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Polarimeters were developed to measure the polarization of the proton beam at RHIC in relative scale through the asymmetry measurement of the elastic proton-carbon scattering. Recoil carbon ions with kinetic energy of 400 ≤ E ≤ 900 keV were detected by silicon strip detectors installed at 90° with respect to the beam. The absolute polarization is given by normalizing against another polarimeter implemented at RHIC, namely a polarized hydrogen gas jet polarimeter. In this report, the details of polarization measurements, data analysis, and systematic uncertainties are discussed based on the data taken during √s = 200 GeV operation of Run05 at RHIC.

Elastic scattering of polarized protons at small four momentum transfer squared t is described by interference of Coulomb and nuclear amplitudes. Coulomb amplitude is well calculable by QED and such interference provides a unique opportunity to study the nuclear amplitude. At high energies this amplitude is believed to be dominated by Pomeron exchange. Measurement of asymmetries can provide evidence for contribution of other Reggeons, including hypothetical Odderon. Polarized proton collider at RHIC facility is a perfect place for such experiment.A one‐week dedicated run with special beam optics in June 2009 allowed us to collect statistics of more than 30 millions of elastic triggers with transversely polarized beams in the ‐t range 0.005–0.035 (GeV/c)2 at s = 200 GeV. In this paper we present preliminary results of single and double transverse spin asymmetries.

Precise measurements of the single spin asymmetry ${A}_{N}$, and the double spin asymmetry ${A}_{NN}$, in proton-proton ($pp$) elastic scattering in the region of four-momentum transfer squared $0.001l\ensuremath{-}tl0.032\text{ }\text{ }(\mathrm{GeV}/c{)}^{2}$ have been performed using a polarized atomic hydrogen gas jet target and the Relativistic Heavy Ion Collider (RHIC) polarized proton beam. We present measurements of ${A}_{N}$ and ${A}_{NN}$ at center-of-mass energies $\sqrt{s}=6.8$ and 13.7 GeV. These spin-dependent observables are sensitive to the poorly known hadronic spin-dependent amplitudes. Comparing ${A}_{N}$ at different energies, a $\sqrt{s}$ dependence of the hadronic single spin-flip amplitude is suggested. A hadronic double spin-flip amplitude from the ${A}_{NN}$ data is consistent with zero within a 2-$\ensuremath{\sigma}$ level. We also present $\ensuremath{\Delta}{\ensuremath{\sigma}}_{T}$, estimated from the measured ${A}_{NN}$ data. The results for $\ensuremath{\Delta}{\ensuremath{\sigma}}_{T}$ are consistent with zero. Our results provide significant constraints toward a comprehensive understanding of the reaction mechanism for $pp$ elastic scattering.

The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.

The relativistic heavy ion collider (RHIC) as the first high energy polarized proton collider was designed to provide polarized proton collisions at a maximum beam energy of 250 GeV. It has been providing collisions at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during the acceleration from injection to 100 GeV with careful control of the betatron tunes and the vertical orbit distortions. However, the intrinsic spin resonances beyond 100 GeV are about a factor of two stronger than those below 100 GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were accelerated to the record energy of 250 GeV in RHIC with a polarization of 46% measured at top energy in 2006. The polarization measurement as a function of beam energy also shows some polarization loss around 136 GeV, the first strong intrinsic resonance above 100 GeV. This paper presents the results and discusses the sensitivity of the polarization survival to orbit distortions.

The polarized hydrogen Jet target at RHIC continues its mission to provide absolute calibration for the polarized proton beam polarimeters at RHIC. Data were collected at incoming beam momenta of 100, 24, and 32 GeV/c respectively. The statistical and systematic accuracy of the jet data at 100 GeV/c achieved its goal of statistical accuracy of measuring the beam polarization to 3% in Run 5. Attempts at reducing the jet systematic uncertainty due to molecular hydrogen are also described.

The Brookhaven Relativistic Heavy Ion Collider (RHIC) has been providing collisions of polarized protons at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during acceleration from injection to 100 GeV. However, the intrinsic spin resonances beyond 100 GeV are about a factor of 2 stronger than those below 100 GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were first accelerated to the record energy of 205 GeV in RHIC with a significant polarization measured at top energy in 2005. This Letter presents the results and discusses the sensitivity of the polarization survival to orbit distortions.

