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1.1.1} Hadron inelastic nuclear interactions


  The FLUKA hadron-nucleon interaction models are based on resonance
  production and decay below a few GeV, and on the Dual Parton model
  above. Two models are used also in hadron-nucleus interactions. At momenta
  below 3--5 GeV/c the PEANUT package includes a very detailed Generalised
  Intra-Nuclear Cascade (GINC) and a preequilibrium stage, while at high
  energies the Gribov-Glauber multiple collision mechanism is included in a
  less refined GINC. Both modules are followed by equilibrium processes:
  evaporation, fission, Fermi break-up, gamma deexcitation. FLUKA can also
  simulate photonuclear interactions (described by Vector Meson Dominance,
  Delta Resonance, Quasi-Deuteron and Giant Dipole Resonance). A schematic
  outline is presented below:
  * Inelastic cross sections for hadron-hadron interactions are represented by
    parameterised fits based on available experimental data [PDG].
  * For hadron-nucleus interactions, a mixture of tabulated data and
    parameterised fits is used [Bar72, Moh83, She91, Pra98, Pra98a].
  * Elastic and charge exchange reactions are described by phase-shift
    analyses and eikonal approximation.
  * Inelastic hadron-hadron interactions are simulated by different event
    generators, depending on energy:
    - Momentum < 20 TeV and > 5 GeV/c:
      Dual Parton Model (DPM) [Cap94]. The version used in FLUKA has been
      derived by A. Ferrari and P.R. Sala [Fer94, Fas95, Fer95, Fer96b] from
      the original version by J. Ranft and collaborators [Ran83, Ran83a]. A
      description of modifications and improvements can be found in [Fer96b,
      Col00]
    - Momentum from threshold to 5 GeV/c:
      Resonance production and decay model [Fer96b] (Improved version of the
      H"anssgen et al. model [Han79, Han80, Han84, Han84a, Han84b, Han86,
      Han86a])
  * Inelastic hadron-nucleus interactions are simulated by different event
    generators depending on energy and projectile:
    - Momentum < 20 TeV and > 5 GeV/c: Glauber-Gribov multiple scattering
      followed by Generalized Intranuclear Cascade (GINC)
    - Below 5 GeV/c for nucleons, anti-nucleons and pions; below 1.5 GeV
      kinetic for kaons:
      Preequilibrium-cascade model PEANUT (Ferrari-Sala) [Fer94, Fas95]
    - In between PEANUT and DPM for kaons: K. H"anssgen et al. GINC modified
      to take into account correlations among cascade particles and more
      refined nuclear effects (Ferrari-Sala).

  * All three models include evaporation and gamma deexcitation of the
    residual nucleus [Fer96, Fer96a]. Light residual nuclei are not evaporated
    but fragmented into a maximum of 6 bodies, according to a Fermi break-up
    model.
  * Treatment of antiparticle capture: the basic antinucleon-nucleon process is
    modeled through the production and decay of two or more intermediate states 
    whose branchings are adjusted to reproduce experimental pion/kaon/resonances
    multiplicities.
    In nuclei, all nuclear effects (density, Fermi motion, Pauli-blocking,
    reinteraction of secondaries...) are treated by the PEANUT model as for all
    other hadronic interactions. Annihilations occur at shallow depths inside
    the nucleus. The depth is chosen as a function of the atomic number,
    the interaction being more and more pheripheral as the nuclear mass
    increases. 
    In case of compounds, the relative annihilation probabilities are 
    calculated following [Pon73] for hydrogenated compounds, and [Dan75] for
    other compounds. 

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