I found a lot of research papers in radon diffusion coefficient through polymer membranes like as example PVC but there is no one talking about uncertainty or degree of error in measurements?
It is an intelligent query. Very few Papers report it. It depends upon experimental conditions.
Hardev Singh Virk thanks professor, I know its depends upon experimental conditions. but i cant found any papers discuss it acorrding experimental conditions or else?
i think its very important!!!
The answer is - the uncertainty is large, and it is largely ignored. To illustrate it, it's enough to look at the emanation coefficients of Rn an Tn (thoron), half-lives differing by a factor of ~10K, yet the emanation coefficients are comparable, using about the same size samples. To investigate this anomaly one has to make an experiment similar to what we did (Holub and Brady, Radon emanation from rock under stress, available on RG), for thoron emanating from rock, or scale up our experimental setup to 2x, 4x greater samples for Rn emanation. If it doesn't scale up according to the equations in our paper, then it is a different diffusion coefficient depending on size, clearly an anomaly. Only then one can obtain a proof that the "uncertainty" is an anomaly.
We cannot do this experiment because our lab has been abolished in 1996.
Few researches directed to study diffusion coefficient or pear mail it. The condition are more complicate need high accuracy to be determined. Also the health risk of radon attracted the scientists to study the radon problem intensively to find such solutions to the problem.
Hi, it is true that depends hardly of the experimental setup. If is made properly and you control the main parameters influencing the permeability via the membrane the error is few percents. If you take "a priori"+ some of the parameters that may influence the permeability may increase significant. Also it depends too of the instrument of measurement.
My point was that we do not understand the mechanism of emanation. Those measurements assume the mechanism is diffusion. Different situation is when measuring permeability - then it is forced (Darcy) flow. When forced flow is present there is always some diffusion (sometimes called dispersion).If we don't understand diffusion, then no meaningful measurement can be made.
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