We report the first measurements of the A_N absolute value and shape in the -t range from 0.0015 to 0.010GeV/c^2 with a precision better than 0.005 for each A_N data point using a polarized atomic hydrogen gas jet target and the 100 GeV RHIC proton beam., Comment: 4 pages, 5 figures

Polarized proton beam has been accelerated and stored at 100GeV in Relativistic Heavy Ion Collider (RHIC) to study spin effects in the hadronic reactions. The essential equipment includes four Siberian snakes and eight spin rotators in two RHIC rings, a partial snake in the AGS, fast relative polarimeters, and ac dipoles in the AGS and RHIC. This paper summarizes the performance of RHIC as a polarized proton collider and of AGS as the injector to RHIC.

Preliminary results from the ’03 RHIC Proton Spin Run on the spin dependence in the elastic scatterring of polarized protons off a carbon target at very low momentum transfer (0.005 < |t| < 0.05 GeV2/c2) are presented and discussed. Proton polarimeters based on this process are used in RHIC and AGS to measure reliably and in very short times the polarization of the proton beams. Polarimetry results from the just completed RHIC polarized proton run are also presented.

We successfully injected polarized protons in both RHIC rings and maintained polarization during acceleration up to 100 GeV per ring using two Siberian snakes in each ring. Each snake consists of four helical superconducting dipoles which rotate the polarization by 180° about a horizontal axis. This is the first time that polarized protons have been accelerated to 100 GeV.

The analyzing power for proton-carbon elastic scattering in the Coulomb-nuclear interference region of momentum transfer, $9.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}l\ensuremath{-}tl4.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$ $(\mathrm{G}\mathrm{e}\mathrm{V}/c{)}^{2}$, was measured with a $21.7\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$ polarized proton beam at the Alternating Gradient Synchrotron of Brookhaven National Laboratory. The ratio of hadronic spin-flip to nonflip amplitude, ${r}_{5}$, was obtained from the analyzing power to be $\mathrm{R}\mathrm{e}{r}_{5}=0.088\ifmmode\pm\else\textpm\fi{}0.058$ and $\mathrm{I}\mathrm{m}{r}_{5}=\ensuremath{-}0.161\ifmmode\pm\else\textpm\fi{}0.226$.

The RHIC polarized proton complex utilizes polarimeters in each of the Blue and Yellow beams that measure the beam polarization through the p-Carbon elastic scattering process in the Coulomb Nuclear Interference kinematic region. This along with a Polarized Hydrogen Jet Target that utilizes the proton-proton elastic scattering process to first measure the analyzing power of the reaction and using the reverse process to measure the beam polarization. The latter is used to calibrate the p-Carbon polarimeters at the desired beam energy. In Run 9 RHIC ran with beams at center-of-mass energies of 200 and 500 GeV respectively. The higher beam intensities as well as the fact that the 250 GeV beam size is much smaller than that at 100 GeV resulted in significantly higher rates seen by the polarimeters and led to observed instability. In this paper, we will discuss the problems encountered and the tests that were carried out using the AGS as a proxy in an attempt to solve the problems and the path forward we took towards the upcoming polarized proton Run11.

The experimental study of the single, $A_\text{N}(t)$, and double, $A_\text{NN}(t)$, spin analyzing powers was carried out at The Polarized Atomic Hydrogen Jet Target polarimeter (HJET) at The Relativistic Heavy Ion Collider (RHIC). Large statistics of elastic $pp$ events accumulated during RHIC Runs 2015 ($E_\text{beam}=100\ \text{GeV}$) and 2017 ($E_\text{beam}=255\ \text{GeV}$) allowed us to measure analyzing powers in the CNI region $0.001\lesssim-t\lesssim0.02~\text{GeV}$ with unprecedented precision $|\delta A_\text{N,NN}|\lesssim2\times10^{-4}$. The hadronic single spin-flip $r_5$ and double spin-flip $r_2$ amplitude parameters were reliably isolated. Based on this two beam energies measurement, Pomeron and Regge-pole contributions to the hadronic single- and double- spin-flip amplitudes were evaluated. Extrapolation of the measured $r_5(s)$ to $\sqrt{s}=200\ \text{GeV}$ is in agreement with STAR measurements at this energy. A possibility to use HJET data to search for an Odderon contribution to the spin-flip amplitudes is discussed.