  Short-baseline reactor antineutrino experiments with shallow overburden
usually have large cosmogenic neutron backgrounds. The Taishan Antineutrino
Observatory (TAO) is a ton-level liquid scintillator detector located at about
30 m from a core of the Taishan Nuclear Power Plant. It will measure the
reactor antineutrino spectrum with high precision and high energy resolution to
provide a reference spectrum for JUNO and other reactor antineutrino
experiments, and provide a benchmark measurement to test nuclear databases.
Background is one of the critical concerns of TAO since the overburden is just
10 meter-water-equivalent. The cosmogenic neutron background was estimated to
be ~10% of signals. With detailed Monte Carlo simulations, we propose several
measures in this work to reduce the neutron backgrounds, including doping
Gadolinium in the buffer liquid, adding a polyethylene layer above the bottom
lead shield, and optimization of the veto strategy. With these improvements,
the neutron background-to-signal ratio can be reduced to ~2%, and might be
further suppressed with pulse shape discrimination.
