# High Energy Electron

1. Dec 11, 2014

### Mizies

greetings..

i have 1 question:
When a very high energy electron hits a target material, four particles emerge from the target, that is three electrons and a positron, instead of just two electrons, the incident and ejected electrons. It seems that the two extra particles are created out of nothing. Do you agree with this statement?

2. Dec 11, 2014

### Staff: Mentor

No. They are created, via Einstein's famous $E=mc^2$, from the energy of the incoming electron.

3. Dec 11, 2014

### Staff: Mentor

I would say 5 particles emerge. 3 electrons, a positron, and a cation. The cation is important because it is required for conservation of charge. The net charge before the collision is -1 and the net charge afterwards is also -1. All other quantities are also conserved.

4. Dec 11, 2014

Staff Emeritus
The description of what happens is correct. "Created out of nothing" is just a set of words. I do not think there is any additional meaning here, just opportunities for confusion.