Hi John:
Yes. I think using the isotope with the shortest half-life will make
for the most sensitive measurement, nest pas?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.End2PartyGovernment.com/
J. Forster wrote:
You measure the number of counts in a constant time interval. That gives
you a rate, which is predictable from the known half-life of the source.
What you are looking for ius deviations from the rate that correlate wqith
the sun's rotation (or something else).
The best way might be to measure the rate, and then auto-correlate it or
cross-correlate it with, say, the known sun rotation.
-John
===================
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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