On the determinations of the size and shape of the interaction region   from Bose-Einstein correlations
  Determinations of the size and shape of the interaction region from k-particle (k=1,2,...) momentum distributions of identical particles are analyzed. The full group of transformations changing the single particle density matrix without affecting any of the measurable momentum distributions is identified. The corresponding uncertainties in the inferred parameters of the interaction region are discussed. 
K. Zalewski