Measurement of Bose-Einstein correlations in ATLAS

The measurement 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 is presented. The multiplicity dependence of the BEC 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 is discussed.