A minute amount of this infamous gas is contained in each of these ampules. Radon is found in nature as a byproduct of the decay of several other radioactive elements. In this case, a very precisely measured amount of thorium dioxide, a whitish powder, is placed inside a hermetically sealed glass ampule. Because the starting amount of the thorium is known, as well as its purity, a correspondingly precise amount of radon can be calculated which in this case yields 1.7x10-11 grams of this element. While radon is itself radioactive, and thus decays into other elements, the total amount reaches a “steady state” as the decaying atoms are constantly being replaced from the new atoms being created from the decay of the thorium. And since thorium has an extremely long half life the amount of gas will remain constant essentially forever…. so long as the ampule remains intact.

As an additional note of interest, radon born from thorium’s decay is unimaginably radioactive. The Rn220 isotope has a half life of only 55 seconds…. far, far higher than the radon naturally present Rn222 variety that lurks in many a basement creating endless worries for homeowners wanting to rid themselves of this unwelcome guest. Rn222 is created from the decay of uranium and has a half life of 3-4 days (which is still incredibly radioactive!). However, even though these are some lively atoms the tiny amount renders it trivial…. always assuming of course that it remains inside the glass. Allowing even minimally radioactive particles to become airborne is never a good thing as it can cause tissue damage in the lungs which could eventually lead to cancer.

Each ampule measures about 25mm in length and 5mm in diameter.