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Energy Dependence of Spin Effects in p ↑ + p ↑ → p + p

1986; American Physical Society; Volume: 57; Issue: 5 Linguagem: Inglês

10.1103/physrevlett.57.507

1092-0145

G.R. Court, Donald G. Crabb, I. Gialas, F. Z. Khiari, A. D. Krisch, A. M. T. Lin, R. S. Raymond, Raymond R. Raylman, T. Roser, K. M. Terwilliger, Kevin Brown, L. G. Ratner, D. C. Peaslee, P. Cameron, J. R. O’Fallon, T. S. Bhatia, L. C. Northcliffe, M. Simonius,

Particle Accelerators and Free-Electron Lasers

We measured the analyzing power $A$ and the spin-spin correlation parameter ${A}_{\mathrm{nn}}$, in large-${P}_{\ensuremath{\perp}}^{2}$ proton-proton elastic scattering, using a polarized-proton target and the polarized-proton beam at the Brookhaven Alternating-Gradient Synchrotron. We also used our polarimeter to measure $A$ at small ${P}_{\ensuremath{\perp}}^{2}$ at 13 GeV with good precision and found some deviation from the expected $\frac{1}{{P}_{\mathrm{lab}}}$ behavior. At 18.5 GeV/c we found ${A}_{\mathrm{nn}}=(\ensuremath{-}2\ifmmode\pm\else\textpm\fi{}16)%$ at ${P}_{\ensuremath{\perp}}^{2}=4.7$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$. Comparison with lower-energy data from the Argonne Zero-Gradient Synchrotron shows a sharp and surprising energy dependence for ${A}_{\mathrm{nn}}$ at large ${P}_{\ensuremath{\perp}}^{2}$.