Measurement of the antiproton-proton total cross section at √<i>s</i>=546 and 1800 GeV

We report a measurement of the proton-antiproton total cross section ${\mathrm{\ensuremath{\sigma}}}_{\mathit{T}}$ at c.m.s. energies \ensuremath{\surd}s =546 and 1800 GeV. Using the luminosity-independent method, we find ${\mathrm{\ensuremath{\sigma}}}_{\mathit{T}}$=61.26\ifmmode\pm\else\textpm\fi{}0.93 mb at \ensuremath{\surd}s =546 GeV and 80.03\ifmmode\pm\else\textpm\fi{}2.24 mb at \ensuremath{\surd}s =1800 GeV. In this energy range, the ratio ${\mathrm{\ensuremath{\sigma}}}_{\mathrm{el}}$/${\mathrm{\ensuremath{\sigma}}}_{\mathit{T}}$ increases from 0.210\ifmmode\pm\else\textpm\fi{}0.002 to 0.246\ifmmode\pm\else\textpm\fi{}0.004.