Neutron Source

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.
Starfire
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Neutron Source

Post by Starfire » Sat Feb 09, 2002 12:20 am

I was in communication with AEI uk about sources, [ nearly bought 1mg of Californium-252 @ £84,000 by mistake hehehehe I ask for a quote for 1 mg instead of 1 mico g -- had only looked at the neutron output] {perhaps I should have bought two - they are very small } - Anyway, -- they have other neutron sources as - Am-241/Be - in S.S. case, but these are also very expensive. However they also supply Am-241 as a source in a plastic disc, which is much cheaper. I was thinking of obtaining an Am-241 source and then placing a plate of Beryllium in front of it - to produce neutrons this way.
Has anyone ever heard of this being done? I can't see why it won't work -- what do you think?

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Re: Neutron Source

Post by guest » Sat Feb 09, 2002 12:39 pm

Beryllium is seriously toxic stuff isn't it?. I heard some old urban lab legend about a scientist's wife who died after washing a lab coat her husband had wiped his beryllium compound coated gloved hands on. Beryllium oxide is used on ceramic power valves (tubes) as the base insulator and is considered ok so long as you don't grind it or break it in any way (licking is probably no good either) and may give some neutron response.

regards
Mark Harriss

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Re: Neutron Source

Post by guest » Sat Feb 09, 2002 8:49 pm

Yes beryllium is very serious bad stuff.
Ounce for ounce it is more than 200 times more toxic than cobra venom. It is second only to Plutonium for potential damage to human lungs. Radon runs a lack luster third.
It causes an always fatal disease called berylosis.
When inhailed as a dust or halide compound.
It is a cross between lung cancer and heavy metal poisoning. When I was in service they used beryllium for jet brakes and as a neutron booster in H Bombs.
Scores of people from the fifties and sixties are retired
in the VA dying of this stuff. It is a sight to see. Most take twenty years for the exposure to really become visible. Most die in abject pain wracked by seizures up to the final curtain call. It only take just one offhand exposure. I know a flight crewdog who just walked by where aircraft brakes were being blown out. Under sevear braking the beryllium copper brake shoes burn to make beryllium oxide + copper2 oxide. Snakes use copper compounds as a metabolite poison to kill prey.
Imagine the double whammy beryllium + copper2 oxide. Bad Mojo. In Australia they mined a virulent ore that consisted of beryllium oxide plus asbestos. The miners all passed away from berylosis. It is imortalised in the song Blue Sky Mine by Midnight Oil.

Use metal powder or better yet a thin sheet of it

Larry Leins
Physics Teacher

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Re: Neutron Source

Post by guest » Sat Feb 09, 2002 9:56 pm

Better still, don't bother. Check the old "Songs" archive. A couple of folks tried to make a neutron generator with americium sources and beryllium, and did not get a lot for their efforts. Alpha particles have a very short range, so the alpha emitter and beryllium need to be intimately mixed for best results. Also, the basic reaction that produces the neutrons is very inefficient. Depending on the alpha energy, you get somewhere between 20 to several hundred neutrons per 10^6 alpha particles, so you need an intense source to do any good. Your money will probably be better spent if you can find an agency that will calibrate your detector using their own (intense and licensed) neutron source. In the States, I believe both Eberline and Ludlum will calibrate detectors, though Ludlum appears easier to deal with, as they have a posted price schedule, and offer to calibrate anyone's instruments. Overseas is another story.

Starfire
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Re: Neutron Source

Post by Starfire » Sat Feb 09, 2002 10:50 pm

Beryllium is indeed extremely toxic but much less so as a metal of small surface area --in powder or small particulate it is extremly dangerous due to the possibility of inhalation or ingestion - [see coshh sheets] but I was intending to encapsulate it with the Am-241 { in close contact, Richard} how ever - the suggestion of calibration of the scintillator at a cal./std. lab. is worth thinking about.

http://www.istc.ru/istc/db/pra.nsf/pran/5257

Starfire
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Re: Neutron Source

Post by Starfire » Sat Feb 09, 2002 11:18 pm

Tks Larry,
It is also used in modern I.c's and transistors because of the excellent thermal transfere it has - as BeO - points taken -- I would only use a fume cabinet and tongs to work with it.

