Air sample UK
07.30hrs GMT
South Devon England (near Plymouth)
Geiger: Inspector EXP+
Weather: lovely and dry, practically no wind.
I just took a air reading from my usual spot, my bedroom window on 2nd floor and the window wide open. I had the plastic cap off my Inspector EXP+ so it was able to measure the full spectrum, alpha, beta and gamma and I just measured after a 10min timed count 39.5cpm not that high eh but that is the highest reading I have ever recorded in air from this location when it's has been dry. My average is 34cpm. Some times I may get slightly higher like 35 maybe 36 or lower like 32.
But this 39.5cpm is just over 13% increase over my average background in my maths are correct.
I've just checked my records and on the 12th Dec 2012 I measured 40.3cpm after a ten min count but that was in very damp and drizzly weather.
UPDATE:
Just retested two more identical outdoor tests so here are all three of the 10min timed counts.
07.30hrs = 39.5cpm
07.45hrs = 37.3cpm
07.58hrs = 39.3cpm
As a comparison I replaced the cap which will block any alpha from being detected. So now only beta and gamma are to be measured.
08.05hrs = 34.2cpm
08.20hrs = 35.9cpm
Same test but now indoors in almost same location but with window closed and alpha shield removed.
08.42hrs = 34.4cpm I expected this as this is my average.
Conclusion: hum?
I'm on the 2nd floor and the Geiger pancake probe is completely outside of the house. There is defiantly an increase in the first three readings so alpha radiation was the cause for this increase over the 4th and 5th 10min test (which had the alpha shield on). I believe I am high enough up and it's well ventilated, obviously the pancake was outdoors so it shouldn't be from radon especially as radon is heavier than air so less likely to be of a concern outdoors and as I am so many meters above the ground. This in my view is confirmed by talking an indoor test and the levels were normal and it's said that radon concentrations are normally always higher indoor especially in lower rooms (Canadian radon report), well I'm up on the 2nd floor. Also the air pressure is not low today it's 1117hPa nor is it cold. So the increase in radiation outdoors over my normal average was mostly caused by some alpha particles which were
floating about today where I live. NICE.
I've not noticed this before.
Just thought I would share all that with you.
I know 10min timed counts are not ideal for air sampling. A better way is to hook up ones unit to some software and laptop and plot the readings over time and so to capture any trends. I don't have the connecting cable or software. So short timed counts is next best I guess. Longer counts could give an inaccurate result. You could for example be conducting a 60mins timed air count. In the first 2mins the readings could be high but then if the plume passes by and the rest of the 58mins are normal than the mean cpm wouldn't reflect those high number at the beginning so the theory being that a short ten min count would be less effected if the above happened. But for food testing the opposite is true. Longer counts are more accurate than shorter ones.
Now do you think I closed my window? Lol
I didn't I wanted to breath in the fresh alpha laden air loll
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