Using a relativistic hadron transport model, we investigate the utility of the elliptic flow excitation function as a probe for the stiffness of nuclear matter and for the onset of a possible quark-gluon-plasma (QGP) phasetransition at AGS energies 1 < ∼ E Beam < ∼ 11 AGeV. The excitation function shows a strong dependence on the nuclear equation of state, and exhibits characteristic signatures which could signal the onset of a phase transition to the QGP.PACS 25.75.Ld, 24.85.+p, 24.10.Jv Typeset using REVT E X 1

Transverse momentum spectra for charged hadrons and for neutral pions in the range 1 GeV/c