Im Building a Cloud Chamber. (This Post is Still In Progress)

[Patrick]

O.K. looks like I'm going in to this head first.

I've been fascinated with the idea of cloud chambers since I've been seeing more and more of them on You Tube. Though I've known of them since I was a kid, as an adult I guess its time to muddle my way into this branch of science too, hopefully without killing myself.


Here's the background:
Ive seen some good examples and explanations and I've seen some poor ones but the "Cloudy Labs", "Hyperspace Pirate" and "Tech Ingredients" episodes on You Tube were the final motivations that set things in motion.
Those sources can be seen here:

• Cloudy Labs: https://www.youtube.com/@Cloudylabs
• Hyperspace Pirate: https://www.youtube.com/watch?v=-qWQaX8_EDY
• Tech Ingredients: https://www.youtube.com/watch?v=ZlvK5OlGF2A

As I said I've seen many good and poor implementations and I'm going to make some improvements based on my own observations, research and the comments of the previous builders themselves.
So far recurring requirements for success seem to include:

• Lighting
• Cold, -25 C or better
• Viewing angle
• Working volume, type, materials, etc.
• Working volume, composition of the atmosphere
• Addition of a high voltage field to sweep out expired ions. (Version 2)
• The source type, strengths and properties

The design:
The basic design is based on a liquid tight 1/8" glass fish aquarium 9" x 9" x 9". This was chosen to be glass as it is resistant to both ethyl and methyl alcohol and should survive -109 F, it was also cheap at the pet store. There is a thin sheet of steel to act as a cold source of constant temperature painted flat black which sits at the bottom during operation, this will ensure a uniform cold area and good viewing for the camera. It will be contained on an epoxy coated plywood sheet with a liquid tight square base. This square tank will be heavily insulated with foam and will contain the ethyl alcohol-dry ice bath, calculations and experiments have been made that indicate 45 minutes of useful observations can be made. There will be a resistive heating method used to volatilize methyl alcohol below its boiling point at the top of the apparatus from which cooled vapors will drift downward into the chilled active volume. Thermocouples will be placed at appropriate hot and cold locations a thermal camera may be used for troubleshooting. External cameras and lighting will be used for the first attempt, modifications can be made for later attempts if needed. Though any radioactive sources can be studied in such an apparatus I will be using manufactured sealed non-dispersible type.

Lessons Influencing the Overall Project:
post in progress.

The Hazard Matrix:(Weighted for probability and severity)
0 = no Hazard to life or limb, 5 = Potential for great harm or death

• 4 Methyl and Ethyl alcohol vapor - flash fire and/or explosion
• 1 Radioactive sources
• 2 Cryo hazard - Dry ice + Ethyl alcohol, -109 F
• 3 High voltage - if used
• 2 Methyl alcohol - poisonous

The Build:
Im not sure how to add pictures so I guess there going to be attachments. Post in progress


The Procedure:


Radioactive Sources:

• Sodium-22, 5 uCi, Positron / Electron (1.1 MeV Gamma)
• Cesium-137, 5 uCi, Gamma
• Polonium-210, 0.1 uCi, Alpha
• Strontium-90, 0.1 uCi, Beta
• Cobalt-60, 1 uCi, Gamma
• Thullium-204, 1 uCi, Beta

Experiments:
Post in progress

[ZakW]

Nice work, Patrick!

I have been wanting to make one for a long time as well.

I appreciate all of the details and layout of the information.

How are you planning on cooling the base of the tank down? From what I can tell the base is insulated with plywood and foam, how will you cool it via dry ice?

Looking forward to your updates!

-Zak

[Patrick]

How are you planning on cooling the base of the tank down? From what I can tell the base is insulated with plywood and foam, how will you cool it via dry ice?

Yes that liquid tight square area is going to hold dry ice and ethyl alcohol. Experiments have shown -109 F when even modest insulation was used. That epoxy is about 0.060 inches thick and alcohol proof.
I'm hoping to have a first test conducted the weekend of 10/28 - 29, so exactly a week to get all the stuff together and hopefully the sources will arrive... cant do it without those! The real worry is my camera its really noisy despite good lighting and being true 4k, I've got to sort that out too.

I'd like to insert a table but cant figure out our forum's syntax in the toolbar and I'd like to insert pictures in the post itself, so I'm going to sleep and hopefully someone can help me out.

[ZakW]

Yes that liquid tight square area is going to hold dry ice and ethyl alcohol. Experiments have shown -109 F when even modest insulation was used. That epoxy is about 0.060 inches thick and alcohol proof.
I'm hoping to have a first test conducted the weekend of 10/28 - 29, so exactly a week to get all the stuff together and hopefully the sources will arrive... cant do it without those! The real worry is my camera its really noisy despite good lighting and being true 4k, I've got to sort that out too.

