Luminosity determination in $pp$ collisions at $\sqrt{s}=13$ TeV using the ATLAS detector at the LHC

The luminosity determination for the ATLAS detector at the LHC during Run 2is presented, with $pp$ collisions at $\sqrt{s}=13$ TeV. The absoluteluminosity scale is determined using van der Meer beam separation scans duringdedicated running periods in each year, and extrapolated to the physicsdata-taking regime using complementary measurements from severalluminosity-sensitive detectors. The total uncertainties in the integratedluminosities for each individual year of data-taking range from 0.9% to 1.1%,and are partially correlated between years. After standard data-qualityselections, the full Run 2 $pp$ data sample corresponds to an integratedluminosity of $140.1\pm 1.2$ fb$^{-1}$, i.e. an uncertainty of 0.83%. Adedicated sample of low-pileup data recorded in 2017-18 for precision StandardModel physics measurements is analysed separately, and has an integratedluminosity of $338.1\pm 3.1$ pb$^{-1}$.