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peltier cooled cloud chamber

by:Sibai      2020-03-02
Cloud chamber is one of the easiest ways to build your own particle detectors.
With the cloud chamber, you can imagine the trajectory left by cosmic radiation, Environmental Radioactivity, or radioactive samples, such as minerals containing uranium or uranium.
Historically, cloud chambers belong to the oldest particle detectors, and today they are mainly used for demonstration purposes. In a diffusion-
A super saturated steam in a cloud chamber (Alcohol, usually)
Condenses along the trajectory left by the ionising particles, thus making the trajectory visible.
For a more detailed description of how it works, you can refer to the Wikipedia article.
The Cloud Room described in this manual has the following functions. There are a few other Cloud Room projects that helped me build.
This design was basically adapted from this cloud room by David Aceituno.
The following instructions from Nothinglabs are also very helpful.
I used the following materials in this project, I used some 3D printing components, a lot of \"DuPont\" wires, ATX Molex cables, some packaging foam and hot glue (
Because there is no way to build a project without hot glue)
White baking paper for diffusion LEDs.
Tools used include 3D printers, laser cutting machines, soldering iron, drill bits and infrared thermometers.
I used the thoriated electrode as a radioactive sample (amazon. de)
And a small piece of asphalt (uraninite)
You can find it on ebay sometimes.
To make the cloud room work, the temperature should be lower-25°C.
In many other instructions, this is done by cascading two peltier elements and running the bottom element at a higher voltage.
I tried many different configurations, including two to three TECs running at different voltages, but always ended up running at the same temperature.
Finally, I used two-
Stage TEC elements can be a little more expensive than two single
Stage elements with the same cooling power, but only one voltage is required.
TEC is connected to a CPU cooler with a heat pipe.
While these CPU coolers are designed to work with an upward heat pipe, they also seem to provide sufficient cooling capacity when used upside down.
TEC is connected to the CPU cooler with hot grease.
At the beginning, I used the popular Arctic MX-
But I don\'t recommend it because its viscosity is very high and it\'s hard to distribute evenly on a larger surface.
It is hard to remove because it is too sticky.
Obviously, I even managed to use it to permanently combine the two tec together.
Finally, I changed a different kind of thermal conductivity (
Also cheaper)
As shown in the figure, this reduces the temperature by nearly 10 °c (! ).
TEC is connected to 12 v output (yellow wires)
ATX power supply.
The picture shown in the figure is that the jumper wire is connected to the power supply (
See step 11)
So after activating the switch at the back, it turns on immediately.
The fan of the CPU cooler is also operated by the power supply.
Note placing TEC on the correct side facing upe.
As shown in the figure, the red line should be facing the right.
My body temperature has reached-
42 °c after a few minutes.
If you don\'t reach below-
Check thermal coupling at 25 °C.
Warning: be careful when handling high pressure!
Although the electric photo may not kill a person (
Unless your DNA is disrupted in a failed attempt to transmit; -))
You will fiddle with the electronics so try to keep it safe.
I removed the high voltage generating circuit from the electric Cang ter.
The circuit runs on two 1.
5 V battery so that it can be connected to 3 later. 3 V wires (orange)
ATX power supply.
The PCB contains an instant button that will slowly discharge again once the button is released, which will charge the capacitor.
To keep the voltage constant, I replaced the button with a flip switch.
Also, the status LED was replaced by the panel mounted LED and I connected the DuPont connector at the input and output.
I am not sure how high the voltage is generated, I can only say that it is somewhere outside the measurement range of my multimeter (1 kV)
But below the point where it was destroyed.
I have attached stl files for all 3D printed parts.
The top plate is used as the base of the glass clock and the LED light strip is installed.
The PVC pipe connecting for the installation of the sponge and the high voltage grid requires two top brackets.
Another bracket is used to mount the copper plate to the CPU cooler.
Drill four holes (4. 5 mm diameter)
The distance between the copper plate and 50mm (
See attached pdf).
Black vinyl foil is also attached to the board.
I didn\'t leave the edge because the electrical connection is required between the plate and the screws that fix the high pressure plate.
The M4 screw enters the 3D printing bracket and is used later to secure the copper plate.
The high-voltage power grid is cut off from the electric photo, and The Wire has been conveniently connected.
I installed the grid about 4 cm above the copper plate, and the smaller the distance, the higher the electric field.
The plastic screw is glued to the PVC pipe and the mesh is connected to the corresponding nut.
The sponge would be above the grid and I adjusted the length of the PVC pipe so that it could still be placed inside the glass bell.
I think it would be convenient to place a sponge from a cold plate at a long distance so that more alcohol would evaporate.
I designed this box using the Makercase tool and then modified it in Fusion 360.
As already mentioned, the case was cut from a black acrylic resin 3mm thick and I have attached the dxf file.
You may ask yourself why the house looks like Swiss cheese.
This is because once the CPU cooler is installed in the housing, I first ran into a problem where the temperature is not low enough, so I started adding more and more ventilation holes.
Finally, as already mentioned, the use of different types of hot compounds has greatly improved my temperature, so the chamber may also work with fewer ventilation holes.
I think it would be nice to add some lighting signs to the housing as LEDs make almost everything look cool.
So I printed some elements in transparent HD glass wire 3D (
Stl file attached.
The part is printed with 0.
4mm layer height and 100% fill.
