# Particle collisions with magnetic forces

1. May 14, 2010

If positive charged particles curve in the presence of a magnetic field does that mean the particles colliding in ATLAS create magnetic fields? I ask this because some of the detected particles curve perpendicular to the collision in ATLAS. From what I observed the trajectory maintains a constant curve from the collision. So if it was a magnetic field from an outside source being the accelerator tunnel why are the detected trajectories curved from both sides of the collision. If the magnetic force acting on the charged particles was generated from the tunnel, it would increase the velocity because the particles direction is the same as the force. Where the tunnel on the opposite direction to the collision could be seen to act on the particle moving in the opposite direction,but its force is dismissed because of its opposite equal magnetic force.

This to me looks like R is defined from the centre of the collision. Please help me to understand this better. Is the magnetic field from the collision?

2. May 15, 2010

### ansgar

no one has an external magnetic field, in the case of atlas it is a toriodal and in CMS a solenoidal

3. May 15, 2010

Not the sensor the tunnel that accelerates the particles using individually fired magnets to accelerate the particles. I was told that the curve was because of charged particles in a magnetic field. i want to know where the generated force of the field comes from. Please don’t say EARTH. The curved trajectories show that the magnetic force is generated from the centre of the collision. I state this because if charged particles curve like this because of magnetic force, the arguing law is R radius of the magnetic force. If it was the earth generating this there would be no curve observable in the sensor because the distance required to see a shift in the trajectory would be to far. I would like to know if this curve is from a magnetic field. If so, then R would suggest the collision is the generator of the field. Please help.

4. May 15, 2010

### ansgar

what? one has a superconducting coil surrounding the detector, how hard is that to understand?

5. May 15, 2010

If there is a superconducting coil in atlas, is that the reason for this curve. Why do they have a superconducting coil in the sensor?

6. May 15, 2010

### ansgar

7. May 15, 2010

I have asked this question before but not in this thread, that thread was about particle interaction. But specifically charged particles can’t be seen out side a magnetic field. If a magnetic field can’t be eliminated from the experiment. how can there trajectories be itemized defined in magnetic fields.

8. May 16, 2010

### ansgar

from my point of view the experiment is simple.

you put a huge magnet aroud your detector so that charged particles can bend.

how hard IS that to understand?

"The curved trajectories show that the magnetic force is generated from the centre of the collision" = nonsense

9. May 16, 2010

I accept and thank you for your help, but to annoy you further. The particles are detected with matrixes of metallic sensors. So could it be possible the particles are influenced by a possible magnetic induction on these sensors from the “huge magnet”. So could this possible induction to the sensors be affecting the particles as they pass through the detectors sensor thingy?

10. May 16, 2010

### ansgar

tell me where you have found information about these metallic sensors and how large their magnetic field strength is.

11. May 18, 2010

You could start by watching the construction of the LHC and find some lectures on its operation, my favorite is DR Frank Wilczek a theoretical physicist in a discussion of unified field theory. I found it thought provoking and amusing with his eccentric humor.

12. May 18, 2010