Radiation Length

  Scaling variable for the probability of occurrence of bremsstrahlung pair production, and for the variance of the angle of multiple scattering. The radiation length is given by

with

A detailed discussion can be found in [Rossi65] or in [Jackson75], also [Kleinknecht82]; for numerical values, [Barnett96].

The average energy loss due to bremsstrahlung for an electron of energy E is related to the radiation length:

and the probability for an electron pair to be created by a high-energy photon is 7/9 X₀.

A brief discussion, more references, and a table of radiation lengths for various materials are also given in [Barnett96].