Measuring the Electromagnetic Properties of the Nucleon at HIγS

The electromagnetic properties of the nucleon arise from its composite nature. External electric and magnetic fields induce dipole moments described by the scalar polarizabilities (α_N and β_N), while the response of the nucleon spin is described by four spin polarizabilities. Consequently, studying these observables offers a window into the interaction among the constituent charges and currents in the nucleon, described theoretically by QCD. In particular, high precision measurements of the scalar and spin polarizabilities provide a means for studying the low-energy, non-perturbative regime of QCD. Such measurements are needed to constrain emerging calculations from lattice QCD and Chiral Effective Field Theories and are critical inputs to descriptions of the proton-neutron mass difference. To this end, a program of Compton scattering experiments on light nuclei is underway at the High Intensity Gamma Source (HIγS) at Duke University, with the aim of providing the world's most precise data to extract the polarizabilities. We report preliminary measurements fom Compton scattering experiments on ⁴He, ²H, and ¹H and discuss the sensitivity of these data to the polarizabilities.