  Two particle correlations are used to extract information about the
characteristic size of the system for proton-proton collisions at 900 GeV
measured by the ALICE (A Large Ion Collider experiment) detector at CERN. The
correlation functions obtained show the expected Bose-Einstein effect for
identical particles, but there are also long range correlations present that
shift the baseline from the expected flat behavior. A possible source of these
correlations is the conservation of energy and momentum, especially for small
systems, where the energy available for particle production is limited. A new
technique, first introduced by the STAR collaboration, of quantifying these
long range correlations using energy-momentum conservation considerations is
presented here. It is shown that the baseline of the two particle correlation
function can be described using this technique.
