A Global Analysis of Light and Charge Yields in Liquid Xenon

Abstract

We present an updated model of light and charge yields from nuclear recoils in liquid xenon with a simultaneously constrained parameter set. A global analysis is performed using measurements of electron and photon yields compiled from all available historical data, as well as measurements of the ratio of the two. These data sweep over energies from 1 - 300 keV and external applied electric fields from 0 - 4060 V/cm. The model is constrained by constructing global cost functions and using a gradient descent minimizer, a simulated annealing algorithm, and a Markov Chain Monte Carlo approach to optimize and find confidence intervals on all free parameters in the model. This analysis contrasts with previous work in that we do not unnecessarily exclude data sets nor impose artificially conservative assumptions, do not use spline functions, and reduce the number of parameters used in NEST v0.98. We report our results and the calculated best-fit charge and light yields. These quantities are crucial to understanding the response of liquid xenon detectors in the energy regime important for rare event searches such as the direct detection of dark matter particles.