Final PROSPECT-I analysis: Data Splitting and Single Ended Event Reconstruction implementation and its impact on the oscillation analysis*

The Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) is a short-baseline above-ground antineutrino experiment at short baselines located at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). The PROSPECT detector comprises 4-tons of Li-6 doped liquid scintillator divided into an 11x14 array of optically separated segments. This experiment's physics goals include searching for the existence of sterile neutrinos and precisely measuring the antineutrino energy spectrum. Antineutrinos are detected via the inverse beta decay (IBD) interaction which provides a near-unique space-time correlated signal pair consisting of a positron energy deposition and a delayed neutron capture in the liquid scintillator, both of which are recorded by PMT pairs in double-ended segments. The first data-taking campaign concluded in 2018 and resulted in new oscillation limits and a high precision energy spectrum. However, during the data collection period, information coming from a small number of PMT’s had to be excluded, reducing statistical impact and degrading the detector energy response. To recover this lost information, the combined implementation of two new data recovery approaches is being employed. These methods consist in the use of Single Ended Event Reconstruction capabilities of the detector, along with parsing the available data into five independent periods. In this talk, I will describe the impact of these improvements on the signal to background ratio, effective IBD statistics, and an optimized selection process used to identify IBD events. Additionally,  the impact of these on the sensitivity of the experiment to short baseline oscillations will be described.