Simulating The Neutrino Day Night Effect With a 4th Sterile Neutrino

The day-night effect describes the difference in state of solar neutrinos observed during the daytime compared to nighttime. We derive a computational model that simulates the day-night effect, taking the Earth's electron density to be radially piecewise-constant with sections corresponding to the inner and outer core, mantle, and crust. Our model outputs expected neutrino fluxes averaged over 1 hour intervals, taking into account the differing measurement cross-sections for different neutrino flavors. Using a 4-flavor version of the model, we explore the sensitivity of the day-night effect to the existence of a 4th sterile neutrino.