# 2014 CAP Congress / Congrès de l'ACP 2014

15-20 June 2014
Laurentian University / Université Laurentienne
America/Toronto timezone
Welcome to the 2014 CAP Congress! / Bienvenue au congrès de l'ACP 2014!

## The NPDgamma Experiment: Hadronic Parity Violation in the Capture of Cold Neutrons on Protons

17 Jun 2014, 09:30
15m
C-309 (Laurentian University / Université Laurentienne)

### C-309

#### Laurentian University / Université Laurentienne

Sudbury, Ontario
Oral (Non-Student) / orale (non-étudiant) Nuclear Physics / Physique nucléaire (DNP-DPN)

### Speaker

Michael Gericke (University of Manitoba)

### Description

The NPDGamma experiment has completed a measurement of the parity-violating directional gamma-ray asymmetry in the capture of cold neutrons on protons in a liquid hydrogen target. The asymmetry is directly related to the weak pion-nucleon coupling constant $h^1_{\pi}$, within the framework of the meson exchange model, and it is related to the effective field theory couplings $\tilde C^{\pi}_6$ and $m_N \rho_t$. The asymmetry has a predicted size of $-5\times 10^{-8}$, with large uncertainties in the theoretical prediction for the coupling constants. The goal precision of the measurement is $1\times 10^{-8}$, which would serve as the most precise constraint on the couplings in both theoretical frameworks. Since the asymmetry is a result of the interference between the weak and strong nucleon-nucleon forces, this measurement also provides an experimental benchmark for theoretical developments in the non-perturbative strong interaction regime. NPDGamma completed a two year long second phase run at the Spallation Neutron Source (SNS), at Oak Ridge National Laboratory and the final analysis is currently ongoing. I will provide an overview of the experiment, the analysis procedure, and some preliminary results.

### Primary author

Michael Gericke (University of Manitoba)

 Slides