  Coherent elastic neutrino-nucleus scattering (CEvNS) provides a unique probe
for neutrino properties Beyond the Standard Model (BSM) physics. REactor
neutrino LIquid xenon Coherent Scattering experiment (RELICS), a proposed
reactor neutrino program using liquid xenon time projection chamber (LXeTPC)
technology, aims to investigate the CEvNS process of antineutrinos off xenon
atomic nuclei. In this work, the design of the experiment is studied and
optimized based on Monte Carlo (MC) simulations. To achieve a sufficiently low
energy threshold for CEvNS detection, an ionization-only analysis channel is
adopted for RELICS. A high emission rate of delayed electrons after a big
ionization signal is the major background, leading to an analysis threshold of
120 photo-electrons in the CEvNS search. The second largest background, nuclear
recoils induced by cosmic-ray neutrons, is suppressed via a passive water
shield. The physics potential of RELICS is explored with a 32 kg-yr exposure at
a baseline of 25 m from a reactor core with a 3 GW thermal power. In an energy
range of 120 to 240 PE, we expect 4902.4 CEvNS and 1318.4 background events.
The sensitivity of RELICS to the weak mixing angle is investigated at a low
momentum transfer. Our study shows that RELICS can further improve the
constraints on the non-standard neutrino interaction (NSI) compared to the
current best results.
