Cloud Chamber

[reubenthorpe1992]

does the ionizer supply the 7.5 kv supply how is it attached via a bolt? btw would a flyback transformer of 7kv be ok

[nkip9230]

I also wanted to ask- was it difficult getting source out of the Smoke Detector?

[nkip9230]

Can you still do this while not taking apart a lot of the smoke detector? Im not to sure how my school would feel about a radioactive source that is highly exposed.

[skonkfactory]

@nkip9230 No. Alpha particles don't go through the body of the smoke detector. (In fact, they won't even go through the dead outer layer of your skin- alpha emitters are only dangerous if inhaled or ingested.)

If your school is very worried about such things, you could buy a small piece of uranium ore from United Nuclear, or maybe a TIG welding electrode (some contain thorium, which is mildly radioactive).

[nkip9230]

@skonkfactory I completely forgot about that with Alpha Particles. And considering that they Americium will be in the container....

Im going to see what my physics teacher says. Do you think your design is large enough to catch Cosmic Rays?

[skonkfactory]

@nkip9230 Yes, it catches cosmic rays quite nicely. Most of the tracks in the video are from cosmic rays.

[onthecuttingedge2005]

could you take a piece of glow in the dark material and place it over the 241Americium to see if it excites the Phosphor and causes it to self illuminate, I want to see if alpha is better than beta to self illuminate a glow in the dark object or phosphorescent compound

[skonkfactory]

Why don't you spend the $10 on a smoke detector and try it yourself?

[kpshc707]

Yes you can but you will need something to magnify it so you can see it unless its a really powerful alpha emitter. i know activated zinc sulfide glows but only from alpha particles.

[vmelkon]

@onthecuttingedge2005 I've tried it with the white powder from fluorescent tubes and it works but the glow is weak.

[alidab34r]

Hey - why did you need to apply electricity to drop dust out of the air? I was looking this up on Wikipedia and following links around, and I didn't see references to this step (then again, it also didn't explain why the ions act as cloud condensation nuclei. I suspect it is get-a-book-from-the-library time.)

This is a seriously awesome project :D

[skonkfactory]

You don't need to- the chamber will settle on its own after about a half hour or so, but this is quicker. You also get to see cool ion streamer patterns.

[polonium9]

ooooooh a radioactive bagel! the new way to get Tc99m into the body! without needles! just kidding, i do like those huge alpha trails in the beginning!

[JohnQP]

I'm not too clear on what the conditions are inside the chamber.. (I really should look this up and embiggen my mind in this area), but assuming that it is not *too* hostile, have you got a camera you could put inside the chamber for the next round? Maybe some cheapo webcam?

[skonkfactory]

The chamber contains air with a supersaturated alcohol vapour that constantly rains from the pad at the top. It's not a great place for lenses or most plastics. Fortunately, polycarbonate doesn't dissolve in isopropanol.

[jayjomofro]

What's with the half eaten bagel?

[skonkfactory]

That's the radioactive source from a smoke detector. Does not taste good with cream cheese.

[skonkfactory]

By my calculation, the range of a 5.5 MeV alpha particle in the cloud chamber is about 3.7 cm; the disc containing the source is 2.8 cm in diameter, for scale. The source is a 1 uCi 241Am gold bonded dot.

The average length of trails from the source is about 1.8 cm; many end in fuzzy blobs as presumably the alpha particle loses energy and fails to make forward progress. You can't see the short ones because the source is embedded in a shiny disc that is too bright for the camera.

[JohnQP]

Some of it is clearly coming from the source.. and some is clearly just background.. but there is a lot that is hard to tell.

Do you get many (any?) trails without the source in place?

[skonkfactory]

Yes. All the trails further from the source than about 3 cm are from background, including the rather spectacular "oh hey some energetic neutral particle just hit a nucleus and SMASHED it" one I annotated.

The source actually makes a lot more trails than you can see in the video but it's difficult to get a good angle on them. We're going to try again with a better light source and more viewing ports and see if we can do a little better.

[mophead6912]

Cool experiment!!

[skonkfactory]

This looks much better in HD, by the way.

[fmhtonight]

sweet!!!!