GEANT4 Simulation of Empty Target for the NPDGamma Experiment

The NPDGamma experiment was designed to detect a very small parity violating asymmetry ($\sim 10^-8$) in the n + p $\to$ d + $\gamma$ reaction. Background rates will be modeled to determine the dilution of the asymmetry. To validate these models, data were taken with the detector array fitted with a mock-up version of the liquid hydrogen target in the neutron beam. Rates were measured from four targets: empty, water, and two concentrations of MgCl, which has a large parity violating asymmetry. A comparison of these results with a Geant4 simulation of this simple target will be used to tune the simulation of the real hydrogen target.