Two-particle Bose-Einstein correlations in $pp$ collisions at $\mathbf {\sqrt{s} = 900}$ GeV and 7 TeV measured with the ATLAS detector

The paper presents studies of Bose--Einstein Correlations for pairs of like-sign charged particles measured in the kinematic range $p_T >$ 100 MeV and $|\eta|<$ 2.5 in proton--proton collisions at centre-of-mass energies of 0.9 and 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. The multiplicity dependence of the Bose--Einstein Correlations parameters characterizing the correlation strength and the correlation source size are investigated for charged-particle multiplicities of up to 240. A saturation effect in the multiplicity dependence of the correlation source size parameter is observed using the high-multiplicity 7 TeV data sample. The dependence of the Bose--Einstein Correlations parameters on the average transverse momentum of the particle pair is also investigated.