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

[Brooke Clarke]

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

ISOTOPE 	ACTIVITY 	HALF-LIFE 	ENERGIES (KeV)
*Barium^133 * 	1uCi 	10.7 years 	*Gamma: *81.0, 356.0
*Cadmium^109 * 	1uCi 	453 days 	*Gamma: *88.0
*Cesium^137 * 	*1*uCi 	30.1 years 	*Gamma: *32, 661.6
*Beta: *511.6, 1173.2
*Cesium^137 * 	*5*uCi 	30.1 years 	*Gamma: *32, 661.6
*Beta: * 511.6, 1173.2
*Cesium^137 * 	*10*uCi 	30.1 years 	*Gamma: *32, 661.6
*Beta:* 511.6, 1173.2
*Cobalt^57 * 	1uCi 	270 days 	*Gamma: *122.1
*Cobalt^60 * 	1uCi 	5.27 years 	*Gamma: *1173.2, 1332.5
*Europium^152 * 	1uCi 	13.5 years 	*Gamma: *121.8, 344.3, 1408.0
*Manganese^54 * 	1uCi 	312 days 	*Gamma: *834.8
*Sodium^22 * 	1uCi 	2.6 years 	*Gamma: *511.0, 1274.5
*Strontium^90 * 	0.1uCi 	28.5 years 	*Beta: *546.0
*Thallium^204 * 	1uCi 	3.78 years 	*Beta: *763.4
* Polonium^210 * 	0.1uCi 	138 days 	*Alpha: *5304.5
*Zinc^65 * 	1uCi 	244 days 	*Gamma: *511.0, 1115.5


Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.End2PartyGovernment.com/


Jim Lux wrote:
> On 8/3/11 12:14 PM, J. Forster wrote:
>> Hi Brooke,
>>
>> Maybe. The photon counting gear is pretty trivial. You'd need:
>>
>> A scintillator
>> A PMT (Photo Multiplier Tube) and HV stable HV PS.
>> A preamp
>> A SCA (Single Channel Analyzer). These can be built.
>> A counter, stable time base, and data recorder
>>
>> The main difficulty, IMO, would be getting a sufficient sized lump of 
>> the
>> material. Chunks of Cs don't grow on trees, at least not where I live.
>>
>
> Does it have to be Cs?  United Nuclear sells a wide variety of 
> calibration sources for <$100.  Yes, they have Cs137 (10 microCuries)...
>
>
>
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