  The possibility of using a trap with ultracold neutrons as a detector of dark
matter particles with long-range forces is considered. The basic advantage of
the proposed method lies in possibility of detecting the recoil energy 10-7 eV.
The restrictions on parameters of Yukawa type interaction potential between
dark matter particles and a neutron are presented for different dark matter
densities on the Earth. The assumption concerned with long-range interaction of
dark matter particles and ordinary matter leads to a substantial enhancement of
cross section at low energy. Consequently, there arises a possibility of
capture and accumulation of dark matter in a gravitational field of the Earth.
Rough estimation of accumulation of low-energy dark matter on the Earth is
discussed. The first experimental restrictions for existence of dark matter
with long-range forces on the Earth are presented.
