I My cloud chamber didn't make any tracks....

[doggonemess]

Greetings all,

I finally made a cloud chamber using an old aquarium and dry ice. Now, I got the expected result to happen, with a fine mist falling from the top like snow, but didn't see a single particle track. Any ideas why this might be? I have some guesses, but wanted someone with experience to help me troubleshoot.

My guess would be that the volume of the chamber was too large compared to the amount of dry ice used, making the chamber cold, but not cold enough. It could also be that air was entering the chamber, as I could definitely see convection in the mist.

I have a few videos, which I'll try to upload just for fun.

Thanks!
Jamie

 

[doggonemess]

I uploaded a low-res copy of the video here:



The plate at the bottom of the tank is Fiestaware. I figured I'd give myself the best shot I could at 'seeding' the chamber with radiation. It is absolutely the most energetic beta source I have - it makes my Geiger counter go nuts. Still nothing.

Oh, and that's my son singing in the background. At first I thought he was singing "Ode to Joy", but then I think after it might be Star Wars...

 

[Avenir]

Hi!
Have you any luck with your cloud chamber?

 

[doggonemess]

Not my original one, but I found a cool instructable at https://www.instructables.com/id/Peltier-Cooled-Cloud-Chamber/ about how to build a Peltier device cloud chamber and I'm going to try that next. A smaller chamber would probably be more effective anyway.

 

[MRBlizzard]

Maybe there aren't very many cosmic ray particles.
I used a project from Scientific American about 56 years ago. Aluminum sheet and epoxy glue. Coolant was dry ice in methanol, about -40 degrees. You need a very, very bright light.

A speck of Americium from an old smoke detector should provide good alpha tracks.

 

[doggonemess]

It's funny that you mention Americium, as I do have a sample of that. But I have a better sample - Fiestaware. Judging by my Civil Defense radmeter, it should be spitting out beta particles like crazy. I think the problem was my setup. I plan to do much better next time.

 

[Nik_2213]

IIRC, the 'Nuffield' cloud-chamber in our school's physics lab had 'bad hair days' when it would fog okay but not track. We never did figure why...

 

[davenn]

A speck of Americium from an old smoke detector should provide good alpha tracks.

It's funny that you mention Americium, as I do have a sample of that.

but remember that the Americium will have to be inside the chamber
as the alpha particles won't penetrate the glass case and any paths seen
will be very short.

But I have a better sample - Fiestaware

what is that ? never heard of it

Judging by my Civil Defense radmeter, it should be spitting out beta particles like crazy

most radiation detectors respond primarily to gamma particles (rays) tho some will respond to
them, maybe your unit is of that type

 

[StevenWayne]

Geiger counters around Fiestaware (about 14% by weight uranium in the glaze of the depression era orange-red version) catch mostly beta radiation, according to the literature I've seen. I worked in a museum for 3 years with a cloud chamber. It typically took about an hour after startup to start getting good tracks. Chamber also needed periodic maintenance for best results. I think the ethanol (recycled in a museum-class cloud chamber) was picking up moisture from the air, and became ineffective when the water content got excessively high. Lab-grade high-purity ethanol is recommended. Good lighting is also a big issue.

 

[MRBlizzard]

The light source I used was my father's slide projector. The light shines in from the side. Another problem was getting the right amount of water onto the black felt on the bottom of the cloud chamber. (I'm amazed I remember these problems.)