  Boosted dark particles of astrophysical origin can lead to nonstandard
nuclear or electron recoil signals in direct detection experiments. %It has
been shown that this interpretation successfully explains the excess of keV
electron recoil events recently observed by the XENON1T experiment, and that a
daily modulation of the signal in the detector is expected. We conduct an
investigation of the daily modulation feature of a potential future signal of
this type. In particular, we perform simulations of the dark particle
interactions with electrons in atoms building up the Earth on its path to the
detector, and provide in-depth predictions for the expected daily changes in
the signal for various direct detection experiments, including XENONnT, PandaX,
and LUX-ZEPLIN.
