  The low-energy monochromatic neutron emission from an Y-88/Be source can be
exploited to mimic the few keVnr nuclear recoils expected from low-mass Weakly
Interacting Massive Particles (WIMPs) and coherent scattering of neutrinos off
nuclei. Using this source, a ~<10% quenching factor is measured for sodium
recoils below 24 keVnr in NaI[Tl]. This is considerably smaller than the 30%
typically adopted in the interpretation of the DAMA/LIBRA dark matter
experiment, resulting in a marked increase of its tension with other searches,
under the standard set of phenomenological assumptions. The method is
illustrated for other target materials (superheated and noble liquids).
