Measurement of the Neutron Radius of (208)Pb through Parity Violation in Electron Scattering

We report the first measurement of the parity-violating asymmetry APV in the elastic scattering of polarized electrons from 208Pb. APV is sensitive to the radius of the neutron distribution (Rn). The result APV=0.656±0.060(stat)±0.014(syst)  ppm corresponds to a difference between the radii of the neutron and proton distributions Rn-Rp=0.33-0.18+0.16  fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus

New Measurements of the Transverse Beam Asymmetry for Elastic Electron Scattering from Selected Nuclei

<p>We have measured the beam-normal single-spin asymmetry An in the elastic scattering of 1–3 GeV transversely polarized electrons from H1 and for the first time from He4, C12, and Pb208. For H1, He4, and C12, the measurements are in agreement with calculations that relate An to the imaginary part of the two-photon exchange amplitude including inelastic intermediate states. Surprisingly, the Pb208 result is significantly smaller than the corresponding prediction using the same formalism. These results suggest that a systematic set of new Anmeasurements might emerge as a new and sensitive probe of the structure of heavy nuclei.</p

Measurement of the Neutron Radius of 208Pb through Parity Violation in Electron Scattering

We report the first measurement of the parity-violating asymmetry APV in the elastic scattering of polarized electrons from Pb208. APV is sensitive to the radius of the neutron distribution (Rn). The result APV=0.656±0.060(stat)±0.014(syst)  ppm corresponds to a difference between the radii of the neutron and proton distributions Rn−Rp=0.33+0.16−0.18  fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.</p