Bose-Einstein correlations between identical particles are measured in samples
of proton-proton collisions at 0.9 and 7TeV centre-of-mass energies, recorded by the CMS
experiment at the LHC. The signal is observed in the form of an enhancement of number of
pairs of same-sign charged particles with small relative momentum. The dependence of this
enhancement on kinematic and topological features of the event is studied. Anticorrelations
between same-sign charged particles are observed in the region of relative momenta higher
than those in the signal region
