The NDTGamma experiment: Hadronic Parity Violation in Counting Mode

The recent NPDGamma and n3He experimental constraints of $h_\pi^1$ and $h_{\rho{-}\omega}^{0}$ are important milestones towards the goal of a complete spin and isospin characterization of the Hadronic Weak Interaction. The remaining experimentally accessible few-body observables pose special challenges--for example, the neutron spin asymmetry $A_\gamma^{\vec{n}d}$ of gamma rays in the reaction $\vec{\mbox{n}} + \mbox{d} \to \mbox{t} + \gamma$ in an experimentally achievable D$_2$O target would be highly diluted by the low signal-to-background ratio of the suppressed (~mb) n-D capture cross section in a traditional current-mode experiment. Given the moderate event rates from this reaction and modern capabilities of high-speed digital pulse-processing electronics, we describe progress towards the possibility of detecting and discriminating on individual gamma-rays from the 6.2 MeV neutron capture photopeak in real time. This will enable the first counting-mode measurement of Hadronic Parity Violation in a few-body system in which quasi exact (3-body) calculations in the DDH potential and chiral EFT are possible.