Polarized 3He(e,e'n) Asymmetries in Three Orthogonal Measurements

TL;DR

This study measured three orthogonal asymmetries in polarized helium-3 electron scattering at various momentum transfers, providing critical tests for nuclear models and confirming PWIA validity at higher Q² values.

Contribution

First simultaneous measurement of three orthogonal asymmetries in polarized helium-3 electron scattering, enabling comprehensive model testing.

Findings

PWIA holds above Q² of 0.953 (GeV/c)²

First measurement of all three asymmetries simultaneously

Results support helium-3 as an effective neutron target

Abstract

Asymmetry measurements were conducted in Jefferson Lab's experimental Hall A through electron scattering from a polarized $^3$He target in the quasi-elastic $^3\mathrm{He}(e,e'n)$ reaction. Measurements were made with the target polarized in the longitudinal direction with respect to the incoming electrons ($A_L$), in a transverse direction that was orthogonal to the beam-line and parallel to the q-vector ($A_T$), and in a vertical direction that was orthogonal to both the beam-line and the q-vector ($A_y^0$). The experiment measured $A_y^0$ at four-momentum transfer squared (Q$^2$) of 0.127 (GeV/$c$)$^2$, 0.456 (GeV/$c$)$^2$, and 0.953 (GeV/$c$)$^2$. The $A_T$ and $A_L$ asymmetries were both measured at Q$^2$ of 0.505 (GeV/$c$)$^2$ and 0.953 (GeV/$c$)$^2$. This is the first time that three orthogonal asymmetries have been measured simultaneously. Results from this experiment are compared with the plane wave impulse approximation (PWIA) and Faddeev calculations. These results provide important tests of models that use $^3$He as an effective neutron target and show that the PWIA holds above Q$^2$ of 0.953 (GeV/$c)^2$.