"EGS to Order" Stop 1: Pictorial Code for Particles
As we saw in the introduction, the EGS simulation images (output) is color coded by type of particle (electron, photon, or positron). The diagrams used to describe the interaction in this tour are also color coded. The table below shows the relationship between the EGS simulation images, the diagrams used here, and the traditional Feynman Diagrams that visually describe the particle interaction.
Particle Type EGS
OutputFeynman Diagrams Real Electron Virtual or Bound Electron not shown Real Photon Virtual photon or electric fields in atom not shown Real Positron Virtual Positron not shown
In the color coded diagrams we use dashed lines to indicate any of the following:
- Virtual particles
- the intermediate stage in a Feynman diagram
- Bound electrons
- electrons initially bound in matter that can absorb a (virtual) photon and appear as real electrons
- Photons absorbed by or emitted from matter
- these represent the interaction of an electron with the intense electromagnetic field inside an atom
In all three of these cases the particles do not satisfy the usual real particle relationship
E2 = p2 c2+ m2 c4
where:
- E is energy
- p is momentum
- m is particle mass, and
- c is the speed of light.
However, all the real particles shown in actual EGS simulation images do satisfy this relationship.
Go to Stop 2: Simple Two Particle Physics Processes
