Measurement of the transverse-spin asymmetries in \textit{pp} elastic

The single transverse-spin asymmetry (analyzing power $A_N$) for pp elastic scattering is expected to reach a peak of $0.045$ in the Coulomb Nuclear Interference (CNI) region at very small momentum transfer $-t$ of $0.003$ $(\rm{GeV/\textit{c})^2}$. During the 2004 RHIC run, we completed a measurement of $A_N$ in the CNI region by detecting the recoil protons from pp elastic scattering using a polarized hydrogen gas jet target and the 100 GeV RHIC proton beam. In this talk, we will show the first measurements of the $A_N$ absolute value and shape in the $-t$ range from 0.0015 to 0.032 $(\rm {GeV/\textit{c})^2}$ with a precision better than $0.005$ for each $A_N$ data point. The recoil protons were detected with an array of Si detectors. The absolute target polarization as monitored by a Breit-Rabi polarimeter was stable at $0.924\pm 0.018$. At the same time, exploiting the polarization of target and beam, we have also measured the double transverse-spin asymmetry ($A_{NN}$). These results allow us to further investigate the spin dependence of elastic \textit{pp} scattering in the very low $-t$ region.