Investigating Proton Backscattering in the Nab Experimental Data

The Nab Experiment’s primary objective is to study the process of unpolarized neutron beta decay using the Spallation Neutron Source at Oak Ridge National Laboratory. Specifically, we plan to measure two values: a, the electron-neutrino correlation coefficient to a precision of Δa/a = 10-3, and the Fierz interference term, b, to Δb = 10-3. The experimental set-up includes two silicon detectors on either end of a large electromagnetic spectrometer that will detect the proton and electron decay products. The proton’s path is typically straight to the upper detector; occasionally, it will bounce off the lower detector first. We are analyzing experimental data to determine if this backscattering effect causes an increase in longer measured proton times-of-flight and consequently an added systematic effect in our ability to determine a. We will give an overview of our methodology and report our findings.