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 processes (e.g., proton decay).

在云室中，量子测量问题相当于解释带电粒子轨道中的第一个液滴。随后的液滴由Mott于1929年关于碰撞引起的波函数准直的波理论论证进行了解释。我为云腔轨道中的第一个液滴如何产生的机制制定了一个机制，但没有提及量子测量公理。我专门研究以最简单的慢衰减方式发射的带电粒子的轨迹，因为我可以推理而不是猜测波包采取的形式。当通过随机发出的带电粒子的微弱波函数触发电离而将随机出现的，几乎不亚临界的蒸汽液滴推过临界点时，就会出现第一个可见液滴。这是可能的，因为当电离的蒸汽分子使液滴中的其他分子极化时产生的势能可以平衡所发射的带电粒子首先产生离子所需的激发能。这种简并性是库仑散射的奇异条件，导致无限大或接近无限大的电离横截面，并从那里到位置空间中出现的Born规则，而不是像投影假设中那样的算子投影。类似的机制可以解释检测器（例如电离室，比例计数器，光电倍增管或气泡室）中的规范量子测量行为。