Cloud chamber temperature I'm planning to build a small cloud chamber.
The design is the usual: alcohol evaporates at the top by gently heating it with a thin wire and small current. The vapour sinks to the bottom of the chamber, where the temperature is significantly lower than at the top, and causes the vapour to super-cool. Ion tracks caused by fast moving particles can be observed as mist tracks.
My question is about the bottom plate temperature.
The usual design uses a (near) room temperature solvent and very cold bottom plate to achieve a big temperature gradient.
Could a cloud chamber be constructed that would use just a slightly cold bottom plate, and a more aggressively heated liquid? I'm thinking about ethanol or isopropyl alcohol evaporated at 60°C, and a bottom plate temperature at maybe only 0°C
Could this work? Is it just the temperature gradient, or the temperature itself is important?
 A: This is a generic phase diagram :

I looked up the construction of a demonstration for classes cloud chamber using alcohol. For the   air/alcohol  gas line 3, constant pressure, change in temperature is where you want to work for your cloud chamber. Cooling it without condensation. The gradient of temperature in your chamber will define the thickness over the iced bottom where supersaturation can be maintained. So your choice of alcohol should depend on how slowly the phase diagram changes with temperature as to have a larger distance from the cold plate where the vapors will be supersaturated and tracks can form.  
I do not think it is the gradient in the chamber that is decisive, but the one from the triple point to the vapor  phase in line 3.The hot on top is to generate the vapour phase in the chamber. It will all depend on the phase diagram of your specific choice for vapor.
A: Hi please refer to this article and related literature:
Yoshinaga, K., Kubota, M., & Kamata, M. (2014). Simple cloud chambers using a freezing mixture of ice and cooking salt.
Physics Education, 50, 23-27.
I am not in a position to comment about the underlying physics and probably cloud chambers with lower bottom temperatures work better. Anyways, yesterday I managed to observe clearly tracks for around 20 minutes using a frozen mixture of water and salt encased an aluminum jar while the top was heated with hot water. I measured previously the temperature of the jar and it was beteeen -16 and -18 C. There are also commercial (educational) prototypes of cloud chambers that work that way. For the vapor, I used, generously, 2-propanol 99.9%.
Hope this helps
regards
A: Yes, the original cloud chamber user water to form the supersaturated vapour, and ethylene glycol has also been used. Alcohol just happens to be very convenient as it's easy to get a lot of vapour and it doesn't freeze at the the chamber operating temperatures.
