Solar induced neutron counter background increase.

[Richard Hull]

******NEWS*****

This is being placed here rather than in the announcements forum due to its bearing on counting backgrounds.

Some of you may not know that on Tuesday November 4th 2003, the largest CME x-ray flare recorded in history came off of the sun related to the giant sun spot group just going around the limb. We might miss the intense blast as it is off center for an earth hit. Nonetheless, it was so powerful, it swamped all instrumental attempts to measure its real intensity. A quick check on the many URLs that follow such events, a crude conservative guess is currently in the X-29 range but some feel it could be as high as an X-40 catagory which is unbelievable and has solar scientists reeling.

My story is about my totally unrelated work with a friend at a local college using a very weak 1mCi neutron source over the past three days. We have done the work late in the evening. On Tuesday evening around 11pm we were taking 10 minute counts of the source and stacking paraffin to determine its effect in scattering the neuts. The up shot is that the naked source puts out a reliable and steady, statistically valid, 8.2 CPM onto my neutron counter calibrated recently by Ludlum. This indicated an isotropic emission of about 6000 n/s. We took three ten minute background counts, one before the work began and two after finishing. The background worked out to 0.18 cpm over the entire enterval. It was late so I left my counter and all cabling to the ratemeter in place so that on Wedneday night we could begin anew.

On wednesday night we decided to get some grub at the local Awful House (Waffle House) and this put us late starting, again. At 11:30PM we did a background check and within 2 minutes I had 4 counts! I turned the instrument off and back on again and restarted the count. Same deal. I restarted a tird time after wiggling the associated cables and tapping on all the instruments to make sure of no connection issues. At the end of 10 minutes I had 21 counts. We ran the source for two ten minute counts and it was much higher than the night before showing 10.6 cpm after averaging. Once we subtracted background the real count came to 8.5 cpm which was almost exactly what we had the night before. Two more finishing background counts at 12:30AM (late night) indicated that the background was high indeed. The average of 2.1 cpm was incredible as compared to 24 hours earlier where a 0.18 cpm background was recorded!

I left the counter inplace and my friend just called this morning and the background is now back to 2 counts in 10 minutes or 0.2 cpm.

What happened! Something was kicking that counter up to 10 times normal background at around 0400-0500 hours UT Nov 6 2003!

It was most likely cosmic ray flux.

I found a site in Moscow that provides 24 hour, round the clock, neutron counter, ground based counting data and charts. This data is extremely well organized and easy to view. I can't really see an increase for my time frame, but I sure measured a horrific increase here. It is half a world away to Moscow. I may have been on the magnetic flux loop point or something at that period that Moscow was not. This may have focused or otherwise steered a burst towards Richmond or the east coast. I did note that the Moscow data did show a massive spike during the last large X-19 event of a week ago. It was also a full order of magnitude or more increase. I was prepared for 30% but not an order of magnitude!

It would be better to observe such events with neutron counters than geiger counters as N counters are totally insensitive to all forms of NORM which are highly variable. This makes the geiger counter, especially the mica windowed versions, highly sensitive to local conditions and weather.

That Russian URL is posted here and in the links forum.

http://helios.izmiran.rssi.ru/cosray/main.htm


Richard Hull

[ChrisSmolinski]

I don't have the URL handy, but there is a site that shows neutron counts at six locations around the world. The one near the north pole showed a massive spike with one of the recent flares (Sunday's?). Others showed smaller spikes. They also showed smaller spikes for the other flares. The data bears out your hypothesis that the increase in neutron counts various by location. Perhaps Richmond was ground zero?

I'm still searching for equipment to get a neutron detector going here online 24/7. I curiously do see a spike around midnight local time on the GM detectors. It does not have the "normal" shape of weather/radon daughter induced spikes. Take a look, maybe I am just seeing faces in the clouds... (we used to joke about a coworker who would always see patterns in strip chart recordings)

http://www.blackcatsystems.com/GM/compare.html

[Richard Hull]

This background so astounded me as I have never seen this level for background in a neutron counter, ever!

The GM might pick it up due to the cosmics scattering other easily detectable stuff. According to the Russkies the neutron counter detects in the Gev range and that seems reasonable as a 5R blast of 1-2mev gamma doesn't make the device count above background at all. Thus the counter is totally impervious to nuclear gamma, alpha or even intense beta.

Richard Hull

[Jon Rosenstiel]

Richard,

Don't you just love serendipity?

Jon Rosenstiel

[Richard Hull]

You bet I do. I am off for another evening of neutron work. We will see what tonight's background is.

You can bet that only the most nasty non-neutron radiation will set off a properly functioning BF3 counter!

Next morning addendum:

Well the background last night was 0.10 cpm which is more in line with what is the "normal" around here. So, it appears that Wednesday night was a real storm of cosmics in the Richmond area.

Ya' never know when to put on the lead lined jock strap with cosmics.


Richard Hull

[Frank Sanns]

Radio propagation for short wave listening is highly dependent on the solar flux and planetary A index. The site http://dxlc.com/solar is an active log of what the earth is "seeing". Notice how low the solar flux was on the earth on the 6th. Nothing, nada, zip. Strange that such a huge x-ray flare produced no 2.8 Ghz radiation to be detected here on earth.