  Measurements of various particle species over an extended momentum range
provide a sensitive experimental tool for investigating particle production
mechanisms in hadronic collisions. Comparison of the spectral shapes from
different collision centralities measured with the STAR detector at RHIC allows
one to study the interplay of soft and hard particle production for mesons and
investigate various baryon-meson effects. Systematic studies of identified
particle spectra for various colliding systems and different incident energies
provide additional insights toward the interplay between fragmentation and
non-fragmentation contributions to the particle production. In these
proceedings we present a systematic study of transverse momentum spectra for
charged pions, protons and antiprotons from Au+Au and Cu+Cu data at
sqrt(s_NN)=200 and 62.4 GeV as a function of collision centrality. We compare
those measurements with p+p and d+Au data, investigating the system effects on
energy loss.
