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.

*This work is supported by the US Department of Energy (contract DE-FG02-96ER40980).

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