Identify the isotopes

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
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Jon Rosenstiel
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Identify the isotopes

Post by Jon Rosenstiel »

Here’s something for all you gamma spectrometrists out there to hone your skills on… ID the peaks to see what makes this sand radioactive.

Photopeaks in the attached Excel file are within 0.5 keV (hpGe is awesome!) so searching out the correct radionuclide shouldn’t be too difficult, but beware, there are a few peaks that will probably make your head hurt!

My favorite on-line search site is: http://nucleardata.nuclear.lu.se/nucleardata/toi/
Click on “Radiation search” and in the next window that comes up enter the peak value in the energy box and 0.5 in the plus/minus box and click “Search” to bring up a table of likely suspects within the range specified on the previous page.

Hmmm, the Excel file wouldn’t attach here so I placed it in the files section, link here: viewtopic.php?f=19&t=8014#p57418

Have fun…
Jon Rosenstiel

PS: Does anyone know how I can attach the Excel file here? Size is 1.1 Mb.
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Steven Sesselmann
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Re: Identify the isotopes

Post by Steven Sesselmann »

Jon,

This is impressive...., the resolution is as good as in the Heath catalog.

You didn't mention why the sand was active...did you cook it in your neutron oven?

Steven

PS: I am interested in learning how you came up with the formula on your spread sheet to convert bins to KeV
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Jon Rosenstiel
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Re: Identify the isotopes

Post by Jon Rosenstiel »

Hi Steven,

The sand is naturally radioactive; it is left to the reader to identify the radionuclides present. See: http://en.wikipedia.org/wiki/Decay_chain
Thorium series? Neptunium series? Uranium series? Actinium series? Or a combination?

As to the energy calibration... It starts with this program: (Written by one of your fellow countrymen).
viewtopic.php?f=19&t=7958#p57362
After using the program for some years I discovered it only calculates out to a couple of places so I wrote a small macro to do the energy calibration in Excel.
If you'd like more info please email me.

Jon Rosenstiel
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Richard Hull
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Re: Identify the isotopes

Post by Richard Hull »

Living within 30 miles of the Ligon mine in Amelia VA, this is monazite sand. You must have obtained it at the 2010 HEAS event from my pal and HEAS regular member, T.R. Leary.

Tim Raney and I hazarded the walk across the horse pasture to the creek where much of the mine waste gets washed down to and panned out several pounds of this special thorium rich sand.

We call it "horse bite farm" because the horses think you are coming to feed them and gallop over. When ingored they tend to bite you. Tim got bit, but I did not.

As you decend down into the creek bed on a slow sloped hill, the GM counters went up when we were there due to stagnant air allowing the fast decaying Thoron gas to build up radpidly to equilibrium. Thoron is the original name given to thorium's radon emissions.

The black bits are ferritic iron and red garnets abound in this stuff. Both are attracted by NdFeB magnets and can be separated out using this technique. Only the orange-yellow and brownish granules are monazite and appear not to be attracted to super magnets.

To be expected, there are Uranium and Thorium series Daughters crawling all through that spectrum This is why Monazite sand will load up a gamma spec with lines. Unfortunately, using a NaI:Tl crystal many of those lines merge that are cleanly split using your plus ultra setup.
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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Steven Sesselmann
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Re: Identify the isotopes

Post by Steven Sesselmann »

Jon,

I tried to identify some of the isotopes in your spectrum, hopefully I got some of the right.

Looks like you bag of sand has a lot more stuff in it than meets the eye..

Steven
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Re: Identify the isotopes

Post by Jon Rosenstiel »

Hi Steven,

Ok, I finally “graded your paper”, looks like you got about half of them right, pretty much on par with my first efforts into gamma spectrometry. (I’m attempting to keep up with the times and am trying to use spectrometry in place of spectroscopy). As previously mentioned, there are a few peaks that will make your head hurt. Two that I struggled with for longer than I care to admit are the Tl-208 (2615 keV) single and double escape peaks at 2104 and 1593 keV respectively.

And I should point out that in certain parts of the spectrum (mainly in the higher energy portion) my energy calibration is not as good as I initially thought. Bi-214 @ 2204.2 keV is one example that I ran across.

