Jefferson Lab GEp-V Proton Electromagnetic Form Factor Ratio Measurment at High Momentum Transfer

The Jefferson Lab Hall A Super Bigbite Spectrometer (SBS) experimental program was developed with the goal of making precision measurements of the nucleon elastic electromagnetic form factors. In particular, SBS experiment E12-07-109 (GEp-V) measures the proton electromagnetic form factor ratio G^P_E/G^P_M, extending the range of data to high momentum transfer Q² with unprecedented precision. GEp-V uses the recoil polarization technique in which a longitudinally polarized electron beam is scattered off a fixed unpolarized proton target. The resulting transfer of polarization to the recoiling proton is measured by a spin-dependent secondary scattering process in a CH2 analyzer block, which leads to an azimuthal asymmetry in the final scattering distribution. Finally, the ratio of the longitudinal and perpendicular components is directly proportional to the form factor ratio. Currently, data collection for the GEP-V experiment is ongoing and is expected to conclude at the end of August 2025. An overview of the GEp-V will be presented, including a discussion of the experiment's goal, method, and a post-run status update.