Measurements of the Electric Form Factor of the Neutron up to Q2=3.4 GeV2 using the Reaction He3(e,e'n)pp

TL;DR

This study measures the neutron's electric form factor at higher momentum transfers than previously achieved, using polarized electron scattering off helium-3, providing new insights into neutron structure.

Contribution

It extends the Q2-range of neutron electric form factor measurements up to 3.4 GeV2 using a novel polarized electron scattering technique.

Findings

Neutron electric form factor values at Q2=1.72, 2.48, 3.41 GeV2.

First measurements of GEn beyond previous Q2 limits.

Results support models of neutron structure at high momentum transfer.

Abstract

The electric form factor of the neutron was determined from studies of the reaction He3(e,e'n)pp in quasi-elastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2-range over which it is known, we find GEn = 0.0225 +/- 0.0017 (stat) +/- 0.0024 (syst), 0.0200 +/- 0.0023 +/- 0.0018, and 0.0142 +/- 0.0019 +/- 0.0013 for Q2 = 1.72, 2.48, and 3.41 GeV2, respectively.