Grant: Subatomic Physics Envelope - Project

The Measurement of a Lepton- Lepton Electroweak Reaction (MOLLER) experiment is being commissioned at Jefferson Laboratory (JLab) with Canadian contributions supported by NSERC grant SAPPJ 2022--00019 (PI Prof. Michael Gericke). As a new faculty member at the University of Manitoba and new MOLLER collaborator, this bridging grant will support my new research program, which expands Canada's MOLLER leadership roles. MOLLER will measure the weak mixing angle at low momentum transfer to world--leading precision through observing the parity-violating scattering asymmetry of an 11 GeV polarized electron beam on a liquid hydrogen target. This precision test of the Standard Model will have unparalleled sensitivity to new elementary particles and forces through their virtual quantum interactions. My proposed research program will achieve unprecedented beam polarization monitoring precision for MOLLER by leading the commissioning and operation of the upgraded Compton Photon Detector installed in JLab's Compton Polarimeter. This recently became an open responsibility in the MOLLER Collaboration and will be essential to achieve MOLLER's overall precision goal. The newly installed Compton Photon Detector is optimized for photon energies up to several GeV by employing a 2x2 array of PWO scintillation crystals connected to a single photomultiplier tube. A MSc student will begin by characterizing its energy resolution and linearity as well as perform GEANT4 simulation validations. The 11 GeV beam energy at MOLLER is predicted to produce a significant synchrotron radiation background near the Compton Photon Detector. I will deploy Synchrotron Radiation Monitors (SRMs) to gain invaluable feedback on the beam polarization dependence of these photon backgrounds. The SRMs will also facilitate a novel strategy to monitor the beam polarization at JLab using the polarization dependent component of synchrotron radiation. A PhD student will lead the SRM commissioning and be the MOLLER expert in the synchrotron background and Compton Photon Detector operation. My proven record of scintillation detector innovation as well as experiences coordinating Belle II Neutrals Performance and conducting SuperKEKB beam -background studies, is well suited to accomplish this high-priority open MOLLER responsibility. This work is highly synergistic to the ongoing Canadian group effort commissioning the independent Compton Electron Detector component of the Compton Polarimeter. My research program features valuable opportunities for PhD, MSc, and undergraduate students to make high-impact contributions to internationally collaborative research. HQP training will encompass a range of important skills including detector commissioning, GEANT4 simulation, data--analysis, and test beam operations. With MOLLER commissioning to begin in 2025, the timeline is urgent to commission these systems and for HQP to position themselves in important MOLLER leadership roles in time for first data.