Precise Measurement of the Neutron Magnetic Form Factor in the Few-GeV$^2$ Region

ORAL

Abstract

The neutron elastic magnetic form factor $G_M^n$ has been extracted from quasielastic scattering from deuterium in the CEBAF Large Acceptance Spectrometer at Jefferson Lab. The kinematic coverage of the measurement is continuous from 1~$\rm{(GeV/c)^2}$ to nearly 5~$\rm{(GeV/c)^2}$ in four-momentum transfer squared and eclipses the previous data in this region. High precision was achieved with a ratio technique, where many uncertainties cancel, and a simultaneous in-situ calibration of the neutron detection efficiency, the largest correction to the data. Neutrons were detected using the CLAS electromagnetic calorimeters and the time-of-flight scintillators. Data were taken at two different electron beam energies, allowing up to four semi-independent measurements of $G_M^n$ to be made at each value of $Q^2$. The dipole parameterization is found to provide a good description of the data for $Q^2 >$ 1 $(GeV/c)^2$. The impact of these new data on the world data for $G_M^n$ will be presented.

Authors

  • Gerard Gilfoyle

    University of Richmond

  • Jeffrey Lachniet

    Carnegie Mellon University

  • William Brooks

    Universidad Tecnica Federico Santa Maria

  • Brian Quinn

    Carnegie Mellon University, Carnegie-Mellon University

  • Michael Vineyard

    Union College