Accurate Determination of the Neutron Skin Thickness of Pb 208 through Parity-Violation in Electron Scattering
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 ± 0.0...
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Veröffentlicht in: | Physical review letters 2021-04, Vol.126 (17), Article 172502 |
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Sprache: | eng |
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Zusammenfassung: | 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: ρ$^0_W$ = -0.0796 ± 0.0036(exp) ± 0.0013(theo) fm-3 leading to the interior baryon density ρ$^0_b$ = 0.1480 ± 0.0036(exp) ± 0.0013(theo) fm-3. Finally, 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. |
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ISSN: | 0031-9007 1079-7114 |
DOI: | 10.1103/PhysRevLett.126.172502 |