In remote outdoor air samplers, moving filters are the norm. This allows filter changing without an the sites. IMPEX has such a head, we don't have that, nor would I want that option.
I do have some rolls of filter material from such a site, new, sealed in tin cans and further sealed in factory plastic bags That filter material is glass fiber on paper backing. What came in the Impex is similar but seems to have a mesh interlayer. Looking closely at the supplied filter there are pinholes present. A clone of the filter card was attempted. When used to replace the worn-out test filter as suppled, everything changed on the spectrum readout, for the better. We will of course consider using the OEM filters for serious work but these will be no cost playthings to gain experience.
Now the PO peaks from Radon 222 daughters seem to be falling much more in line with predicted values. No other changes made.
There are still other issues that need attending to, but those have been there since day 1, it's probably a matter of more training needed.
PS if you request some of there be aware they have a textured? side which goes towards the sensor (i.e. UP). It covers a 25mm hole perfectly.
The cards used here are double weight 3X5's because it's what I had. 4X6 would be better raw material, that size could simply be folded in half longways forming a 'book", trimmed to size using the original card as a template, the filter material secured inside and the edges taped shut
It a pleasure to see the correct energy peaks from the Po species.
I suggest printing the U-238 and Th-232 decay chains from the INL "Natural Decay Series: Uranium, Radium, and Thorium" and where it shows the alpha decays, pencil in the correct energy levels. This really helps not having to remember or look up what's what, If you don't have that link, it's also on my webpage
K0FF@...PS Readings will be different on all instruments now, the weather has warmed, the widows screened,? open,? and an attic fan pumping fresh air in. It should prove interesting to retest everything, as the natural air should have far less Rn-222 present.
A topic I would like to see discussed here is the broadening of the peaks, due to interaction of the Alpha Particles with matter (air).
Geo
Pics attached
Nick Andrews