In the X-ray Free Electron Laser XFEL which is built at DESY in Hamburg a periodic magnetic structure (undulator) with a period λu = 5 cm forces electrons with an energy of 25 GeV to emit photons. This period determines the wave length of the photons emitted in the rest system of the moving electrons.
- How long is the period of the magnet in the electron rest system?
- What is the wave length of the emitted photons in the laboratory system?
2. Homework Equations and 3. The Attempt at a Solution
Gamma-factor =E/m= 25GeV/511keV = 50000
But I'm struggling to have an image of this problem.
Is the period in the electron rest system just the given period divided by the Gamma-Factor (length contraction)?
And how is the photon wave length connected to the undulator period?
Thanks for any hints.