Richard, being from the area, hit the nail on the head; this is monazite sand containing both Uranium and Thorium series daughters. (Richard, the sand was a gift from a mutual friend of Bill Kolb and me).

Jon Rosenstiel
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Re: Identify the isotopes

Post by Starfire »

nice one Jon - I am fascinated by the fact that particular isotopes always produce given energy of a particular strength - and wonder why?
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Steven Sesselmann
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Re: Identify the isotopes

Post by Steven Sesselmann »

John,

My opinion FWIW.

It's the rungs on the ladder to the future..

The proton is on it's way down the potential energy ladder, to meet it's antiparticle, the electron.

Just like the anchor in a mechanical clock only allows the escape wheel to move one step at the time, so too, the atoms may only move by certain allowed steps.

What we are attempting to do with fusion, is to fiddle with the anchor, and make the escape wheel jump several steps in one go, and as we know it can be dangerous, if the wheel is allowed to spin freely. It's what we call a runaway reaction, literally the equivalent of pulling the anchor off a fully wound clock. The future will come real quick!

This is part of a new theory I am working on, where the electron and the proton are a particle pair, and we "the observers" are at the same potential as the proton, while the electron is at a potential of -938 Mev !

Imagine the H atom as an extremely deep fusor, with the grid sitting at -938 Mev, the grid is strongly attracted to the shell and the shell to the grid, but the two can not easily meet, as the potential energy difference is too large (same reason why the moon doesn't fall down), they end up circling each other instead.

However, certain dance steps are allowed....

The first rung is the conversion of H to D, which allows the p and n to loose a little bit of potential, then there is D to He3, and so on...

Were it not for these nuclear reactions, time would actually stand still. The end of all time is when the proton and the electron eventually meet at ground potential......, 939 Mev from now.

Can we measure time in electron volts ?

Steven

PS: It's fortunate that I don't rely on funding
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Re: Identify the isotopes

Post by Starfire »

Steven

Still does not explain why particular isotopes emit with characteristic energy - isotopes from the same element emit at different energy levels.
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Steven Sesselmann
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Re: Identify the isotopes

Post by Steven Sesselmann »

Jon,

Fascinating, the little K40 peak at 1460...., must be from you sitting next to the experiment

Steven
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Jon Rosenstiel
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Re: Identify the isotopes

Post by Jon Rosenstiel »

Steven,

You should see how much larger it gets when the detector is not inside its 5 cm thick lead shield. Main source of the K40 is the concrete floor in my lab.

Jon R
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Re: Identify the isotopes

Post by Richard Hull »

Most any good nuclear physics reference will do a pretty good job of explaining the characteristic gamma signatures of the isotopes. The wild and unpredictable beta decay energy spans are luck of the draw and without explanation other than neutrinos mysteriously fill the energy gap as needed to satisfy mass/energy conservation.

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
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Re: Identify the isotopes

Post by Steven Sesselmann »

more spectrometry....

Using Jon's meticulous spectrum from Amelia Country River sand, has enabled me to unlock the peaks recorded with my own system.

Allthough not as sharp as a HpGe spectrum, I am very happy to see that all the main peaks are visible with my spectrometry on a shoestring system, NaI detector and GS-900 with PRA.

These recordings were made without any lead shielding.

See attached files.

My bin to energy calculation is simply (bin#)^1.189

Steven

Excel File attached below.
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Re: Identify the isotopes

Post by Starfire »

Richard the text books more or less explain the levels but not the reason an atom can remain stable for millions of years before decaying while its neighbour remains stable for another million and some decay in subnano sec
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Re: Identify the isotopes

Post by Steven Sesselmann »

Jon,

Here is another spectrum I took last night from a little milk jug with Uranium glaze.

I used the web site you recommended to try and find the peaks, but there are so many possibilities, I may not have got them right. I made the assumtion that I should be looking for isotopes in the Uranium decay series.

Could you please take a look the spectrum, with your experienced eyes, and let me know if I have made any mistakes.

