A Peltier Cooled Cloud Chamber For Observing Subatomic Particles
A cloud chamber is a device for visualizing the passage of electrically charged, subatomic particles through a supersaturated cloud of alcohol vapor. The behavior of charged particles such as alpha and beta radiation, occurring naturally in the surrounding atmosphere and muons, created within a cosmic ray shower, can be observed as tracks through the vapor cloud. The actual particles are too small to be seen by eye but their tracks, created by ionization and condensation of the cloud , are readily seen as white traces or tracks.
The cloud chamber operates by evaporation of isopropyl alcohol near the top of a glass chamber, maintained at about 70 degrees F , and condensation of the alcohol near the bottom of the chamber, maintained at about - 30 degrees F. The supersaturated area occurs near the bottom on the chamber where the subatomic particle tracks can be seen in a area about 0.375" deep. A strong magnet is placed beneath the cloud chamber as a means to identify the polarity of very light weight, negative charge (electrons) and positive charged (positrons) beta particles by the curved direction of their tracks.
The -30 degrees F temperature of the cloud chamber bottom is maintained by a stack of three Peltier thermoelectric modules typically used in micro refrigerators and wine chillers.
The cloud chamber operates by evaporation of isopropyl alcohol near the top of a glass chamber, maintained at about 70 degrees F , and condensation of the alcohol near the bottom of the chamber, maintained at about - 30 degrees F. The supersaturated area occurs near the bottom on the chamber where the subatomic particle tracks can be seen in a area about 0.375" deep. A strong magnet is placed beneath the cloud chamber as a means to identify the polarity of very light weight, negative charge (electrons) and positive charged (positrons) beta particles by the curved direction of their tracks.
The -30 degrees F temperature of the cloud chamber bottom is maintained by a stack of three Peltier thermoelectric modules typically used in micro refrigerators and wine chillers.
Elliott Liggett
Retired engineer, 42 years with Lockheed Martin, Loral Defense Systems, Goodyear Aerospace and Goodyear Tire. Member of the Schantz Maker Group helping to teach high school and middle school students how to build and use 3D printers.