Two-particle correlations have been measured for identified pi(-) from cent
ral 158 A GeV Pb+Pb collisions and fitted radii of about 7 fm in all dimens
ions have been obtained. A multi-dimensional study of the radii as a functi
on of k(gamma) is presented, including a full correction for the resolution
effects of the apparatus. The cross term R-out-long(2) of the standard fit
in the Longitudinally CoMoving System (LCMS) and the upsilon(L) parameter
of the generalised Yano-Koonin fit are compatible with 0, suggesting that t
he source undergoes a boost invariant expansion.
The shapes of the correlation functions in Q(inv) and Q(space) = root<(Q(x)
(2) + Q(y)(2) + Q(z)(2))over bar> have been analyzed in detail. They are no
t Gaussian but better represented by exponentials. As a consequence, fittin
g Gaussians to these correlation functions may produce different radii depe
nding on the acceptance of the experimental setup used for the measurement.