Design and Performance of the Spin Asymmetries of the Nucleon Experiment

TL;DR

The SANE experiment measured spin asymmetries in polarized electron-proton scattering at Jefferson Lab, providing new insights into proton spin structure through innovative detector and target technologies.

Contribution

This work introduces a novel experimental setup and analysis methods to access transverse polarization observables in proton scattering.

Findings

Measured spin asymmetries at specific Q^2 and x ranges

Accessed proton structure functions $A_1$, $A_2$, $g_1$, $g_2$, and $d_2$

Demonstrated operation of advanced polarized target and detector systems

Abstract

The Spin Asymmetries of the Nucleon Experiment (SANE) performed inclusive, double-polarized electron scattering measurements of the proton at the Continuous Electron Beam Accelerator Facility at Jefferson Lab. A novel detector array observed scattered electrons of four-momentum transfer $2.5 < Q^2< 6.5$ GeV$^2$ and Bjorken scaling $0.3<x<0.8$ from initial beam energies of 4.7 and 5.9 GeV. Employing a polarized proton target whose magnetic field direction could be rotated with respect to the incident electron beam, both parallel and near perpendicular spin asymmetries were measured, allowing model-independent access to transverse polarization observables $A_1$, $A_2$, $g_1$, $g_2$ and moment $d_2$ of the proton. This document summarizes the operation and performance of the polarized target, polarized electron beam, and novel detector systems used during the course of the experiment, and describes analysis techniques utilized to access the physics observables of interest.