Target-Chamber-Post Vetos for the MUSE Experiment

The MUon-proton Scattering Experiment (MUSE) is currently operating at the PiM1 beam line of the Paul Scherrer Institute. MUSE seeks to provide insight into the proton radius puzzle by extracting the proton charge radius. MUSE will obtain precise cross sections and form factors from simultaneous measurements of elastic electron-proton and muon-proton scattering from a liquid-hydrogen target using lepton beams of both charge polarities, allowing direct measurement and then cancellation of two-photon effects. To determine the charge radius with sufficient precision, thorough understanding of the MUSE detector system and beam properties is required. The structural integrity of the large-scattering-window target chamber is maintained by two forward-angle support posts. Particles that scatter from these support posts are known to contaminate data; a new veto detector, the Target Chamber Post Veto (TCPV), was installed in 2022 to reduce these post-scattered backgrounds. In this presentation, I will discuss recent efforts towards characterizing the operation of the TCPV and evaluating its efficiency as a veto detector for MUSE.