Luminosity-Independent Measurement of the Proton-Proton Total Cross Section ats=8 TeV
The TOTEM collaboration has measured the proton-proton total cross section at $\sqrt{s}=8\text{ }\text{ }\mathrm{TeV}$ using a luminosity-independent method. In LHC fills with dedicated beam optics, the Roman pots have been inserted very close to the beam allowing the detection of $\ensuremath{\sim}90%$ of the nuclear elastic scattering events. Simultaneously the inelastic scattering rate has been measured by the T1 and T2 telescopes. By applying the optical theorem, the total proton-proton cross section of $(101.7\ifmmode\pm\else\textpm\fi{}2.9)\text{ }\text{ }\mathrm{mb}$ has been determined, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: ${\ensuremath{\sigma}}_{\mathrm{el}}=(27.1\ifmmode\pm\else\textpm\fi{}1.4)\text{ }\text{ }\mathrm{mb}$; ${\ensuremath{\sigma}}_{\mathrm{inel}}=(74.7\ifmmode\pm\else\textpm\fi{}1.7)\text{ }\text{ }\mathrm{mb}$.