I also used the enable ironing feature in Cura to get a smoother top layer.
The print quality on my 3D printer is not very good because the filament is very sticky.
After printing, I attached some white LED strips to the back with hot glue.
Since the HV logo only needs one LED, but the LED strip contains three LEDs, I blocked the other LED with a black belt.
I also put some hot glue on the LEDs before to help spread the light (
A trick I learned in this structure).
Finally, the part is also attached to the shell with hot glue.
Prepare the top plate by sticking the LED strip to the inside and feeding the wire through the opening.
Here I attach the baking paper to the LEDs to spread the light.
The 3D printing plate is then connected to the top plate of the laser cut housing using M3 screws and nuts.
Apply hot paste on the top of the peltier element and place the top plate (
3D printed ring)on top.
After that, the copper plate is at the top of the TEC element.
I also cut a square piece from some packaging foam and put it in the middle.
Fix the copper plate with a 3D printing bracket using M4 screws.
I attached a wire to a screw that was later connected to high pressure.
After assembly, it is a good idea to connect everything to the power supply and measure the temperature again.
As you can see, I was able to reach-36°C.
In my experience, reaching a low temperature is the most important thing for the chamber to work.
If the temperature is not less-
25 °C, you may not see any track.
Assemble the case according to the attached picture.
The walls are secured together by 10mm long M3 screws and nuts, which are located at t-slots.
I also reinforced the shell with hot glue as much as possible and stuck the small feet made of foam to the bottom.
The ATX power supply is connected to the back panel using M3 screws.
The shell is more or less intentionally designed, a little higher than needed.
To get the CPU cooler to the right height, I put a small piece of foam underneath.
Install the high-voltage PCB on the bottom plate using the PCB gasket.
The LED and flip switch are mounted on the front panel.
The 12 v output of the fan, TEC and all LED light strips connected to the power supply (yellow wires).
Hv pcb is connected to 3. 3 V output (orange wire).
The high-pressure output is connected to the copper plate via a wire on one of the screws.
Another output can be printed via a hole input on the top plate in 3D and then connected to a metal mesh.
In my experience, the polarity of high pressure is not important.
As suggested in the Wikipedia article, this seems to reject the fact that high pressure increases sensitivity by drifting ionization orbitals in the active region.
I would rather believe that, as others have suggested, it helps to clear the excess fees accumulated in the Chamber of Commerce.
As there is only a small amount of space in the housing, the cable has to be a bit crowded.
I am trying to fix all the cables in place with a cable binder.
After the housing is assembled, the high voltage grid and sponge can be placed on the top of the cold plate.
Wire connecting the high voltage grid and sealing the chamber with a glass bell after construction is completed.
To make the chamber work, soak the sponge thoroughly with acetone and place the sample in the middle of the copper plate.
When opening the chamber, after a few minutes you should see an alcohol mist forming at the bottom and the track should start to appear.
If you turn on the high voltage power supply, the visibility of the track will be greatly increased.
In particular, the high pressure makes the track more concentrated and less distributed.
I have tried two samples so far, the first one is several thoriated electrodes containing 2% titanium oxide.
These samples are readily available as they do not produce any dust or a large amount of radioactive gas (Th-Production Rn-232
220 but half
The latter has a very short life span). Th-
232 is the first isotope in the natural decay chain, I. e.
The sample will contain a large amount of radioisotopes and emitts α, β and γ radiation.
The second sample I got was a stone with mineral asphalt uranium mine (uranium oxide).
You can already see from pictures and videos that the activity of this sample is much higher. U-
238 is the first isotope in another natural decay chain, so the sample contains all the isotopes of the series, which include several α, β, and γ emitters.
I would not recommend keeping more of this mineral at home as the activity of this mineral is quite high.
In addition, it also produces some dust and gas Rn-222.
This means that even if you put it in a container made of lead radioactive gas, it will spread out.
What would be the problem if you couldn\'t see the track?
At the beginning, I often saw the fog of alcohol, but there was no trace.
Normally, the room did work without the housing, but not after I closed the housing.
This made me suspect that the temperature was not low enough, so I tried different combinations of various TEC elements.
I also had only one CPU cooler fan at the beginning, and for ventilation there were fewer gaps on the housing.
I have also tried liquid CPU coolers, but I have never reached a much lower temperature than the current configuration.
In the end, the biggest improvement for me is the change of hot compounds.
I am not entirely sure that this is just a temperature issue and it may also be related to the indoor air turbulence caused by the fan, which prevents the formation of a stable steam cloud.
In addition, the environmental temperature and humidity may also play a role.
One of the biggest downsides, I would say, is the very small area of activity in this Chamber.
This is not a problem if you are measuring small samples, but it would be better to have a larger area in order to visualize environmental radioactivity or cosmic muons.
In principle, one can increase the size of the copper plate, but in order to reach the same temperature, it is also necessary to increase the size of the TEC element or use multiple elements.
In this case, you may also need a different cooler for the hot side of peltier.
To reach a very large area, CloudyLabs shows the possibility of cooling with a compressor in this impressive cloud room.
Because of this, the chamber can run continuously for at least 15 minutes.
To achieve true continuous operation, one has to add a pump to collect concentrated alcohol from the bottom and move it back to the top.
Finally, a heating wire can also be implemented at the top to increase the temperature gradient, thus increasing the thickness of the active layer.
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