Speaker
Description
The recent PRad experiment at Jefferson Lab has precisely measured the cross sections for elastic electron proton scattering at four momentum transfer square ($Q^2$) from $2\times10^{-4}$ to $6\times10^{-2}$ GeV$^2$/c$^2$. The charge radius of proton was extracted based on the measured proton form factors at very low $Q^2$. This experiment utilized a high precision, hybrid calorimeter (HyCal) that can precisely determine the energy and position of electrons and photons. The HyCal's inner array of PbWO$_4$ modules can also separate two incident particles with a distance greater than about 30 mm ($\sqrt{2}$ of the module size) on the detection plane. Together with the GEM detectors placed in front of the HyCal, which serve as a veto detector for neutral particles, the PRad detector system is capable of measuring and identifying the scattered electrons and the radiative photons simultaneously from the elastic $ep$ scattering process. In this talk, I will present the preliminary results of the direct radiative effects measurement from the PRad experiment. I will also discuss the expected improvements with the upcoming PRad-II experiment.
