Results From The NPDGamma Experiment: A New Measurement of the Parity-Violating Gamma Asymmetry in Polarized Neutron Capture on Protons

The NPDGamma Experiment was performed to measure the parity-violating (PV) asymmetry in the angular distribution of gammas from polarized neutrons captured on protons at the Spallation Neutron Source in ORNL. This PV asymmetry $A_{\gamma}$ is proportional to the $\Delta I = 1$, $^3S_1\rightarrow^3P_1$ transition in the weak nucleon-nucleon interaction and is directly related to the long range pion coupling constant $h_{\pi}^1$ in the DDH meson exchange model and the low energy constant $C^{^3S_1\rightarrow^3P_1}/C_0^{^3S_1}$ in pionless effective field theory. We will present a description of the experiment, analysis, and the final result and its implications.