  As part of an experimental effort to demonstrate sensitivity in a large-mass
detector to the ultra-low energy recoils expected from coherent
neutrino-nucleus elastic scattering, we have designed and built a highly
monochromatic 24 keV neutron beam at the Kansas State University Triga Mark-II
reactor. The beam characteristics were chosen so as to mimic the soft recoil
energies expected from reactor antineutrinos in a variety of targets, allowing
to understand the response of dedicated detector technologies in this yet
unexplored sub-keV recoil range. A full characterization of the beam properties
(intensity, monochromaticity, contaminations, beam profile) is presented,
together with first tests of the calibration setup using proton recoils in
organic scintillator.
