FAQ - Extensive paper on neutron activation

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Richard Hull
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FAQ - Extensive paper on neutron activation

Post by Richard Hull »

We already have a post here on activation, but I put a lot of effort over the past two days to come up with a 6 page document that is much more specific and a lot more of a "take you by the hand" explanation of neutron activation suited for the first timer puzzling over this quest once they have a real fusor running or dare to attempt to activate as proof of fusion.

As the old boys know, it is really tough to prove fusion via activation with under 50,000 n/sec isotropic and over 200,000 n/sec are typically needed for easy to detect activation using good technique and instrumentation as well as using the best of amateur element activation materials. Both of these are tough for first pass fusor operation by the novice operator.

I have struggled somewhat to make sure the content is scientifically correct. A greater struggle was spelling, structure and punctuation.
For those capable of pointing out major errors, I would appreciate any critical comments and feedback so that this paper will serve, well, all who read it in future.

Reference:

"Table of Isotopes" Lederer, Hollander, Perlman

Thanks

Edit 5/10/18
I have updated the paper. I used the term collision cross sections.... Corrected to Capture cross section. Updated pricing of Rhodium. A few other nuances added as well.

Edit 5/11/18
The 7th edit of the file includes extras suggested by John Futter and Rich Normand. Thanks guys.

Edit 7/28/21
changed some sections for clarity and corrections.


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Re: FAQ - Extensive paper on neutron activation

Post by John Futter »

Richard
well done
It might pay to indicate early on that the neutron interacts with the nucleus in most situations jiggling/ upsetting the contents and modifying the atomic weight gain / loss (ie isotopic makeup) some nuclear outputs being happy (stable) others in a bind (unstable)
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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

John thanks for the suggestion. I have clandestinely updated the paper over the last few days about 5 times, on my own. I just did it a sixth time and noted it in the original posting. It happens that in re-reading my own paper I found some faux pas worth correcting a sixth time.

I will work on it again. Nothing like making a posting better with suggestions.

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Re: FAQ - Extensive paper on neutron activation

Post by richnormand »

Very nice Richard.

1)
I too end up doing revisions a few times on manuscripts, papers and posting to forums. It was easier in the past (review, typing pool, review again, etc...before sending to publisher) but now, with instant posting, I do appreciate the few days this forum allows me to clarify, correct and edit posts.
2)
You might consider putting your name as the author and a perhaps link here in the text proper. The idea is it will probably be forwarded to other people by a reader and attribution for the work will be lost. Your call, off course.

Hope you are enjoying retirement as much as I am. :-)
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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

Rich, I will throw the authorship idea in the mix for the 7th upgraded attachment posting. Thanks for the suggestion.

I will soon delete all the responses as I have given credit for the suggested updates in my original posting.

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Re: FAQ - Extensive paper on neutron activation

Post by Luke Harrill »

The IAEA currently has an android application entitled "Isotope Browser" It contains a chart of the nuclides, but I still find myself referencing the physical book more. Some here may find it helpful...

https://play.google.com/store/apps/deta ... s.nuclides

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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

Yes, there is something about the handiness of a real book that this old guy appreciates. Got used to getting on the bus and going downtown or to a nearby college to get data from books and books alone until the 90's. Those old tomes are now available to own for little money to make up my own technical/scientific library.
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Re: FAQ - Extensive paper on neutron activation

Post by Rex Allers »

Luke,

In your post of the Isotope Browser app, you said, "I still find myself referencing the physical book more." I did some looking around on
https://www.iaea.org/

but I didn't see a document or book that seemed to parallel the app. Can you share what you mean by "the physical book"?
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Re: FAQ - Extensive paper on neutron activation

Post by Luke Harrill »

By "the physical book" I meant the book "Nuclides and Isotopes : Chart of the Nuclides 16th Edition" published by Knolls Atomic Power Laboratory.

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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

The physical book I referred to is "Table of Isotopes" Lederer, Hollander, Perlman. I mentioned it twice in my PDF above. There are several to chose from.

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Re: FAQ - Extensive paper on neutron activation

Post by Rex Allers »

Thanks.

For some reason I (incorrectly) interpreted that "the book" was something coming from IAEA.

