I How many magnets are in the CMS experiment

[BillKet]

Hello! When I google about the CMS magnet I see that there is a 4 T magnet. However in the diagrams with muons, like this one, it seems to be another 2 T magnet beyond that. Where is that placed exactly. I assume it doesn't go around the whole detector, as that would affect the central region (the one with 4 T), but I am not sure where it is placed exactly.

 

[Vanadium 50]

I assume it doesn't go around the whole detector

You should look for more pictures.

You should also Google "magnet return yoke".

This should answer all your questions.

 

[BillKet]

You should look for more pictures.

You should also Google "magnet return yoke".

This should answer all your questions.

I am not sure that helps me understand. On the CMS page it says: "The outer part of the detector, the iron magnet “return yoke”, confines the magnetic field and stops all remaining particles except for muons and neutrinos." I am not sure I understand how confining the magnet is equivalent with making the lines go in the opposite direction. Is this like a structure that actually rotates the field lines after a point?

 

[mfb]

Magnetic field lines are closed circles. If the field in the center of CMS goes in one direction then the field must go back in the other direction somewhere farther out. Here is a simple solenoid field.

 

[Vanadium 50]

I am not sure that helps me understand.

You really want to get more pictures than that one. You really do.

 

[BillKet]

Magnetic field lines are closed circles. If the field in the center of CMS goes in one direction then the field must go back in the other direction somewhere farther out. Here is a simple solenoid field.

Thanks for this! It makes more sense now. However I am still confused about how the field can point in the opposite direction (at least based on their diagram) in the endcap of the detector (it should point at an angle due to the curving of the field lines). Do they have some way to deflect it even more than just the normal deflection of the solenoid?

 

[BillKet]

You really want to get more pictures than that one. You really do.

Showing me one such picture would be helpful. It's kinda hard to look for better pictures if I don't know what I am looking for. All diagrams showing the trajectory of a muon in the detector (including the CMS logo) are like that picture, so I am not sure what pictures are you referring to.

 

[Vanadium 50]

Well, a picture that shows that the detector is cylindrical was what I was hoping you'd find.

The field lines look like this.