Organic liquid scintillator neutrino detector experiment, theoretical modeling, and computational simulation

Abstract

The Liquid Scintillator Neutrino Detector (LSND) experiment aimed at investigating neutrino oscillations, particularly the transformation of muon-type antineutrinos (\(\overlineν_μ\)) into electron-type antineutrinos (\(\overlineν_e\)). This phenomenon challenges the Standard Model's assumption of massless neutrinos. The LSND employed a large organic liquid scintillator (LS) to detect low-energy neutrino interactions, enhanced by the addition of metal ions such as gadolinium (Gd) for improved signal sensitivity and noise suppression. Theoretical modeling and simulations are used in this paper to accurately interpret experimental results. The FLUKA Monte Carlo code was employed to simulate particle interactions and transport in the detector. Key processes modeled included neutrino interactions (\(\overlineν_e + p \to e^+ + n\)), neutron capture (\(n + p \to d + γ\)), and the corresponding light output in the scintillator. The simulations accounted for quenching effects using Birks' law, enabling precise predictions of light yield and detector response to secondary particles. Neutrino fluxes from decay-at-rest (DAR) and decay-in-flight (DIF) processes were calculated, capturing the energy spectra of neutrinos generated by pion and muon decays. Pion production cross-sections and light output efficiency for various particles were also modeled to understand detector performance comprehensively. The theoretical modeling and simulation framework validated the experimental observations and provided insights into the detector's sensitivity and limitations. The LSND results hinted at deviations from the Standard Model, stimulating further investigations into neutrino oscillations and the potential existence of sterile neutrinos.