Background: Measurements of the neutron charge form factor, GnE, are challenging because the neutron has no net charge. In addition, measurements of the neutron form factors must use nuclear targets which require accurately accounting for nuclear effects. Extracting GnE with different targets and techniques provides an important test of our handling of these effects.

Purpose: The goal of the measurement was to use an inclusive asymmetry measurement technique to extract the neutron charge form factor at a four-momentum transfer of 1 (GeV/c)2. This technique has very different systematic uncertainties than traditional exclusive measurements and thus serves as an independent check of whether nuclear effects have been taken into account correctly.

Method: The inclusive quasielastic reaction 3He(e, e′) was measured at Jefferson Laboratory. The neutron electric form factor, GnE, was extracted at Q2 = 0.98 (GeV/c)2 from ratios of electron-polarization asymmetries measured for two orthogonal target spin orientations. This Q2 is high enough that the sensitivity to GnE is not overwhelmed by the neutron magnetic contribution, and yet low enough that explicit neutron detection is not required to suppress pion production.

Results: The neutron electric form factor, GnE, was determined to be 0.0414 ± 0.0077 (stat) ± 0.0022 (syst), providing the first high-precision inclusive extraction of the neutron's charge form factor.

Conclusions: The use of the inclusive quasielastic 3He(e, e′) with a four-momentum transfer near 1 (GeV/c)2 has been used to provide a unique measurement of GnE. This new result provides a systematically independent validation of the exclusive extraction technique results and implies that the nuclear corrections are understood. This is contrary to the proton form factor where asymmetry and differential cross section measurements have been shown to have large systematic differences.

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Notes/Citation Information

Published in Physical Review C, v. 96, issue 6, 065206, p. 1-6.

© 2017 American Physical Society

The copyright holder has granted permission for posting the article here.

Due to the large number of authors, only the first 30 and the authors affiliated with the University of Kentucky are listed in the author section above. For the complete list of authors, please download this article or visit: https://doi.org/10.1103/PhysRevC.96.065206

This group of authors is collectively known as the Jefferson Lab Hall A Collaboration Collaboration.

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Funding Information

It is supported by DOE Contract No. DE-AC05-06OR23177, under which Jefferson Science Associates (JSA), LLC, operates the Thomas Jefferson National Accelerator Facility.