Radon decay products

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Radon decay products

Post by Hans-Jörg » 25 Feb 2020, 04:09

A radiation source almost everywhere aviable is Radon-222 and its decay products.
Rn and the decay products can be collected in different ways:
If air is moved through an activated carbon filter, radon is
adsorbed on the surface of the carbon. After a few hours, the decay chain is established and the typical spectrum with
Pb-214 peaks at 242, 295 and 352 keV and Bi-214 with the main peak at 609 keV can be seen.
A more simple way is sucking the air through an filter (with a vacuum cleaner). By doing so,
only the decay products are collected, radon passes through the filter.
Another possibility to collect the decay products is collecting them with high voltage.
When an alpha decay occurs, an alpha particle is ejected with very high speed.
As a consequence, the nucleus gets a recoil (radioactive recoil). It looses some electrons
and because of this, the nucleus gets a positive charge. If it comes near a negative charged surface,
it is attracted. So it is possible to collect decay products on negatively charged foils.
In my office, I have an activity of about 100 Bq/m³, not very much, but a little bit more as at home.
About three and a half years ago, I took an alustrip of about 40X2 cm and put it to about -6000V with a
self-made power supply. This system collects the decay products without noise and needs only very
little power.
With this long time sampling, Pb-210 (half-live 22years) at 46.5 keV is visible.
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Re: Radon decay products

Post by Geoff » 25 Feb 2020, 11:52

That’s a very interesting experiment!
Geoff Van Horn

Former Alaskan living in rural Wisconsin

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Re: Radon decay products

Post by Go-Figure » 01 Mar 2020, 09:04

I need some time to think about this one!


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Re: Radon decay products

Post by gwgw » 02 Mar 2020, 02:58

I've taken some rainwater spectra, sometimes the sample was surprisingly hot (like 20-30CPS) and they did have the radon byproducts photopeaks - Bi-214 and Pb-214. Most of the time it was below 10CPS though.

BTW I've heard some people that have those Brita filter jugs discovered that the newly replaced filters give higher readings on a geiger counter for some hours after replacement, then go back to normal and that is most likely due to dissolved radon in the water. I tried that at home but there weren't any radon byproducts in it. Looks like there isn't radon in the drinking water here.
Milen Rangelov

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Re: Radon decay products

Post by Peter-1 » 18 Mar 2020, 03:26

A little experiment on the subject.
I put a thin wire 3 meters long for 5 hours on a high voltage of 10 kV. Negative pole on the wire, positive pole grounded. After this time the high voltage is switched off and the wire is wiped off with a filter paper soaked in acetone. Immediately place the filter paper on the scintillator and measure. The decay products are very well visible and the decay over time can also be seen.

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