Nuclear Cloud Chamber With No Dry Ice

Nuclear Cloud Chamber With No Dry Ice

An hour of putting stuff together and glopping thermal paste yielded a nuclear cloud chamber that doesn't need dry ice!

The wine goblet is filled with 99% isopropyl (rubbing) alcohol which gets supercooled and turns into a fog in the the glass goblet. Then you can see alpha, beta, gamma and muon tracks zipping through the fog: visible radiation! I have various radioactive sample sources, plus if you put no radioactive stuff in the chamber every 3 or 3 minutes you'll see a particle zing through and that'll be the result of a cosmic ray interaction: a muon!

My other nuclear cloud chamber is MUCH simpler: an upside down aquarium resting on a metal plate that sits on top of a block of dry ice. I want to eventually bring this into work (I'm a librarian) and while the radioactive stuff is safe (unless you swallow it) the dry ice is just annoying to deal with after the awesomeness of it gets old: it's cold, melts (well, sublimates), will explode any container it gets sealed it, burns, little kids want to touch it...all not so great for a science demonstration. Plus the only place that sells it is the Walmart that's like 15 minute drive. With this design I just plug it into a wall outlet and dump in a little rubbing alcohol: bam! Coldness.


Contrary to what the internet says, my Peltier Coolers have their hot side on the printed logo side. I hooked a 9v battery up to them for less than 2seconds to be able to feel and mark the cold side.

Arctic 5 thermal paste works at very low temperatures. I didn't even finish the first teeny, tiny tube.

A lump of AM-241 getting a pure alcohol shower.

Starting top to bottom:

Glass wine goblet

Rubber gasket

Piece of thin plexiglass

Arctic 5 thermal paste

Peltier 12709 thermal electric cooler

Arctic 5 thermal paste

Peltier 12710 thermal electric cooler

Arctic 5 thermal paste

Cooler Master 212x dual fan (upside down)


Atx computer supply which provides: 12vdc, 5vdc and a shared ground.


Both fans and the bottom Peltier 12710 go to the 12vdc and the ground.

The top Peltier 12709 goes to the 5vdc and the same ground.

I used the ATX power supply I converted to a bench power supply a few posts ago because it has the two voltages I needed along with (most importantly) lots of amps! Wall wart power plugs can easily be found to give 5v and 12v but not at the large amount of amps. Wall warts usually max out at 1 or 2 amps but the Peltier Coolers take up to 10 amps! The ATX can provide 12vdc at a monstrous 28 amps.

How does it do? Here some video:

Note the curly particle tracks! In my dry ice nuclear cloud chamber I get lots of boring, straight and short alpha tracks-not these awesome whirly curlies.

Here's a video of the whole setup:

I thought it wasn't working until I moved the flashlight way far away. This probably collimated (narrowed and focused) the light beam. My dry ice chamber is foggy, but this electrically cooled chamber rains down the alcohol!

I'm happy it works. I'm happy it shows different types of tracks than my other chamber. Just add a piece of radioactive material, 99% rubbing alcohol and plug it in.




The Cooler Master 212X Fan and Heat Sink Unit

It came with 2 fans. One fan was already attached. The other fan I needed to: attach two plastic brackets with 4 screws and then just plunk it on the other side. You get TWO little rubber pads that you must cut and make into FOUR rubber pads. You then stick these on the 4 screws OR ELSE THE FAN YOU INSTALLED WILL SLIDE RIGHT OFF THE FINS AND FALL ON THE FLOOR! For most applications that doesn't matter at all and if your fan might hit your RAM or something else leave them off and you can easily slide the fan up a little for extra clearance. However, since I'm making a mobile nuclear cloud chamber I put the four pads on--just the like the first pre-installed fan.

On the edges of the square fan bodies you will find arrows: one shows the direction of spin, the other shows the exhaust side of the fan. One fan should have it's arrow pointing toward the fins (intake/push) and the other facing away from the unit (exhaust/pull).

