital x}{sub Bj} below 0.003.