The latest measurements of the proton radius through muonic hydrogen Lamb shift show a discrepancy of about 7sigma from a global analysis of standard hydrogen Lamb shift and elastic ep-scattering. In order to understand this proton radius puzzle, the PRad experiment1 , that was designed through an independent method, successfully performed in June 2016, taking elastic ep and Møller-scattering data with rich statistics on a wide Q2 range including very low momentum transfer (Q2 ∈ [10-4; 10-1 ] GeV2 ) with very accurate angle and energy measurements to minimize the systematic uncertainties.
We will present in this seminar the framework around this proton radius puzzle and how the specic setup of the PRad experiment is designed to improve the previous measurements on elastic ep -scattering cross-sections. This talk will be completed by a characterization of both detectors used in this experiment: a hybrid calorimeter (HyCal) and a plane of two GEM detectors. Finally we will show the current status of the data analysis toward the extraction of the proton radius and the latest preliminary ep cross-sections from this experiment.
