My father and I built our first cloud chamber when I was in junior high school, back in the late 1950s. We based our cloud chamber on the design shown in the BELL TELEPHONE HOUR program titled "STRANGE CASE OF THE COSMIC RAYS".

Our first cloud chamber used a Pyrex double boiler cooking pot which rested on a piece of dry ice. The cloud chamber shown on the "STRANGE CASE OF THE COSMIC RAYS" film had a cardboard lid saturated with alcohol. Heat was applied to the cardboard lid with an electric iron. In an attempt to reduce fire hazard, my father and I used an asbestos cooking diffuser instead of cardboard for the top of the cloud chamber.

Frankly, we were very disappointed with our results. The electric iron was a difficult heat source to control, and the asbestos cooking diffuser did not form a tight enough seal with the Pyrex pot. We did succeed in producing a cloud of alcohol vaporsort of. When we didn't see any cosmic ray vapor trails, we added a particle source of our own: a small container of real radium paint from my grandfather's watch repair supplies! (We knew the dangers of working with radium paint. Our next door neighbor had died in his early twenties after a very short career as a watch dial painter!) Even with the radium paint inside the cloud chamber, it was very difficult to produce good vapor trails of particles.

There were too many convection currents inside our three-quart Pyrex cloud chamber! We could never set the electric iron at a low enough heat level to create a good, uniform cloud. Steamy vapor hovered over the bottom of the Pyrex pot, but convection currents in the pot caused vapor trails to break up as fast as they formed. Fortunately, the Chicago Museum of Science and Industry had a good-operating commercially installed cloud chamber display. Since I grew up in the Chicago suburbs, I visited the museum frequently, and spent many, many hours staring at vapor trails inside the museum's cloud chamber.

The made-for-television film, "STRANGE CASE OF THE COSMIC RAYS" left a lasting impression on me, and I've used a video copy in both eighth and ninth grade science classes for at least eight years. I wanted to use cloud chambers in my classroom, but based on my early experience, I did not know how to build a successful cloud chamber without an electric iron as a heat source. The cloud chamber design used by Dr. Jodi Cooley in the first ASTRONOMY IN THE ICE course worked surprisingly well without a strong heat source. The cloud chambers used in this year's SCIENCE ON THE ICE course are similar in design.

A page with many more movies like this

Roger Carlson's Lab Instructions

Complete Cloud Chamber Lesson Plan, including "standards"

Tips & Tricks

Costs & Materials list

Materials & Construction steps

Cloud Chamber reference books

Questions on Cosmic rays based on the movie "The Strange Case of the Cosmic Rays"