Determination of the Q2 and kinematics for the MOLLER experiment

The MOLLER experiment proposes to precisely measure the parity violating asymmetry in electron-electron (Moller) scattering. Integrating detectors will be used to count the number of events for each rapidly alternating helicity window without event-by-event kinematic information. The kinematic factor involving the 4-momentum transfer (Q2) must be independently determined to extract the weak mixing angle from the measured asymmetry using low beam current calibration runs, where individual events will be tracked with special purpose Gas Electron Multiplier (GEM) detectors. These tracking events will enable sufficient understanding of the magnetic optics of the spectrometer/collimator system, given the novel and unusual forward angle kinematics. A special collimator with judiciously placed and precisely machined holes (so-called "sieve") will be used to build a map between the reconstructed variables at the tracking detectors and the variables at the target, as well as for determining the acceptance function. An overview of the optics plan for the MOLLER experiment will be presented.