Analysis Progress of the NTPE Experiment with Super BigBite Spectrometer at Jefferson Lab

The first measurements of elastic electron nucleon scattering with polarization transfer, which provided values for the ratio of the electric and magnetic nucleon form factors, showed a significant discrepancy with the same ratio as extracted from Rosenbluth measurements of the cross section for the same process. Two photon exchange, which is suspected to be the cause of this observation, received a major focus since then.

While this effect has been evidenced on electron-proton data, it has never before been measured in electron neutron scattering.

Using the BigBite/Super Bigbite Spectrometer combination in Hall A at Jefferson lab, we have simultaneously measured the ratio of electron-neutron to

electron-proton scattering cross section ratios off deuterium using the Durand technique (proposed in 1959), at two different beam energies, but at the same momentum transfer Q^2. This measurement, combined with the input from previous Rosenbluth measurements on

the proton, allow us to perform the first high Q2 Rosenbluth measurement in electron-neutron elastic scattering. The comparison between this

measurement and polarization transfer measurements in electron-neutron scattering will provide an estimation of the magnitude for the two-photon exchange in this process.

We will present the NTPE experiment and the experimental analysis method, review the remaining analysis challenges to overcome, and

finally conclude with our preliminary estimation of the neutron Rosenbluth slope.