Why Cherenkov light leave rings instead of full circles?

• A.R.
In summary, the image we obtain from Cherenkov light is actually a projection of a continuous wave front on a vertical plane, orthogonal respect to the direction of propagation of the incident particle. However, because Cherenkov light is produced only for a brief period, between the entrance of the incident particle in the radiator medium and the instant when its velocity drops below the threshold, we just see a ring, instead of a full circle.
A.R.
If the image we obtain from Cherenkov light is actually the projection of a continuous wave front (Fig. 1) on a vertical plane, orthogonal respect to the direction of propagation of the incident particle, why we just see a ring (Fig. 2), instead of a full circle? Is it because Cherenkov light is produced only during a brief period, between the entrance of the incident particle in the radiator medium and the instant when its velocity drops below the threshold (Fig. 3)?
Fig. 1
Fig. 2
Fig. 3

What is the difference between a ring and a full-circle?
To me fig.2 looks pretty much as a full-circle...however you can find its fluctuation around the circle by trying a fit and looking at the point differences...However that would be too crude, because your events are of course pixels and not points, and your machine (itself) has some offset signals (the points which are very far away from the circle)

Do you know how light/particle detectors work?
Fig. 2 is a ring, because only border detectors are activated, while inner detectors are off as well as outer ones. I'm asking, if the wave front is continuous, from the axis of the cone, to the maximum radius of the projection, why the image is not a full ring? I.e., why Fig. 2 is not a full orange circle? My answer is Fig. 3, where the red segment is the path the particle makes between the entrance in the medium and the drop of its velocity under the threshold for Cherenkov production, with the stop of light production and introduction of the discontinuity. But, is it really in this way?

There are two options:

(1) the one you mentioned, a short slab of material where the radiation is emitted and then a long distance to the detector.
(2) (curved) mirrors that reflect all light emitted in a specific direction to the same position

Both are used.

mfb said:
There are two options:

(1) the one you mentioned, a short slab of material where the radiation is emitted and then a long distance to the detector.
(2) (curved) mirrors that reflect all light emitted in a specific direction to the same position

Both are used.

So, if the detector is in contact with the material, the particle radiates until it reaches the detector, and the detector is just a plain sheet of PMs, what we'll see is actually a full circle, right?

It would be a filled circle (a disk), yes.

1. What is Cherenkov light?

Cherenkov light is a type of electromagnetic radiation that is produced when a charged particle, such as an electron, travels through a medium at a speed greater than the speed of light in that medium.

2. Why does Cherenkov light leave rings instead of full circles?

This is due to the angle at which the light is emitted. When a charged particle travels faster than the speed of light in a medium, it emits light in a cone-shaped pattern. This cone of light is then projected onto a detector, creating a ring-shaped pattern.

3. What determines the size of the Cherenkov light rings?

The size of the rings is determined by the velocity of the charged particle, the refractive index of the medium, and the distance between the particle and the detector. The faster the particle is traveling, the larger the ring will be.

4. Can Cherenkov light rings be observed in different mediums?

Yes, Cherenkov light rings can be observed in any medium with a refractive index greater than 1. This includes water, air, and even some solids.

5. How is Cherenkov light used in scientific research?

Cherenkov light is used in various fields of research, including particle physics and astrophysics. It is used to detect and measure the energy and direction of high-energy particles, providing valuable information about the nature of these particles and the processes that produce them.

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