Speaker
Description
The Polarized Hydrogen Gas Jet Target Polarimeter (HJET) at the Relativistic Heavy-Ion Collider (RHIC) is utilized to accurately measure the vertical polarization of proton beams with low systematic uncertainties of approximately $\sigma^\text{syst}_P/P\le0.5\%$. These measurements are conducted in the CNI region, $0.0013<|t|<0.017~\rm{GeV}^2$. By measuring the elastic single $A_\text{N}(t)$ and double $A_\text{NN}(t)$ spin analyzing powers for 100 and 255 GeV proton beams, the contributions from hadronic spin-flip amplitudes were isolated. A Regge fit was performed, revealing a non-zero Pomeron spin-flip component. Preliminary results for inelastic $p^{\uparrow}p$ and elastic $p^{\uparrow}A$ (for $d$, O, Al, Ru, Zr, and Au nuclei) analyzing powers were also obtained. However, the completion of these studies requires the development of a theoretical parametrization for the corresponding analyzing powers. The successful implementation of HJET at RHIC has prompted its potential use for proton beam polarimetry with a desired accuracy of 1\% at the upcoming Electron-Ion Collider (EIC). The feasibility of using HJET for $^3$He $(h)$ beam polarimetry at EIC will also be discussed. To accurately measure the helion beam polarization using HJET, knowledge of the hadronic spin-flip amplitudes for the $p^{\uparrow}h$ and $h^{\uparrow}p$ is essential. These amplitudes can be derived with sufficient precision from the proton-proton hadronic spin-flip amplitude determined at HJET. Another potential concern for $^3$He polarization measurement is the possibility of helion breakup in $hp$ scattering. An estimate of the breakup effect indicates that while it can introduce corrections of up to 4\% to the spin-flip interference terms, these effects cancel out and have negligible impact on the calculating the $^3$He beam polarization (which depends on the effective $A_\text{N}^{ph}(t)/A_\text{N}^{hp}(t)$ analyzing power ratio).
