Updated Event Selection for the PROSPECT Experiment

PROSPECT aims to measure highly enriched $^{235}$U reactor anti-neutrino energy spectrum with high precision and to model-independently search for eV$^2$ sterile neutrino oscillations. PROSPECT is an optical segmented detector filled with $\sim$4 ton $^6$Li-loaded liquid scintillator and deployed at $\sim$7m from compact reactor core in HFIR(High Flux Isotope Reactor). In order to detect reactor anti-neutrinos via IBD (Inverse Beta Decay) processes, we developed an analysis framework based on the liquid scintillator PSD (Pulse Shape Discrimination) particle-identification and the temporal-spatial correlations in the IBD processes. Additional cosmogenic veto cuts mitigate high on-surface cosmogenic backgrounds. Previously we reported $^{235}$U anti-neutrino spectrum and sterile neutrino oscillation result based on $\sim$ 30 days' reactor on data-taking. Here we describe improvements to the IBD event selection applied to a larger data set with approximately twice the IBD statistics.