This Letter presents a measurement of the inelastic proton-proton cross section using 60??µb -1 of pp collisions at a center-of-mass energy vs of 13 TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using rings of plastic scintillators in the forward region (2.07<|?|<3.86 ) of the detector. A cross section of 68.1±1.4??mb is measured in the fiducial region ?=M 2 X /s>10 -6 , where M X is the larger invariant mass of the two hadronic systems separated by the largest rapidity gap in the event. In this ? range the scintillators are highly efficient. For diffractive events this corresponds to cases where at least one proton dissociates to a system with M X >13??GeV . The measured cross section is compared with a range of theoretical predictions. When extrapolated to the full phase space, a cross section of 78.1±2.9??mb is measured, consistent with the inelastic cross section increasing with center-of-mass energy.
Funding
STFC Consolidated Grant Supplement; G1316; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/M000753/1