A Review of NEST Models, and Their Application to Improvement of Particle Identification in Liquid Xenon Experiments

The Noble Element Simulation Technique (NEST) is a widely adopted and reliable simulation toolkit for rare-event physics searching experiments using liquid xenon. The key part of signals and backgrounds simulation in liquid xenon is accurate modeling of charge and light production. To achieve this, based on various experimental data, NEST has its signal and background production models fit using comprehensive and empirical formulae for the average charge and light yields and their variations. NEST also simulates the final scintillation pulses and exhibits the correct energy resolution as a function of the particle type, the energy, and the electric fields. After vetting of NEST against raw data, with several specific examples pulled from XENON, ZEPLIN, LUX / LZ, and PandaX, we interpolate and extrapolate its models to draw new conclusions on the properties of future detectors (e.g., XLZD's). It turns out that for the future detectors, the discrimination power of electronic recoil backgrounds from a potential nuclear recoil signal (especially WIMP dark matter) can be improved by another order of magnitude (99.95% discrimination) from the oft-quoted one, with a reasonably high photon detection efficiency and achievable drift fields.