Measurement of the Neutron Spin Structure Function $g_1^n$ with a Polarized ^3He Target

TL;DR

This paper reports measurements of the neutron spin structure function g_1^n using polarized helium-3 targets at HERA, providing insights into neutron spin contributions in deep inelastic scattering within a specific kinematic range.

Contribution

The study presents the first measurement of g_1^n in the specified kinematic range using polarized ^3He, extending understanding of neutron spin structure.

Findings

Measured g_1^n(x,Q^2) in the range 0.023<x<0.6 and 1< Q^2 <15 (GeV/c)^2

Determined the integral of g_1^n over x from 0.023 to 0.6 at Q^2=2.5 (GeV/c)^2

Estimated the first moment Γ_1^n with associated uncertainties

Abstract

Results are reported from the HERMES experiment at HERA on a measurement of the neutron spin structure function $g_1^n(x,Q^2)$ in deep inelastic scattering using 27.5 GeV longitudinally polarized positrons incident on a polarized $^3$He internal gas target. The data cover the kinematic range $0.023<x<0.6$ and $1 (GeV/c)^2 < Q^2 <15 (GeV/c)^2$. The integral $\int_{0.023}^{0.6} g_1^n(x) dx$ evaluated at a fixed $Q^2$ of $2.5 (GeV/c)^2$ is $-0.034\pm 0.013(stat.)\pm 0.005(syst.)$. Assuming Regge behavior at low $x$, the first moment $\Gamma_1^n=\int_0^1 g_1^n(x) dx$ is $-0.037\pm 0.013(stat.)\pm 0.005(syst.)\pm 0.006(extrapol.)$.