They included a TON of brackets, a cool sort of socket thingy to turn your phillip's head screwdriver into a hexonal computer board stand off wrench-thingy, rubber sticky pads and thermal paste. The thermal paste is fine, but since I'm trying to freeze isopropanol (and started at room temperature and not a hot computer) I needed a paste that could work closer to -50 C, so I just squirted some Arctic 5 thermal paste (and NOT the thermal EPOXY which will never come off). Let me repeat that: SOME Arctic 5 is paste and some is on-forever-epoxy.Get the paste.

How do you apply the thermal paste? If your application is round use the pea-shaped blob in the center and smoosh. If it's a square/rectangle use a spreader. On test after test on YouTube it really didn't matter. In my application my cold plate is plexiglas and I can SEE the thermal paste from the top-side of the chamber and had to use the spreader method (old credit card) to get it looking nice. Smoosh method and "hope" it's everywhere (it won't be) or spreader and "know" it's everywhere. LOL!

This is underneath two Peltier cooler tiles > plexiglas cold plate >rubber gasket and a big old wine goblet. Most of the aforementioned pieces are coupled with thermal paste. Power comes from an ATX computer power supply I made into a bench top power unit a while ago.

So, how is this unit itself? HUGE, tall, incredibly well finished on the cooling block. I just spun both fans up with a 9 volt battery and they: spun so fast I couldn't see them and were dead silent!


The Two Peltier Coolers

I'm using two different Peltier Coolers (12709 & 12710) stacked to make the cooling portion of a Nuclear Cloud Chamber. This replaces the dry ice. The more powerful 12710 goes on the bottom, touching the Cooler Master 212X.

As a test I briefly hooked each to a 9volt battery. In less than a second, with the red wire going to the positive post on the battery the coolers became almost painfully cold one one side and warm on the other. The Cold side was the one with the model number printed on it.

Do not run these for more than a second without them being mounted to a heatsink with fans using thermal paste or else you'll ruin them.

Arctic 5 thermal paste is a popular choice. These can get down to -50C° and some thermal pastes only go down to -20C°. I'm starting with room temperature 99% isopropyl alcohol so I might actually get close to that bottom temp... The online spec sheets specify the Tmax Delta (how many degrees it'll cool from your starting temperature).


The Rubber Mat (LASCO 02-1048E Rubber Sheet, 6X6-Inch and 1/16-Inch Thick)

This is creating a seal between the cold plate (which is sitting on top of two Peltier cooler tiles) and a big old wine goblet. This rubber was REAL rubber. Good feel and that new car tire smell. I was able to easily cut it with a pair of scissors.

The sheet was really "floppy" and could conform to curves if needed. You could easily roll this up and line the inside of a coffee mug or something. Not sure why you'd want to do that, but it'd take zero effort: nice and bendy.

The only bad thing was that at the center of one edge was a retail hanger tag, the kind with the hole in it to hang off of metal rods in a store. It was STAPLED to the rubber sheet. Just a regular old small staple, and for my purposes it made no difference. Even if I were pulling a strong vacuum (which I'm not) the two staple holes would probably seal themselves up, plus they're at the extreme edge so it wouldn't matter anyway.

Well, that's about all the comments I can muster on a boring old piece of rubber, lol.



The Wrap Up

I get most of my supplies from Amazon. Some stuff I find in eBay and the Disabled American Vets' (DAV) resale shop up the street (just like a Salvation Army store). Many things I find in the trash. Except for my fusor build, which got me into the Plasma Club on fusor.net, I rarely buy things from actual industrial/scientific suppliers. 

So, this project had some cool benefits: no dry ice, I got to see particles I never saw in my other cloud chamber, I got to use my ATX power supply for something finally. It was fun. It can travel/be set up without any dry ice.

On the downside: It's a much smaller chamber and harder to see what's going on. My fish-tank and dry ice nuclear cloud chamber can be viewed by an entire classroom. This chamber is probably only for a single person (holding a flashlight in a dark room) at a time. It's sort of fiddly: you have to hold the flashlight away at arms length and sort of tilt your head and squint and work to see it.

I tilted my head...but I can't hold the flashlight good. Meow!

The Power of Cold (and Hot) II: Thermoelectric Generator

The Power of Cold (and Hot) II: Thermoelectric Generator

A few posts ago (The Power of Cold and Hot) we looked at a Stirling Engine, which converted temperature differences into pressure and fast movement.

