Needing more than a spark test?

A one for one emission would seem to be a lot of gamma radiation with 37,000 disintegrations per uCi.

I have to relocate some reference that I found earlier but exposure from gamma radiation from smoke detectors was considered minimal.


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The last reference has a formula for calculating dose from radioactivity:
***********************************************************************************************************************************************
"An empirical rule which may also be used is
6 x Ci x n x E = R/hr @ 1 foot,
where
Ci = source strength in curies.
E = energy of the emitted photons in MeV.
n = fraction of decays resulting in photons with an energy of E.

It should be noted that this formula and the gamma constants are for exposure rates from gamma rays and x-rays only."
***********************************************************************************************************************************************
Ci = .9E-6 Ci, E = .0597 MeV

Furthermore R (Roentgens) = .86 Rad = .86 rem. (ref. #3) and the equation becomes:

6 x Ci x n x E= .86 x rem/hr @ 1 ft.

Substituting, 3.75E-7 x n = rem/hr@1ft. or 3.75E-4 x n = mrem/hr@1ft. and

n = mrem/hr/3.75E-4 = 2.67E3 x mrem/hr@1ft

Now for the hard part. We have an number for the annual exposure in a typical home with an ionization type smoke detector of .008 mrem The inverse square law applies to radiation so we need to make an assumption as to the distance from the source. Let's say 10 ft. also, we need to estimate the number of hours/yr in proximity of the source. Let's say 2000. This will make the exposure 4E-4mrem/hr@1ft. Substituting in the equation, n = 2.67E3 x 4E-4 = 1.068. While the assumptions are just a wag, it implies that there is one 59,7 KeV x-ray photon emitted for each alpha particle.
 
I did some browsing for thin Manganese foil. There are some sources that are breathtakingly expensive -- Goodfellow will sell you a .025mm x 25x25mm sample for ONLY $632. Sigma Aldrich is even worse. Jeez....makes me wonder what it takes to electroplate the stuff (not possible with all metals, at least in water solution). I wonder if a manganese salt solution would work. Potassium permanganate is fairly easy to come by and water-soluble (and the solution is a really pretty dark-purple color) . Sounds too easy though.
 
Wow!

Umm.. 0.025 x 25 x 25 = 15.625 cubic mm.
Which is 0.015625 cubic cm.
At Manganese density 7.21 g/cm3
0.015625 x 7.21 = 0.11265 grams of manganese.
$632 for that much is $5609.98 per gram.

Gold --> $55.94 per gram
Platinum --> $24.63 per gram
Palladium --> $67,34 per gram

Cheapest diamonds are $4500/caret, or $22,500 per gram.
So manganese worth about a quarter of gem diamonds.
Unless rolling manganese into thin foil is unusually tricky and expensive, that just feels wrong!
[Then again - I have encountered Aldrich before. One would think they make their products atom by atom]
 
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I have some relatively pure electrolytic Mn that I use for casting alloy. Manganese dioxide in fine powder is easy to get. How could you modify the physical form to work? How about a layer deposited on another material? Could you electroplate Mn onto something?
Robert
Edit: apparently Mn is very difficult to e-plate.
 
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@rwm : Robert
I think he wants to use it as a filter in a separation test mode to help tell if there is cobalt in the iron alloy
Very thin is probably OK. Maybe precipitated onto something X-Ray transparent, then held down with a whiff of Rustoleum clear.

(OK - I admit the Rustoleum bit was just make it to sound like the thread well belongs in HM).
 
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Yes, I understand the application. You really just need a thin homogeneous layer of the element. I was wondering if something like a powder with a binding resin could substitute for a foil. Mix it with JB Weld! (I followed your lead.)
R
How about a layer of Manganese based paint? It is used for a blue oil paint.
R
 
I am thinking a foil from "Aldrich_may_as_well_be_made_of_Unobtainium" is not needed. All we need is some stuff with Manganese in it, the better it does not contain any other metal.

OK - even potassium permanganate might do, but manganese dioxide sounds better.
Apparently several kinds, the stuff is widely used in the alkaline battery industry.
Batteries need "electrolytic manganese dioxide".
Ferrites need "chemical manganese dioxide".
Wikipedia explains how to make it.

Either way - if there is manganese in there, just use the stuff. Can that be right?
Should I be breaking up alkaline batteries to find out if the stuff can be a filter? I dunno, but when I get something going, I just might give it a try!
 
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graham-xrf said:
I am thinking a foil from "Aldrich_may_as_well_be_made_of_Unobtainium" is not needed. All we need is some stuff with Manganese in it, the better it does not contain any other metal.

OK - even potassium permanganate might do, but manganese dioxide sounds better.
Apparently several kinds, the stuff is widely used in the alkaline battery industry.
Batteries need "electrolytic manganese dioxide".
Ferrites need "chemical manganese dioxide".
Wikipedia explains how to make it.

Either way - if there is manganese in there, just use the stuff. Can that be right?
Should I be breaking up alkaline batteries to find out if the stuff can be a filter? I dunno, but when I get something going, I just might give it a try!
Click to expand...

You may be on to something. According to information I found here x-rays are generated by inner-shell transitions so it doesn't matter if the metal is in its elemental state or not.

The thickness (and density) of the metal compound will only affect the overall attenuation of the x-rays so you're looking at a balancing act -- overall signal vs peak separation. I believe the paper I referenced in post# 159 was shooting for a ratio of 25:1 to 50:1. With metal foils you can easily calculate the needed thickness from the u/p factor for that particular metal, but it's going to be a trial-and-error thing if you're using a composite like MnO2 in casting resin.

I did find a source of metal powders on ebay here for Mo, Fe, Co and Ni, among others.

Iron through nickel can be electroplated but the choice of a substrate could be an issue. From an availability standpoint, copper would work nicely but it is a pretty good absorber of X-rays. However, I just thought of a substrate that could be the ticket. It's pyrolytic graphite. You can buy it in adhesive-backed sheets from DigiKey for WAY less than moly sheet, and it's electrically conductive! As RJ has pointed out, carbon is quite transparent to x-rays so it won't affect x-rays in the energy range we're interested in. Not to say it might not be problematic to make good thin films with pyro graphite -- electroplating often results in layers that have built-in stress, which will cause the metal to peel off. If the film stays in place long enough to plate it up to the right thickness this isn't necessarily a bad thing, you'd just need to transfer it to a flexible substrate. Peel it off with adhesive-backed tape...and you've got something much like the Goodfellow/Sigma-Aldrich stuff, which has some sort of backing as well.

For working this approach up into a viable analysis tool it also will be necessary to get our hands on some pure elemental standards; or stable and relative nontoxic compounds like MnO2. If folks try the metal powder or pyrolytic graphite approach they already will have the standards they would need.

One negative about the electroplating approach is that it will involve the use of some unpleasant metal compounds in the electroplating baths, and each metal will require its own separate witches brew of chemicals. The powder approach would need a uniform density of metal that's not TOO high -- remember, in the X-ray filter paper they indicated that it only took 25um of copper to do the trick....and the ebay powder vendor didn't specify the particle size of the powders.

I'm an amateur chemistry guy so I'd be inclined to try the electroplating method but others may feel differently.

Although interesting to think about, this aspect is quite a ways down the road (but maybe we now have a crack at a possible roadmap). First we need a few working gamma spectrometers and functional S/W.
 
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