A New Measurement of the Neutron Elastic Magnetic Form Factor, G_Mⁿ, up to Q² = 13.5 GeV² at Jefferson Lab.

A new experimental program of nucleon elastic form factor measurements at large Q² began in Hall A at Jefferson Lab last year. The program is based on two large acceptance spectrometers, the BigBite for detecting electrons, and the SuperBigBite for detecting hadrons. In this talk I will present the first experiment, a measurement of the elastic magnetic form factor of the neutron, G_Mⁿ, up to Q² = 13.5 GeV², with expected statistical precision better than all previous experiments above Q² = 1 GeV². The measurement was made with beam energy up to 10 GeV using the "ratio” method where G_Mⁿ is extracted from the ratio of d(e,e’p) to d(e,e’n) events in quasi-elastic scattering. By measuring a ratio, we are less sensitive so many systematics. The first pass data analysis is now completed. Preliminary results will be shown.