Neutron Irradiated Dime REDUX

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Mark Rowley
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Neutron Irradiated Dime REDUX

Post by Mark Rowley »

Just for fun I reactivated a vintage Neutron Activated Dime from the Museum of Atomic Energy at Oak Ridge National Laboratory. Using Fusor 2020, the dime was exposed to a roughly estimated TIER of 1,300,000 (1.3E+6) neutrons per second for 5 minutes. The end result was a 350cpm peak of mostly beta radiation emanating from the Ag110 decay. Within 5 minutes any readily identifiable trace of activation was gone. I used a pancake paired up to a Ludlum Model 3 for detection.

Due to the reduced physical size of the activation surface and the lessened purity of the silver, it was hardly a blazing result as I normally get with 1.5x1.5” pure silver foil. But I’m not complaining as the results were still pretty decent.

Here’s the complete video:
https://youtu.be/UK8RIJn88Y0

The Oak Ridge National Lab website has a really good write-up on the old dimes.
https://www.orau.org/PTP/collection/med ... /dimes.htm

Mark Rowley
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Richard Hull
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Re: Neutron Irradiated Dime REDUX

Post by Richard Hull »

Yes that was when money was real money and carried its own weight in real value. 90% is a good activator for near mega mark fusors if one can't obtain 999 or better Ag foil.

Whether a blazing result or not, it alone, is enough to prove fusion. It is a pity so many first pass, DIY fusors, as so poorly powered and not operated well that activation is, often, just not possible.

On my Arduino box, to read beta activation within my moderator, I chose a 10 minute (60 10-sec counts). This tracks the full decay over time. In general, in a given flux, 5 half-lives period must be suffered by that which is to be activated to rather fully activate it. the Ag108 is a bit over 2 minutes, thus the 10 minute exposure. As seen in my Xcel spread sheets, I can capture the stepped decay of both the rapid 110 and the tapering off of the more leisurely 108.

The world's fare item, I have 4, and if you visited the atomic energy museum prior to 1964 you got a smaller, aluminum metal cased, plastic domed button with your dime in it. I have several of those as well. I see you have both of them in your fine video... They are (were) common on E-bay in the 90's.

Good work Mark! That was a great video with a clear explanation of your effort! The ORAU nuclear history museum is a great site to visit. Both Bill Kolb and I have contributed data to Paul Frame's effort to fully catalog much of the fine details related to our nuclear history and instrumentation.

I am struggling to obtain some rhodium, (the ultimate metal to activate), but it is now about $11,800 per troy ounce. Even a 1X1-inch ultra thin foil might cost $400! For those activating........ The easiest materials to activate are those with produced isotopes which are heavy beta emitters like silver, rhodium and indium. As Mark notes, he uses his 2" pancake GM counter, you can easily use a GM counter to detect betas. GM counters are cheap, so try and activate the easy ones that are principally beta emitters. Many worthy and nice materials are very low or non-beta emitters, but do produce copious gammas. A GM counter is of little use here, for the most part. A good Gamma ray spectrometer is needed to show off what might be a lot of nice gamma activation energies.

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
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Mark Rowley
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Re: Neutron Irradiated Dime REDUX

Post by Mark Rowley »

Rhodium would be great. Anyway you could get a small piece of foil on loan? Couldn’t imagine paying that much.

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Richard Hull
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Re: Neutron Irradiated Dime REDUX

Post by Richard Hull »

Unfortunately, I can easily imagine my paying that much for the "ultimate" activation material. I haven't found that source yet, but I do have a number of "feelers" out there working at it for me.
Rhodium is a bastard to deal with, it is a hard and brittle metal at room temps. It doesn't like to be rolled unless at very high temps. So the typical 1/10 ounce bar is of little value for activation beyond its outrageous price. The ideal is a 2 X 2 inch ultra thin foil.

As noted before, 100% of rhodium is composed of only one single isotope, so 100% of it fully activates into only one single isotope in any given thermal neutron field within only 5 minutes! (55 sec half life). Its activated isotope is a heavy beta emitter.

