# Effect of magnetic field on pair prooduction

Hi
Its just me again! I kindly need help on this question. Its as follows:

The tracks of a positron and an electron created by pair production in a magnetic field curve in opposite directions.
a) Why do they curve in opposite directions
b)Both particles spiral inwards. What can you deduce from this observation about their kinetic energy.

a)I surmised the following. The electron and positron are obviously particles/antiparticle. Therefore, they have opposite charges. A magnetic field can act as a south and north pole. Based on this, charges can be alternately attracted and repelled. This is as far as I got. However, I dont know whether I am on the right line of reasoning. Should I consider the effect of charges in a magnetic field?

b)Momentum will be conserved during the porcess of particle production. Since momentum is related mass and velocity, they will have the same but opposite amount of momentum. Kinetic energy is related to velocity. If they both spiral inwards, they seem to have the same amount of kinetic energy. Therefore, kinetic energy seems to the same(LOOKING LIKE AN ELASTIC COLLISION).

Regards
Ben
a) The charges experience a force in the magnetic field as described by Fleming's Left Hand Rule. As they have opposite charge the forces they experience are in opposite directions. This magnetic force is not one of "attraction" or "repulsion". It acts at right angles to the direction of motion. Hence the spiral path.
B) the particles are eventually brought to rest through inelastic collisions with the atoms in the cloud chamber.
Original post by Stonebridge
a) The charges experience a force in the magnetic field as described by Fleming's Left Hand Rule. As they have opposite charge the forces they experience are in opposite directions. This magnetic force is not one of "attraction" or "repulsion". It acts at right angles to the direction of motion. Hence the spiral path.
B) the particles are eventually brought to rest through inelastic collisions with the atoms in the cloud chamber.

Thanks. You have made my day.
1.They carry opposite charges (+e and -e)

2.They lose kinetic energy gradually as they travel along their paths

3.• the speed is greater where the track is less curved
the straighter track must therefore be before the particle met the plate
the direction of the curve shows that the charge is positive
the track must therefore be due to a positron