Homebrew neutron test sources

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.
Locked
User avatar
Carl Willis
Posts: 2841
Joined: Thu Jul 26, 2001 7:33 pm
Real name: Carl Willis
Location: Albuquerque, New Mexico, USA
Contact:

Homebrew neutron test sources

Post by Carl Willis »

A while back, Richard Hull mentioned his methodology for comparing neutron pulses from the Tom Dressel vs. Bicron scintillator units, including a brief statement and a caution, I believe, about the making of a simple RaBe source from radium paint and beryllium. (This source is not very hot in terms of neutron output but I gather it is hot enough to see an occasional pulse, and good for checking the gamma response as well.)

Richard, would you mind going into some more detail about that source? I have the materials (Be metal lumps and plenty of radium-faced meters) but have held off on messing with either of these particularly dangerous substances until I hear of a reasonably clean way to manipulate them into a source.

What advantages do you see in the paint (which has to be scraped loose from gauges in most instances) vs. smoke detector Am-241 sources (sealed 1 uCi) and Po-210 staticmaster brushes (500 uCi and sealed as well)? Do you have some order-of-magnitude suggestions about the activity of the paint on dials? How should it be scraped off the instruments without causing undue loose contamination or undue dilution or loss of material?

My other problem is with the beryllium, about which I have heard mostly horror stories. Thus far I have concluded that there is no reasonably safe way to turn chunks into fine powder with the stuff I have at home or college.

Please add your comments about this source if you don't mind. If others on this forum have experience with Ra paint or beryllium I'm interested in how you do things also.

Thanks,
Carl
Carl Willis
http://carlwillis.wordpress.com/
TEL: +1-505-412-3277
guest

Re: Homebrew neutron test sources

Post by guest »

We covered this stuff in the tread:
2002-02-08 18:20 Neutron Source (John Hendron.) [Latest: 2002-02-16 10:49] (11)
You can get the whole scope of the problem there.

Larry Leins
Physics Teacher
User avatar
Carl Willis
Posts: 2841
Joined: Thu Jul 26, 2001 7:33 pm
Real name: Carl Willis
Location: Albuquerque, New Mexico, USA
Contact:

Re: Homebrew neutron test sources

Post by Carl Willis »

Larry,
You're right that this stuff has been covered (and better than I remembered it, so most of my questions have been answered)! Richard Hull's "Scintillator Test" post from April actually describes that the paint was not scraped off his instrument needles...and also there is an estimate of the total radium activity in those needles based on the observed neutron counts from the source.

I am curious how many gauge needles were packed into the cigar tube. I'll also point out that I am still confused about smoke detector Am-241 activity. Richard said in the post I refer to that 4 uCi is about 40 detectors worth, but the detectors I use state they contain "a maximum of 1.0 uCi," which should mean that 4, rather than 40, should do the job of all the radium hands in his source. It's certainly a picky thing to want to clear up, but I am trying to make an optimal, safe neutron test source for the little money I have.

-Carl
Carl Willis
http://carlwillis.wordpress.com/
TEL: +1-505-412-3277
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Homebrew neutron test sources

Post by Richard Hull »

Gee, this is a gray zone. I will not post details on such construction, but will refer you to any one of the references regarding neutron physics in the ref forum. Paticularly good discriptions and methodolgies are given in the book by Beckertz and Wurtz on Neutron Physics.

I will mention that scraping the Ra paint is a near death sentence for any younger person. That stuff is mainly binder with the remainder old burned out ZnS:Ag. In an average watch hand of the late 40's there might be a micro gram of RaBr distributed on the entire hand. Making each one a 1 uC source, but not really. That's 4 pi. For a surface that halves to 2pi. With self absorption and measurement by a window it comes to about a measurable .2 X pi situation. 1 ugram of RaBr ingested and retained has about a 60% chance of inducing an internal related cancer within 20 years.......Well.. do you feel lucky?

DO NOT DISTURB A RADIUM DIAL.... MY only advice.

Po210 is totally out as it has far too short a half life. (couple of hundred days). How fresh is the static master refill in your wallet?

Am241-Be is the neutron source of choice and currently the only one licensable NEW in the US. Giving off no effective gamma or beta radiation it is much safer to handle and be around.

