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I don’t build thermoelectric cloud chamber anymore like you see in the video in the experiences page (I started them in 2010).  Thermoelectric technology don’t permit to have big interaction surfaces. In the long term run, I’m not convinced about their reliability because peltier cells have to be periodically replaced by new cells to keep good performance of cooling (and they are more and more costly).

Now, I build cloud chamber cooled by a compressor (like a fridge). After some years of research, I finally obtained good results regarding the quality of tracks. 

A cloud chamber is a powerful pedagogical tool but remain a scientific experiment. For my point of view, a cloud chamber should : 

  • Display particles with a very good quality. In this way single glass enclosure should be use, instead of two for a better viewing. But this need to use the cloud chamber in a room temperature > 20°C,
  • Permit the introduction of radioactive sources inside the chamber with sufficient space (minerals, gas, metals…),
  • Allow to use magnetic fields to observe the deflection of light particles (electrons, positons, slow muons),
  • Should be easily operated and easy to modify for anyone with a minimum knowledge.

 I don’t trust electronics. So to have a reliable machine it should work only with mechanical switches and simple features. The components in the machine should also be easily replaceable at reasonable cost. Reasonable mean a few dozen of euros, and easily mean that you can buy spare components from any source like ebay, amazon and not from proprietary reseller. 

I made a new cloud chamber during the covid events in april 2020. I didn’t have access to new materials so I made it from scratch parts, so the aesthetic could be a bit better. 

The weight is about 20 kg. The active surface is 40×20 cm. The dimensions of the whole machine are (including light) 45 x 55 cm, the height is 42 cm. 

My cloud chambers have the following electrical components :

  • An isolated refrigerating circuit (compressor-condenser with fan-evaporator). It provide an active surface cooled at about -35°C. This circuit is designed to work for 10/15 years without maintenance (like a fridge). After this period, It will necessary to add a bit of refrigerant charge, a really easy operation that any HVAC technician can do trough the two service valve present (any pressurized circuit have infinitesimal leaks and with time the circuit lose it’s charge). You can also do it yourself if you can afford the material needed (a manifold gauge, a vacuum pump and a refrigerant canister, that’s about 200$ max.). The refrigerating circuit is made of solid thick copper and is impossible to destroy, unless you do it intentionally !

 

  • A peristaltic pump to provide alcohol in the upper tank. Two switch can control it’s speed and the direction of flow : pumping or putting alcohol in the tank.

 

  • A main switch to ON or OFF the machine. 

 

  • A temperature controller . It indicate the temperature of the active surface and the temperature inside the alcohol tank in the chamber. You can control the temperature in the tank with this controller (if you want). This controller keep at any time the temperature to the desired value with a relay and a resistive wire that heat or let cool the alcohol tank.

 

  • Two 12V led light bar to provide illumination in the chamber.

 

  • high voltage circuit (Cockroft Walton type, not shown below) to provide about 3000V in the chamber, above the alcohols trays. If you touch this circuit with your hand you will feel a spike like an electrostatic discharge. So « high voltage » don’t mean it will kill you because the amperage is about a few microamps ! 

 

There is space under the active surface to place a magnet of dimensions max : 20 x 20 x 2,8 cm. This is used to deflect light particles.

The machine work like this :

  1. Remove the glass chamber,
  2. Pour about 200 ml of alcohol (methanol or best isopropanol which is not toxic) in the alcohol tank,
  3. Put the glass chamber back,
  4. Switch on the machine with the main switch. 
  5. Wait 15 min to observe the first particles. 

The machine will work for 2 hours alone. If you want to operate it for a day long, it will be necessary to put back periodically some alcohol in the tank. For this, use the peristaltic pump to pour alcohol in the tank by operating the pump switch. When the alcohol tank is full, stop the pump.

The alcohol evaporate from the alcohol tank and condense on the active surface. The excess of liquid is automatically collected by a tube which is connected to the alcohol reservoir next to the pump. To stop the machine, collect the maximum alcohol from the pump to the alcohol reservoir, switch off the main switch. Remove the glass chamber and collect the rest of alcohol in the surface with a sponge for a later operation.

I will make better videos in the next weeks to show how it works and about the quality of the particles displayed. But here is a rapid video :

 

 

The price will be in ~ 4500 € range shipped to Europa for 220V country. For a 110V version, I need to build a specific one and invest in some materials so it will be a little more costly ;). If you are interested to get a cloud chamber you can contact me below. Note : This machine is built for teachers, speakers, researchers, or enthusiastic technicians. It’s not designed for museum as it’s not fully automatic in operations. I can’t build many machines because it requires a very lot of time so the shipping time will be long.

My lab is located near Avignon, France. 

 

  Please don’t ask me how to build your own cloud chamber, I don’t have time to help everyone and there is enough information on my website to make your own :/