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Simple expansion cloud chamber

Visualize the paths taken by ionizing alpha particles

Yeah, atom physics find one's way into LMR. Here is my simple expansion cloud chamber. An expansion cloud chamber works by saturating the air in a chamber with water or isopropyl alcohol vapour. Dropping the pressure in the chamber suddenly, causes super-saturation. Cloud will form wherever electric charges are. Unwanted charges in the chamber are eliminated by an electrostatic clearing field. Alcohol droplets then forms on the tracks of charge recently left by ionizing alpha particles. An advantage of the expansion cloud chamber is, that you don't need try ice like for a diffusion cloud chamber.

The alpha particle source is again Am241 from a dismantled ionization smoke detector. The HV generator to produce the electrostatic clearing field is the same as for my oxy-hydrogen cannon.

The photographs below show typical alpha particle tracks. The tracks are displaced from the original paths by the air flow during expansion. The tracks only last for a fraction of a second, so I converted the recorded video into individual frames.

Things I have learned:

  • Water, methyl alcohol, ethyl alcohol work also but isopropyl alcohol is best
  • The syringe for expansion should be as big as possible (100 ml glass syringe)
  • I got the best results in compressing the air in the chamber first by the syringe, putting the squeezed rubber hose from the syringe and open then the hose suddenly to release the overpressure
  • The felt I used on the metal platform is not really felt. It is a piece of cloth from an old laptop bag. It sop up the isopropyl alcohol very well, but it has a kind of structure which produces unintended light reflections. Fine black felt would be better
  • The required voltage for the electrostatic clearing field is not problematic, works in a wide range

This guy here also built an expansion cloud chamber as well as other amazing stuff.

I'll try to upload a video within today or tomorrow.

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Hi Markus, do you know if these particles move on or are they just being absorbed really fast? I was just wondering, you made me thinking about particles and radiation. Since I'm building that lamp and there's general consensus that the perfect reef lamp still doesn't exist (they're close) I looked at many of them. Then you came along with radiation and ionizing particles.

I'm probably thinking silly now (hey thats me), these ionizing particles are stuffed with energy. The best reef lamps so far are probably HQI, power hungry monsters. So I'm just guessing that there's quite a bit of high powered particles hitting the tank from these lamps. You can get them in like small bulbs of 200watts. I already found out that other light systems are not that good yet, T5 lights seem to be second best when taking about stuff with lower power consumption. These things emit lots of light in the uv spectrum, these also seem to be ionizing particles. Correct me if I'm wrong please.

Then there is the thing that a certain level of radiation/ionizing particles is benificial to life. (maybe even more so for sun loving corals)

So just for an experiment I was wondering if this could work on a watertank.

I think I'm starting to understand the use of your cloud chamber to :)

Hi Dutchbot,

A cloud chamber is a detector for ionizing radiation. Am241 emits above all alpha particles. Alpha particles are Helium atoms. Due to their "heavy mass" the range is small --- about 10 cm in air. They will be stopped by a piece of paper.

If you ask me if UV light are particle, then it getting complicated and we have to dive into the world of quantum mechanics. Light behaves sometimes like a particle, sometimes like a wave. Physicists call this Wave–particle duality.

I don't see any possibility to use radioactivity to power your tank. And I don't think you want to power your tank by a Radioisotope thermoelectric generator.

Where you get your haircut from, btw? :D

I would love to have a radioisotope thermoelectric generator! Just to see how corals would react on being nuked (which pretty much happens under a tropical sun). So not for powering the actual aquarium.

I stopped getting haircuts after 3 years in Bosnia breathing in Nato issued depleted uranium :)

I just went wikipedia and found out 2 things. I know now where you got your haircut since it contains radio active stuff ;). And the other thing is I don't have a clue what you would use it for? Can you identify parts by their paths or do you just get to know if they are arround?

Sorry m8, my knowledge about nuclear physics stops at depleted uranium and haircuts ;)

i am always get new idea from your post.

This sounds very cool, can't wait for the video!

Thanks, OB, video is up