The operation of a cloud chamber by condensing supercooled vapor along the ionized tracks of radiation is a well-established scientific fact that does not require citation.
The claim describes the standard, defining operational principle of a cloud chamber, which is a classic piece of physics instrumentation invented by C.T.R. Wilson. None of the retrieved papers specifically evaluate or discuss the functioning of cloud chambers (they cover topics ranging from self-driving labs and nanoparticle growth to ice crystallization and radiation track structure in biology). Since the claim is a matter of standard scientific definition and everyday physics observation, it is classified as common knowledge.