Wednesday, December 7, 2011

Trying to visualize beta particles in supercritical CO2 (still no success)

In an earlier video, I tried to visualize alpha particles in supercritical CO2, similar to an isopropanol vapor cloud chamber. Someone commented that the alpha particles will not travel very far (maybe 10 microns) in liquid or supercritical CO2, and recommended that I try beta particles, which should have a path length of almost 10mm. Unfortunately, I still don't see any bubble or droplet trails using strontium-90 and thallium-204 sources. It's possible that the ionizing effect of the radiation particles does not interact with the CO2 phase change as it does by condensing droplets in a cloud chamber. Also, cloud chambers are very finicky, and if this CO2 visualization method is as finicky or worse, it may take some more time to figure out the right combination of environmental variables.


  1. this might help, and your right, it should work, i think that the S-CO2 must be extreamly close the boiling point in order or it to work,

  2. i would also recommend only using a few drops of s-co2 as well

  3. As odd as it sounds, you might want to try rotating your setup 90 degrees and adding a magnetic field. If you tune your field right, you should be able to measure the diameter of the arc traced out by the beta particle and determine what the energy of the particle is.

    As for the rotating 90 degrees, if your chamber is flat, you might be able to have a little more space to view traces in- and try to light it from the side.

    I have actually seen the supercritical method working before. I have a setup that I might be able to reproduce it, and if I can, I'll video it and send it to you.

    Nice job on the Make Magazine article this month, by the way.

  4. Oh, and what you're trying to do is similar to the old bubble chambers. It requires a very careful maintenance of both temperature and pressure.