Preliminary Results of the Proton Charge Radius Experiment at JLab

In order to investigate the proton radius puzzle, the PRad experiment (E12-11-106) was performed in 2016 in Hall B at Jefferson Lab, with both 1.1 GeV and 2.2 GeV unpolarized electron beams to measure the ep elastic scattering cross section at very low four-momentum transfer squared, Q², from 2×10⁻⁴ to 6×10⁻² (GeV/c)² region with a sub-percent precision. The experiment utilizes a non-magnetic calorimetric method with a high resolution calorimeter (HyCal), and two large area, high spatial resolution Gas Electron Multiplier (GEM) detectors. The experiment also uses a windowless H₂ gas flow target to remove typical backgrounds from target cell windows. The systematic uncertainties of the absolute ep elastic scattering cross section is also controlled by the well-known Moller scattering process, which is measured simultaneously in this experiment within similar kinematics and acceptances. In this talk, the preliminary results from both beam energy settings will be presented.