Improved Event Reconstruction and Spectrum Analysis using PROSPECT Antineutrino Data*

The Precision Reactor Oscillation and SPECTrum (PROSPECT) experiment is a short-baseline reactor experiment aimed at to measure the spectrum of antineutrinos from the High Flux Isotope Reactor and search for potential short-baseline oscillations by the existence of sterile neutrinos. The data gathered during 2018 has allowed PROSPECT to reject a large portion of the available parameter space for sterile oscillations while providing additional evidence for the relative excess of antineutrinos detected in the 4-6~MeV region. However, the analyses performed to produce the last published results from PROSPECT excluded a portion of initially unusable data obtained within some of the segments of the detector containing non-operating PMTs. Recent efforts from the collaboration have resulted in a more sophisticated analysis that includes the Single Ended Event Reconstruction (SEER) of the previously unused segments, and the careful splitting of data periods to maximize the available statistics. The significant increase in statistics and signal to background ratio provides PROSPECT with a unique opportunity to further its physics outreach.

In this talk, a detailed description of SEER will be given together with its application as a core part of PROSPECT's event selection. The impact of the improved analysis on the spectral studies will also be discussed, emphasizing its effect on the unfolding of the visible prompt spectrum into the antineutrino energy space. Aiming for the extraction of further applicable physical results, a series of different applications for the unfolded spectrum will be reviewed, including a comparison with modern summation predictions with modified fission yields and effective extensions of the Huber spectrum.