Step 1: Materials
– Insulation foam (I bought some that was conveniently cut to fit between the framing boards on a house which proved a perfect width)
– Fish tank
– Metal plate
– Black Modeling clay
– Black Cardstock
– Black Electrical Tape
– Glue (to glue the foam pieces together)
– Sand paper (to smooth the foam)
– Black Foam Poster board (this was used to create a cover for the fish tank to make the pictures and video come out nicer)
– Flashlight or old slide projector (basically you need a solid beam of light to see the cosmic rays)
– Dry-Ice (Used to cool the base of the cloud chamber)
– 91% or higher Isopropyl alcohol (70% does not work!!!)
– Water (this was poured into the clay channel on the base to create an air tight seal)
– Razor Blade
– Paint Scraper (I used it to help cut the foam)
– Yard Stick
– Hot Glue (used to attach the felt to the top of the fish tank)
– Magnets (used to attach the felt to the top of the fish tank)
Step 2: Constructing the Insulated Box (for the Dry-Ice)
Step 3: Preparing The Metal Base Plate
Step 4: Modifying the Fishtank
Step 5: Putting it All Together!
Then pour some alcohol onto the felt until the felt is pretty well soaked in at least 91% isopropyl alcohol and place the fish tank ontop of the metal baseplate.
Then pour some extra water or alcohol into the clay channel that you made in the baseplate to ensure an airtight seal.
Now darken the room and illuminate the cloud chamber with your light source. I covered all but one of the fish tank’s faces with black poster board to make it easier for the cosmic rays to be filmed but that is not necessary. Almost immediately you should see a cloud of alcohol vapor start to rain down and after about 10 min a super saturated vapor of alcohol should form. Now you should be able to observe some vapor trails towards the bottom of the cloud chamber.
Basically the alcohol vapor is so saturated that when a cosmic ray passes through the chamber it ionizes the molecules in the air and the alcohol vapor condenses around these trails of ionized molecules. This is how the cloud chamber allows us to “see” particles that are moving close to the speed of light. To start learning more about why this works check out the wikipedia link.