  There are recent interests with CsI(Tl) scintillating crystals for Dark
Matter experiments. The scattering signatures by neutrons on a CsI(Tl) detector
were studied using a neutron beam generated by a 13 MV Tandem accelerator. The
energy spectra of nuclear recoils from 7 keV to 132 keV were measured, and
their quenching factors for scintillating light yield were derived. The data
represents the first confirmation of the Optical Model predictions on neutron
elastic scatterings with a direct measurement on the nuclear recoils of heavy
nuclei. The pulse shape discrimination techniques to differentiate nuclear
recoils from $\gamma$-background were studied. Internal consistencies were
obtained among the different methods of light yield measurements. The projected
capabilities for Cold Dark Matter searches with CsI(Tl) crystals are presented.
