Beam Stability in PSI MUSE*

The Muon proton Scattering Experiment (MUSE) uses a mixed beam of electrons, muons and pions from the PiM1 beam line of the Paul Scherrer Institute (PSI) in Switzerland. The aim of the experiment is to measure elastic scattering cross-sections for both electrons and muons, from a liquid hydrogen target. From this, the charge radius of the proton will be extracted, providing data for the proton radius puzzle - a 4%discrepancy in the proton radius when measured through muonic hydrogen spectroscopy as compared to regular hydrogen spectroscopy and electron-proton scattering. Measuring precise cross sections to compare e and mu and the two beam polarities requires stability of the beam and electronics. I will be discussing recent analyses and observations of the time particles arrive at the experiment detectors relative to the accelerator clock. The studies were done to establish the stability of MUSE detectors and electronics and the PiM1 channel at PSI. Changes in the beam momentum of order 0.1% lead to measurable, correlated changes in the times of muons and pions relative to electrons, of a few tens of ps.