Mapping Background Gamma Ray Activity with GPS Scintillation Detector

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Hunter Long
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Mapping Background Gamma Ray Activity with GPS Scintillation Detector

Post by Hunter Long » Mon Sep 09, 2019 5:19 pm

Hey everybody,

Hope you don't mind some shameless self promotion, but here is a YouTube video I made detailing a GPS logging scintillation detector I built recently: https://www.youtube.com/watch?v=ReM5nC2OOUU

I've been using it to map background radiation levels around Charlottesville, VA and I found out that there are some interesting (in the radiological sense) places near where I live. One field a few miles from my house has some Thorium containing dirt that puts off about 1mR/h (by my rough estimation).

Thanks,
-Hunter Long

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Richard Hull
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Re: Mapping Background Gamma Ray Activity with GPS Scintillation Detector

Post by Richard Hull » Mon Sep 09, 2019 8:56 pm

Interesting..........I have just in the last two years been doing the same. I found a geographic "bowl" of trapped Thoron gas (Radon from thorium), here in Richmond!! Sadly, this hot zone is in a tiny public park. What is it with parks!!!! Do they find a hot zone not good for housing and make them parks??? It's like trailer parks and their attraction for Tornadoes!! So far we are the only ones to report this and the parks are batting a thousand! Check your local parks folks! LOL.

There is a link, (URL cited below)), that has recorded all radon levels in many local areas as reported by the nation's many radon detection businesses. I found this hot park area by punching in the zip codes of the Richmond area. Note*** this is not a geographic ground survey, but a home radon survey. This mimes a ground survey only in inhabited areas where the businesses involved have taken readings.

Note**** When I say radon/thoron, a gamma scintillator will not read the presence of those gases directly. Instead it will read the horrid, gamma ray emitting, fast decaying daughters deposited rapidly wherever the gas exists. Thorium is the worst of all natural radioactive elements. Its radon (thoron) has a nasty 54 second half life. Thus, the first solid daughter Ra228 is created nearly instantly which settles out and needs 35 years in the grounds soil to reach equilibrium and make the full compliment of Ac228 which emits the nasty near 1mev gammy ray. Thus all of these gammas will sail right through deep soil and car bodies!! From this is is realized that such radiation from thoron daughters has been around undisturbed for at least 40+ years!! Radon is radon and is emitted by any of the principal 4 known decay series. However, we only need worry about radon from Uranium and Thorium in massive mineral deposits.

It is cool how the hot gamma daughters betray the presence of Thorium and Radium alpha only emitting elements and their alpha only emitting gas first daughters to the gamma only detecting scintillator.

Using this reference, I found the zones with measured basement readings of 20pCi/l, and well above that, located in the area of the University of Richmond. This is a high-end value home area where the wealthy and upper end white collar live.

I set my superlative TSA scintillator to a 3 sigma detection level and zero'd it for my neighborhood, (2-3pCi/l). As I drove to the park, along the way, I would get a chirp of localized detection on occasion. However, once in the area, over a 9 square block area about "the bowl", through the steel body of my automobile, the alarm never stopped sounding, no need to exit the vehicle!!

At the tiny park at the bottom of the bowl with its sliding board, juggle gym, flat merry go round and wood chip pile, I noticed that a creek flowed through it. Exiting my vehicle, I had my scintillator on a long, leather sling that I have used in Colorado and Utah for hunting the U stuff that lay just below the surface. ....( Some of the best hot U stuff from the mines fell off the bouncing, over filled, ore trucks in the 50's and is now covered with a washed overburden of from 3 inches to 18 inches of dirt. You have to dig these gems up and only a top flight scintillator will find them. A GM counter is worthless.).....As I entered the park I let the scintillator swing back and forth just off the ground, (1-2 inches), and observed the digital meter. No matter where I went, all over the park, the alarm blared out constantly with little or no increase in reading. NO buried thorium rock! Over near the creek there were a number of giant multi-ton, matt-grey boulders. Placing the scintillator in contact all over many of them did not increase the digital count to any significant degree. Weird! I noticed a number of larger cobbles in the stream. A contact reading on them and just over the water, again, did not register an increase.

I realized I was in a pure thoron, (Radon), environment!

Piedmont Virginia is famous for its many massive pegmitite deposits, a source of thorium minerals. This thoron gas was rising through the ground from below and the bowl collected it and due to it's mass, preserved it and its recent daughters from all but strong winds. The nearby homes trapped it. Wow! The nasty solid daughters are readily buried into the soil as rains fall. This explains the rather invariant gamma ray levels in the area.

All of the uranium in Virginia is in the "Valley" over 150 miles west of Richmond. The giant multi-million ton, un-worked reserve deposit exists near Chatam, Virginia in Pittsylvania Co. It is referred to as the "Coles Hill" deposit. Current Virginia law prohibits any form of Uranium mining in Virginia of this major national reserve of Uranium.

