Comparison of High-pTEvents Produced by Pions and Protons

We have measured high-$p_T$ ${\pi }^0$'s and jets with a two-arm calorimeter detector. Pions produce large-$x_T$ jets more readily than do protons. We report the first direct measurement of two-arm jets. We find that the jet pairs have roughly balanced $p_T$ and that pions produce jet pairs at more forward angles than do protons. These results give evidence for a constituent-scattering model, with constituents of higher average momentum in the pion.