Needing more than a spark test?

[WobblyHand]

But, even if thorium were active enough in terms of decays/second, examination of its decay chain didn't reveal any fissions that result in gamma rays, just alpha and beta particles. But I admit to a very cursory examination of the Wikipedia article on the subject.

RJ's reference shows 59 Kev gamma for thorium 232. There's also 4.081 MeV alphas. When high energy particles slam into objects, as they violently stop, they can give off X-rays. The term is bremsstrahlung. That's how x-ray tubes work. Violent high energy collision of electrons into a target. Edit: not sure if applicable to alphas, lots of references to beta+ and beta-.

 

[WobblyHand]

In view of the fact I have 4.5 litres of 36% hydrogen peroxide kept in a cupboard in a cold and very dark place (cellar) ..
and then I found --> THIS --> How to make thorium dioxide
.. and allowing for the now fairly well known nature of me..
What do you suppose is going to happen next?

Please give serious consideration to not making your abode or surrounds a hazardous waste site. As in think it all though at least 3 times before proceeding. Not telling you to not do it, but, do be careful and think though any waste issues.

 

[graham-xrf]

Please give serious consideration to not making your abode or surrounds a hazardous waste site. As in think it all though at least 3 times before proceeding. Not telling you to not do it, but, do be careful and think though any waste issues.

We think alike!
Definitely the post #669 from @homebrewed is serious real experience that I trust way more than a YT video done to Mozart. Real explanations given, so we know what happens to all the ingredients in there, would have had the ring of truth to it.

Also yes - the right way to do decay rates is by using the proper equations. It's an asymptotic exponential relationship.
---
For Mark: Regarding whether the energy is alpha, beta, or gamma, I also need to get it clear in the mind what happens. I do know that these decays are accompanied by energy release, and here we get to, "the particle has got mass, so how come it behaves like a wave stuff"? Which is it?

We can see from measured spectra in #660 that there is high energy release all over the place, with the big fat 239keV gamma coming from the Pb212 Beta decay near the end of the chain. The half-life of that lead is only 10.6 hours. The Bismuth half-life is only 61 minutes, also by Beta decay. The Polonium it makes loses half in 30 microseconds, by Alpha decay.

Consider the Am241. Most of it's decay is by Alpha.
So what is that 59.5keV Gamma all about? Is it in the momentum of the Helium nuclei?
As I understand it, it is the same as one gets in all radioactive processes. You add up the masses of what you started with. You add up the masses of all the stuff you ended up with. You subtract to find the mass that has "disappeared", and refer to Mr Einstein's contribution to figure out how much energy that was. The alpha particle can't even penetrate a piece of paper. But the process that accompanied it's creation releases electromagnetic radiation.

The other thing people should appreciate is that the wastes with incredibly long half-lives are usually not the dangerous ones. You can normally handle them, or their ores, so long as you don't eat them, or get their dust in your lungs. It is the daughter products with the short half-lives that are incredibly, dangerously, radioactive!

 

[WobblyHand]

Interestingly, Th232 also gives off a 59.0 keV gamma, at least according to the the pdf handbook.

 

[homebrewed]

Back to my concerns that I got some defective smoke detector sources, I used my detector plus the preexisting lead aperture plate to check a few of them They all appear to generate about the same number of counts/second so the sources are a mix of slightly different designs.

No need to build a separate radiation detector.

Now I have to think about whether to pull them off my now-deprecated source plate, trim and re-install; or just buy more sources and use them. I used cheap 2-part epoxy to glue the sources down, which will soften if heated up to a couple hundred degrees C. I don't have a hot plate but I do have a heat gun that should do the job.

 

[graham-xrf]

Back to my concerns that I got some defective smoke detector sources, I used my detector plus the preexisting lead aperture plate to check a few of them They all appear to generate about the same number of counts/second so the sources are a mix of slightly different designs.

No need to build a separate radiation detector.

Now I have to think about whether to pull them off my now-deprecated source plate, trim and re-install; or just buy more sources and use them. I used cheap 2-part epoxy to glue the sources down, which will soften if heated up to a couple hundred degrees C. I don't have a hot plate but I do have a heat gun that should do the job.

Epoxy stuff of all natures will yield to methylene chloride, also called dichloromethane, the ingredient in the more effective kind of industrial paint strippers. I got a can from eBay. The liquid is not so available anymore, apparently in the same class as carbon tetrachloride.

