[RCLifeOn] happened to come into possession of some radioactive uranium ore. He thus decided to build a cloud chamber to visualize the products of radioactive decay in a pleasing visual manner.
The construction is fairly straightforward stuff. A 3D-printer build plate was used to heat isopropyl alcohol to a vapor, while a bank of thermoelectric coolers then cool the alcohol down to -30 C to create a dense fog. The build uses a glass chamber with a bank of powerful LEDs to illuminate the fog, making it easier to see the trails from radioactive particles passing through. [RCLifeOn] later used a variety of radioactive sources to deliver a bunch of particles into the chamber for more action, too. He also experimented with blocking particles with a variety of materials.
It’s one of the bigger cloud chambers we’ve seen, and seems to work great. You can build a simple version pretty easily, or you could travel to a local museum or science center if you’re too busy to tackle it at home. Video after the break.
The build relies on a Peltier device to cool a 10 cm square copper plate down to temperatures as low as -30 °C (-22 °F). Isopropyl alcohol is evaporated via warming resistors within the cloud chamber, and then condenses in the cooled area, creating a thin layer of fog. Ionizing radiation that passes through the chamber can then be spotted by the the trails it leaves through the fog. It’s even possible to identify the type of radiation passing through by the type of trail it leaves. Alpha particles leave shorter traces, while more energetic beta particles which are difficult to stop tend to streak further.
It bears noting that if you see a ton of activity in your cloud chamber at home, it might be worth making some enquiries. Some cloud chambers you’ll see in museums and the like use a small radioactive source to generate some excitement for viewers, though. Video after the break.
If you are a science fiction fan, you probably hate the theory of relativity. After all, how can the Enterprise get to a new star system every week if you can’t go faster than the speed of light? [Nick Lucid] wants to set you straight: it is real, and you can prove it to yourself for under $100.
The idea uses muons created in our atmosphere by cosmic rays colliding with gasses in the atmosphere. So how do you detect muons yourself? [Nick] shows you how to do it with a fish tank, dry ice, and rubbing alcohol. If that sounds like a cloud chamber, you aren’t wrong.
A cloud chamber is undeniably cool, but how does it prove relativity? You’ll see several kinds of particles interacting with your cloud chamber, but you can tell which ones are muons by the size and motion of the streaks. The muons don’t last very long. So you’d expect very few muons to make it to the surface of the Earth. But they not only reach the surface but go deep under it, as well.
So how do you explain it? Relatively. The muon experiences its average 2.2 microseconds lifetime in what appears to us to be over 150 microseconds, even if it is moving relatively slowly for a muon. Some muons are faster or live longer, so we see a lot of them hit the Earth every minute of every day. This is due to time dilation and also explains length contraction because the muon moves at a certain speed, yet it appears to go further to us than to the muon.
Coincidentally, we recently discussed this same effect relative to using muons for underground navigation. If you want an easier way to count muons with a computer, you can build a detector for about the same price as the cloud chamber.
[Advanced Tinkering] over on YouTube has some pretty unique content, on subjects of chemistry and physics that are a little more, interesting let’s say — anyone fancy distilling cesium? The subject of this build is the visualization of ionizing radiation tracks, with one of our old favorite physics demonstrators, the venerable cloud chamber. The build video (embedded below,) shows the basic construction and performance of a Peltier effect cooler setup. The system is used to create a layer of supersaturated (and cold) alcohol vapor in which the radiation source or other experiment can be immersed.
Peltier modules are a great solution for moving heat from one surface to another, but they are not terribly efficient at it, especially if you don’t keep the hot side temperature in check. Effectively they are a short-distance heat pump, so you need to dump the hot-side heat elsewhere. The method [Advanced Tinkering] chose here was to use a pair of off-the-shelf water cooling blocks, mounted into a 3D printed plate. The hot side dumps into a pair of fan-cooled radiators. Four double-layer Peltier modules are wired in parallel to a 60A power supply, which seems like a lot, but Peltier modules are hungry little things. A reasonable amount of power is needed to drive the cooling fans and water pump. The vapor source is a simple pad of liquid alcohol at the top of the stack, just above a metal screen which is held at a high voltage. The vertical electric field allows visualization of the charge of emitted particles, which will curve up or down depending on their polarity.
As can be seen from the second video linked below, some really nice cloud trails are produced, so it looks like they got the setup just right!
Have you ever seen a Wilson cloud chamber — a science experiment that lets you visualize ionizing radiation? How hard would it be to build one? If you follow [stoppi’s] example, not hard at all (German, Google Translate link). A plastic bottle. some tape, a flashlight, some water, hot glue, and — the only exotic part — a bit of americium 241. You can see the design in the video below and the page also has some more sophisticated designs including one that uses a CPU cooler. Even if you don’t speak German, the video will be very helpful.
You need to temper your expectations if you build the simple version, but it appears to work. The plastic bottle is a must because you have to squeeze it to get a pressure change in the vessel.
We doubt that few of us ever thought that snow globes contain real snow, but now that we’ve seen a snow globe that makes its own snow, we have to admit the water-filled holiday decorating mainstay looks a little disappointing.
Like a lot of the Christmas decorations [Sean Hodgins] has come up with over the years, this self-frosting snowman is both clever in design and cute in execution. The working end is a piece of aluminum turned down into the classic snowman configuration; the lathe-less could probably do the same thing by sticking some ball bearings together with CA glue. Adorned with 3D-printed accessories, the sculpture sits on a pedestal of Peltier coolers, stacked on top of a big CPU cooler. Flanking the as-yet underdressed snowman is a pair of big power resistors, which serve as heating elements to fill the globe with vapor. [Sean]’s liquid of choice is isopropyl alcohol, and it seems to work very well as the figurine is quickly enrobed with frost.
Cloud chambers are an exciting and highly visual science experiment. They’re fascinating to watch as you can see the passage of subatomic particles from radioactive decay with your very own eyes. Many elect to build small chambers based on thermoelectric Peltier elements, but [Cloudylabs] decided to do something on a grander scale.
[Cloudylabs] started building cloud chambers after first seeing one in a museum back in 2010. The first prototype was an air-cooled Peltier device, with a cooled area of just 4x4cm. Over the years, and after building many more Peltier-based chambers, it became apparent that the thermoelectric modules were somewhat less than robust, often failing after many thermal cycles. Wanting to take things up a notch, [Cloudylabs] elected to build a much larger unit based on phase-change technology, akin to the way a refrigerator works.
The final product is astounding, consisting of a 32x18cm actively cooled area mounted within a large glass viewing case. A magnet is mounted underneath which causes certain particles to curve in relation to the field, as well as an electrically charged grid up top. The chamber is capable of operating for up to 12 hours without requiring any user intervention.