Current Experiments Archive
E08-011: e-2H Parity-Violating Deep-Inelastic Scattering (PVDIS) at CEBAF 6 GeV
During this experiment, scientists will measure the parity-violation asymmetry in deep-inelastic scattering (PVDIS) between a 6 GeV beam and a liquid deuterium target. The PVDIS asymmetry has been measured only once, in the E122 experiment at SLAC. The E122 results established the current Standard Model of electroweak physics, which connects two fundamental forces of nature: the electromagnetic force and the weak force. E122 provided, for the first time, the value of sin2(theta_W). Now experimenters are going to measure this asymmetry to a much higher precision than was possible 30 years ago, hoping to provide insights to our understanding of both strong and electroweak interactions.
More specifically, the data will provide the first limit on hadronic physics effects on PVDIS asymmetries. And if these hadronic effects are found to be small, the experiment can optimally provide precision data on the product of the vector electron neutral weak couplings g_V^e and the axial quark neutral weak couplings g_A^q. A precise knowledge of this product can help to search for new physics beyond the Standard Model in a reaction complementary to other new physics search experiments around the world.
E08-011 requires a 6 GeV beam with up to 120uA of current. Such high currents requires the highest target cooling power available to Hall A. The high DIS rate with high pion electro- and photo-production background also poses a chanllenge, for which the experimenters have developed a new, fast-counting data acquisition system with online particle identifications. From both the physics and technical point of view, E08-011 serves the exploratory step for the PVDIS program at 11 GeV.