Status of the MOLLER Tracking System and Recent Advances in Tracking Software

The MOLLER experiment will perform an ultra-precise measurement of the parity-violating asymmetry in Møller (e−– e−) scattering using an 11 GeV polarized electron beam at Jefferson Lab, providing a clean low-Q2 determination of sin2 θW and sensitivity to new neutral currents at multi-TeV scales. This contribution focuses on the tracking system and the current status of hardware and software. The system comprises 28 Triple-GEM detectors arranged as four layers in each of seven azimuthal sectors on a rotator, enabling counting-mode measurements at low current to validate spectrometer optics, determine quartz Čerenkov acceptance, and map backgrounds and non-uniformities. We report production/QA progress and four-module-stand results demon- strating uniform 2D efficiencies and sub-mm position resolutions meeting acceptance and optics-verification needs. On software, we have finalized geometry/rotator support and core reconstruction (mapping, common-mode/zero-suppression tuning, clustering, multilayer track fits) with automated alignment/efficiency workflows tied to quartz-acceptance studies, and we outline a streamlined plan for beam-time commissioning (run configurations, triggers, validation).