Where does it all come from

I finished a MSC in nuclear physics then during a student trip to the museum « Visiatome » near Avignon in 2008, I saw a PJ45 cloud chamber. 

In university, we studied pages and pages of nuclear physics theory. This was interesting, but boring. It’s the physics of infinitesimal world, with particles traveling nearly at speed of light. This is just impossible to feel it in our macroscopic world. Practical classes were just to use Geiger counters or computer simulated programs to check the equations. We were just learning, making exercises and resolving problems without asking questions.

When I saw the cloud chamber in the museum, I remember saying :

Seriously what is that. What is this machine, who dared to build this? is this really nuclear particles ? am I really seeing an alpha particle ? and this is an electron, bouncing all over in the cloud ? this is really what I’m seeing ? so all is true they really exist !

But why on earth, why didn’t we begin with THAT experiment first ! all is clear now : alphas, protons, electrons, X-rays… they really exist and we can observe how they travel and interact in matter, just being in front of a machine with our eyes, without a computer, this is just… I have no words.. Unbelievable.

The exact moment the 4th December 2008 when all began. Discovering the cloud chamber with my schoolmates

  I studied sciences in university for 8 years and never a teacher, a book or Internet (in 2009 cloud chambers were not common) did mention about this wonderful experiment. During my student life I built dozens of sciences experiments and have interest in a lot of domain : I thought I known a lot in science. Then I saw the existence of such experiment by chance, coming from nowhere. This machine, forgotten by most of the minds, had the humble task to reveal an invisible world : the difficult equations or annoying theories just becomes clears and logicals, just by seeing the interactions in the cloud.

So who is to blame ? my teachers who spent so much energy to stuff us pages of nuclear physics without using the right pedagogical tools ? me because I didn’t make enough research in my domain of studying ? there is only one culprit : time. No one have time to check the bases, but the answers are always there. Only the up-to-date technology is worth our attention. Since his invention in 1912, cloud chamber was simply forgotten as time passed and was relegated in sciences museums. It was the case in 2008 when I accidentally see one in a museum. 

10 years later, cloud chambers are very common. Maybe I contributed a bit with all the thermoelectric pioneers to make it a valuable science project and an useful pedagogical tool. I’m really happy that nowadays clouds chambers are put under the spotlights and have the merits they truly deserve. « The most original and wonderful instrument in scientific history » I can’t be more agree with that. Even now, I just simply don’t understand how it’s possible to see so easily, the quantum world. I always thought is was something theoretical and inaccessible, but with some raw materials, anyone can force this world to show.


Some of my photos of interactions published in a scientific revue


Back in 2008. At this time, I was frustrated with this visit, particularly about my ignorance. In the bus, returning to the university, I said I have to build one. I asked the price of the machine I saw : 29 k€. Ok, this explain why our university didn’t have one to play with. I didn’t understand why this amazing experience was scarce simply because some company decided to sell it to astronomic prices.  

It would be awesome, if our university or college had this type of experiments. It would simplify the understanding of abstracts theories and change the perception of our world, showing that radioactivity is anywhere. But we didn’t have any.



Cloud chambers are so astonishing for me that I bring some to do live shows during my job. Engie – Château de Romainville 04/2013


So I decided to put all my energy and time to study cloud chambers. My goal was to democratize them in different manner : 

  1. make tiny, affordable cloud chamber for school projects (see this page to build one),
  2. build a website which explain what we see and what we can experiments in a cloud chamber. 
  3. make a reliable machine, which can work for years, dedicated to university/college to study nuclear physics, at an affordable price (/5 the regular amount asked by some companies).


Back where all began : I returned in Visiatome several years later to make a presentation about cloud chambers and what experiences we can do with them.


It began with aircooled then watercooled thermolectric cloud chambers. I got more and more confident about the behavior of supersaturated environments, how to set them and obtain the right equilibrium. I learned that by doing numerous iterations of machines until I had satisfactory results. The ancients articles and reviews published by scientifics of the last century were precious and uncontournable indications too.  I saw the PJ45 in the museum 10 years ago and now I can say that I have almost « reproduced » it. 


WNE cloud

2014 : Paris World Nuclear Exhibition. For my job, I presented my cloud chamber with live experiments.


The final developments are slower because as I work as engineer in the nuclear industry, I have to make frequent displacements. But surely, the most difficult part has been done. 

WNE Cloud

A thorite mineral is in the chamber. A camera show the interactions on the screen. Most present people, whom worked during all life for nuclear industry never saw what an alpha particle look like.