Method

FLUKA [,,,,,,] is a simulation program which as a standalone code contains transport and the physical processes for hadrons and leptons and tools for geometrical description. In GEANT, only the hadronic interaction part is included.

The total cross-section of the hadronic processes is computed by FLUKA routines called from FLDIST (the cross-section for neutrons below 20 MeV is computed in GHEISHA). If hadronic intercation is chosen in GEANT tracking routine, the particle is passed to FLUFIN.

If particles are stopping (i.e. their energy is below the cut-off energy), their kinetic energy is deposited. However, if the particle can decay ($\pi +$ , $K\pm$ ) it is forced to decay, or if it is an annihilating particle ($\pi -$ , $n$ , $p$ ), it is sent to FLUKA routines for annihilation. The neutrons with kinetic energy below 20 MeV are passed to GHEISHA.

If the particle is not stopping, a sampling is done between elastic and inelastic processes. The cross-sections have been computed in FLDIST in the same time as the total cross-section. The particle is sent correspondingly to the elastic or inelastic interaction routines. After the interaction, the eventual secondary particles are written to GEANT stack. The program flow is shown in figures and .

When the tracking media is a mixture or a compound material (defined by GSMIXT, see [CONS110]), the atom with which the interaction is taking place is chosen by sampling on the basis of the cross-sections. This is important especially in hydrogenous materials.

Figure:  Program flow for calculation of the distance to the next interaction point

Figure:  Program flow for generating secondary particles

K.Lassila-Perini

PHYS530