Re: Cloud Chamber

["rick strickert" <rick_strickert@pc.radian.com>]

David Bromwich (Griffith University) wrote:

>I saw something in a physics journal 10 (or was it 20 ) years ago
>describing a simple cloud chamber for demonstrating the range of
>alpha particles in air.

>Does anyone have a good, simple design?

    Yes, there are numerous articles on inexpensive cloud chambers and
    other radiation equipment in the _American Journal of Physics_, The
    Journal of Chemical Education_, _The Physics Teacher_, and various
    physics books such as _Demonstration Experiments in Physics_, edited by
    R.M. Dutton (1938).

    Some cloud chamber references I found were -

    J.Chem.Ed. 11 (1934), p. 576
    J.Chem.Ed. 32 (1955), p. 269
    J.Chem.Ed. 29 (1952), p. 511

    Am.J.Physics 22 (1954), p. 38
    Am.J.Physics 26 (1958), p. 12
    Am.J.Physics 29 (1961), p. 99
    and a recent one - Am.J.Physics 59 (1991) p. 285

    During the "atomic heyday" (1930-1960), cloud chambers and other
    radiation monitors were sold by a number of commercial science
    distributers to the general public.  (I even got a spinthariscope in my
    Porter chemistry set.)

    I have seen cloud chambers advertised in the Edmund Scientific catalog.
    Supersaturated Environments (Madison, WI 608-238-5068) makes several
    cloud chambers, but in the US$400-1200 price range.  The Electronic
    Goldmine (POBox 5408, Scottsdale, AZ 85261) sells a thin-window geiger
    counter kit for US$60).

    Radioactive sources are available, but check your national/local
    regulations.  In the US, some radiation sources are available in exempt
    and general license quantities, in addition to licensed amounts.  For
    the classroom I suggest you limit the sources to naturally occurring
    radioactive materials - uranium ore, uranium minerals (see Ward's
    Natural Science catalog), uranium or thorium compounds, black glaze
    porcelain (if still made), Fiestaware plates, Coleman lantern mantles
    (containing thorium, not the recent ones with yttrium).

    Rather than hassle with dry ice and alcohol, I have done high school
    radiochemistry demonstrations using the thorium lantern mantles,
    muriatic acid (HCl, for non-chemists) and a US nickel coin.  The
    thorium decay product, Bi-212, self-deposits on the nickel (a good
    chemistry lesson on why) and one can count the decay using a simple
    thin-window geiger counter (and do half-life calculations).  What's
    nice is that the 1-hour half-life radioactivity on the nickel is gone
    in a day, and the acid solution containing the lantern mantle is ready
    to be "milked" for another demo!  Similar demos are possible using
    radon daughters collected on a filter (or on a handball! - see The
    Physics Teachers 30, (1992) p. 16).

    Rick

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