I have gone through the math in past posts on this subject and if memory serves me correct here it is 10-20k alphas of 5mev/sec/neutron per second in an intimate mixture of the Am241/Be dust. Thus, a 1uC source in absolute intimate mixture would give about .5n/s maybe. the Am241 sources in smoke alarms are vapor deposits you could never get even 1/4 of the .5n/s with the source covered with Be dust. Thus, realistically you are looking at say 10 little alarm buttons covered with Be dust or metal yeilding a grand total of 1.25 n/s @ 4pi isotropically. Assuming ideal pi distribution into a BC-720 fast neutron detector that mean a maximum of .3n/s in the scintillator. The system is about .6% efficient and that means you will see 1 count due to the intimate contact detector to source every 500 seconds or 1 count per 10 minute time period. Real hard to pick out of background noise fluctuations.

The beryllium is a non-issue compared to the Ra issue and doesn't even make the EPA score card in this discussion. wallowing in all your Be naked and washing good behind your ears with the stuff can't compare to the risks with the Ra material even if the Ra is well handled. If you are ready to roll the dice on the Ra gathering and condensing then forget even mentioning the Be problems for they are just icing on the biohazard cake.

Remember there is not a problem here at all! No immenent danger like instant death. However it might all come home to roost when 10, 15, 20 years down the road you are told sullenly by the doctor in a consultation that you have inoperable bone cancer, lukemia, etc.

My advice is DO NOT ATTEMPT TO DO IT!!!

Do you feel lucky?

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
MarkTomlinson
Posts: 3
Joined: Fri Oct 06, 2023 1:24 pm
Real name: Mark Tomlinson

Re: Homebrew neutron test sources

Post by MarkTomlinson »

Hello... I know this is an old thread, but I am very interested in the document that Mr. Willis referred to. I have attempted to contact him by email with no reply. Would anyone else happen to still have a copy? Again, my apologies for starting this thread up again...

Mark
Frank Sanns
Site Admin
Posts: 2119
Joined: Fri Jun 14, 2002 2:26 pm
Real name: Frank Sanns

Re: Homebrew neutron test sources

Post by Frank Sanns »

This thread is over 21 years old. It was made in the early days of the site coming into its own and people were doing all sorts of things. Not all consequences were yet fleshed out by some.

The site has been strictly by the book for a very long time. That means no tritium, no neutron sources; no illegal activities of any kind.

What Mr Willis does on his own site is entirely his and his alone. He mostly likely gets lots of traffic and emails and does not usually answer strangers. He is a good guy that plows his own grounds. I think if you stomp around on his website, you may find what you are looking for. I know he had a properly licensed polonium-210 source that he did lots of experiments with detection and productions. You might search his site for that.


Frank Sanns
Site Administrator
Achiever's madness; when enough is still not enough. ---FS
We have to stop looking at the world through our physical eyes. The universe is NOT what we see. It is the quantum world that is real. The rest is just an electron illusion. ---FS
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Homebrew neutron test sources

Post by Richard Hull »

I will boost what Frank has posted. In my reply early, back in 2002, I noted that removing radium paint could be a death sentence and that no one should ever do it. Beyond that, here in the U.S. doing such activities will get you in trouble. We do not support nor advise on the manufacture of any homemade neutron sources, period! It is against NRC regulations. Let a well made fusor be your source of neutrons, extremely limited though it may be by any real nuclear standard.

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
MarkTomlinson
Posts: 3
Joined: Fri Oct 06, 2023 1:24 pm
Real name: Mark Tomlinson

Re: Homebrew neutron test sources

Post by MarkTomlinson »

Hello,

OK, my mistake in that I didn't post the reply asking for the document to the right thread: it belonged in the thread titled "Teflon neutron source" @ viewtopic.php?p=34094 which says said he would not be putting the document in the public documents area, and that you should contact him for it. I do apologize as perhaps my request would not have looked as rogue and like I was planning to buzz through a few hundred old clocks. It probably looked as though I didn't care about the hazards addressed in the multiple posts about neutron sources. Rather my intent would be more along the lines of the various materials he had studied in re: α reactions from the aforementioned "Teflon..." thread. I only took him at his word that I could send an email or ask about the document. I felt his experience in what was sometimes a difficult area would be helpful.


It was stated in one of the replies "I think if you stomp around on his website, you may find what you are looking for." .. yes quite a bit, including at the very beginning, a link to THIS site and a post which no longer properly resolves: http://www.fusor.net/board/view.php?bn= ... 1139195753 It was from that information I found his posts on fusor.net and the placement of the link on his own site to an outside source seemed to be reasonable, hence I asked.


