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Global Radiation monitoring system

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Mads Barnkob

Thu Jan 23 2014, 09:07PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

I moved the unit from a protective wooden box and it is now directly exposed to the weather in a water tight plastic pouch. The temperature dropped and so did the sensitivity of the tube, atleast the CPM fell about 1-2 cpm in average.

radhoo

Thu Jan 23 2014, 09:48PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

Nice one, Mads. Don't forget to take photos of the two enclosures/setups - it would probably be interesting to see the differences, as the level drop is significant.

Mads Barnkob

Thu Jan 23 2014, 10:11PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

I only moved it from the drawer to the small post it is sitting on. Perhaps the Ikea furniture have radiation enhancing abilities. Could be the proximity to the brick wall... Not exactly a pretty installation, but what I had time for before weekend :)

I plan on moving it about a meter further away form the building when I get time to make a power supply cable that is long enough.

Patrick

Thu Jan 23 2014, 10:11PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

how much do these SI-29BG tubes cost you each?

I am re-reading this entire thread, im willing to participate if the California pacific coast interests you.

my location:
243 meters above sea level. Pacific ocean is 166 km directly west.

EDIT: what would be really cool is to take one of these 100 meters above ground level in a UAV.

Shrad

Fri Jan 24 2014, 08:15AM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

I'd also be willing to participate, but will need to consider things beforehands like tidying my mess etc...

if interested, I can help in plotting data variation on a map for a period of time, but a wider network would be needed over an area to achieve good interpolation

Conundrum

Sat Jan 25 2014, 01:49PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Wonder why there is such a profound effect on the tube from temperature?
Sure it isn't some other part drifting such as the zeners?

IIRC silicon is about -2mV per Celsius, could also be something in the HV circuit sensitive to humidity.

Re. UAV, I had that thought too.
I might hack together a small module with one of the new tubes and see how much the count increases with altitude.

Proud Mary

Sat Jan 25 2014, 02:35PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Mads Barnkob wrote ...

I moved the unit from a protective wooden box and it is now directly exposed to the weather in a water tight plastic pouch. The temperature dropped and so did the sensitivity of the tube, atleast the CPM fell about 1-2 cpm in average.

Why do you think that the sensitivity of the tube had dropped? One of the reasons that GM tubes have reamined popular despite their very basic character, is because they are quite insensitive to ambient changes.

Much more likely that your tube is detecting fewer particles because there a fewer particles to detect. Perhaps you should think of air temperature as being part of a weather process. It may be colder because the wind is blowing from a different direction, for example, so fewer radioactive airborne particulates are arriving at Haus Barnkop than happens when the wind is blowing from a contaminated area. The height of airborne particulate smogs will rise and fall with temperature and affect counting, as does the release of radon from rocks as cold weather splits them. Then there is the diurnal and semi-diurnal flux of solar cosmic rays which will certainly be very significant when you are talking about 1 - 2 cpm.

The re-suspension of Chernobyl particulates by high winds on Swedish mountains might also be carried aloft by northerly winds, but fall to the ground as precipitation before reaching Denmark when the temperature drops.

Marine pollution can be re-suspended in the air as waves break on shore, for example, giving another example of how a change of wind direction could alter counting rates inland, that might - or might not - be associated with a rise in air temperature.

The interaction of weather systems allows many possible scenarios in which a falling (or rising) air temperature may be associated with a lower or higher counting rate, but is not its cause.

Wind direction is, I think, a far more useful parameter than height above ground, which is constant, and tells us very little once the baseline has been established.

Conundrum

Sat Jan 25 2014, 03:41PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

My equipment did show a slight increase during the last large solar flare, and also during an intense thunderstorm.
It might also be worth adding an E field monitor so that this can be compensated for and logged.

Re. Altitude, what about a kite? Low tech but useful and on a windy but gust free day a box kite would be a reliable way to do tests.

Proud Mary

Sat Jan 25 2014, 03:54PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Conundrum wrote ...

My equipment did show a slight increase during the last large solar flare, and also during an intense thunderstorm.
It might also be worth adding an E field monitor so that this can be compensated for and logged.

Perhaps, but not nearly such a powerful explanatory tool as the wind direction and wind speed indications of a simple home weather station.

Conundrum wrote ...

Re. Altitude, what about a kite? Low tech but useful and on a windy but gust free day a box kite would be a reliable way to do tests.

Do you remember Benjamin Franklin's famous experiment with an electrified key:

"The kite being raised, a considerable time elapsed before there was any appearance of its being electrified. One very promising cloud had passed over it without any effect; when, at length, just as he was beginning to despair of his contrivance, he observed some loose threads of the hempen string to stand erect, and to avoid one another, just as if they had been suspended on a common conductor. Struck with this promising appearance, he immediately presented his knuckle to the key, and (let the reader judge of the exquisite pleasure he must have felt at that moment) the discovery was complete. He perceived a very evident electric spark. Others succeeded, even before the string was wet, so as to put the matter past all dispute, and when the rain had wet the string he collected electric fire very copiously. This happened in June 1752, a month after the electricians in France had verified the same theory, but before he heard of anything they had done."

Electrocuted somewhere in Guernsey.

Mads Barnkob

Sat Jan 25 2014, 07:39PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

Proud Mary wrote ...

That was my first thought at the time as I moved it from the wooden enclosure to the post and its temperature dropped over 10 degrees, the counting dropped at the same instant. But the counting also went up again without temperature changing when I moved it further away.

I suspect it could be the lead plates used at the edges of the roof construction that shielded the detector.

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