FAQ - Dysprosium activation - more lessons on activation

If you have a question about this topic, the answer is probably in here!
Post Reply
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

FAQ - Dysprosium activation - more lessons on activation

Post by Richard Hull »

I decided to place this item in the FAQs as it continues to teach how to use and understand the "Table of Isotopes". Neophytes grasp some knowledge of how to use and table of isotopes to ferret out elements that the low flux amateur fusor might activate with ease. The rule is look for a large activation or "capture" cross section or sigma of a stable isotope of an element and see if its product isotope has a short half-life.

Sounds easy enough, but there are elements that can be a bit tricky and require a bit more knowledge of nuclear physics to interpret the Isotope table data to the fullest degree.

Dysprosium is one of these and I attach a short paper (PDF) on the activation of dysprosium which elaborates on some of the twists. To supplement the verbiage I have scanned two pages from the book Table of Isotopes which I have profusely annotated. For those weak in the physics of activation and some of its nuances this can be a teaching moment.

You must click to enlarge the pages in order to read them.

Richard Hull
Attachments
Dysprosium Activation.pdf
(165.63 KiB) Downloaded 133 times
Dy1 anno.jpg
Dy2 anno.jpg
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
Finn Hammer
Posts: 298
Joined: Sat Mar 05, 2016 7:21 am
Real name: Finn Hammer
Contact:

Re: FAQ - Dysprosium activation - more lessons on activation

Post by Finn Hammer »

Richard,

A lot of numbers in those diagrams, and a lot of hard to grasp graphic too. I sorely wish I could sit down with you for an hour or so, to ask many questions about how to interpret these diagrams, found on page 94 and 327 of the "bible".
The amount of knowledge lodged in these diagrams seems to be insurmountable, so I hope you will go along with me on some questions.
Referring to the picture below, I will start with 3 questions, the first one referring to the fractions of which a couple of them has been circled in red.
1) Some of these fractions are in brackets (), some not, why?
2) These fractions are not lined up under each, not left, center or right arranged, but spread over the place, does this have a meaning?.
3)do the fractions relate to the line above or the line below?
4) Some of the lines are solid, some of them are dashed, why?

Speaking of the lines, referring to the green circle, which highlights another oddity:

5) In the middle of the diagram, a few of the lines pass right through the diagram from left to right, but most of them display a "dip" , a few of them have a hump upwards. What does these dips and humps tell us?

There is a column of numbers, I circled a few of them in blue. They say something about the gammas emitted.

6) which property of the gamma is displayed?

In the blue/green circle it says M2, but I think it should say M1?

With the answers to these questions, I hope to be better vetted to deciphre what happens in the rest of the diagram.
83% of the Dy165 finds rest as Ho165 by beta emission. The remaining 17% is also decaying with Betas, but they land at intermediate energy levels, which prompt further gamma decay before reaching Ho165 (or so I thought).

Hoping for a bit of enlightenment

Cheers, Finn Hammer
Attachments
decay.JPG
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: FAQ - Dysprosium activation - more lessons on activation

Post by Richard Hull »

I will correct the one mistake that you caught. The M1 correction will replace my M2 error in my red text annotation. Mea culpa.

Now as to your questions related to all the humps an fractions. At present, I do not know the answers and do not care as these are all minutia from someone else's work to a tight level of detail that should not concern us in our quest, nor will it impact or impede our search through the table.

It is a pity for one would love to know all the little details, as you seek to understand. Typically, and I have seen some actual attempts to, with similar diagrams in other texts, to explain some of this, but not all of it in great detail. In most cases of such cryptic diagramming, there is always an example of same preceding the bulk of such efforts to follow. This seems to exist only in text in the case of these diagrams in the table of the Isotopes.

In short, I come up short on what you wish to know. I will endeavor to dig into it and either supply a URL or attempt a lame explanation that I hope will satisfy in future.

The dips might refer to the ability of the straight line associated with its energy level to just, on occasion, skip down past all the intervening energy levels to this base dip. You will notice in the first page listing under particles emitted it dare not give all the possible gammas and just notes a gamma spectrum. Just musing.

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
Finn Hammer
Posts: 298
Joined: Sat Mar 05, 2016 7:21 am
Real name: Finn Hammer
Contact:

Re: FAQ - Dysprosium activation - more lessons on activation

Post by Finn Hammer »

Richard,

Thank you for your consideration. Any pointers will be appreciated.
For now I will rest content that if you don't know, then certainly I don't need to know either.
Cheers, and happy hollidays
Finn Hammer
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: FAQ - Dysprosium activation - more lessons on activation

Post by Richard Hull »

Finn, all smart people are in a constant need to know. However, as you note, we are on a mission to understand to our level of incompetence the path of activation and its outcome within our level of needful use. The table does this very well once we understand the basics involved in its use.

I use to avoid the "back of book complex diagrams" like the plague, but by some form of osmosis have absorbed their value and now use them regularly.
This is due to the old Rhodium postings where such diagrams as introduced by Jim Kovalchick assisted mightily in showing how more of the Rhodium radioactive isotope was sort of "recycled" on the trailing end of the long running decay curve.

So it is in this thread by me. I show the gobbling up of valuable thermal neutrons by other stable Dy isotopes and the boosting of the net cross section of the Dy 164 after 10 minutes due to the equilibrium decay of the metastables. All made manifest by study of both pages of the table of Isotopes through familiarization of what was once a mystery. It all boils down to how deep a dive you are willing to go in study to obtain the knowledge that accrues from the effort.

Yes, they seem a jumble of lines and pointers but understanding to a deeper level can be brought forth in their study. I find it amazing that some folks "back when" devoted a year or two of study of just one or two of these decay chains to find all the gamma/beta energies waded up in the jangle that are these seemingly hopeless nuclear spider web diagrams.

I have long stated I don't give a fig regarding fusion. For me, fusion is a path to neutrons and thereby, to activation experiments. What kind of guy would I be to come into activation studies without a willingness to learn some of its physics once at the threshold?

As a young man of 8 building electronics, the complex schematics of electronics symbols amazed me, but by osmosis and working with them, they became second nature by 10 years of age. The same dilemma faced me with all the mnemonics of computer assembler and programming codes. Still young in my 20's, I absorbed them and used them. So it is with the isotope table's back of book spider webs. You learn these things because of a need. I find I learn things like this in stages of complexity allowing it to sink in, as needed. Now as to those bizarre fractions and humps and bumps in the gamma lines......??

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
Post Reply

Return to “FAQs: Neutron - Radiation Detection”