Final Project: The Peletier Cloud Chamber
The cloud chamber is one of the first particle detector that has been invented, it requires a cold source and a volatil substance such as isopropyl.
The result is a system that allows you to "see radioactivity"
Each little white trail that you see is one single particle (alpha,beta,electrons,gamma ray..)
What we want, is to have a very strong temmperature gradient between the top and the bottom of the chamber.
If we diffuse alcohol in this chamber, and that the conditions are stable enough (no convection) a small volume of alcohol vapors at the bottom will in an unstable state.
Meaning that they will have only one goal: condense on something (dust,ion..) to return to the liquid state.
Only ,that, if the chamber is well made, there shouldn't be much on what those vapors could condense!
This is were the particles enter the game, as they pass in the chamber, they ionise locally the atoms of the air, creating nucleation points for the alcohol vapors, allowing them to condense, just as the water condenses behind a plane and leaves trails:
So finaly what we see is the footprint of the particles.
The simple way of doing this is by using dry ice, which is perfect to reach the required temperature (-30°C), but I would like to use instead, a thermoelectric device : the Peltier module.
I have already made a chamber using that device but it was really tricky to use and super unstable, I would like to use all the tools in the FABLAB to build the perfect "Saloon Cloud Chamber" : plug & watch.
Plus this project involves 3D and 2D designing (for the case) , sensor monitoring (for the temperature control),electronics (for the HIGH Voltage ), and some knowledge on thermodynmics of metastable states, a perfect project for a physicist!
There are different reasons why I think this project would be interesting to develop in a FABLAB.
Wouldn't be cool to have a cosmic ray detector whithin your lab?
Cosmic rays are those immensly high radiation (mostly originating outside the Solar System) that may produce showers of secondary particles that penetrate the atmosphere.
Composed primarily of high-energy protons and atomic nuclei, they are of mysterious origin.
So even with no radioactive source we could already detect some activity with our chamber!
And what about just having a super fast freezing system?
If nuclear physics is not your thing, this project can still interest you!
Peltier modules are really amazing, they can freez water in seconds and boil it in a few more!
But as you see on this graph (Pinguins Lab) pushing it to very low temperatures (-20°C) can be a bit tricky.
In this project, I will explain how you can reach those temperatures.
High-Voltage?
And what about making a super simple High Voltage circuit?
I will show you how to make a 20kV power supply with a 555timer, a Mosfet, and a flyback from an old TV.
This project involves almost all the different aspects of the FABLAB:
Electronics: for the High voltage circuit and the power circuit of the Peltier.
2D and 3D modeling: for the case and some structural parts.
Microcontrollers and sensors: for the temperature control and the link with the other components.
Other options: we could add a Raspi camera inside the chamber to do some video analysis of the trails.
