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Title	Measuring the Proton Radius in High-Energy Muon-Proton Scattering
Author(s)	Friedrich, Jan (Munich, Tech. U.) ; Hoffmann, Martin (Bonn U., HISKP) ; Inglessi, Alexander (St. Petersburg, INP) ; Kabuß, Eva (Mainz U., Inst. Kernphys.) ; Ketzer, Bernhard (Bonn U., HISKP) ; Kiselev, Oleg (Darmstadt, GSI) ; Maev, Evgeny (St. Petersburg, INP) ; Paul, Stephan (Munich, Tech. U.) ; Petrov, Gennady (St. Petersburg, INP) ; Uhl, Sebastian (Munich, Tech. U.) ; Vasilyev, Alexander A (St. Petersburg, INP) ; Veit, Benjamin M (Mainz U., Inst. Kernphys. ; CERN) ; Vorobyov, Alexey A (St. Petersburg, INP)
Collaboration	COMPASS++/AMBER working group
Publication	SISSA, 2019
Number of pages	6
In:	PoS DIS2019 (2019) 222
In:	The XXVII International Workshop on Deep Inelastic Scattering and Related Subjects, Turin, Italy, 8 - 12 Apr 2019, pp.222
DOI	10.22323/1.352.0222
Subject category	Particle Physics - Experiment
Abstract	The proton charge radius can be determined by measuring the slope of the electric form-factor $G_E$ at small four-momentum transfer squared $Q^2$. Numerous elastic-scattering and laser-spectroscopy measurements of the proton radius have been performed with contradicting results, often referred to as the proton-radius puzzle. We propose to measure the proton charge radius in high-energy elastic muon-proton scattering at the M2 beam line of CERN's Super Proton Synchrotron (SPS) in 2022. A high-precision measurement at low $Q^2$, performed with a high-pressure hydrogen-filled time-projection chamber (TPC), can contribute to the resolution of the puzzle, especially due to the different systematic effects of this approach compared to those of electron-proton scattering. In 2018, we performed a test measurement with silicon tracking detectors up- and downstream of a prototype TPC to study the feasibility of the measurement concept. We present initial results of the on-going analysis of the test data and discuss ideas for a possible experiment at CERN in 2022.
Copyright/License	publication: © 2019-2024 Authors (License: CC-BY-NC-ND-4.0)

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