  Using publicly available video of a diffusion cloud chamber with a very small
radioactive source, I measure the spatial distribution of where tracks start,
and consider possible implications. This is directly relevant to the quantum
measurement problem and its possible resolution, and appears never to have been
done before. The raw data are relatively uncontrolled, leading to caveats that
should guide future, more tailored experiments. Aspects of the results may
suggest a modification to Born's rule at very small wavefunction, with possibly
profound implications for the detection of extremely rare events such as proton
decay, but other explanations are not ruled out. Speculatively, I introduce two
candidate small-wavefunction Born rule modifications, a hard cutoff, and an
offset model with a stronger underlying physical rationale. Track distributions
from decays in cloud chambers represent a previously unappreciated way to probe
the foundations of quantum mechanics, and a novel case of wavefunctions with
macroscopic signatures.
