Accurate Determination of the Neutron Skin Thickness of ^208Pb through Parity-Violation in Electron Scattering
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).
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