Large-angle elastic proton-proton polarization at 5.15GeVc

Abstract

We present herein the initial results of a large-angle elastic $p\ensuremath{-}p$ polarization experiment which is now in progress at the Argonne ZGS (Zero-Gradient Synchrotron) accelerator. Data for the incident proton momentum of 5.15 $\frac{\mathrm{GeV}}{c}$ are presented for ${30}^{\ensuremath{\circ}}\ensuremath{\lesssim}{\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}\ensuremath{\lesssim}{90}^{\ensuremath{\circ}}$. These results, which extend to $t\ensuremath{\approx}\ensuremath{-}4.0{(\frac{\mathrm{GeV}}{c})}^{2}$, represent the first high-statistics $p\ensuremath{-}p$ polarization measurements for $|t|$ values greater than \ensuremath{\sim}2.5 ${(\frac{\mathrm{GeV}}{c})}^{2}$. We observe a minimum in the polarization near $t=\ensuremath{-}0.8{(\frac{\mathrm{GeV}}{c})}^{2}$, a smooth increase in the polarization until a maximum is attained near $t=\ensuremath{-}1.8{(\frac{\mathrm{GeV}}{c})}^{2}$, and then a monotonic decline in the polarization until the value of zero is reached at ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}={90}^{\ensuremath{\circ}}$. The data are analyzed in terms of an optical model.