On 8/3/11 2:20 PM, Brooke Clarke wrote:
Hi Jim:
The problem I'm having is that just counting the clicks from a source is
a way to get random numbers. If you average the clicks over a large
amount of time and plot that average, it will decrease over time. So to
see the change in decay rate the source needs to have a short half-life.
The article mentions (ordered by half life):
manganese-54 (312.03 days or 26.9E6 sec)
cesium-137 (30.17 years)
silicon-32 (170 years or 5.4E9 sec)
radium-226 (1601 years)
manganese-54 looks like the shortest half life that was mentioned and
it's avaialble from United Nucular:
http://unitednuclear.com/index.php?main_page=product_info&cPath=2_5&products_id=819
Here's their table of Disk Sources which has some isotopes that have a
shorter half life:
*Cobalt^57 *270 days
*Zinc^65 *244 days
*Polonium^210 * 138 days (also available as a needle source)
So in the disk sources Polonium-210 has the shortest half life.
http://en.wikipedia.org/wiki/Polonium
Don't forget that there are daughter products that have short half
lives. Radon and daughters can be collected easily with a coffee
filter, and some of them have half lives in the "tens of minutes" range,
and with a pretty simple counter (Aware Electronics RM-60, for instance)
you can easily see the half lives of the daughters stacked up.
http://www.aw-el.com/f_decay.htm
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