Measurement of small angle antiproton-proton elastic scattering at √s =546 and 1800 GeV

Antiproton-proton elastic scattering was measured at c.m.s. energies √s =546 and 1800 GeV in the range of four-momentum transfer squared 0.025<-t<0.29 ${\mathrm{GeV}}^2$. The data are well described by the exponential form ${\mathit{e}}^{\mathit{b}\mathit{t}}$ with a slope b=15.28±0.58 (16.98±0.25) ${\mathrm{GeV}}^{\mathrm{-}2}$ at √s =546 (1800) GeV. The elastic scattering cross sections are, respectively, ${\mathrm{\sigma }}_{\mathrm{el}}$=12.87±0.30 and 19.70±0.85 mb.