The MUon Scattering Experiment, MUSE, at the Paul Scherrer Institute, Switzerland, investigates the proton charge radius puzzle, lepton universality, and two-photon exchange, via simultaneous measurements of elastic muon-proton and electron-proton scattering. The experiment uses the PiM1 secondary beam channel, which was designed for high precision pion scattering measurements. We review the properties of the beam line established for pions. We discuss the production processes that generate the electron and muon beams, and the simulations of these processes. Simulations of the π/μ/e beams through the channel using TURTLE and G4beamline are compared. The G4beamline simulation is then compared to several experimental measurements of the channel, including the momentum dispersion at the intermediate focal plane and target, the shape of the beam spot at the target, and timing measurements that allow the beam momenta to be determined. We conclude that the PiM1 channel can be used for high precision π, μ, and e scattering.
Bibliographical noteFunding Information:
We acknowledge the Paul Scherrer Institute for its hospitality and support. This work was supported by the US National Science Foundation (NSF) Grants No. 1436680, No. 1505934, No. 1614456, No. 1614773, No. 1614850, No. 1614938, No. 1649873, No. 1649909, No. 1807338, No. 1812382, No. 1812402, No. 1913653, No. 2012114, and No. 2012940 by the United States–Israel Binational Science Foundation (BSF) Grants No. 2012032, No. 2017673, and No. 2017630, by the U.S. Department of Energy (DOE) with Contracts No. DE-AC02-06CH11357, No. DE-SC0012589, No. DE-SC0016577, No. DE-SC0012485, No. DE-SC0016583, and No. DE-FG02-94ER40818, by PSI, Villigen, Switzerland, by Schweizerischer Nationalfonds (SNF) 200020-156983, 132799, 121781, 117601, by the Azrielei Foundation, by the Swiss State Secretariat for Education, Research and Innovation (SERI), Switzerland grant FCS 2015.0594, and by Sigma Xi, USA Grants No. G2017100190747806 and No. G2019100190747806.
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