Development of a trigger scintillator for the MOLLER experiment

The Measurement Of Lepton-Lepton Electroweak Reaction (MOLLER) experiment will measure the weak charge of the electron Q^e_W to a fractional accuracy of 2.4% at an average Q² of 0.0056 (GeV/c)². A set of 14 Trigger Scintillators, positioned upstream and downstream are an integral part of the tracking detector system. These scintillators track individual electrons in calibration runs to measure the detailed shapes of all particle trajectories which will help calibrate the detectors and understand the kinematics of the MOLLER apparatus. Trigger scintillators serve as the primary trigger of the tracking detector system, help in spectrometer calibration, determining electron momentum distribution, and understanding background measurements. This tracking detector system is instrumental in ensuring that the rate distribution matches that predicted from simulation.

At Louisiana Tech University, we are building Trigger scintillators using an organic scintillator embedded with wavelength shifting (WLS) fibers. Using WLS fiber instead of a light guide leads to the efficient collecting and guiding of light photons toward the photo-multiplier tube (PMT) efficiently. We have constructed and tested both initial and final prototypes where we achieved a cosmic muon efficiency exceeding 99%. Currently, a second version of the final prototype is under construction. Results of both initial and final prototypes, current status and progress of the final prototype version 2, and plans for final detector constructions will be given.