Peltier Cloud Chamber

DIY cloud chamber using a beefy CPU cooler and a single Peltier module too see ionizing radiation with your own eyes!

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This cloud chamber is based on a standard dual-tower CPU cooler and a TEC2-25408 Peltier cooler. The Peltier cools down the 10 x 10 cm copper plate on top to less than -30°C so that the Isopropyl alcohol evaporating above condenses at the base, creating a thin fog layer. Ionizing radiation can then fly through this alcohol vapor and with some luck create a visible cloudy trace.

Trace thickness and length depends on the type of radiation: thin and long traces come from beta radiation and thicker as well as shorter traces are a sign of alpha particles.

Short demo video:

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  • 1 × TEC2-25408
  • 1 × Thermalright Peerless Assassin 120 CPU cooler
  • 1 × 100 x 100 x 2mm copper plate
  • 1 × Bell jar or glas cylinder
  • 1 × Sheet of acrylic

View all 9 components

  • New Video (more action!)

    NuclearPhoenix01/05/2024 at 18:22 0 comments

    I tried the cloud chamber with a small piece of thorianite today, look for yourself:

  • Improved Cloud Chamber

    NuclearPhoenix08/06/2023 at 14:57 0 comments

    Here's a small update, I stuck a little more PE tape to the glass around the LEDs so that the light doesn't dazzle so much. I also stapled a few resistors between the two layers of felt and attached them to the 12 volt rail of the power supply. This definitely allows you to see a lot more (especially on camera) now, so thanks for all the suggestions!

    What is still missing is an extraction voltage of a couple hundred to maybe a thousand volts to extract all the extra electrons that are left over after the ionisation. That'll definitely help with visibility/contrast of the traces and how long it takes for them to clear up again. But I don't know if I'll do that yet. For this I would have to build a large frame inside the glass jar and get an high-voltage PSU module.

View all 2 project logs

  • 1
    Mount Peltier to cooler

    Put some thermal paste on the CPU cooler, where the processor would normally sit. Then mount the Peltier module onto it, so that most of the area is covered.

  • 2
    Prepare the copper plate

    Cut the copper plate into a size of around 10 x 10 centimeters. Then drill four holes into the copper that match the location for the mounting screws of the CPU cooler mount.

  • 3
    Insulate the copper

    Put some PE insulation tape on the bottom of the copper plate around the location where the peltier element will sit.

View all 12 instructions

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j wrote 08/04/2023 at 08:55 point

What a wonderful detector! It looks like a very clean build.

If you cover the LEDs from the top, so they shine only in the middle, your eyes (and camera) sees more contrast of the traces. If you need even more light i used a strong laser (green) as line laser (shining it sideways through a LED)

best wishes, j

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NuclearPhoenix wrote 08/04/2023 at 09:20 point

Hi there, that's a really good suggestion actually! Don't know why I didn't think of that, so... thanks! :D

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