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Old 19th April 2017, 6:08 PM   #16
Sabot68
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So, I'm currently building a Geiger counter and I would like a radioactive 'source' of a known strength so I can calibrate it. I have been looking around the net and this popped up:
http://unitednuclear.com/index.php?m...510d68b370a8aa

I'm assuming that any of those products would be illegal in the united nanny state of Australia?
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Old 19th April 2017, 8:22 PM   #17
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Quote:
Originally Posted by Sabot68 View Post
So, I'm currently building a Geiger counter and I would like a radioactive 'source' of a known strength so I can calibrate it.
A Geiger counter doesn't measure "strength" of radiation. It counts the number of photons, alpha and beta particles that ionize the gas in the tube.

Quote:
I have been looking around the net and this popped up:
http://unitednuclear.com/index.php?m...510d68b370a8aa

I'm assuming that any of those products would be illegal in the united nanny state of Australia?
They're pretty much pointless for a your purpose. All you need to do is test the thing works and some readily available Vaseline / Uranium glass is all you need.

If you want to check that your meter is correctly counting then 1uCi = 37,000 Bq = 37KHz.
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Old 20th April 2017, 7:22 PM   #18
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Ookkaay, not sure how a radioisotope source of known activity/strength can be pointless with regards to a instrument that is pacifically designed to detect such...I'll take your word for it as I'm still learning about this stuff.

I any case with regards to my question would importation of these samples be prohibited or at the very least need paperwork/customs declarations?
From the web site is seems fairly easy to order them if you are in the states.
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Old 20th April 2017, 9:59 PM   #19
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Ookkaay, not sure how a radioisotope source of known activity/strength can be pointless with regards to a instrument that is pacifically designed to detect such...I'll take your word for it as I'm still learning about this stuff.
Never take my word for it
Do take my word when I say not every radiation measuring instrument is a Geiger Counter.

As you said the sources have a known activity and strength.
A Geiger-Muller tube can only measure activity, the strength makes no difference.
Quote:
so no spectral information can be generated and there is no discrimination between radiation types, such as between alpha and beta particles.

Activity is measured in counts per second ( Becquerel) and the tube will either register the particle or not. Most tubes cannot detect alpha particles as they don't have enough strength (energy) to travel far through air let alone the glass of the tube. Certain tubes can detect alpha particles but they're expensive and fragile.

The energy is measured in electron volts and if you look at the table of isotopes from United Nuclear you'll notices many of their source have the same activity but different energies. An instrument such as a Gamma Ray Spectrometer certainly does need calibration and that's what those sources are for. The energy of the decay of most isotopes is known with some accuracy and by measuring that energy which element / isotope is decaying can be determined. You can buy portable instruments that can give you an indication of what's the source of the radiation but they're $100s

It might help if you look at the table from United Nuclear. Note for Cs137 you can by it in different levels of activity but the energies are the same.

Quote:
I any case with regards to my question would importation of these samples be prohibited or at the very least need paperwork/customs declarations?
From the web site is seems fairly easy to order them if you are in the states.
According to the "black letter" law you need permits and paperwork for anything radioactive which is clearly absurd as all of us are around 7,000 Bq. Problem is try as I could I could find nothing about these kinds of sources. So I don't want to say yes or no. As I said before contact United Nuclear, pretty certain you wouldn't be the first person from Au to ask.

I'd suggest if there's no issue with getting them into the country and having them go with the Sr90 as it has the lowest activity. Geiger Counters become inaccurate at high activity levels as the gas takes time to recover from each particle ionizing it. Forget the Po210 as it's only an alpha source.
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Old 20th April 2017, 11:28 PM   #20
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Thanks for the info, I suspect the terminology I am using is incorrect.

So I have sent an email to ARPANSA, Australian Radiation Protection and Nuclear Safety Agency to get some info.
It will be interesting to see what they say.

I will also ask the US site as you suggest.
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Old 21st April 2017, 6:20 PM   #21
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You may need to do a "Safe use of radiation" course and obtain a radiation license before being able to legally obtain a radiation source for your testing purposes. I know ANSTO offer a one day course.
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Old 21st April 2017, 6:46 PM   #22
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Thanks, that wouldmactually be very interesting, however I have heard back from united nuclear, it will cost over $US350 just for shipping!!!!

Think i will give it a miss!!
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Old 21st April 2017, 9:24 PM   #23
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Thanks, that wouldmactually be very interesting, however I have heard back from united nuclear, it will cost over $US350 just for shipping!!!!

Think i will give it a miss!!
For not that much more you could buy the Gamma Scout. These have a tube that can detect alpha particles. A moveable "filter" will let the unit measure all, beta and gamma or gamma only.
Article with a good explanation of how Geiger-Muller tubes work: http://cdn.shopify.com/s/files/1/051...nters.pdf?1114
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