On the Possibility of Measuring the Polarization of a ³He Beam at EIC by the HJET Polarimeter

Abstract

The requirements for hadron polarimetry at the future Electron Ion Collider (EIC) include measurements of the absolute helion ( 3 He, h) beam polarization with systematic uncertainties better than σ syst P /P ≤ 1%. Recently, it was proposed that the Polarized Atomic Hydrogen Gas Jet Target (HJET) be utilized for the precision measurement of the polarization of the ∼100 GeV/n helion beam. At the Relativistic Heavy Ion Collider, HJET serves to determine the absolute proton beam polarization with low systematic uncertainties of about δ syst P/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. A potential problem with the suggested method is that the breakup of 3 He in polarization measurements could drastically affect the analyzing power ratio. However, an analysis of the breakup corrections, presented in this paper, reveals that while these corrections can be as substantial as ∼ 4%, the effect cancels out to a negligible level in the measured beam polarization.

Probing the Pomeron spin structure with Coulomb-nuclear interference

“…Second, an important application of CNI-generated azimuthal asymmetry is the possibility to measure the polarization of the beam, in particular at RHIC. The usage of CNI as a polarimeter has been intensively studied in [8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Polarization Measurements of p↑ and 3He↑ Beams at RHIC and Future EIC Using the Polarized Atomic Hydrogen Gas Jet Target

“…Since only low-energy events with T R < 10 MeV (−t < 0.02 GeV 2 ) occur in the HJET, the missing mass excess for the breakup events is constrained by ∆ ≲ 10 MeV. Consequently, (i) the detection rate of breakup events is significantly suppressed by the space phase factor, (ii) for the 3 He breakups observable in the HJET, the 2-body mode h → pd (see Figure 10) dominates prominently, and (iii) with the 100 GeV/nucleon helion beam, practical separation of breakup events from elastic ones is not achievable [44]. If the detection of the scattered 3 He beam is unavailable, the breakup can be identified by an effective alteration of the elastic cross-section:…”

“…Furthermore, there has been a proposal [6] to utilize the HJET target for measuring the 3 He (h) beam polarization at the EIC. It is recognized that the ratio a beam /a jet used for calculating the beam polarization needs adjustment based on the ratio of p ↑ h and h ↑ p analyzing powers.…”

Coulomb-Nuclear Interference in Polarized pA Scattering

“…Second, an important application of CNI-generated azimuthal asymmetry is the possibility to measure the polarization of the beam, in particular at RHIC. The usage of CNI as a polarimeter has been intensively studied in [8][9][10][11][12][13][14][15][16][17][18][19][20].…”