  The first lead neutron slowing-down spectrometer (LSDS) from a pulsed source
in elastic scattering on lead nuclei has been constructed in the laboratory of
the atomic nucleus of the Physics Institute of the Russian Academy of Sciences
LPI. Currently, there are several operating lead neutron slowing-down
spectrometers: LSDS-100 in Russia, RINS in United States, KULS in Japan and
others. A relation between an energy of lead slowing-down moderated neutrons E
(eV) and the time delay of t ({\mu}s) is described by the expression: E(t) =
K/(t + t_0)^2, where values of K=170.5 (keV {\mu}s^2), t_0 = 0.3 ({\mu}s) in
the case of the LSDS-100 have been measured in the previous experiment. The
energy resolution of LSDS is low (30-45%) and is being determined
experimentally, but the aperture ratio luminosity of the neutron flux detector
is 10^2-10^4 times greater than in the case of a time of flight method
technique. It allows to make experiments with small amount of substance and
small cross-sections of its interaction with the slowed moderated neutrons.
