Nab Si detector systematics, response and calibration measurements

The Nab experiment at the Spallation Neutron Source (SNS) will precisely measure the electron-neutrino correlation parameter and the Fierz interference term in neutron beta decay.  Nab uses a novel field expansion spectrometer to measure electron energy and proton momentum.  At either end of the spectrometer, particles are detected with a pixelated Si detector.  Several important systematic uncertainties depend on a precise understanding of detector response.  Nab's precision goals require $10^{-4}$ level precision in detector energy, as well as $\le$3 ns timing precision.  Preliminary detector testing has been done at Los Alamos National Laboratory and the University of Manitoba.  In addition to a discussion of Nab's detector systematics, an overview of planned detector calibration, as well as linearity and timing tests, to be done at the SNS, will be presented.