Neutron Magnetic Form Factor Gⁿ_M Measurement at High Q² with CLAS12

The neutron magnetic form factor Gⁿ_M is a fundamental absorvable, but there are few high-precision measurements of Gⁿ_M for Q² > 5 GeV. The upgrade of CEBAF with the CLAS12 detector in Hall B at Jefferson Lab (JLab) provides the opportunity to measure Gⁿ_M at higher Q² . The ratio of quasi-elastic e-n to e-p scattering on a deuteron target is used to extract Gⁿ_M. This method reduces our sensitivity to systematic uncertainties like detector acceptance, live-time corrections, etc. High-statistics data were collected with the CLAS12 Forward Detector (FD) in quasi-elastic (QE) kinematics. Measuring quasi-elastic e-n requires determining the neutron detection efficiency (NDE) of the electromagnetic calorimeter. A liquid hydrogen target is used to produce tagged neutrons from the p (e,e'π⁺)n reaction to measure NDE. A preliminary result for the NDE reached a maximum value of ∽ 74% at high neutron momentum. We have also developed algorithms to select the quasi-elastic e-p and e-n events.

We will present the results and validations of the event selection and the NDE measurement and the status of the ratio measurement.