Here is that URL for radon readings. It can be tough to make work for you. Follow the trail, you will get there. It will generate a google-like map of the areas chosen.


http://www.radonreporting.com/DBSearch/Standard.asp


Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Hunter Long
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Re: Mapping Background Gamma Ray Activity with GPS Scintillation Detector

Post by Hunter Long » Tue Sep 10, 2019 2:16 pm

Interesting! What is the name of this park you found? I might have to check it out next time I'm in Richmond.

I have a couple of ziplock bags containing some soil from the field I found. The bags make my 2" Geiger probe register around 1k-2k cpm. It looks just like normal red clay dirt, no visible rock particles in it.

Has anyone done any experiments in trying to deliberately collect Radon gas (I wouldn't want to do it in an enclosed space)? I could imagine having a 5 gallon bucket of this Throium containing dirt with holes in the bottom that let Radon flow out into a container below. After some time I wonder if you could detect the radiation from the daughter products of Radon that have built up in the lower container. I'm not saying I would actually do this, I don't know enough to do something like this safely, but I'm just wondering if it would work.

-Hunter

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Richard Hull
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Re: Mapping Background Gamma Ray Activity with GPS Scintillation Detector

Post by Richard Hull » Tue Sep 10, 2019 7:57 pm

Google Earth - Tuckahoe public park, Henrico, VA ........ It is a very tiny park tucked into a neighborhood. There is a sign at the entrance at the dead end of a street, but no indication of where it is or where to turn off the main street down the dead end street. A rather secret park for sure. I would imagine only the nearby locals even know it exists. I have visited it several times and have never seen children there. Too busy on their smart phones to go out and play.?

Information on making uranium/radium cows and Thorium/thoron cows can be found in a number of old texts. My favorite is found in the Interpretation of Radium by Soddy 1908. Reprints go into the 1920s it is available on line and as a currently printed book. Fabulous!

You can milk these cows for the daughter products. Be careful to seal up the cow well to avoid letting out the radon. If you build the one as mentioned in Soddy's book, you will be stunned!

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Hunter Long
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Re: Mapping Background Gamma Ray Activity with GPS Scintillation Detector

Post by Hunter Long » Wed Sep 11, 2019 7:44 pm

Thanks! I looked at Soddy's book, it's really interesting. I'm not familiar with the term Thorium cow. Is this the device he mentions where daughters of Radon gas are collected onto a negatively charged needle in a beaker?

-Hunter

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Richard Hull
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Re: Mapping Background Gamma Ray Activity with GPS Scintillation Detector

Post by Richard Hull » Thu Sep 12, 2019 12:45 am

No! All collection must be done is a totally sealed environment. Ideally, in a metal sphere just as the radium cow shown in Soddy's work. (silvered florence flask) The object is to trap all the radon gas and wait until all of the following short lived daughters are in equilibrium. then stick a needle into the sphere (still tightly sealed) and put the ground of an HV supply, 1000 volts or so, on the metal sphere, and the hot or positive lead on the insulated needle. The cow as shown is Soddy's book is for radium. The same works for Thorium....However, the thorium chemical must be prepared 40 year ago. (forty year old thorium).

A careful review of both decay chains will show why. (Thorium chemicals produce no radon until it is 40 years old.

The cow collects all daughters below radon. You must keep the voltage applied for at least 5 half-lives of the longest lived of the short half life daughters.

For radium this is about 2 hours. For thorium is is about 5 hours. Radium daughters are a lot more fun.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Frank Sanns
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Re: Mapping Background Gamma Ray Activity with GPS Scintillation Detector

Post by Frank Sanns » Thu Sep 12, 2019 9:56 pm

Some of you here may remember my work during the first days of the Fukushima accident and the year following. While I was stateside, I found a person that had two Geiger counters in the Tokyo area and north. He was willing to bicycle around certain areas in and around Tokyo and fairly far north toward Fukushima. He would send me the data with and without a beta and alpha shield. It helped to determine the progress of the accident and the days of fallout in Tokyo and north. While these reports and my comments were broadcast through social media, an organization called Safecast began to expand the readings from just one or two individuals to thousands. Today there is an extensive network of GPS enabled radiation sensors that traverse the entire country on a daily basis. Here is a link to Safecast. It might inspire more people to build GPS devices and map your local areas. https://blog.safecast.org

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Richard Hull
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Re: Mapping Background Gamma Ray Activity with GPS Scintillation Detector

Post by Richard Hull » Fri Sep 13, 2019 6:52 am

I did an extensive search of the decay chain for Thorium... Ac228 has the .9mev gamma ray, but at the very end of the chain, the killer is the Tl208 2.6 mev gamma ray and the 1.8mev beta particle. Tl208 will go through anything, anywhere and to deep depths in the soil. Super hot!

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Richard Hull
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Re: Mapping Background Gamma Ray Activity with GPS Scintillation Detector

Post by Richard Hull » Fri Sep 13, 2019 10:36 pm

I would suggest that all future posts of this nature go in the radiation forum even if you have a cool link. This is a most interesting thread and bears on taking interesting radiation measurements and gamma ray metrology, something not often talked about in the forums related to fusor work.

I will kick-start a post in the Radiation forum to post to in future and reference this thread there.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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