On the possibility of measuring the polarization of a ${}^3\rm{He}$ beam at EIC by the HJET polarimeter

TL;DR

This paper explores the feasibility of using the HJET polarimeter to measure the polarization of a ${}^3\rm{He}$ beam at the EIC with high precision, addressing potential challenges and preliminary solutions.

Contribution

It demonstrates that HJET can potentially be adapted for ${}^3\rm{He}$ beam polarization measurement at EIC with systematic uncertainties below 1%.

Findings

HJET can achieve ~0.5% accuracy in polarization measurement.

Potential issues like analyzing power ratio and beam breakup are manageable.

Preliminary analysis suggests successful adaptation of HJET for ${}^3\rm{He}$ beams.

Abstract

The requirements for hadron polarimetry at the future Electron Ion Collider (EIC) include measurements of the absolute helion (${}^3\text{He}$, $h$) beam polarization with systematic uncertainties better than $\sigma^\text{syst}_P/P\lesssim1\%$. Here, we consider a possibility to utilize the Polarized Atomic Hydrogen Gas Jet Target (HJET) for precision measurement of polarization of the $\sim$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 $\delta^\text{syst}P/P\sim0.5\%$. Potential problems for adapting the HJET method for the EIC helion beam include (i) necessity to know the ratio of $p^\uparrow{h}$ and $h^\uparrow{p}$ analyzing powers $A_\text{N}^{ph}(t)/A_\text{N}^{hp}(t)$ with high precision, ({ii) possible beam ${}^3\text{He}$ breakup, and (iii) operation in a 10 ns bunch spacing beam. Preliminary results of an analysis discussed here indicate that the listed problems can be overcome and the helion beam absolute polarization can be measured by HJET with the required accuracy.