Development and performance studies of the Shower-max Detector for the MOLLER Experiment.

The MOLLER experiment at Jefferson Lab, scheduled to begin commissioning in late 2026, will measure the weak charge of the electron via parity-violating electron scattering, offering a precise test of the Standard Model and sensitivity to new physics. Among the auxiliary detector systems supporting the main apparatus is the Shower-Max, a Cherenkov-based sampling calorimeter designed to provide an independent measurement of the parity-violating asymmetry in Møller scattering and to serve as a crucial cross-check of the main detector.



Developed at Idaho State University and currently in final testing at Jefferson Lab, the system consists of 28 detector modules surrounding the beamline. Each module employs alternating layers of high-purity tungsten and fused silica (quartz), where electromagnetic showers generated in tungsten produce Cherenkov light within the quartz layers, collected by photomultiplier tubes through air-core aluminum light guides. Using Geant4 simulations, the detector geometry and material configuration have been optimized to achieve the required energy resolution and kinematic acceptance. This presentation focuses on the development and several performance studies of the Shower-max detector.