  The channeling of the ion recoiling after a collision with a WIMP in direct
dark matter crystalline detectors produces a larger scintillation or ionization
signal than otherwise expected. Channeling is a directional effect which
depends on the velocity distribution of WIMPs in the dark halo of our Galaxy
and could lead to a daily modulation of the signal. Here we compute upper
bounds to the expected amplitude of daily modulation due to channeling using
channeling fractions that we obtained with analytic models in prior work. After
developing the general formalism, we examine the possibility of finding a daily
modulation due to channeling in the data already collected by the DAMA/NaI and
DAMA/LIBRA experiments. We find that even the largest daily modulation
amplitudes (of the order of 10% in some instances) would not be observable for
WIMPs in the standard halo in the 13 years of data taken by the DAMA
collaboration. For these to be observable the DAMA total rate should be 1/40 of
what it is or the total DAMA exposure should be 40 times larger. The daily
modulation due to channeling will be difficult to measure in future
experiments. We find it could be observed for light WIMPs in solid Ne, assuming
no background.
