Physical Review Letters
We report a precision measurement of the parity-violating asymmetry APV in the elastic scattering of longitudinally polarized electrons from 208Pb. We measure APV=550±16(stat)±8(syst) parts per billion, leading to an extraction of the neutral weak form factor FW(Q2=0.00616 GeV2)=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is Rn−Rp=0.283±0.071 fm. The result also yields the first significant direct measurement of the interior weak density of 208Pb: ρ0W=−0.0796±0.0036(exp)±0.0013(theo) fm−3 leading to the interior baryon density ρ0b=0.1480±0.0036(exp)±0.0013(theo) fm−3. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.
Adhikari, D.; ...; Armstrong, David S.; and al., et, Accurate Determination of the Neutron Skin Thickness of ^208Pb through Parity-Violation in Electron Scattering (2021). Physical Review Letters, 126(17).
This work is made available for educational and personal use only. Copyright is credited to the authors. Any other uses should be directed to the publisher.