GEn/GMn from Neutron Polarimetry at 4.5 GeV2 with SBS

The Super BigBite Spectrometer (SBS) program at JLab aims to measure nucleon electromagnetic form factors (EMFFs) at high momentum transfers. The GEn-RP experiment, the third in the SBS experiment series, concluded data taking in May 2024. This experiment is focused on measuring the neutron EMFF ratio GEn/GMn through recoil polarimetry at a Q2 = 4.5 (GeV/c)². Two polarimetry techniques have been used in this experiment: charge-exchange np→pn with a passive Fe analyzer, and conventional np→np scattering with an active CH analyzer. The results of this experiment will serve to optimize future even higher Q2 experiments aimed at measuring GEn/GMn. Among the various detector subsystems, the gas electron multiplier detectors (GEMs) played a major role in particle tracking and polarimetry. An overview of the experiment and post- experiment data analysis efforts will be presented with a focus on contributions from the GEM detector subsystem.