Jlab Hall-A's Magnetic Form Factor of the Neutron (G_Mⁿ) Experiment and Improvements Made to the Gas Electron Multiplier Detectors' Tracking Algorithms

The Measurement of the Magnetic Form Factor of the neutron (G_Mⁿ) experiment (E12-09-019) ran from October 2021 through February 2022 in Hall-A of the Jefferson Lab. The "ratio method" was used in this experiment which involved the detection of both neutron tagged, d(e,e'n) and proton tagged, d(e,e'p), quasi-elastic electron scattering off a deuteron target. This experiment explored five kinematic points ranging from 3.5 GeV²/c² to 13.5 GeV²/c² with beam energies going up to 9.91 GeV. This measurement is part of Super Bigbite Spectrometer (SBS) project which provides a large solid angle acceptance and the capability to operate at high luminosity using Gas Electron Multiplier (GEM) detector based particle trackers. In the G_Mⁿ experiment, GEM trackers were used in the BigBite Spectrometer (electron arm) which determined the q vector of the scattering reaction. Background rates exceeding 100 KHz/cm² were experienced especially by the front most GEM detectors. Tracking efficiency goes down under these conditions due to the pileup of events both in space and time. Several techniques are under development to cleanup these pileup events and to extract good events and reject background events, before performing the track reconstruction analysis.