Material parameters
The m a t e r i a l parameters describe the material of the layer to calculate
multiple scattering and interactions. Possible parameters are: X0 (number of
radiation lengths), A (atomic number), and INTLEN (number of nuclear
interaction lengths, only for calorimeters).
The atomic number is used when interactions (ie. gamma-conversions and
brems-strahlung off electrons) in the detector material are to be
simulated. If the number of radiation-lengths is 0, then the atomic number
is also 0, otherwise it defaults to 10, as a compromise between the most
likely for a detector to be built of: Carbon (ie. plastic)(6), Aluminium(13),
and Silicon(14).