The design and use of a Peltier-powered cloud chamber for outreach and classroom laboratory measurements*

One challenge facing the scientist who studies anything at the nuclear level is convincing both the general public and students that what they are studying is real. Astronomers are able to show beautiful images of stars and galaxies, geologists let you hold a 3 billion year-old rock in your hand, but the nuclear physicist must come up with other methods to demonstrate the equally fascinating science that they engage with. At Siena College, we have worked for almost 10 years to improve upon a design for a Peltier-powered cloud chamber that does not require dry ice and is very portable. The design has been driven primarily by students in our Applied Physics program who have used their general design skills and 3D printing acumen to make the device easier to build and transport. This makes it ideal for both outreach activities and in-classroom demonstrations, usually in a Modern Physics class. In addition, Siena students have worked hard to document the construction process on the popular website, Instructables, so that others can build their own. Recently, we have developed a lab in which students use the device to extract scientific data. This involves a video analysis of a radioactive sample placed in the cloud chamber and the lengths of tracks are measured from a video analysis program. These lengths are used as an analog of the energy of the emitted particles and a spectrum is produced and compared to literature. A similar study can be done with cosmic rays where the lengths of the tracks map onto the angle of entry. The current status of both the cloud chamber design and the efforts to turn this into a classroom lab will be presented.