Lorentz force and pair production Question: The following figure shows the phenomenon of pair production and the subsequent tracks made by the respective particles in a magnetic field. What is the direction of the magnetic field applied in the experiment?

Answer: Applying Lorentz force F = q v × B , the magnetic field is directed outwards from the plane of the paper.
My View: Since the positron is moving anti-clockwise, the magnetic field produced by it is to oppose the external magnetic field applied (Lenz's law). Hence the external field should be directed into the plane of the paper as right hand thumb rule gives the magnetic field of the positron directed out of the paper.
Did I make any wrong interpretation from the figure? Are there any exceptions in "pair production"? Please help
Additionally, please help me find y and x with an explanation.

 A: Lenz derived his rule from the phenomenon of a time varying current in a wire. This process was called a self-induction and it describes how accelerated electrons in a wire produce a magnetic field which produces some electric field opposed to the primary electric field.
The main process for the movement of a particle with its magnetic dipole moment inside an external magnetic field is the following. At the beginning this magnetic dipole moment is randomly distributed to the external magnetic field. Since the external field is much stronger it doesn't undergoes a notable change. The particles magnetic dipole moment is under the heavy influence of the external field and the particle moment gets aligned with the external field.
By this photons get emitted from the particle and now take place two reactions. Thirst the particles magnetic dipole moment gets disaligned again and secondly the particle gets deflected. This process repeats until the kinetic energy of the particle is exhausted and the spiral path ends.
But there is a moment you find out right. In any case the force between fields is working in both directions. The external field is comparable to a mechanical spring. It's strength oscillates in dependence from the alignment and disalignemnt of the particles field. Having a lot of particles this phenomenon would be noticeable and Lenz law would be in game again.
The best example for the above stated is the free-electron laser

Source:Wikipedia
