Understanding the Paul Scherrer Institute's PiM1 Beamline for MUSE

The MUon proton Scattering Experiment (MUSE) at the PiM1 secondary beam line of the Paul Scherrer Institute will simultaneously measure elastic scattering of electrons and muons from a liquid hydrogen target to extract the charge radius of the proton. By comparing the two scattering cross sections, the experiment will shed light on the proton radius puzzle and test lepton universality and the two-photon exchange. This talk will present results from the summer 2019 beam studies. It will be shown how the beam line can be used as a relative momentum spectrometer to extract the momentum of each particle species in the beam. The understanding of the production source distributions will also be presented.