First of all, the name of that thing is called a PMT which stands for photo-multiplier and this detector is used in many experiment. It is use to convert a photon into an electron with the photo electric effect.

Okay, okay, the light, the thing that makes us see colors and the environnment as a finite speed. I know that might be weird, but you need to consider light as a particle that travel at a certain speed, 300 000 000 m/s. But how can light be everywhere if it is a particle ? it should enter in collision with many things right ? Okay, first of all, by things we mean ordinary matter (the difference will be explained in more detailed in another article) but the short answer is that light can also be a wave. Wait wait, how can something be a particle and a wave at the same time ? It is an effect we have observe since 1900. There has been many experiment proving this theory, it is what we call the Wave–particle duality. One of the important experiment that showed that light can be particle is the photoelectric effect. Here is a really quick and brief explanations of this experiment. You throw light at a metal piece and for an unknow reasons you can measure some current, in other words, electron moving towards a certain direction, the only reason for this current to exist is that the light your throw is made of particle that interact we the materiau and release an electron which creates the current. For detailed information about the experiment see :…

So we now know that light is a particle but how can it be a wave ! Let’s talk about the interference experiment ! If you throw water into a slit the water will went throw and create a maximum at a certain place (the center), okay this is normal since it is a wave (picture 1).If you do the same experiment with light the result that you should expect is the picture 2. However, we observe the result on the picture 3. Therefore, the only plausible explanation is that sometimes it is a waves and sometimes it is a particles called photon ! Depending on how your experiment is based you will observe a different state. You will then ask youself why ? why is light behaving so weirdly, I will just repat as I said, unfortunetely, we don’t really know, we just know how it is happening and this is science !

Wanna know something funny about the photon ?

The photon is massless What ? What does that mean ?How can something be massless ? We assume that since it travel as the speed of light is as not rest mass, meaning that you can never slow this particle and weight it .That being said, it is affected by gravity (see picture 4) so it is made of matter and as a tiny mass that we can’t really measure.

Okay, getting back now to are main subject. What is exactly a PMT (photo-multiplier )and why does it looks like a flower ? A photo multiplier is a detector used to detect a photon, see this was not for nothing. How it works ? Well it used a photo cathode, meaning the photo electric effect to convert the photon emitted into a electron as we as seen before. Then, the electron is acellerated by the high voltage on the small piece of metal (high voltage create a field that accelerate the particle, see picture 5). The electron has actually so many energy, as a buble of boiling water, then when he will hit the metal, it will transmit some of his energy to the electron of the metal and then if the electron have enough energy to be free of the metal, it will move and then hit the other piece of metal and etc. So at the end you have a current (bunch of electrons) that orignally came from the photon detected. Of course, the efficiency is not 1, about only 3 photon out of 10 are converted into electron with the photo electric effect. However, to also try to increase this efficency, you can reflect the light at a point you know it will work. So, you can create a certain reflector that will increase the effiency. In our case, this particular reflector as the shape of a flower.

So, just a quick wrap up, you want to detect a particle of light, so you use a photo multiplier, that will convert that photon into an electric signal using the photo electric effect.This conversion is not really efficient, so to make better, you build a reflector that looks like a flower.

Questions ? Comments ( Too long, unclear, too complicated, boring) Any feedback will be highly appreciated !

Okay let me say something clear about science just before starting, it is not something about an opinion, it is not something that you can argue, it is simply facts that have to be proven again and again by different people and at some point only then we accept this theory. It is not a matter of what you believe, it is simply about how can we explain what we see. It is not about why does the world exist, why are we alive, it answer only the how but never the why. The «why» is more link to philosophy and religion, it has to be clear science have no intention of being a religion for example you can yourself try to reproduce every experiment and argue about the method, discuss the result. However, you have to be able to explain why you would really reject the result.

Unfortunetely, it seems that people are forgetting how science is done. If this happen then you can argue every single result and maybe think that the result are not really valid and that they maybe not true or that alternative facts are real ;).

So just so that everyone is on the same page, Let’s recap what is the science method:

1- To an hypothesis that could explain a known phenomena or a effect that we still don’t fully understand.

2-Try to think about things you could measure that could test this theory.

3-Design an experiment to find these measurements.The key thing is that your experiment most be reproductible.

3-Try to thing of every background source or effect that could influence the measurements.

4-Take the data, do the analysis trying to take in account every bias of the experiment.

5-Look at your result as objectibly as possible and conclude about the result of your experiment.

6-Make a query for a publications and revise your article again, again and again, so that everything you did was perfectly clear and as objective as possible

7-After a long time of revision , publish your article

In conclusion, all this process can take a very long time and maybe your result is quite useless but it will maybe help someone in 50 years so we never know.