  Among the direct search experiments for weakly interacting massive particle
(WIMP) dark matter, the DAMA experiment observed an annual modulation signal
interpreted as WIMP interactions with a significance of 9.2$\sigma$. Recently,
Jonathan Davis claimed that the DAMA modulation may be interpreted on the basis
of the neutron scattering events induced by the muons and neutrinos together.
We tried to simulate the neutron backgrounds at the Gran Sasso and Yangyang
laboratory with and without the polyethylene shielding to quantify the effects
of the ambient neutrons on the direct detection experiments based on the
crystals.
