  The transverse momentum spectra of the produced hadrons have been compared to
a model which is based on the assumption that a nucleus-nucleus collision is a
superposition of isotropically decaying thermal sources at a given freeze out
temperature. The freeze-out temperature in nucleus-nucleus collisions is fixed
from the inverse slope of the transverse momentum spectra of hadrons in
nucleon-nucleon collision. The successive collisions in the nuclear reaction
leads to gain in transverse momentum, as the nucleons propagate in the nucleus
following a random walk pattern. The average transverse rapidity shift per
collision is determined from the nucleon-nucleus collision data. Using these
information we obtain parameter free result for the transverse momentum
distribution of produced hadrons in nucleus-nucleus collisions. It is observed
that such a model is able to explain the transverse mass spectra of produced
pions at SPS energies. However it fails to satisfactorily explain the
transverse mass spectra of kaons and protons. This indicates the presence of
collective effect which cannot be accounted for by the initial state collision
broadening of transverse momentum of produced hadrons, the basis of random walk
model.
