  In a cloud chamber, the quantum measurement problem amounts to explaining the
first droplet in a charged-particle track; subsequent droplets are explained by
Mott's 1929 wave-theoretic argument about collision-induced wavefunction
collimation. I formulate a mechanism for how the first droplet in a cloud
chamber track arises, making no reference to quantum measurement axioms. I look
specifically at tracks of charged particles emitted in the simplest slow
decays, because I can reason about rather than guess the form that wave packets
take. The first visible droplet occurs when a randomly occurring,
barely-subcritical vapor droplet is pushed past criticality by ionization
triggered by the faint wavefunction of the emitted charged particle. This is
possible because potential energy incurred when an ionized vapor molecule
polarizes the other molecules in a droplet can balance the excitation energy
needed for the emitted charged particle to create the ion in the first place.
This degeneracy is a singular condition for Coulombic scattering, leading to
infinite or near-infinite ionization cross sections, and from there to an
emergent Born rule in position space, but not an operator projection as in the
projection postulate. Analogous mechanisms may explain canonical quantum
measurement behavior in detectors such as ionization chambers, proportional
counters, photomultiplier tubes or bubble chambers. This work is important
because attempts to understand canonical quantum measurement behavior and its
limitations have become urgent in view of worldwide investment in quantum
computing and in searches for super-rare process (e.g., proton decay).
