Speaker
Description
The requirements for hadron polarimetry at the future Electron Ion Collider (EIC) include measurements of the absolute helion (3He, ℎ) beam polarization with systematic uncertainties better than 𝜎syst𝑃/𝑃≤1%. Here, we consider a possibility to utilize the Polarized Atomic Hydrogen Gas Jet Target (HJET) for precision measurement of polarization of the ∼100\,GeV/n helion beam. HJET, which serves to determine absolute proton beam polarization at the Relativistic Heavy Ion Collider, provides the accuracy of about 𝛿syst𝑃/𝑃∼0.5%. To adapt the HJET method for the EIC helion beam, the experimentally determined ratio of the beam and target (jet) spin correlated asymmetries should be adjusted by the ratio of 𝑝↑ℎ and ℎ↑𝑝 analyzing powers 𝐴𝑝ℎN(𝑡)/𝐴ℎ𝑝N(𝑡) which, in the leading order approximation, is predefined by magnetic moments of the proton and helion, (𝜇𝑝−1)/(𝜇ℎ/2−1/3). However, to achieve the required accuracy in the measured polarization, the corrections due to hadronic spin-flip amplitudes and due to possible beam 3He breakup should be considered. Preliminary results of an analysis discussed here indicate that (i) the proton-helion hadronic spin-flip amplitudes can be related, with sufficient precision, to the proton-proton one and (ii) the breakup corrections are small and cancel in the ratio. So, the EIC helion beam absolute polarization can be measured by HJET with the required accuracy.
