Effect of elastic scattering in the Earth on cold dark matter experiments.

Abstract

The diurnal modulation of fluxes and velocity distributions of cold dark matter (CDM) candidate particles, due to elastic scattering on the constituent nuclei of the Earth, is predicted. The geology, nuclear physics, the Earth's orientation, rotation, and trajectory through the galactic halo are included as well as the isotropic Maxwellian velocity distribution of CDM in the rest frame of the galactic halo. Observable modulations in detection rates and energy spectra are predicted for some interesting theoretical and experimental scenarios. The effects are seen to be maximal at southern latitudes. The differences in the sensitivity of experiments at southern and northern latitudes are explored. It is shown that it would be possible to detect Dirac neutrinos with densities well below those heretofore experimentally excluded.