Neutrino Directionality and Optical Simulations with PROSPECT

The Precision Reactor Oscillation and SPECTrum (PROSPECT) experiment is a short-baseline reactor experiment with the goal of searching for potential sterile neutrino oscillations and measuring the antineutrino spectrum from the High Flux Isotope Reactor (HFIR). The PROSPECT-I detector is a 4 ton, optically segmented detector utilizing a ⁶Li loaded liquid scintillator, sitting at approximately 7 - 9 m from the HFIR core. This dissertation describes my contributions to the PROSPECT experiment. The PROSPECT-I detector's segmentation and ⁶Li loading enable precise measurement of the direction of a compact neutrino source. With an estimated true neutrino (reactor to detector) direction of [phi] = 40.8° ± 0.7° and [theta] = 98.6° ± 0.4°, the PROSPECT-I detector is able to reconstruct an average neutrino direction of [phi] = 39.4° ± 2.9° and [theta] = 97.6° ± 1.6°. This measurement is made with approximately 48 000 Inverse Beta Decay signal events and is the most precise directional reconstruction of reactor antineutrinos to date. The PROSPECT-II detector is set to improve on the world-leading spectrum and oscillation studies performed by PROSPECT-I. Utilizing Geant4, a highly optimized and accurate optical model was built to predict detector response. To not impact detector efficiency, a limit of 5% was set for cross-talk. Cross-talk is a phenomenon where photons generated in one optical segment are detected by an adjacent segment's PMT. My PROSPECT-II optical simulation was able to verify that various detector configurations allow for less than 5% cross-talk to be achieved, even when the PMT grid is slightly misaligned with the optical segments. The PROSPECT-II optical model was also able to reintroduce sensitive detector effects seen in PROSPECT-I, providing confidence in the successful physics program proposed for PROSPECT-II.