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
Dan Knapp
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Re: Neutron Irradiated Dime REDUX

Post by Dan Knapp »

Richard, Have you considered a thin layer of rhodium plating? There are various rhodium plating services available for jewelry at affordable prices.
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Jim Kovalchick
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Re: Neutron Irradiated Dime REDUX

Post by Jim Kovalchick »

Regarding rhodium, dental mirrors are plated with it. I once tried irradiating a larger palate one. I didn't get much output to speak of, but I never determined if it was just too little Rh or too few neutrons.
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Richard Hull
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Re: Neutron Irradiated Dime REDUX

Post by Richard Hull »

You do need some atomic thickness of the stuff. The ideal is a thickness that warrants significant internal capture and a beta release from the surface to be detected and not absorbed in the metal's volume. Kinda' tricky, but doable. I would think, .005 - inch would be nice.

Until Rhodium is obtained, .999 Silver remains the ideal metal for activation, regardless of your neutron flux. Indium is a bit better for the guy with a good gamma spec, if you are looking for a great gamma image of your activation. This, provided you have the flux and can run at that level for a bit longer than doing silver for betas.

I kind of envy the guys who have their fusor and a good gamma spec in their uniformly heated and cooled spaces. (room temp) I would have to get mine set up in the upstairs lab, then extract the activated material, race into the house and up the stairs to place the gamma emitter under the gamma spec. One doesn't operate a NaI:Tl crystal over a range of freezing temps to sweltering heat. Such cycling will kill it.

Again, I love Mark's video!

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
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Mark Rowley
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Re: Neutron Irradiated Dime REDUX

Post by Mark Rowley »

Thanks Richard. I’ve totally caught the activation bug and I doubt there’s a cure!

I gotta add Manganese as a good activation material. The 850keV Mn56 photopeak is big! Reminds me of Cs137.

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Richard Hull
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Re: Neutron Irradiated Dime REDUX

Post by Richard Hull »

Manganese is a medium tough one to get. I did it following the instructions of Carl Willis. Super saturate a gallon of water with manganese sulfate....Irradiatethe jug. The water is the moderator for the saturated manganese sulfate. Put up to your gamma spec.

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
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Bob Reite
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Re: Neutron Irradiated Dime REDUX

Post by Bob Reite »

Silver foil is the best for someone on a tight budget. You can get a "book" of 20 2.5" X 2.5" sheets of 0.999 silver foil for around 25 USD.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Richard Hull
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Re: Neutron Irradiated Dime REDUX

Post by Richard Hull »

Be very careful that it is not pure silver "leaf". Hard to handle and work with.

If it is leaf, cut about 6 pages out, (intact), do not mess with the silver. Mount the thin paper interleaved silvers on a frame and try irradiating that. If you use too many pages the betas might be absorbed in the paper. Leaf can easily be one ten thousandth of an inch thick!! Using and handling it is somewhat of an art. While gilding is no longer a hot job for skilled workers, those gilders remaining have a life-time of experience in the art. Once applied, gilded metals, especially gold leaf, are very tenacious and last many years.

Metals this thin are easily sheared and broken up in application. Leaf metals are ruled by electrostatic and Van der Walls forces.

https://en.wikipedia.org/wiki/Van_der_Waals_force

Wiki also notes........
........................................................
How thick is silver leaf?
0.5 microns
Each leaf is beaten to approx. 0.5 microns thick. Whether you purchase European Silver leaf or chinese, the size (3 3/8" sq) and thickness (0.5 microns) is standard.
......................................................

My final word.....Nasty, nasty stuff!

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
User avatar
Bob Reite
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Re: Neutron Irradiated Dime REDUX

Post by Bob Reite »

I did not order silver "leaf". That stuff as mentioned is incredibly thin at 0.5 microns and hard to work with. Foil on the other hand can be anywhere from 1 to 8 microns thick. I had the best results by "picking it up" with packing tape. The foil faces the GM tube, so there is no attenuation at all between the tube and the foil. It's no big feat for the thermal neutrons to penetrate the layer of packing tape.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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