Measurement of the Inelastic Proton-Proton Cross Section at $sqrt{s}=7$~TeV with the ATLAS Detector

We present a first measurement of the inelastic cross section for proton-proton collisions at a center-of-mass energy $\sqrt{s}=7$~TeV using the ATLAS detector at the Large Hadron Collider. Events are selected on the basis of scintillator hits in the forward region of the detector with a dataset corresponding to an integrated luminosity of 21~$\mu$b$^{-1}$. We measure $57.2 \pm 6.3$~mb for the inelastic cross section excluding diffractive contributions where both of the dissociation masses, $M_X$, satisfy $\xi=M_X^2/s<10^{-5}$.