Technical Design Report for the Paul Scherrer Institute Experiment R-12-01.1: Studying the Proton "Radius" Puzzle with μp Elastic Scattering

Abstract

Beam-Line FIG. 3. Implementation of detectors in the πM1 area in a Geant4 [10] simulation. The beam strikes the thin scintillator beam hodoscope and three GEM chambers, passes through a hole in the annular veto scintillator, enters the cryotarget vacuum chamber and strikes one of the targets, then exits the vacuum chamber and goes through the beam monitor. Scattered particles are detected by two symmetric spectrometers, each with two straw chambers wrapped in RF shielding and two planes of scintillator paddles.

Radiative Correction to Lepton Proton Scatterings in Manifestly Lorentz-Invariant Chiral Perturbation Theory

“…Nevertheless, for µp scatterings, radiative corrections, especially TPE corrections, may play an impotart role in the extraction of FFs and charge radius. It is thus instructive to investigate the validity of our results in elastic µp scatterings such as MUSE [13,14]. For more future planned ep and µp scattering experiments, we recommend the recent report [67].…”

“…Several recent experimental poposals aim at carrying out high precision measurements of low energy e ± p (and µ ± p) scattering cross sections. PRad [11,12] experiment at JLab, and MUSE [13,14] experiment at PSI are two such experiments. In particular, MUSE experiment plans to mesure the elastic µ ± p scattering cross sections at momentum transfer as low as |q 2 | ∼ 0.0002 − 0.08GeV 2 , where q means the four-momentum transfer.…”

Operation and characterization of a windowless gas jet target in high-intensity electron beams

“…A comparison of the main parameters of hydrogen targets used in current nuclear physics experiments at electron accelerators such as Darklight [37], OLYMPUS [38,39], PRad [40,41], MUSE [42,43], and A1 at MAMI [35,44,45,46,47] is given in Table 2.…”

Radiative corrections to the lepton current in unpolarized elastic $lp$-interaction for fixed $Q^2$ and scattering angle

“…Together with widely discussed two-photon exchange [8], the important source of uncertainties for both lepton and anti-lepton scattering is from the real photon emission accompanying any process with the charge particle scattering, as well as the additional virtual particle contributions. Due to smallness of muon beam momentum at MUSE experiment in PSI [9], as well as scattering by extremely small angles in PRAD-II experiment at Jefferson Lab [10], all calculations have a e-mail: afanas@gwu.edu b e-mail: ily@hep.by to be performed beyond the ultrarelativistic approximation, i.e. retaining lepton's mass during the entire calculation.…”

“…While for purely elastic scattering at a given beam energy the four-momentum transfer Q 2 is in oneto-one correspondence with a lepton scattering angle, this is not the case for radiative events. It is therefore of critical importance to understand the role of QED radiative corrections (RC) in different kinematic scenarios: fixed momentum transfer Q 2 vs fixed scattering angle of the detected lepton (as done in MUSE [9] or in high-resolution spectrometers with small angular acceptance used in some of Jefferson Lab experiments).…”