So, 'don't do what he *may* have done?' Fair enough. The source I observed in his videos under "Just Fooling Around" was labelled "Am-241 5.3 mCi," but there was at least one post on THESE forums under "Teflon neutron source" showing a photo of a radium doped strip of metal touching a piece of PTFE to examine the possible 19F(a,n) stripping reaction. It was my understanding that a sealed alpha emitter, like a foil, whether it be of Am-241, Ra-226, or whatever, was at least much safer and reasonable (as well as legal), i.e. to place it directly against a target material and hope for the pittance of neutrons that would follow. The sources he uses *seem* to be foils, not unsealed material. Again, had it been a request posted in the right thread, it would have been more logical. Depending on his Am sources, 5.3 mCi would be between 85-90 Pyrotronics units (you know the specific model) if the main foil only was utilised. Perhaps this mysterious document would have gone into more depth on that, I don't know. Those who had access to it seem to be the ones commenting, so perhaps it isn't anything special.


It *seems* the prevailing feeling is that he shouldn't do what he goes into depth about doing, from threshold reactions/activations which a fusor is often unsuitable for, to neutron moderation-attenuation measurements, etc. Then there seems to be a feeling that while he shouldn't do what he does, he does it anyway and that's OK. If not OK, at least sufficiently acceptable to remain a post here. Mixed message, so I ask forgiveness at the naivete displayed. In the correct "Teflon" thread, Mr. Hull remarks on it being a "superb little experiment," and then proceeds to ask for a copy of the document. Again, nothing to indicate that asking for some amateur information was now unwelcome. Perhaps I should have just asked Mr. Hull, but that's not very good etiquette to pull and end run around. It seems there is reference to a cigar tube with Ra watch hands, another reference to the 5mCi Po-210 source (which can only be specifically leased, not owned), and then sealed sources from exempt distribution of ionization technology smoke detectors. While this was a while ago and people may have learned better, a simple document doesn't seem like a big deal.


My question, which I thought I had answered: Are neutron sources unlawful per se, or only when they involved unlicensed material such as Ra-based paint taken from old devices? It again seems that as long as the material is licensed or exempt, such as a foil, then temporarily affixing it to a target material, which is just what was depicted, was acceptable.

"We do not support nor advise on the manufacture of any homemade neutron sources, period! It is against NRC regulations." Got it, I believe you. May I ask, solely for my own edification, what CFR regs would apply?


This was not a post referring to anything, but a document circulated by a member, offered for dissemination, and then requested. It turned into me seemingly having to identify the backwards way the verboten nature of it was communicated, point-for-point. Never did I mention anew any materials, construction, etc. that would seem to document an unlawful activity. It was a tiny resource I was asking about, but I wanted to give adequate context for the inquiry, hence this lengthier reply.

Thanks,
-Mark
Frank Sanns
Site Admin
Posts: 2119
Joined: Fri Jun 14, 2002 2:26 pm
Real name: Frank Sanns

Re: Homebrew neutron test sources

Post by Frank Sanns »

Without a proper license, an individual cannot own enriched uranium, Pu, or own or manufacture neutron sources.

Disassembly of a smoke detector to be able to touch the foil is disassembly and illegal.

The NRC has a complete website of regulations. https://www.nrc.gov/about-nrc/regulator ... -regs.html

The teflon thread did have some academic results value so it has remained in the distant archive.

Your extensive narratives bringing up long resolved issues from decades ago is counter productive to the site. It is like somebody in the media digging up what you might have done in high school, describing it in great detail, then bringing it up in a job interview when you are in your 50s. There is no constructive purpose for such actions.

The site will not tolerate discussions of illegal materials, sources, or procedures. I hope this closes this matter here.
Achiever's madness; when enough is still not enough. ---FS
We have to stop looking at the world through our physical eyes. The universe is NOT what we see. It is the quantum world that is real. The rest is just an electron illusion. ---FS
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Homebrew neutron test sources

Post by Richard Hull »

The bottom line....

We cannot control the conduct of those here. Any thing people do who are on this site is on them. (legal or illegal)
Read and obey the regulations.
As such, for many years now we have taken a hard stance against illegal activities and as Frank says, and I quote our official stance.....

This site will not tolerate discussions of illegal materials, sources, or procedures. I hope this closes this matter here.


As the "trash" man here, I will erase any and all future posts containing discussions that involve any illegal source manufacture or actions regarding same.

Richard Hull


EDIT: All posts after this one have been deleted because they offered no substance and only served to continue to bump this ancient thread to the top of the list again and again. - Frank Sanns
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
Locked

Return to “Neutrons, Radiation, and Detection (& FAQs)”