Sensitivity of pp-bremsstrahlung to meson-exchange currents

We present pp-bremsstrahlung cross section calculations at the π-production threshold to search for kinematics that best differentiate model-dependent descriptions of the NN t-matrix and accentuate the contributions of isoscalar meson-exchange currents. Existing optimization procedures are shown to be completely unreliable due to the neglect of meson-exchange currents and phase space variations. We show that phase-space hides the most important differences in model t-matrices, but that improved data will be critical to further investigations of exchange currents.