8.2 Displacement damage expression

a. The displacement damage shall be expressed either by:

¾ Displacement damage equivalent particle fluence (DDEF) for mono-energetic spectra,

NOTE For example, damage induced as a function of fluence from 10 MeV protons, 1 MeV neutrons or 1 MeV electrons, identified by DDEF(particle, energy, material).

¾ The non-ionising energy loss (NIEL) dose or (total) non-ionising dose ((T)NID), i.e. the energy deposition in a material per unit mass by radiation through displacements.

NOTE 1 This is distinctly different to TID for which energy is deposited as ionisation and excitation.

NOTE 2 Units of TNID are Gy(material) or rad(material), but for space radiation effects analysis, MeV/g is more commonly used to avoid confusion with TID-related quantities.