Abstract
First results of the mT dependence of π+π+ and K+K+ correlations from S+Pb collisions at 200 GeV /c per nucleon measured by the focusing spectrometer of the NA44 experiment at CERN are presented. Multidimensional fits characterize the pion and kaon emission volume. The pion radius parameter decreases with increasing pT. Furthermore, the pion and kaon radii show a common 1/mT dependence. This behavior can be interpreted as a result of a strong momentum-position correlation arising from collective flow.