pi (-)pi (-)pi (-) correlations from Pb+Pb collisions at 158 GeV/c per nucl
eon are presented as measured by the focusing spectrometer of the NA44 expe
riment at CERN. The three-body effect is found to be stronger for Pb+Pb tha
n for S+Pb. The two-dimensional three-particle correlation function is also
measured and the longitudinal extension of the source is larger than the t
ransverse extension. (C) 2001 Published by Elsevier Science B.V.