I guess I was thinking along the lines of the Gamma-ray Spectrum Catalogs that can be had as pdf's from INL.
(Although I tried a link I had saved today and it failed. Then, starting at the top of inl.gov I never found my way to them. A search on the whole web for "gamma-ray spectrum catalog" did find the pdf's at an INL page, but way down the search results list.)

Oh well, that's really unrelated... but shows how things I expect are out there on the net are getting harder to find.
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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

Internet content, websites and data can disappear, websites die or be re-named, data that might prove dual use, gets pulled off. Assume the internet is a place loaded with material that may or may not be there again, once found long ago. Whatever is in a book is there for as long as the book exists.

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Fusion is the energy of the future....and it always will be
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Re: FAQ - Extensive paper on neutron activation

Post by Bob Reite »

https://archive.org/web does a pretty good job of preserving sites from the past.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Re: FAQ - Extensive paper on neutron activation

Post by Joe Gayo »

I think you meant Manganese 55
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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

Corrected in the new version attached

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Re: FAQ - Extensive paper on neutron activation

Post by vivekanandan c »

hi in ur pdf uve mentioned
"To activate our lovely choice isotope in any given slow “neutron flux”, (The number of neutrons per
square center, per second entering our element), we would have to run our fusors continuously at full
bore for 75.6 days just to reach the 50% radiation level of activation based on our normally pitiable
neutron flux in our moderator. It would take more than a year of continuous fusor operation to fully
activate and maximize the radiation from the new isotope"
if the half life is 75 days ,why do u need the fusor to run for 75days ,once the neutron gets absorbed into the nucleus ,the job of converting an isotope to another isotope with next higher atomic number is done in few seconds (neutron capture) , the 75 days of beta decay or electron capture or gamma decay ,needs only the detector (geiger counter)running for 75 days,it does not need the fusor to run for 75 days, more time the fusor runs more neutron capture only will happen (neutrons will get added to the nucleus) ,please correct me if im wrong
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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

The key part is, "in a given neutron flux" from a fusor or any source of neutrons. This means that keeping a fusor running for 75 days would only create half of the maximum number of new isotopes atoms, (mass), possible at that given bombardment flux. Look at the activation equation in the PDF file below. Study it carefully and you should understand.

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Re: FAQ - Extensive paper on neutron activation

Post by vivekanandan c »

thank you for reply,im an amateur who got exposed through this by online reading
can u explain beta decay for example if tunsten 186 captures one neutron it becomes tungsten 187 that has half life of 24 hours after which it beta decays to rhenium 187 ,do u mean to say only when tunsten 186 is irradiated for 24 hours or more it will become rhenium187 thats is decay time equal to irradiation time ,doesnt the neutron already get captured when tunsten becomes 187 ,or does it need whole 24 hrs to get captured ,only then it will decay simultaneously, im confused here .also what will happen if thhere is no beta decay half life ,for example tunsten 183 becomes tungten 184 by neutron capture doest beta decay ,how much irradiation time it will take, could you please explain
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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

You really do need to read up on isotope manufacture and decay. Both are exponential processes. complex decays involving many daughters can be handled by a series of complex simultaneous equations. Still, we might intuit what takes place in complex chains once a full understanding sets in through some time of study and osmosis within the brain to become one with manufacture and decay scenarios.

One neutron is captured by W184 and the result is one atom of W185 (27 day t1/2)....W185 decays to stable Re185 with a good cross section to Re186 (90min t/12) under continued neutron bombardment to stable Osmium 186.

Let us back up to one neutron turning W184 into one atom of W185. There is no guarantee that that one atom of W185 will decay even after 365 days! It might be out on the tail of the exponential curve and might not decay for 2 years!!!

Now , let 10e10 atoms of W185 be produced by neutron bombardment at saturation (27days X 6) =162 days of constant neutron bombardment. There is still no guarantee that that first atom will decay in a year! However, there is a high probability of .5 X10e10 atoms of those 10e10 atoms with decay to Re185 in 75 days after removal from the neutron flux on day 162 of W184 bombardment.

