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Once we got the cloud chamber built, we tried to make clouds with it. The cloud chamber sits on the marble tile, which sits on top of the dry ice - the fish tank that makes up the chamber sits upside down on the tile.  We glued a felt pad to the bottom of the fish tank and then soaked it in ethyl alcohol, which is supposed to make good particle droplets.  The key is that the drops have to be small enough to rain down from top to bottom like, fog, but not so big that they fall like rain.  The radioactive particles we are trying to see should make a trail through the fog that we can see.

We learned that the fog won't happen fast enough without putting something hot on top of the fish tank.  This discovery cost us a whole week, but we felt like we were getting close.

It really made sense to us that we needed to use the hot pad on top of the tank - when the earth makes fog, the sun is the energy source that makes water evaporate into tiny droplets.  As they fall through the cooler atmosphere, the droplets can join together to make droplets of fog.  

It turned out to be really hard to see the particle tracks we were after. We thought we saw some, but it was very difficult to see them on the video we took. You can see how hard it was to get the lighting just right, but we definitely thought we saw tracks from radioactive particles.

Building the cloud chamber meant that we had to research how build one, and then get the materials to build it.  That meant getting felt cloth, a fish tank, styrofoam for insulation, a black marble floor tile and duct tape.  We decided to use black so that the fog of the cloud chamber would show up agains the black.  We also lined the tank with black paper for the same reason.

Here are Owen and Maanik making the insulation for the base of the tank, which has to be kept really cold - we used dry ice that Drew's father got us.  That turned out to be a lot of fun, so we gave it its own blog post, which you can read here.

We worked on building the cloud chamber for two or three weeks, and figured out that dry ice doesn't do enough by itself to make the cloud that we were hoping for.  In our next post, you can see that we figured out how to make good clouds.  By the way, this photo is Drew and Owen working on building the bottom of the chamber.