Bates 12C parity violation experiment

An experiment measuring the parity violating asymmetry in the elastic scattering of longitudinally polarized electrons from 12C has been successfully completed. The asymmetry, which is due to the isoscalar vector hadronic piece of the weak neutral current, is dependent only on the weak mixing angle and predicted to be 0.70 ± 0.006 ppm by the Standard Model for our experimental kinematics. Our measured value is 0.60 ± 0.14 ± 0.02 ppm where the first error is purely statistical and the second is systematic, dominated by uncertainties in our normalization. From this asymmetry we extract a value for the coupling constant γ = 0.136 ± 0.032 ± 0.009, which is consistent with the prediction of the Standard Model