Thanks...Steven

[edit 12/01/10....after advice from Jon Rosenstiel I have edited the image below to reflect the most likely radio isotopes]
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Re: Identify the isotopes

Post by Jon Rosenstiel »

Hi Steven,

Having a rough idea of what to look for is a big help, narrows the field considerably.

Looking at your spectrum… (53) and (85) are most likely the 63 and 93 keV peaks of Th-234. U-235 is spot-on. (825) and (1057) are most likely the 766 and 1001 keV peaks of Pa-234m. Your spectrum is quite similar to what I got from a piece of depleted uranium. Don’t know if your milk jug is red Fiesta ware or not, but Fiesta ware contained natural uranium from 1936 ~ 1943 and depleted uranium from 1959 ~ 1973. See:
http://www.orau.org/ptp/collection/cons ... fiesta.htm

Jon Rosenstiel
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Steven Sesselmann
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Re: Identify the isotopes

Post by Steven Sesselmann »

Jon,

I updated my chart wit your suggestions, but my scale conversion is slightly out. When I set K40 to 1460 with (X = X^1.193), my 766 and 1001 peaks are too high by 40.

It is possible that I have had some drift between the actual measurement and the background measurement.

Thanks for the input.

Steven
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Re: Identify the isotopes

Post by Jon Rosenstiel »

Hi Steven,

I see similar non-linearity’s (particularly over long count times) with my NaI(Tl) detectors. Could be because the detectors I have came from eBay, but I suspect all NaI detectors suffer similarly.

Jon Rosenstiel
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Re: Identify the isotopes

Post by Steven Sesselmann »

Jon and others,

I bought this little Polycrase rock from ebay...

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... K:MEWNX:IT

It gave me an interesting spectrum, but I am having trouble identifying some of the peaks.

The red numbers are the Excel points calibrated as good as I can, the blue numbers are the peaks that I believe I am seeing.

Can anyone help me complete the picture?

Steven

[15 Jan 2011 - added spectrum after corrections]
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Re: Identify the isotopes

Post by Richard Hull »

Looks more like thorium in the rock to me.

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
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Re: Identify the isotopes

Post by Steven Sesselmann »

Richard,

You are right, according to one reference it is supposed to contain around 6% Uranium and 6% Thorium.

http://www.webmineral.com/data/Polycrase-(Y).shtml

What do you think may be causing the peak at 938 kev?

Steven
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Re: Identify the isotopes

Post by Kr85 »

Hi Steven
I was looking at that spectrum and noticed you have a well detectable 511keV peak from positron annihilation, so I guess the peak at 938keV could be maybe at 1022keV and due to sum of 2 annihilations within the scintillator about at the same time

just guessing, as always

if so your identification of energy for this peak is understimate by 84keV, maybe the macro needs more tuning or linearity of the scintillator probe in the 1MeV region is an issue, anyway even if so, the results you get from your setup are impressive to me

Regards
Marco
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Richard Hull
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Re: Identify the isotopes

Post by Richard Hull »

There is classically a double hump in this region with thorium.

These are due to the Thorium's 2nd daughter, Actinium 228 or Mesothorium 2, (old name), 6.1 hours half-life.

There are two decent gammas emitted by Actinium 228 at 911kev and 969kev. These are potent enough to penetrate a rahter large sized specimen. Thus, most in the detector's included angle will enter it, but equally, most will not be detected, making the resolving of the double hump require a decent collection time on low Th content specimens.

With pure Th, the humps rise out of the scud in about 200 seconds. With a very heavily thoriated WWII lens or several mantles, they are fully defined in under 1000 seconds.


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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Jon Rosenstiel
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Re: Identify the isotopes

Post by Jon Rosenstiel »

Hi Steven,

My 2-cents on your spectrum…

110 keV…..Th-234 @ 93 keV
191………..Ra-226 / U-235 @ 186
298………..Pb-214 @ 295
771………..Bi-214 @ 768
938………..Bi-214 @ 934
1357………Bi-214 @ 1378
1694………Bi-214 @ 1764
2027………Bi-214 @ 2204
2406………Bi-214 @ 2448

Jon Rosenstiel
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