[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.
By stacking several Peltier coolers in a cascade, it’s possible to increase the temperature differential generated. In this design, the copper plate of the chamber is cooled down to -33 degrees Fahrenheit (-36.11 Celcius), more than cold enough for the experiment to work. Alcohol is added to the glass chamber, and when it reaches the cold plate, it creates a super-saturated vapor. When disturbed by charged particles zipping out of a radioactive source, the vapor condenses, leaving a visible trail.
Cloud chambers are a popular experiment to try at home. It’s a great science fair project, and one that can be easily constructed with old computer parts and a couple of cheap modules from eBay. Just be careful when experimenting with radioactive sources. Video after the break.
Remember when a homemade cloud chamber was a science fair staple? We haven’t participated for decades, but it seemed like every year someone would put a hunk of dry ice in a fish tank, add a little alcohol, and with the lighting just right – which it never was in the gymnasium – you might be lucky enough to see a few contrails in the supersaturated vapor as the occasional stray bit of background radiation whizzed through the apparatus.
Done right, the classic cloud chamber is a great demonstration, but stocking enough dry ice to keep the fun going is a bit of a drag. That’s where this Peltier-cooled cloud chamber comes into its own. [mosivers] spares no expense at making a more permanent, turn-key cloud chamber, which is perched atop a laser-cut acrylic case. Inside that is an ATX power supply which runs a Peltier thermoelectric cooling module. Coupled with a CPU cooler, the TEC is able to drive the chamber temperature down to a chilly -42°C, with a strip of white LEDs providing the required side-lighting. The video below gives a tour of the machine and shows a few traces from a chunk of pitchblende; it’s all pretty tame until [mosivers] turns on his special modification – a high-voltage grid powered by a scrapped electronic fly swatter. That really kicks up the action, and even lets thoriated TIG welding electrodes be used as a decent source of alpha particles.
When Marie and Pierre Curie discovered the natural radioactive elements polonium and radium, they did something truly remarkable– they uncovered an entirely new property of matter. The Curies’ work was the key to unlocking the mysteries of the atom, which was previously thought to be indivisible. Their research opened the door to nuclear medicine and clean energy, and it also led to the development of nuclear weapons.
Irène Joliot-Curie, her husband Frédéric, and many of their contemporaries were completely against the use of nuclear science as a weapon. They risked their lives to guard their work from governments hell-bent on destruction, and most of them, Irène included, ultimately sacrificed their health and longevity for the good of society. Continue reading “Irène Joliot-Curie And Artificial Radioactivity”→