Design and formation of Wilson cloud chamber

1895, he designed a set of equipment for condensing water vapor to form clouds. At that time, people thought that in order to condense water vapor, each fog bead must have a dust as the core. After carefully cleaning the dust on the instrument, Wilson found that the dust was not needed originally, but when the cloud room was irradiated by X-rays, the cloud appeared immediately, which proved that the condensation phenomenon was centered on ions. After four years of research, he came to the conclusion that when the volume expansion ratio of clean air is 1.25, negative ions begin to become condensation nuclei; When the expansion rate is 1.28, all negative ions become condensed nuclei. For positive ions, the expansion ratio is 1.3 1, and all of them become condensed nuclei when the expansion ratio is 1.35. On the other hand, he also pointed out that the charge of ions exerts a force on water vapor molecules, which contributes to the expansion of fog beads. 19 12 years, Wilson added photographic equipment to the cloud room to shoot the trajectories of charged particles, making it an important instrument for studying rays. The image of alpha particles was taken with this cloud chamber.