Identification of baryon resonances in central heavy-ion collisions at energies between 1 and 2 AGeV

The mass distributions of baryon resonances populated in near-central colli sions of Au on Au and Ni on Ni are deduced by defolding the p(t) spectra of charged pions by a method which does not depend on a specific resonance sh ape. In addition the mass distributions of resonances are obtained from the invariant masses of (p. pi(+/-)) pairs. With both methods the deduced mass distributions are shifted by an average value of -60 MeV/c(2) relative to the mass distribution of the free Delta(1232) resonance, the distributions descent almost exponentially towards mass values of 2000 MeV/c(2). The obse rved differences between (p, pi(-)) and (p, pi(+)) pairs indicate a contrib ution of isospin I = 1/2 resonances. The attempt to consistently describe t he deduced mass distributions and the reconstructed kinetic energy spectra of the resonances leads to new insights about the freeze out conditions, i. e. to rather low temperatures and large expansion velocities.