Accurate measurement of F2d/F2p and Rd − Rp

Results are presented for F2d/F2p and Rd − Rp from simultaneous measurements of deep inelastic muon scattering on hydrogen and deuterium targets, at 90, 120, 200 and 280 GeV. The difference Rd − Rp, determined in the range 0.002 < x < 0.4 at an average Q2 of 5 GeV2, is compatible with zero. The x and Q2 dependence of F2d/F2p was measured in the kinematic range 0.001 < x < 0.8 and 0.1 < Q2 < 145 GeV2 with small statistical and systematic errors. For x > 0.1 the ratio decreases with Q2.