1. Wide Q2 range needed to resolve quark sub- structure.
E : Measurement of the Neutron Magnetic Form Factor at High Q2 Using the Ratio Method on Deuterium
GMn: Fundamental quantity related to neutron magnetization and quark substructure (extend DOE milestone HP4).
Wide Q2 range needed to resolve quark sub- structure.
Constraint on GPDs: Guidal et al. in plot.
Test for QCD-inspired models: Miller (light- cone), Cloet et al. (Dyson-Schwinger).
Early challenge for lattice QCD (DOE milestone HP9).
Extension of CLAS6 measurement (PRL 102, , 2009) (red points and bar graph).
Part of 2007 NSAC Long Range Plan

2. E12-07-104: CLAS12 GMn – Experiment Summary
Measure ratio of quasielastic e-n to e-p on deuterium in CLAS12; ratio reduces systematic uncertainties.
Q2= (GeV/c)2 in 30 days; A- PAC rating.
Statistical uncertainty: <3% at high-Q2, much better at lower Q2.
Systematic uncertainty: <3% across full Q2 range.
Simultaneous, in situ neutron efficiency calibrations with dual hydrogen-deuterium target.
Internal consistency check: Neutrons measured in electro- magnetic calorimeter and time-of-flight detectors in CLAS12.
Large CLAS12 solid angle used to reduce inelastic background (hermiticity cut).