Now we are going to make a thermoelectric generator (and a thermosistor).

A thermoelectric generator converts temperature differences into electric voltage.

Two copper wires heated until they are crusted with cuprous and cupric oxide.

When touching, the wires are pressure sensitive and heat sensitive where they meet (pressure and heat at the junction cause Ohm resistance to drop). This is a thermosistor: resistance varies with temperature.

Heating only one wire causes Voltage to be produced. This is a thermoelectric generator / thermocouple. With only a butane barbeque lighter I can produce a consistent -5.2 mV (millivolt) when I apply ice to the other wire.

The weird thing is that the eV (electron Volt) work function is 5.2-5.6eV for cupric oxide and 4.8-4.9eV for cuprous oxide. Coincidence? Yeah, probaby...

Store bought thermocouples for home appliances produce 25-30 mV with 30mV being the norm.

I've looked at the work of Nyle Steiner who is a real whiz in many areas of electronics. Here's how I built my version:

Copper wire of equal lengths.

Wood disk and mounting screws.

Heating with a propane torch. It's hard to see here but the blue flame of the torch turns green after passing the copper wires.

Below you can see the scale left after heating. Red is Cu2O which is cuprous oxide (Copper I). Black is CuO which is the cupric oxide (Copper II). These oxides are used in semiconductors.

With two copper wires the hot wire output is negative voltage and the cooler wire is positive.  Nyle Steiner hooked 16 of these wires together and heated them. The result was enough voltage to light up and LED! 

Simple thermocouples like this are used to measure temperature in appliances: different voltages equal different temperatures. This is because temperature gradients produce an electromotive force (emf).

Here's a picture of my new Pyrometer (like a thermometer but for surface temperature). It can read up to 800° F and takes no batteries since the operating voltage comes from the physics we're discussing in this post.

Thermometers measure temperature. Pyrometers measure surface temperature. My pyrometer has a blunt tip for placing near the exterior surfaces of things that are very, very hot. Most thermometers are pointy for jabbing into things for interior readings: into a roasting Thanksgiving turkey, into container of boiling liquid, into your mouth, etc.

Newer pyrometers use infrared, lasery thingies that can tell you if the outside of your turkey is too hot from the other side of the kitchen! Here's a photo of mine:

Of course that's pretty useless since you want to measure the inside of the turkey. The problem is that thermometers need to touch what they're measuring, which is fine for normal things but not great touching something that is 800° F or way hotter like smelting metal! Because they don't have to make physical contact you can use a pyrometer to measure the temperature of a moving object, like a stream turbine.

Nowadays pyrometers also have probes for jabbing into things, so the lines are blurring even more. Thermometers generally are more delicate, require contact and can't handle high temperatures.

These sunny-side-up-eggs are starting to burn!

My pyrometer above is made by West Instruments, another company that makes this sort of thing is Borg. Yes, the same Borg from Star Track, or was is Star War? Anyway, BorgWarnet makes stuff for kitchen ovens, which is where I got the circuit board below, although the sensing portions and timer were probably made by Diehl. I think they're the same Borg that makes turbochargers for Detroit Diesel up the street.


...anyway, back to metal thermocouples:

With wires of two different materials, copper and steel for example, you create a closed loop thermocouple that is very similar to our Sterling Engine...but with electromagnetic waves!

All you have to do is solder the two ends of the copper and steel wire together. Then apply heat to one of the solder joints. The greater the temperature differential-the more mV it will produce. Since it's a closed loop of (two) wire there are no "ends" for positive or negative multimeter attachment so it's easiest to use a compass needle to observe electric (and thus magnetic) production. 

This is how Seebeck Effect devices such as this, Peltier Cooling Modules and Stirling engines can be used to produce electricity-some improvised units can make enough to charge a cellphone!

Like most things electromagnetic, you can use the output (voltage) and get the input (heat) just by reversing things. Running electricity through a shorted wire produces heat. This is called ohmic heating / Joule heating. It's why short circuits get hot, but it's also how a toaster works, and hot wire saws for sculpting sheets of foam for car seats. 

EMF: electromotive feline. The moving clouds and warm sun make me move back and forth. Meow!