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Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
I have one of Radu's uRadMonitors installed and noticed a peak in CPM doing a heavy thunder storm that went by just above where I live.
I searched around for causes of elevated radiation doing thunder storms and got by Terrestrial gamma-ray flashes (TGF) , a phenomenon where a spray of gamma rays have been measured from space with space crafts and telescopes.
The whole theory behind TGF challenges some of the theoretic models for lightning and thus it is beyond my understanding of physics :) But the production of gamma-rays is only described to emit into space and not down against earth, but given the low readings it could just be very few that goes downwards in such a burst?
But this is however also the only explanation I have been able to find on higher levels of measured radiation doing a thunder storm.
I would like to hear your ideas about this.
Data from the monitor:
Map of lightning strikes that day, I forgot to add a red circle, but I live in the middle of the 2nd largest island in the middle, Funen, between Jutland and Sealand.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
Yup, had similar effects with PM's radiation dosimeters and all three detectors were clicking at the same time corresponding with particularly bright flashes. Even the one in the fridge which was shielded.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Conundrum wrote ...
Yup, had similar effects with PM's radiation dosimeters and all three detectors were clicking at the same time corresponding with particularly bright flashes. Even the one in the fridge which was shielded.
Have you managed to find any online documentation, experiments or other mentions of this phenomenon? Not TGF itself, but that it should be measurable on earth.
Radu made me a graph in higher details where the single lightning strikes can be seen, atleast as summarized by the minute.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
Was in "New Scientist", also TGFs have been linked to sprites and blue jets. In some cases the event occurs milliseconds before the return stroke and seems to be linked to positive bolts.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
From:
The resulting beams of electrons - moving at nearly the speed of light - then radiate gamma rays when they hit and are deflected by atomic nuclei. After emitting gamma rays, the electrons may loop back down to Earth along the planet's magnetic field lines, potentially producing another gamma-ray flash during their descent.
On IRC it was suggested that it is merely EMI that we see on the measurements, I would however expect a much more distorted graph and much other equipment showing signs of lightning EMI if that was the case.
Registered Member #1956
Joined: Wed Feb 04 2009, 01:22PM
Location: Jersey City
Posts: 172
That would be easy, I think, to find out. The Aluminum case has to help some with the EMI. Running one unit with the electronics outside the case would prove EMI is playing a role if the amplitude of the spikes gets higher.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
tobias wrote ...
That would be easy, I think, to find out. The Aluminum case has to help some with the EMI. Running one unit with the electronics outside the case would prove EMI is playing a role if the amplitude of the spikes gets higher.
This would be a experiment that Radu have to set up when he have new units ready to test. He should however run both monitors in the enclosure, else he would get alpha and beta radiation too, one enclosure should just be shielded, grounded and beaded in all possible ways.
Bored Chemist wrote ...
You guys do know that local radon concentrations vary with weather, don't you? A drop in atmospheric pressure sucks radioactive gas out of the ground.
You only see elevated levels of radon gas in houses if the house itself present a vacuum to the exterior, this Danish study is however only in Danish ,d.bGQ&cad=rja
I live on the 2nd floor in a old building, lets just say that ventilation is built in so that on windy days you can feel the breeze going under the sofa :) The cellar is always ventilated by 3 open windows, on 3 different sides of the building. There is a door in the cellar to the staircase and a door to our apartment from the staircase. So there is a very bad airflow for radon gas to get my apartment.
Unless the gas is inside the detector, which is likely as it is not gas tight, the aluminium casing should take care of the alpha and beta decay radiation.
These spikes are however not seen on days with equal air pressure and rain, just without lightning.
Registered Member #230
Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284
All noted but it has been postulated that lightning initiation is from cosmic rays starting the ionisation process. I also would have thought that the measured radiation was x-rays not Gammas there's no difference to the detector the label is just where they are generated. ie jiggling electron shell or mucking around with the weak and strong forces holding nuclei together.
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