On day 237 there will be .5Xe1010 of Re185 atoms. these will not decay!! However, during the long bombardment of W184 some Re186 would have been made and its short t1/2 of 90hours would mean that some amount of stable Os 186 would be produced. The complex of equations mentioned above would solve for the amount of stable Os186 that would result from the 162 day original exposure of the W184.

The term half-life of any radioactive isotope will only have meaning for an unbelievably large number of atoms taken as an aggregate!! It means nothing regarding any specific atom! It is statistically possible, but not very likely that that first atom of W185 created might still be here 50 years after bombardment, in spite of the stated half life of W185 being only 27 days!

Exponentials simultaneous with exponentials upon other exponentials fails simple intuition in both decay and activation scenarios.

Get a good book on this subject.

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Re: FAQ - Extensive paper on neutron activation

Post by vivekanandan c »

without confusing so much i keep it very simple
fist thing first i have to make a fusor, then take a jug of water ,mix a salt of silver ,bombard with neutrons from the fusor for seven times the half life of silver,then it will beta decay to cadmium, then i take the jug and if i found cadmium instead of silver,ive successfully created neutrons and made neutron activation,my fusor attempt is success, the percent of cadmium found depends upon ur equation.
have u done practical neutron activation with ur fusors or neutron generators yourself,what is probability of 100%successful activation,how many times u made full beta decays or what is the likely probability for successful neutron activation 70%,80% can u share ur success rate
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Re: FAQ - Extensive paper on neutron activation

Post by Liam David »

You will not be able to detect any excess (non-impurity) cadmium from neutron activation of silver. No fusor you will ever build will activate silver to even the part-per-trillion level. The beta decays are the only way you would be able to detect activation. The kinds of questions you're asking indicate that you have a whole lot to learn about such topics, and I'd recommend taking a step back to do a lot of reading and research before you get too ahead of yourself.
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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

I have activated various metals with a 100% success rate since 2004 probably hundreds of times. You have obviously not explored this very forum for recent past posts by me for my recent Rhodium activation efforts complete with decay curves presented for all to see, many, many times.

I have activated Silver, Indium, Managanese, Dysprosium, and Rhodium.

Try this post on my Rhodium activation with many runs in it.

viewtopic.php?t=14084

Liam is correct, of course. Silver is an easy activate and a simple GM counter showing well above background count after activation is proof positive of neutron production. It is just that simple. No activation, no neutrons and no fusion taking place.

Depending on how many neutrons you have, every activation should be 100% successful. Rhodium and Silver are easy to saturate and detect with ease at about 350,000 n/s, TIER from a fusor into a moderator in contact with a fusor. (700,000 fusions per second)

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Re: FAQ - Extensive paper on neutron activation

Post by vivekanandan c »

i would like u to look at this pdf https://core.ac.uk/download/pdf/230904085.pdf ( first two pages)

it says the beta decay half life from tunsten187 to 188 to rhenium 188 is 69.7 days, but within 24 hours it says 62% of rhenium 188 is extracted from tunsten188 with a very high neutron flux, is it possible with a high neutron flux such a high amount 62 %can be converted activated from tunsten 188 (to rhenium188) in short time like 24hrs
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Re: FAQ - Extensive paper on neutron activation

Post by Liam David »

You clearly didn't read the paper very closely, or my post for that matter. I did not say that is impossible to separate activation products from irradiated materials. That is done all the time, including with neutron generator systems. I say that you will not be able to do so. The paper you linked discusses rhenium and tungsten irradiated by the extremely high thermal flux found in a fission reactor.
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Re: FAQ - Extensive paper on neutron activation

Post by Richard Hull »

With a huge fission reactor flux, you cannot beat the demanded saturation time period. Any thing less than Saturation time of exposure, (7 half lives), and you will not develop the maximum mass of the created, desired isotope! What is so difficult to understand here.

In a high flux situation, during activation, at any point during activation, you will have more atoms of the isotope than at a lower flux during activation over the same exposure time. Again have a look at the equation that I referenced in the post above.

You cannot boost or escape the rules of the physics of activation with any form of work around. You are stuck in the mud and sorrows of the activation equation. Live with it! It is the only game in town and the game is rigged.

You, as a person with a fusor, will never, ever be able to chemically extract any isotope that you produce via activation.

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