Accurate Determination of the Neutron Skin Thickness of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Pb</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>208</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> through Parity-Violation in Electron Scattering
D. Adhikari, H. Al-Bataineh, D. Androić, K. Aniol, David Armstrong, T. Averett, C. Ayerbe Gayoso, S. Barcus, Vincenzo Bellini, R. Beminiwattha, J. F. Benesch, H. Bhatt, D. Bhatta Pathak, D. Bhetuwal, B. Blaikie, Q. Campagna, A. Camsonne, G. D. Cates, Y. Chen, C. Clarke, J. C. Cornejo, S. Covrig Dusa, P. Datta, A. Deshpande, D. Dutta, Charles Feldman, E. Fuchey, C. Gal, D. Gaskell, T. Gautam, Michael Gericke, C. Ghosh, I. Halilovic, O. Hansen, F. Hauenstein, W. Henry, C. J. Horowitz, Christopher Jantzi, Siyu Jian, S. Johnston, D. Jones, B. Karki, Sumudu Katugampola, C. E. Keppel, P. M. King, David E. King, Matthew Knauss, K.S. Kumar, T. Kutz, N. Lashley-Colthirst, Graham Leverick, H. Liu, N. Liyange, S. Malace, R. Mammei, J. Mammei, M. McCaughan, D. McNulty, D. Meekins, Carrington Metts, R. Michaels, M. M. Mondal, J. Napolitano, A. Narayan, D. Nikolaev, M. N. H. Rashad, V. Owen, C. Palatchi, Jie Pan, B. Pandey, S. Park, K. Paschke, M. Petrusky, M. Louise M. Pitt, S. Premathilake, A. J. R. Puckett, B. Quinn, Robert Radloff, S. Rahman, A. Rathnayake, Brendan T. Reed, P. E. Reimer, R. K. Richards, S. Riordan, Y. Roblin, S. Seeds, A. Shahinyan, P. A. Souder, L. Tang, M. Thiel, Y. Tian, G. M. Urciuoli, E. W. Wertz, B. Wojtsekhowski, B. Yale, Ye Tao, A. S. Yoon, A. Zec, W. Zhang, Jinlong Zhang
Abstract
We report a precision measurement of the parity-violating asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{208}Pb. We measure A_{PV}=550±16(stat)±8(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(Q^{2}=0.00616 GeV^{2})=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is R_{n}-R_{p}=0.283±0.071 fm. The result also yields the first significant direct measurement of the interior weak density of ^{208}Pb: ρ_{W}^{0}=-0.0796±0.0036(exp)±0.0013(theo) fm^{-3} leading to the interior baryon density ρ_{b}^{0}=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.