42// An adjoint CS matrix is used by the model of a reverse process to sample an adjoint secondary (being equivalent to a forward primary).
43// It represents the integration over the energy of the adjoint secondary (therefore the forward primary) of the differential cross section
44// of the equiavlent forward discrete process (Ionisation, Brem, PE effect, Compton,..) . Each reverse model has its own cross section matrix for a given cut,
45// material couple. It is therefore recompute after a modification of the cuts by the user.