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

E. Fuchey
William and Mary, USA

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.