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Specialty Chemistry Forums => Citizen Chemist => Topic started by: SteveB on January 05, 2007, 10:20:20 PM

Title: Radioactive Sample - Questions
Post by: SteveB on January 05, 2007, 10:20:20 PM

Hello.

I have a question regarding a test / experiment I want to do with alpha and radiation sources. I want to buy samples Polonium-210, Strontium-90. My question is, will I be able to detect the amount of radiation that is given off with a geiger counter? (Perhaps around 2 - 4 feet away)

I want to test the sources against materials for blocking the radiation such as lead.. but I'm not sure if I can put them inside a container with the different blocking materials without all the radiation being absorbed.

Here's the link to the 2 samples I want to buy: http://www.unitednuclear.com/isotopes.htm

If you don't want to check.. I wrote it here:

ISOTOPES          ACTIVITY     EMISSION     ENERGIES
Polonium-210      0.1 uCi         Alpha           5304.5 KeV
Strontium-90       0.1 uCi        Beta             546 KeV

Thank you,

Steve

Title: Re: Radioactive Sample - Questions
Post by: jdurg on January 05, 2007, 10:39:27 PM

No, you will not be able to test these.  Alpha particles are VERY hard to detect with a geiger counter unless your counter is specifically designed to detect alpha particles.  This is because alpha particles are stopped in a few inches of air, or by any type of solid surface.  (A piece of paper will completely block all alpha particles given off by a source.  From a few feet away, even if there is nothing blocking it, you won't detect any).

Beta particles can penetrate more deeply, but they too are block by something like a piece of glass or aluminum foil.  Lead sheeting will readily block beta particles, though in some cases when the lead stops the beta particle it generates x-rays in the process.

Geiger counters will typically detect gamma rays, some beta rays, and x-rays so your beta source may be detectable, but your alpha source will be completely undetectable.

Title: Re: Radioactive Sample - Questions
Post by: pantone159 on January 06, 2007, 03:41:17 AM

If you put the Sr-90 near the detector, at least without shielding, it should pick up easily.
The Po-210 won't show up at all, unless your detector has one of those thin-mica windows (that let alphas in), then it would pick up well at very short distances (c. 1 cm) but zippo at 10+ cm.

Title: Re: Radioactive Sample - Questions
Post by: Mitch on January 08, 2007, 03:57:00 AM

I made an alpha detector chamber for shits and giggles last year. I should probably blog about it.