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Home made particle detector


Would it be possible for me to build a small particle detector at home? I would like to observe some of the cosmic ray particles that hit earth.


Dear Tom:

Yes, absolutely. All you need is a container with vapor, and charged particles zipping through will leave a trail similar to the trails left by air planes in the sky. This type of detector is called a cloud chamber.

Instead of writing down all the details, I refer you to a Scientific American website. In January 2001, the magazine published an article on how to build a cloud chamber. You can read this article at:

Please let me know if you need more help.

The cloud chamber method led to two Nobel Prizes: Called the expansion method, this discovery earned C.T.R. Wilson a share of the 1927 Nobel Prize ( Improving on that method, P.M.S. Blackett received the 1948 Nobel Prize ( for the development of the Wilson cloud chamber.

To learn more about cosmic ray particles, the particles that you will observe with your home-built cloud chamber, check out the public webpages of the Pierre Auger Project:

The scientists of the Pierre Auger Project, including Fermilab physicists, are building a detector to capture cosmic rays. They are particularly interested in some of the most energetic particles ever observed in the universe. Since those events are pretty rare, they build a very large array of detectors.

Since there are many more low-energy cosmic particles, there is plenty for you to see with a small cloud chamber.

Best wishes and good luck with the construction of your own detector,

Kurt Riesselmann
Office of Public Affairs

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last modified 8/29/2002