Speaker
Description
The most precise measurements of the mean charge radius of the proton use muonic hydrogen spectroscopy. The significant disagreement between these measurements and earlier atomic hydrogen spectroscopy and electron-proton elastic scattering data is known as the "proton radius puzzle". More recent electronic measurements have produced a range of results, but with poor consistency, far exceeding what should be expected given the claimed uncertainties.
The MUon proton Scattering Experiment (MUSE) at the Paul Scherrer Institute is the only experiment to measure this radius simultaneously using muon- and electron-proton elastic scattering. Data are being taken for both charge states of the incoming leptons. The experiment will cover a four-momentum-transfer range from 0.002 to 0.08 GeV2. These data will be used to study possible differences between electron and muon interactions, to measure two-photon exchange effects which are needed to determine the radius, and to extract the proton charge radius.
This work is supported in part by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