It does not seem to work as a solvent, rather, it seems to break the bonds that let the epoxy hold itself together. I put an image intensifier potted unit containing the 6kV high voltage multiplier components into a drinks glass, poured in C2H4Cl2 , covered with a metal sheet. I left it a couple of days. The epoxy became like yellow flakes and powdery chunks, all the way into the middle.
I think the middle of the sources are an incredibly thin sheet of oxide sintered onto a metal foil, with other stuff overlaid. The little circles are punched out and fixed into the metal discs.

I think they should survive some heat, but you might test one with some paint stripper to see if it lets go.

 

[homebrewed]

I used my heat gun and once the aperture plate got hot enough they came off pretty easily.

Examination of one of the sources revealed a plain raised disk on the opposite side of the Am241-impregnated foil. I saw a little gap between the larger carrier and disk, so I got an X-acto blade in between them and was able to pop the disk off, intact. So it's not necessary to cut or grind away anything in order to get the smaller source disk off the carrier.

I checked the carrier with my detector and it did not pick up any counts above background.

Here's a photo showing the two pieces, source on the left and carrier on the right.. My little point-and-shoot doesn't take good closeups so I set up my tripod and took the photo through one of the eyepieces of my stereomicroscope. It's a little finicky to set up but works OK.

 

[graham-xrf]

There are three outer peenings (swagings?) that held the source into the contact ring.
There are 5 pressings to hold the source onto the inner carrier, looking as if missing a sixth.
That part is small enough that you will be able to put them lots closer, and have a more intense irradiation, and bigger counts.

On mine, the 3 peenings to the contact ring were so pressed over, they were never going to just bend away. I also tried a blade. In the end, I just carefully filed the overhang on them away, to make it possible to pop them free of the contact carrier. At the time, my fooling with a blade (Swann-Morton 25) had it snap, and things slipped, and there was blood!

Also, it took a major tidy-up to find where the Am241 source ended up (floor)!

I am thinking that with the close-up design, maybe you don't need all eight of them. Maybe six is enough.

---------
I am now getting back to my amplifier and ADC. I am disappointed that the (powerful) little Raspberry Pi Zero 2W is just sold out from all outlets until April. I can use my Pi4 for development, but the £11.50 board has it's attractions. It has the grunt to do the computing, drive it's own display, or do Wi-Fi, or Bluetooth, or USB to a computer or a smartphone.

Buy a Raspberry Pi Zero 2 W – Raspberry Pi

Your tiny, tiny $15 computer

www.raspberrypi.com

It seems all Pis have been in shortage since back in 2020, and now, despite making millions of them, the Raspberry Pi Zero 2W is almost always sold out. It's not just about supply chain holdups. It's basically driven by ever expanding demand.

 

[homebrewed]

I measured the "core" and it came to exactly .25"/6.4mm in diameter. If they are tilted at a 45 degree angle, the "focus ring" has to be .177"/4.5mm high.

I'll use this information to come up with my final (sorta, kinda) focus ring+shield ring layout. I'd been using .200" for the pared-down source diameter so my bits will need to be changed a little.

 

[homebrewed]

There are three outer peenings (swagings?) that held the source into the contact ring.
There are 5 pressings to hold the source onto the inner carrier, looking as if missing a sixth.
That part is small enough that you will be able to put them lots closer, and have a more intense irradiation, and bigger counts.

On mine, the 3 peenings to the contact ring were so pressed over, they were never going to just bend away. I also tried a blade. In the end, I just carefully filed the overhang on them away, to make it possible to pop them free of the contact carrier. At the time, my fooling with a blade (Swann-Morton 25) had it snap, and things slipped, and there was blood!

Also, it took a major tidy-up to find where the Am241 source ended up (floor)!

I am thinking that with the close-up design, maybe you don't need all eight of them. Maybe six is enough.

---------
I am now getting back to my amplifier and ADC. I am disappointed that the (powerful) little Raspberry Pi Zero 2W is just sold out from all outlets until April. I can use my Pi4 for development, but the £11.50 board has it's attractions. It has the grunt to do the computing, drive it's own display, or do Wi-Fi, or Bluetooth, or USB to a computer or a smartphone.

Buy a Raspberry Pi Zero 2 W – Raspberry Pi

Your tiny, tiny $15 computer

www.raspberrypi.com

It seems all Pis have been in shortage since back in 2020, and now, despite making millions of them, the Raspberry Pi Zero 2W is almost always sold out. It's not just about supply chain holdups. It's basically driven by ever expanding demand.

Oops! Sorry to learn that the project has now earned one of the badges of "blood, sweat and tears". Too bad that saying bad words doesn't count!

Thanks for sharing your experience. It sounds like I should expect some recalcitrant sources.

BTW, when I did it I held the carrier with tweezers so my fingers were safely out of range. Needle-nosed pliers probably would work better.