Measurement of Parity Violation in Radiative Neutron Capture

The NPDGamma experiment aims to measure parity violating directional gamma-ray asymmetry, $A_\gamma$ in the $\vec n + p \rightarrow d + \gamma $ reaction using para-hydrogen, with sensitivity of $5 \times 10^{-9}$, $10\%$ of its predicted value. The experiment is currently under comissioning at LANSCE at Los Alamos National Laboratory. We have measured $A_\gamma$ in a series of elements with $ 35 \leq A \leq 59 $ as well as B, Al, In and Cu. From the results we will extract the upper limit for the weak spreading width in hadronic weak interaction. Experiment and results will be presented.