Quantum Statistical Correlations for Slowly Expanding Systems
  Quantum statistical correlations and momentum distributions are calculated for a spherically symmetric, three-dimensionally expanding finite fireballs, for non-relativistic expansions applying plane-wave approximation. The new concepts of the geometrical temperature as well as the thermal radius are presented for the simplest case. The symmetry properties of the correlation function are shown to reflect the symmetry properties of the emission function. 
T. Csorgo B. Lorstad and J. Zimanyi