Precision Determination of the Neutral Weak Form Factor of Ca 48

We report a precise measurement of the parity-violating (PV) asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{48}Ca. We measure A_{PV}=2668±106(stat)±40(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(q=0.8733 fm^{-1})=0.1304±0.0052(stat)±0.0020(syst) and the charge minus the weak form factor F_{ch}-F_{W}=0.0277±0.0055. The resulting neutron skin thickness R_{n}-R_{p}=0.121±0.026(exp)±0.024(model) fm is relatively thin yet consistent with many model calculations. The combined CREX and PREX results will have implications for future energy density functional calculations and on the density dependence of the symmetry energy of nuclear…

• NS
  National Science Foundation

  Award: DE-AC05-06OR23177
• UD
  U.S. Department of Energy

  Awards: AC05-06OR23177, DE-AC05-06OR23177, DE-AC05
• OO
  Office of Science

  Awards: AC05-06OR23177, DE-AC05-06OR23177
• NS
  Natural Sciences and Engineering Research Council of Canada
• NP
  Nuclear Physics

  Award: DE-AC05-06OR23177
• TJ
  Thomas Jefferson National Accelerator Facility

  Award: DE-AC05-06OR23177