[time-nuts] Variation in Radioactive Decay Rate with Solar Activity

Jim Lux jimlux at earthlink.net
Wed Aug 3 17:57:04 EDT 2011

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.


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