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Re: Neutron Source

Post by guest » Mon Feb 11, 2002 1:34 am

Unless you are an expert trained chemist with glove box facilities DON'T TOUCH BERYLLIUM. If you look at the LD50 in Merck Index it just says that people have been known to die from incredibly small amounts of this material. Its not worth the risk!!!!!!!!!!

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Richard Hull
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Re: Neutron Source

Post by Richard Hull » Mon Feb 11, 2002 4:00 pm

#1..... Any Am241 source sold as a calibration source in a plastic disk is sold for its 59kev GAMMA radiation! 0.0% of the tens of thousands of alphas/second ever see atmosphere, all being stopped dead in the plastic. I personally cal the low end of my Gamma Spectrograph with an Am241 source and the high end with a Cs137 source.

#2.......You can never obtain an open Am241 source of an intensity even close to what is needed for a neutron source.

#3........I have a line of 20-30 free nice neutron sources using Am241/Be ready to ship to you NOW. All you need to do is give them your federal NRC Source license number and your local state nuclear source handlers license number and they are in the mail to you in 24 hours.

I checked, and you will need a certified health physicist and or a certified and trained nuclear engineer with 20-30 hours of radiation health physics class hours on site to even apply for the Fed license. You must have a sarcophagus on site for entombment of the source when not in use (underground well or chamber). Needless to say private residence storage is out. States are a bit more lax, but both the FEDs and State Authorities do routine inspections of the site where the source is located. (both scheduled and surprise). The paper work is endless and the hoops to jump through unimaginable. With each new law, the bar is raised higher and higher. The free sources are at Los Almos where colleges who are now eagerly shedding themselves of such encumberances send their old sources. From here, they are held or redistributed to qualified license holders once your bonafides are checked out (~24 hours).

I have used intimate contacted electrolytic beryllium flake and a small open Am241 source already, and the neuts were so close to background counting, even when taped directly onto the PE moderator of the BF3 detector, that I gave up in disgust. As mentioned, this was posted on rather extensively in the old Songs board. A minimum of a 0.1 curie Am241 source is needed to do good cal work on neutron detectors.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Carl Willis
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Re: Neutron Source

Post by Carl Willis » Tue Feb 12, 2002 6:39 am

Perhaps the Po-210 antistatic brushes are worth mention as energetic alpha emitters for possible alpha / Be neutron sources available to anyone (they are under general license in the US). They are manufactured by NRD Corp. and sold by such online dealers as SPI Supplies and Warehouse Photo for ~$20. The large replacement cartriges contain 500 microcuries each of Po-210. Too bad the half-life is so short for that isotope.
My "Sourcebook on Atomic Energy" text states "the yield from the bombardment of Be by alpha particles from 1 g. radium [226] is about 10-15 million neuts / sec." I'd guess the polonium brush head could probably manage 7500 neuts per sec with a Be foil according to this info, which according to Richard's statement is still in the unmeasurable zone. But a nice accumulation of such brush heads on a Be foil might just do the job. Has this idea been put into practice? I have a couple pretty fresh brush heads but do not have any beryllium aside from a few oxide transistor standoffs.
Carl Willis
http://carlwillis.wordpress.com/
TEL: +1-505-412-3277

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Re: Neutron Source

Post by guest » Thu Feb 14, 2002 10:45 pm

Tks all. ---- I was looking for a cheap source of neutrons -- I can obtain a Am-241/Be source giving 1.1 x 10e6 n/sec = 2.2 x10e6 n/sec per Ci but is expensive I was looking at the possibility of using a Am-241 disc giving 37 MBq = 1Ci and putting the Be plate against it
-- but ?? ---

the Am-241 should kick out about 10e4 n/Sec due to alpha.n reactions with trace impurites such as Si, Al, O. etc in the source make up -- would this not be enought?

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