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Building a cloud chamber

  1. Oct 4, 2006 #1
    I want to build a cloud chamber. I have tried one approach for which I found directions online. Unfortunately it didn't work out for me. In short, I used an empty pickle jar with felt glued into the bottom of the jar. I poured in 91% Isopropyl alcohol to saturate the felt. I screwed the metal cap on and flipped it over into the top of a styrofoam cooler where I had a cut a hole to allow it to pole through to the inside of the cooler. Inside the cooler was a block of dry ice that the jar cap rested on. I did see small droplets from the alcohol as it cooled and fell towards the bottom of the chamber.

    The problems I came up with in this method:

    1) As the dry ice sublimates, it shrinks and loses contact with the metal cap on the jar, thus stalling the cooling process.

    2) The pickle jar is made of very imperfect glass and I think it would be impossible to see any events even if the project had been successful.

    3) I got fed up with dealing with the cooler and just sat the jar on top of the dry ice on my counter. I eventually left the room and forgot to check back on the jar until I heard a loud crash as the jar fell to the kitchen floor. Oh well, the jar sucked anyway! :)

    4) I don't like dealing with dry ice because the store only sells it in 10lb. quantities if you show up on the day it is delivered. At $1 per pound, it's just a waste of money becaus I'm not using most of the dry ice before it sublimates anyways.

    5) It was suggested to use 95% iso instead of 91% but I don't know where to buy it. Also, Ethyl or Methyl are supposed to give better results, but again, I don't know where to buy it.

    So, this all leads me to this question. Does anyone know of any plans online for building a cloud chamber more like the original Wilson cloud chamber? I believe he used a piston to quickly reduce the pressure in the enclosed system, causing the gas molecules to expand rapidly and cause supercooling. Either way, I want to make a reusable cloud chamber that does not rely on dry ice. Any help would be great.
     
  2. jcsd
  3. Oct 4, 2006 #2
    Hi Trainwreck,

    It seems that you can either use supercooled (dry ice) or superheated (near boiling) water vapor. Wilson used the heated supersaturated water which was then rapidly cooled.
     
  4. Oct 4, 2006 #3
    Ok, so was water vapor allowed into a chamber that was rapidly expanded using a piston-type of setup?
     
  5. Oct 4, 2006 #4
    In the one that I was going to make (13 years ago) you held a rubber diaphragm in and then release it causing the supersaturated air to quickly cool
     
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