Event reconstruction in a liquid xenon Time Projection Chamber with an optically-open field cage

nEXO is a proposed tonne-scale neutrinoless double beta decay (0νββ) experiment using liquid 136Xe (LXe) in Time Projection Chamber (TPC) to read out ionization and scintillation signals. Between the field cage LXe vessel, layer of (“skin” LXe) present, where no signal collected. Only photons are detected, owing lack optical barrier around cage. In this work, we show that light originating skin region can be used improve background discrimination by 5% over previous published estimates. This improvement comes from two elements. First, fraction γ-ray removed identifying interactions with an energy deposition LXe. Second, 222Rn dissolved efficiently rejected tagging α 214Bi-214Po chain