Measurement of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mi>↑</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>+<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mi>↑</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>→p+p with a 16.5-GeV/<i>c</i>polarized proton beam

Using the new Brookhaven Alternating Gradient Synchrotron polarized proton beam and our polarized proton target, we measured the spin-spin correlation parameter ${A}_{\mathrm{nn}}$ in 16.5-GeV/c proton-proton elastic scattering. We found an ${A}_{\mathrm{nn}}$ of (6.1\ifmmode\pm\else\textpm\fi{}3.0)% at ${P}_{\ensuremath{\perp}}$${\mathrm{}}^{2}$=2.2 (GeV/c${)}^{2}$. We also measured the analyzing power A in two independent ways, providing a good test of possible experimental errors. Comparing our new data with 12-GeV Argonne Zero Gradient Synchrotron data shows no evidence for strong energy dependence in ${A}_{\mathrm{nn}}$ in this medium-${P}_{\ensuremath{\perp}}$${\mathrm{}}^{2}$ region.