Cloud Chamber Building for 9th Grader: Dry Ice vs. Peltier Cooler

[Thundagere]

Something a recent obsession has taken me into, I'm attempting to build a cloud chamber, for fun and to observe some particles in action. As a 9th grader, I'm somewhat limited in supplies. Thus, I'm wondering, if I built a cloud chamber, would it be better to use dry ice, or use a peltier cooler based chamber? There's an ice cream shop nearby but I'm not sure if they'd be willing to sell me dry ice, not least because of liability issues.

 

[cragar]

Ive seen cloud chambers that just used circulating ice water. They had ice water in a cooler and then a pump that circulated the water around the base and back into the cooler. And then you wet the inside of the chamber walls with alcohol. I think you have to be 18 to buy dry ice, so you would need someone to buy it for you. What will be your radioactive source?

 

[Vanadium 50]

Let me say again (and again, and again, ...) you do not need a radioactive source. You can see cosmic rays just fine in a cloud chamber.

 

[sophiecentaur]

Ive seen cloud chambers that just used circulating ice water. They had ice water in a cooler and then a pump that circulated the water around the base and back into the cooler. And then you wet the inside of the chamber walls with alcohol. I think you have to be 18 to buy dry ice, so you would need someone to buy it for you. What will be your radioactive source?

Wouldn't 'cold ice', directly out of the freezer, at -22C be better than iced water?

@Vanadium: How frequent are the tracks from cosmic rays likely to be observed? One per second / one per minute ? A cloud chamber is such an easy thing to build and it would be an excellent Christmas Demo for restless kids if they didn't have to wait for long.

 

[Thundagere]

I realize that I can view cosmic rays—however, I'm mostly building this for the experience. I have no plans to throw a chunk of uranium in there :). If I happen to see some Fiestaware...maybe, but that's not the main purpose.
Back on the Peltier method, I found a few good deals for Peltier coolers, and I think I can obtain a heat sink computer fan fairly easily. I'm leaning towards this method as I think it'll teach me how to apply the basic physics I've learned as of yet. I'm going to need some sort of adhesive, which I think I can get.
My main question is the power source. Looking at computer fans, I think I need a 12V power source. That would also power one of my peltier coolers, so then I have one left for 5V or so. I could buy two separate power sources, but I was actually thinking of using an ATX power source, which I think has both 5V and 12 V slots. Am I mistaken? Any ideas on where to get a cheap one?
And also, would it be cheaper to use 2 peltier coolers and 2 power sources (or one ATX), or 1 dual peltier cooler (about 45 dollars) and 1 12V power source? I suppose it depends on the ATX power source, but I'm not sure which way to go now...
The other option I was considering was taking a power adaptor off the wall socket, ripping off the plastic covering, and making a simple transformer, with 6 coils on the primary and 55 on the secondary. If I'm not wrong, that would convert 110 V to 12 V, which I could then connect to the peltier cooler. Similar process for the 5 V (1 coil on primary, 22 on secondary).

EDIT: Concerning he circulating ice water idea—I don't think that'll work without some amount of pressure. Water freezes at 1 degree celsius, and IIRC, the temperature for a successful cloud chamber is about -15 degrees fahrenheit. Converting this results in

C = (-15-32)(5/9)
= -26.11 degrees celsius.
Cold ice isn't at the right temperature and would tend to become warmer as time progresses. Furthermore, the ice water would need to be pressurized, or at that temperature it would freeze and cause issues. I'm not that good with pneumatics and pressure and such, hence why I'm angled towards peltier coolers.

 

[Vanadium 50]

The way I remember the flux is that one cosmic ray goes through your head every second.

 

[Thundagere]

Any ideas on advice as to cheapen this? I'm looking for specifics on where I might be able to get an ATX power supply with dual voltage 5V and 12V, as well as opinions on a 42 dollar dual stage peltier cooler.

 

[cragar]

Wouldn't 'cold ice', directly out of the freezer, at -22C be better than iced water?

Ya probably, but I've seen them with ice water and they worked.

 

[Thundagere]

I've been looking at some diagrams i found of the ice water ones, it seems that they have to be further cooled with a peltier device...so either way I'm buying a peltier cooler. :)