First measurement of the total proton-proton cross-section at the LHC energy of

TOTEM has measured the differential cross-section for elastic proton-proton scattering at the LHC energy of $\sqrt{s} = 7\,{\rm TeV} $ analysing data from a short run with dedicated large-β* optics. A single exponential fit with a slope B=(20.1±0.2stat±0.3syst) GeV−2 describes the range of the four-momentum transfer squared |t| from 0.02 to 0.33 GeV2. After the extrapolation to |t|=0, a total elastic scattering cross-section of (24.8±0.2stat±1.2syst) mb was obtained. Applying the optical theorem and using the luminosity measurement from CMS, a total proton-proton cross-section of (98.3±0.2stat±2.8syst) mb was deduced which is in good agreement with the expectation from the overall fit of previously measured data over a large range of center-of-mass energies. From the total and elastic pp cross-section measurements, an inelastic pp cross-section of $(73.5\pm 0.6^{{\rm stat}}{}{\fontsize{6}{6}\selectfont{\begin{array}{c}{+1.8}\\{-1.3}\end{array}}}\,{}^{{\rm syst}})\,{\rm mb} $ was inferred