Is the dry ice going inside the chamber? I dont think I have seen a cloud chamber constructed that way. I have always seen them cool the base from below which causes the vapor to condense on the cold surface.

[alan sailer]

Looks like you are getting a great start making a chamber.

I found the most interesting thing to view in a cloud chamber is radon gas from the decay of thorium. Injecting the chamber with a syringe containing some of this gas is absolutely fascinating.

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I had some low level thorium ore that I got from a friend. I powdered it and put it into a plastic syringe. A small wad of cotton at the business end of the syringe keeps the powder from escaping. Wait some time to let the radon gas reach equilibrium and inject it into the chamber.

Cheers.

[haversin]

I made a expansion cloud chamber ten years ago. An advantage of the expansion cloud chamber is no dry ice is required and the sensitive volume can have a large vertical dimension which is good for cosmic ray studies. The advantage of a dry ice diffusion cloud chamber is that it's continuously sensitive and fairly simple to construct. Here is a video compilation of a few expansions of the chamber. The head of the pin inside the chamber is coated with radium paint and shows alpha particle tracks.   

[Patrick]

Is the dry ice going inside the chamber? I dont think I have seen a cloud chamber constructed that way. I have always seen them cool the base from below which causes the vapor to condense on the cold surface.

The dry ice and alcohol is outside the working volume, the tank sits inside that square base.

I'm also worried about camera settings, I have a DC-FZ80 but the auto settings are dim and include alot of noisy pixels so I have a week to figure that out.

[Patrick]

And here are the sources !
 
EDIT: I made my first run and it was a disaster 2.5 hours, tried everything not a peep. Im so depressed.

[Patrick]

Here's updated pictures:

[alan sailer]

Keep trying. In my experience with cloud chambers (one cooled by LN2 the other peltier) the my main problem was always getting the chamber properly sealed. Any small leak will allow warm outside air to enter and destroy any possibility of getting tracks.

Are you getting the "rain" of small alcohol mist that signifies that you are getting the proper temperature gradient?

My simplest chamber used a plastic box on top of an aluminum heatsink. I smoothed the open side of the box with sandpaper on a board to get it flat.
The seal to the aluminum heatsink was just a squirt of IPA around the edge. The heatsink was inside another low plastic tray (this was a Styrofoam tray from a discarded package of cut meat) and I just poured the LN2 into the tray. Inside the chamber was the classic black felt pad soaked with IPA.

After you get the chamber working it's worth while to add a HV electrode at the top to erase the trails before they get too diffuse. It really improves the appearance of the whole mess.

Another piece of advice would be to look at some of the super simple cloud chamber designs for student demos. Getting the first chamber to work can be a path to getting your nicer chamber to work.

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Cheers.

[Patrick]

Ok Alan Sailer, I have the alcohol and I'm going to make another run this weekend. I'm also going up to the Lawrence Learning Center tomorrow to video their cloud machine, this way Ill have first hand visual experience on what it looks like.

[alan sailer]

One additional note. Ordinary drugstore alcohol will not work. It has to be pure IPA. I've never tried methanol.

Cheers.

[Patrick]

Ok I have 91% Isopropyl alcohol but I'll buy 99%, I'm going to try to distill what I have.

Bit of a blunder on my part, I have access to The Lawrence Hall of Science, and could have driven 1.4 miles up the hill to see a working one first hand. I have since recorded video and taken pictures of it operating so now I know what to expect. It does have some interesting features. First, it has these "gutters" which are described by others and used often, but also a thin resistive wire runs through it which is a cleaver way to heat it. It has the HV wire feature as well and since it operates through out the day it has a little tube that puts alcohol in continuously drop by drop. Its sounds like it has a Cryo-pump or normal phase change refrigerator in the bottom.

[alan sailer]

Distilling alcohols can be a problem. The initial fraction is pretty pure but as the process goes on there
is less and less separation and no clear transition from alcohol to water.

Since you have some university access I'd go to the chemistry building and plead you case for a bottle
of the pure stuff. It would eliminate one variable.

Cheers.

[Patrick]

Its not the alcohol there are lesson plans that include using Ethyl Alcohol and research papers that describe Methyl Alcohol I've Tried both. I'm not reaching supersaturation and I'm not sure why, the temperature gradient is what I suspect. I'm talking to Hyperspace Pirate on YouTube and I'm just out of ideas. Maybe Ive just made it too tall?